Method, device and program for optimally analyzing joining position of vehicle body, and method for manufacturing vehicle body

Abstract

This method for optimally analyzing the joining position of a vehicle body sets all or part of a vehicle body model as an analysis target model (S1), sets joining candidate lines in the analysis target model to generate an optimal analysis model (151) (S3), sets a variable load condition (S5), sets the reciprocal of a predetermined target fatigue life as a target cumulative damage degree (S7), and optimizes the joining position of the vehicle body. An improvement in the rigidity of the optimization analysis model (151), a reduction in the cumulative damage degree, which is the reciprocal of the fatigue life of the bonding candidate wire (155), and a minimization of the length of the bonding candidate wire (155) are set as optimization analysis conditions (S9), and optimization analysis is performed by applying a variable load condition to the optimization analysis model (151). An optimal arrangement (S11) of the bonding wire (157) that achieves the optimal analysis condition is obtained.

Description

Technical Field

[0001] The present invention relates to an optimization analysis method, device, and program for optimizing joining positions of an automotive body, and a method for manufacturing the automotive body. In particular, the present invention relates to an optimization analysis method, device, and program for optimizing joining positions of an automotive body, and a method for manufacturing the automotive body, wherein the optimal position of a joining line is obtained, and the optimal position of the joining line improves the stiffness of the automotive body and the fatigue life near the welding line for bonding and joining parts assemblies in the automotive body. Background Art

[0002] In recent years, especially in the automobile industry, the weight reduction of vehicle bodies due to environmental issues has been developing, and analysis based on computer aided engineering (hereinafter referred to as "CAE analysis") has become an indispensable technology in the design of vehicle bodies. It is known that in this CAE analysis, the improvement of rigidity and weight reduction are achieved by using optimization techniques such as mathematical optimization, sheet thickness optimization, shape optimization, and topology optimization.

[0003] It is known that a structure such as a car body is formed by joining a plurality of parts as a component assembly by welding or the like. If the amount of joining at the part where the component assembly is joined is increased (for example, if the continuous joining line based on electric arc welding or laser welding is increased), the rigidity of the car body as a whole is improved. If the rigidity is improved, the stress generated in the whole part is also suppressed, and the fatigue life of the part is a direction to be improved. However, on the contrary, there are also cases where the fatigue life is reduced due to the increase of local stress. Moreover, from the perspective of the manufacturing cost of the car body, it is desired to reduce the amount of joining as much as possible. In addition, it is also required to configure the optimal welding position so as to improve the fatigue performance at the same time with respect to multiple input conditions.

[0004] Therefore, in order to improve the rigidity and fatigue life of the vehicle body while suppressing the manufacturing cost of the vehicle body, a method of finding the joining position (continuously joined welding position by laser, arc, etc.) where the parts are joined to each other has been proposed. As such method, there is a method of determining the joining position by experience or intuition, and a method of responding by increasing the joining position at a location with high stress by stress analysis. In addition, in the case of corresponding to multiple performances, there is also a case where the welding position configured to meet a certain performance is determined by trial and error such as evaluating other performances and confirming them.

[0005] However, the method of determining the joining position by experience or intuition cannot find the position of the joining line required to improve both rigidity and fatigue life. Therefore, there are cases where the joining line is set at a position that is not required to improve rigidity and fatigue life, and repeated trial and error is inefficient from the perspective of cost.

[0006] In addition, in the method of adding joints at locations with high stresses through stress analysis, it is seen that the rigidity and fatigue life change compared to before the joint positions are obtained through this method, but since the deformation of the location is suppressed, there are many cases where the local stress increases. Therefore, the joint position obtained by this method is not necessarily the optimal one, and the result is a trial-and-error design with poor efficiency.

[0007] In contrast, Patent Document 1 discloses a method and apparatus for optimizing the joint position of point joining such as spot welding, continuous joining such as laser welding, arc welding or welding adhesive joining, which are used to join a plurality of parts constituting a structural body model composed of two-dimensional elements and / or three-dimensional elements. In addition, Patent Document 2 discloses an apparatus and method for determining a suitable position for continuous joining of a structural body model, which can easily determine a position suitable for continuous joining in a structural body model having two-dimensional elements and / or three-dimensional elements as components without complicated operations.

[0008] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Publication No. 2013-025593 Patent Document 2: Japanese Patent Application Publication No. 2016-71770 Summary of the invention

[0009] Problems to be solved by the invention

[0010] During the driving process of the car, variable amplitude loads whose amplitude, direction, etc. are not constant in time and change in a complex manner are input to the car body. Therefore, the following technology is expected: to find the optimal length and configuration of the joint line that can improve the rigidity of the car body and the fatigue life near the continuous joint line when the complex variable load is input to the car body. In the chassis / travel parts (chassis component or suspension part) of the car, most of them are structures in which the parts are joined to each other by arc welding. However, it is known that even if the strength of the base metal of the part is improved, the fatigue strength around the arc welded part will not be improved due to the influence of the notch geometry of the arc welding end (weld toe). Therefore, in the future, it is expected that the application of high-tensile steel sheets will be expanded for chassis / travel parts, among which the optimization of arc welding joint configuration becomes important.

[0011] However, in the technologies disclosed in Patent Documents 1 and 2, as analytical conditions for performing optimization calculations, the optimal position of spot joining or continuous joining is determined by maximizing the volume ratio of material and rigidity, minimizing displacement and minimizing stress, etc., but no consideration is given to improving the fatigue life of spot joining or continuous joining. In addition, the technology disclosed in Patent Document 2 mainly targets automobile bodies joined by spot welding, and defines spot joining units with a spot joining interval below a specified value as a location suitable for continuous joining. There is also a problem that it cannot be applied to chassis / travel parts of automobiles where parts are continuously joined to each other by arc welding or the like.

[0012] The present invention has been completed in view of the above-mentioned problems, and its purpose is to provide a method, device and program for optimizing the joint position of a vehicle body, and a method for manufacturing a vehicle body, so as to find the optimal configuration of the weld line that improves the rigidity of the vehicle body and the fatigue life of the continuous weld line that joins the component assemblies in the vehicle body and minimizes the length of the weld line when a simple or variable load is input to the vehicle body.

[0013] Technical solutions to solve problems

[0014] A method for optimizing the joint position of a vehicle body according to a first aspect of the present invention performs optimization analysis on all or part of a vehicle body model having a plurality of component models including beam elements, plane elements and / or solid elements and having initial joint lines for joining the plurality of component models as component assemblies by a computer by executing the following steps, wherein the optimization analysis finds an optimal arrangement of the joint lines for the purpose of improving the rigidity of the vehicle body model, improving the fatigue life near the joint lines for joining the component assemblies in the vehicle body model, or minimizing the length of the joint lines, wherein the method for optimizing the joint position of the vehicle body comprises: an analysis object model setting step of setting all or part of the vehicle body model as an analysis object model; and an optimization analysis model generating step of generating an optimization analysis model, wherein the optimization analysis model is generated by setting all candidate joint lines that are candidates for the optimal arrangement to the analysis object model. line); a variable load condition setting step, setting a variable load condition, wherein the variable load condition is divided into a plurality of loading conditions of different vibration patterns, and the loading conditions of the vibration patterns are combined for a predetermined number of cycles as a sequence; a target fatigue life setting step, setting a target fatigue life of the optimized analytical model according to the number of sequences of the variable load condition;The optimization analysis condition setting step is to perform optimization analysis with the optimization analysis model as an optimization object, calculate the number of cycles to failure near each of the candidate joint lines according to the load conditions of each vibration mode, and calculate the sum of the number of sequences of the variable load conditions set by the target fatigue life setting step, which is the ratio of the number of cycles to the number of cycles of the load conditions of each vibration mode to the number of cycles to failure, as the linear cumulative damage degree of each of the candidate joint lines. damage), setting conditions related to the cumulative damage degree of the candidate bonding line remaining after the optimization analysis, conditions related to the rigidity of the optimization analysis model, and conditions related to the length of the candidate bonding line remaining after the optimization analysis as objective functions (objectives) or constraints (constraints) as optimization analysis conditions; and an optimization analysis step, assigning the variable load condition set in the variable load condition setting step to the optimization analysis model, performing optimization analysis under the optimization analysis conditions, and obtaining the configuration of the candidate bonding line that achieves any one of reducing the cumulative damage degree of the candidate bonding line, improving the rigidity of the optimization analysis model, and minimizing the length of the candidate bonding line remaining as the optimal configuration of the candidate bonding line. ;

[0015] Preferably, the optimization analysis step performs topology optimization based on a density method, and in the topology optimization, a penalty coefficient is set to 4 or more to perform discretization.

[0016] The method for optimizing the joint position of a vehicle body according to a second aspect of the present invention is to optimize the joint position of a vehicle body model, which has a plurality of component models including beam units, plane units and / or solid units and has an initial joint line for joining the plurality of component models as a component assembly, by executing the following steps by a computer to perform optimization analysis on all or part of the vehicle body model, wherein the optimization analysis finds the optimal arrangement of the joint line for the purpose of improving the rigidity of the vehicle body model, improving the fatigue life near the joint line for joining the component assembly in the vehicle body model, or minimizing the length of the joint line, wherein the joint position of the vehicle body is The optimization analysis method comprises: an analysis object model setting step, setting all or part of the vehicle body model as the analysis object model; an optimization analysis model generating step, generating an optimization analysis model, wherein the optimization analysis model is obtained by setting all the candidate joint lines that are candidates for the optimally configured joint lines to the analysis object model; a variable load condition setting step, setting a variable load condition, wherein the variable load condition divides the variable load given to the optimization analysis model into load conditions of a plurality of different vibration modes, and combines the load conditions of the respective vibration modes into a sequence for a predetermined number of cycles; and a target fatigue life setting step, wherein the variable load condition is set to obtain the optimal fatigue life by using the variable load condition. The target fatigue life of the optimized analytical model is set according to the number of sequences of dynamic load conditions; an optimized analytical condition setting step, in order to perform an optimized analysis with the optimized analytical model as the object of optimization, the number of fracture repetitions near each candidate joining line is calculated according to the load conditions of each vibration mode, and the ratio of the number of cycles of the load conditions of each vibration mode to the number of fracture repetitions is calculated, and the sum of the number of sequences of the variable load conditions set by the target fatigue life setting step is used as the cumulative damage degree of each candidate joining line, and the conditions related to the cumulative damage degree of the candidate joining line remaining after the optimized analysis and the optimal The conditions related to the rigidity of the optimized analytical model and the conditions related to the length of the candidate bonding line remaining after the optimized analysis are set as the objective function or constraint conditions of the optimized analysis conditions; the optimized analysis step, assigning the variable load condition set in the variable load condition setting step to the optimized analytical model, performing the optimized analysis under the optimized analysis conditions, and making the configuration of the candidate bonding line achieved for any one of reducing the cumulative damage degree of the candidate bonding line, improving the rigidity of the optimized analytical model, and minimizing the remaining length of the candidate bonding line remain as the temporary optimal configuration of the candidate bonding line;A step of generating a model for setting an analysis object by selecting a candidate joining line, selecting a candidate joining line of a specified length from the candidate joining lines remaining as a temporary optimal configuration through the optimization analysis, and setting the selected candidate joining line in the analysis object model instead of the initial joining line, thereby generating a model for setting an analysis object for the selected candidate joining line; a step of calculating the performance of the candidate joining line, assigning the load conditions and restriction conditions of each vibration mode under the variable load condition set in the variable load condition setting step to the model for setting an analysis object for the selected candidate joining line, and using the result of the stress analysis, calculating the fatigue life under the variable load condition near the selected candidate joining line and the rigidity of the model for setting an analysis object for the selected candidate joining line; a step of determining the fatigue life under the variable load condition near the candidate joining line in the model for setting an analysis object for the selected candidate joining line and the rigidity of the model for setting an analysis object for the selected candidate joining line. whether the rigidity of the model satisfies the prescribed performance exceeding that of the analysis target model in which the initial joint line is set; and an optimal joint line determination step, in the case where it is determined in the determination step that the prescribed performance is satisfied, the configuration of the selected joint candidate line is determined as the optimal configuration of the joint line, and in the case where it is determined in the determination step that the prescribed performance is not satisfied, the condition related to the cumulative damage degree of the joint candidate line remaining after the optimization analysis, the condition related to the rigidity of the optimization analysis model, or the condition related to the length of the joint candidate line remaining after the optimization analysis set in the optimization analysis condition setting step is changed, and the optimization analysis step, the selected joint candidate line setting analysis target model generation step, the selected joint candidate line performance calculation step, and the determination step are repeatedly performed until the prescribed performance is satisfied, and the configuration of the joint candidate line selected when the prescribed performance is satisfied is determined as the optimal configuration of the joint line. ;

[0017] The first aspect of the present invention relates to an optimization analysis device for a joint position of a vehicle body, which performs optimization analysis on all or part of a vehicle body model having a plurality of component models including beam units, plane units and / or solid units and having an initial joint line for joining the plurality of component models as a component assembly, wherein the optimization analysis finds the optimal arrangement of the joint line for the purpose of improving the rigidity of the vehicle body model, improving the fatigue life near the joint line for joining the component assembly in the vehicle body model, or minimizing the length of the joint line, wherein the optimization analysis device for the joint position of the vehicle body The method comprises: an analysis object model setting unit for setting all or part of the vehicle body model as the analysis object model; an optimization analysis model generating unit for generating an optimization analysis model, wherein the optimization analysis model is obtained by setting all candidate joint lines that are candidates for the optimally configured joint lines to the analysis object model; a variable load condition setting unit for setting variable load conditions, wherein the variable load conditions divide the variable loads given to the optimization analysis model into load conditions of a plurality of different vibration modes, and combine the load conditions of the respective vibration modes into a sequence for a predetermined number of cycles; and a target fatigue life setting unit for generating a target fatigue life based on the variable load conditions. The target fatigue life of the optimized analytical model is set according to the number of sequences of the parts; an optimized analytical condition setting unit, in order to perform an optimization analysis with the optimized analytical model as the object of optimization, obtains the number of fracture repetitions near each candidate joining line according to the load conditions of each vibration mode, and obtains the ratio of the number of cycles of the load conditions of each vibration mode to the number of fracture repetitions, and the sum of the number of sequences of the variable load conditions set by the target fatigue life setting unit is used as the cumulative damage degree of each candidate joining line, and the conditions related to the cumulative damage degree of the candidate joining line remaining after the optimization analysis and the optimal Conditions related to the rigidity of the optimized analysis model and conditions related to the length of the candidate joining line remaining after the optimization analysis are set as objective functions or constraints as optimization analysis conditions; and an optimization analysis unit assigns the variable load conditions set by the variable load condition setting unit to the optimized analysis model, performs optimization analysis under the optimized analysis conditions, and obtains the configuration of the candidate joining line that achieves any one of reducing the cumulative damage degree of the candidate joining line, improving the rigidity of the optimized analysis model, and minimizing the length of the candidate joining line remaining as the optimal configuration of the candidate joining line.

[0018] Preferably, the optimization analysis unit performs topology optimization based on a density method, and in the topology optimization, a penalty coefficient is set to 4 or more to perform discretization.

[0019] The second embodiment of the present invention is a device for optimizing the joint position of a vehicle body, which performs optimization analysis on the whole or part of a vehicle body model having a plurality of component models including beam units, plane units and / or three-dimensional units and having an initial joint line for joining the plurality of component models as a component assembly, wherein the optimization analysis finds the optimal arrangement of the joint line for the purpose of improving the rigidity of the vehicle body model, improving the fatigue life near the joint line for joining the component assembly in the vehicle body model, and minimizing the length of the joint line, wherein the device for optimizing the joint position of the vehicle body comprises: an analysis object model setting unit, which sets the whole or part of the vehicle body model as an initial joint line for joining the plurality of component models as a component assembly an analysis object model; an optimization analysis model generating unit, generating an optimization analysis model, the optimization analysis model being obtained by setting all the candidate joining lines that are candidates for the optimally configured joining lines to the analysis object model; a variable load condition setting unit, setting a variable load condition, the variable load condition dividing the variable load assigned to the optimization analysis model into load conditions of a plurality of different vibration modes, and combining the load conditions of the vibration modes into a sequence with a predetermined number of cycles; a target fatigue life setting unit, setting a target fatigue life of the optimization analysis model with the number of sequences of the variable load conditions; an optimization analysis condition setting unit, in order to perform an optimization solution with the optimization analysis model as the object of optimization The optimization analysis unit calculates the number of fracture repetitions near each of the candidate joining lines according to the load conditions of each of the vibration modes, calculates the ratio of the number of cycles of the load conditions of each of the vibration modes to the number of fracture repetitions, and uses the sum of the number of sequential times of the variable load conditions set by the target fatigue life setting unit as the cumulative damage degree of each of the candidate joining lines, and sets conditions related to the cumulative damage degree of the candidate joining lines remaining after the optimization analysis, conditions related to the rigidity of the optimization analysis model, and conditions related to the length of the candidate joining lines remaining in the optimization analysis as the objective function or constraint conditions of the optimization analysis conditions; the optimization analysis unit sets the variable load conditions set by the variable load condition setting unit The optimization analysis model is assigned, the optimization analysis is performed under the optimization analysis conditions, and the configuration of the bonding candidate line achieved for the purpose of reducing the cumulative damage degree near the bonding candidate line, improving the rigidity of the optimization analysis model, and minimizing the length of the remaining bonding candidate line is left as a temporary optimal configuration of the bonding line; a bonding candidate line selection setting analysis object model generation unit is selected, a bonding candidate line of a specified length is selected from the bonding candidate lines remaining as a temporary optimal configuration by the optimization analysis, and the selected bonding candidate line is set in the analysis object model instead of the initial bonding line, thereby generating a selected bonding candidate line setting analysis object model;A selected bonding candidate line performance calculation unit is configured to perform stress analysis on the selected bonding candidate line setting analysis object model by assigning the load conditions and constraint conditions of the respective vibration modes under the variable load conditions set by the variable load condition setting unit, and use the result of the stress analysis to calculate the fatigue life under the variable load conditions near the selected bonding candidate line and the rigidity of the selected bonding candidate line setting analysis object model; a determination unit is configured to determine whether the fatigue life under the variable load conditions near the bonding candidate line in the selected bonding candidate line setting analysis object model and the rigidity of the selected bonding candidate line setting analysis object model satisfy the prescribed performance exceeding that of the analysis object model in which the initial bonding line is set; and an optimal bonding line determination unit is configured to determine the configuration of the selected bonding candidate line as the optimal bonding line when the determination unit determines that the prescribed performance is satisfied. When the determination unit determines that the specified performance is not satisfied, the condition related to the cumulative damage degree of the candidate bonding line remaining after the optimization analysis, the condition related to the rigidity of the optimization analysis model, or the condition related to the length of the candidate bonding line remaining after the optimization analysis set by the optimization analysis condition setting unit is changed, and the processing performed by the optimization analysis unit, the selected candidate bonding line setting analysis object model generation unit, the selected candidate bonding line performance calculation unit, and the determination unit is repeated until the specified performance is satisfied, and the configuration of the candidate bonding line selected when the specified performance is satisfied is determined as the optimal configuration of the bonding line. ;

[0020] The optimization analysis program for the joint position of a vehicle body according to the first aspect of the present invention performs optimization analysis on all or part of a vehicle body model having a plurality of component models including beam units, plane units and / or solid units and having initial joint lines for joining the plurality of component models as component assemblies, and the optimization analysis finds the optimal arrangement of the joint lines for the purpose of improving the rigidity of the vehicle body model, improving the fatigue life near the joint lines for joining the component assemblies in the vehicle body model, and minimizing the length of the joint lines, wherein a computer is caused to function as the following units: An analysis object model setting unit sets all or part of the vehicle body model as an analysis object model; an optimization analysis model generating unit generates an optimization analysis model, wherein the optimization analysis model is obtained by setting all candidate joint lines that are candidates for the optimally configured joint lines to the analysis object model; a variable load condition setting unit sets variable load conditions, wherein the variable load conditions divide the variable loads assigned to the optimization analysis model into load conditions of a plurality of different vibration modes, and combine the load conditions of the respective vibration modes into a sequence for a predetermined number of cycles; and a target fatigue life setting unit generates a target fatigue life based on the variable load conditions. The target fatigue life of the optimization analysis model is set by the sequence number; the optimization analysis condition setting unit, in order to perform the optimization analysis with the optimization analysis model as the optimization object, calculates the number of fracture repetitions near each joining candidate line according to the load conditions of each vibration mode, and calculates the ratio of the number of cycles of the load conditions of each vibration mode to the number of fracture repetitions, and the sum of the number of sequence numbers of the variable load conditions set by the target fatigue life setting unit is used as the cumulative damage degree of each joining candidate line, and the conditions related to the cumulative damage degree of the joining candidate line remaining after the optimization analysis and the optimization condition setting unit are used as the cumulative damage degree of the joining candidate line. Conditions related to the rigidity of the analytical model and conditions related to the length of the candidate joining line remaining after the optimization analysis are set as objective functions or constraints as optimization analysis conditions; and an optimization analysis unit assigns the variable load condition set by the variable load condition setting unit to the optimization analysis model, performs optimization analysis under the optimization analysis conditions, and obtains the configuration of the candidate joining line that achieves any one of reducing the cumulative damage degree of the candidate joining line, improving the rigidity of the optimization analysis model, and minimizing the length of the candidate joining line remaining as the optimal configuration of the candidate joining line.

[0021] Preferably, the optimization analysis unit performs topology optimization based on a density method, and in the topology optimization, a penalty coefficient is set to 4 or more to perform discretization.

[0022] The optimization analysis program for the joint position of the vehicle body involved in the second embodiment of the present invention performs optimization analysis on the whole or part of the vehicle body model having a plurality of component models including beam units, plane units and / or three-dimensional units and having an initial joint line for joining the plurality of component models as a component assembly, and the optimization analysis finds the optimal arrangement of the joint line for the purpose of improving the rigidity of the vehicle body model, improving the fatigue life near the joint line for joining the component assembly in the vehicle body model, and minimizing the length of the joint line, wherein a computer is made to function as the following units: an analysis target model setting unit, which sets the whole or part of the vehicle body model as an analysis target model ; an optimized analytical model generating unit, generating an optimized analytical model, the optimized analytical model being obtained by setting all candidate joining lines that are candidates for the optimally configured joining lines to the analytical object model; a variable load condition setting unit, setting variable load conditions, the variable load conditions dividing the variable loads assigned to the optimized analytical model into load conditions of a plurality of different vibration modes, and combining the load conditions of the respective vibration modes into a sequence for a predetermined number of cycles; a target fatigue life setting unit, setting a target fatigue life of the optimized analytical model according to the number of sequences of the variable load conditions; an optimized analytical condition setting unit, in order to perform an optimization analysis taking the optimized analytical model as an object of optimization, The load conditions of each vibration mode are used to calculate the number of fracture repetitions near each joining candidate line, and the ratio of the number of cycles to the number of fracture repetitions of the load conditions of each vibration mode is calculated, and the sum of the number of sequences of the variable load conditions set by the target fatigue life setting unit is used as the cumulative damage degree near each joining candidate line, and the conditions related to the cumulative damage degree near the joining candidate line remaining after the optimization analysis, the conditions related to the rigidity of the optimization analysis model, and the conditions related to the length of the joining candidate line remaining in the optimization analysis are set as the objective function or constraint conditions as the optimization analysis conditions; the optimization analysis unit sets the variable load condition set by the variable load condition setting unit The optimization analysis model is assigned, the optimization analysis is performed under the optimization analysis conditions, and the configuration of the bonding candidate line achieved for the purpose of reducing the cumulative damage degree near the bonding candidate line, improving the rigidity of the optimization analysis model, and minimizing the length of the remaining bonding candidate line is left as a temporary optimal configuration of the bonding line; a bonding candidate line selection setting analysis object model generation unit is selected, a bonding candidate line of a specified length is selected from the bonding candidate lines remaining as a temporary optimal configuration by the optimization analysis, and the selected bonding candidate line is set in the analysis object model instead of the initial bonding line, thereby generating a selected bonding candidate line setting analysis object model;A selected bonding candidate line performance calculation unit is configured to perform stress analysis on the selected bonding candidate line setting analysis object model by assigning the load conditions and restriction conditions of the respective vibration modes under the variable load conditions set by the variable load condition setting unit, and use the result of the stress analysis to calculate the fatigue life under the variable load conditions near the selected bonding candidate line and the rigidity of the selected bonding candidate line setting analysis object model; a judgment unit is configured to judge whether the fatigue life under the variable load conditions near the bonding candidate line in the selected bonding candidate line setting analysis object model and the rigidity of the selected bonding candidate line setting analysis object model satisfy the prescribed performance exceeding that of the analysis object model in which the initial bonding line is set; and an optimal bonding line determination unit is configured to determine whether the optimal bonding line meets the prescribed performance when the judgment unit determines that the optimal bonding line meets the prescribed performance. When the performance is not satisfied by the determination unit, the configuration of the selected candidate joining line is determined as the optimal configuration of the candidate joining line. When the determination unit determines that the specified performance is not satisfied, the condition related to the cumulative damage degree near the candidate joining line remaining after the optimization analysis, the condition related to the rigidity of the optimization analysis model, or the condition related to the length of the candidate joining line remaining after the optimization analysis set by the optimization analysis condition setting unit is changed, and the processing by the optimization analysis unit, the selected candidate joining line setting analysis object model generation unit, the selected candidate joining line performance calculation unit, and the determination unit is repeated until the specified performance is satisfied, and the configuration of the candidate joining line selected when the specified performance is satisfied is determined as the optimal configuration of the candidate joining line. ;

[0023] The method for manufacturing a vehicle body involved in the present invention is a method for manufacturing a vehicle body that optimizes the configuration of a joining line to improve the rigidity of the vehicle body and the fatigue life of the joining line, wherein the joining line joins component assemblies in the vehicle body of an automobile, wherein the optimal configuration of the joining line is obtained using the optimization analysis method for the joining position of the vehicle body involved in the first or second embodiment of the present invention, and the joining position of the component assembly in the vehicle body is determined based on the obtained optimal configuration of the joining line, and the component assembly of the vehicle body is joined at the determined joining position.

[0024] Effects of the Invention

[0025] In the present invention, the whole or part of the car body model is used as the analysis object model, and the optimized analysis model is generated by setting the candidate joining line as the component assembly for the analysis object model, and the optimization analysis conditions (objective function or constraint conditions) related to the length of the candidate joining line as the optimization object, the fatigue life of the candidate joining line, the rigidity of the optimized analysis model, and the length of the joining line are set to perform the optimization analysis for the candidate joining line. In this way, when a variable load that is not constant in time is input to the car body as in the actual driving process of the car, the optimal position of the joining line that can be achieved with the purpose of minimizing the length of the candidate joining line, improving the rigidity of the analysis object model, and improving the fatigue life near the joining line of the component assembly can be obtained. In addition, in this way, the optimal configuration of the welding position of arc welding in the car body structure, the improvement of the fatigue life near the joining line, and the improvement of the rigidity of the car body can be achieved, and the reduction of welding cost and the high rigidity and light weight of the car body can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a block diagram of the optimization analysis device for the joint position of the vehicle body according to the first embodiment of the present invention. Figure 2 This is a diagram showing a rear subframe model serving as an analysis target model in the first embodiment of the present invention. Figure 3 This is a diagram for explaining an initial joining line that is preset in the rear subframe model as an example of an analysis target model in the first embodiment of the present invention. Figure 4 This is a diagram showing an example of an arc welded portion obtained by modeling an initial joining line in calculation of the fatigue life of the initial joining line according to the first embodiment of the present invention. Figure 5 This is a diagram showing an example of load conditions and constraint conditions for the first vibration mode and the second vibration mode given to the rear subframe model as the analysis target model in the first embodiment of the present invention. Figure 6 The diagram shows an example of an optimized analytical model in which an initial joining line pre-set in an analytical target model and an additional joining line added to the analytical target model are set as joining candidate lines in embodiment 1 of the present invention ((a) is the entire optimized analytical model, and (b) is a partially enlarged view of the optimized analytical model). Figure 7 This is a diagram showing an example of variable load conditions set in the first embodiment of the present invention. Figure 8This is a diagram for explaining an SN diagram (SN diagram (stress endurance diagram)) used for calculation of fatigue life under a variable load condition in the first embodiment. Fig. 9 This is a diagram showing an example of the results of the fatigue life of the initial joining line and the position of the initial joining line of the shortest three lower fatigue lives (minimum fatigue life) under variable load conditions in the first embodiment of the present invention. Fig. 9 (b) shows the state of the rear subframe model viewed from the bottom. Fig.10 The present invention is implemented in the first embodiment and the first example, and is a diagram showing an example of the optimal arrangement of the joining line obtained by the optimization analysis in which the optimization analysis conditions related to the rigidity and the fatigue life are set, taking the rear subframe model as the analysis object. ((a) is a stereoscopic diagram, and (b) and (c) are partial enlarged diagrams). Fig.11 This is a flowchart showing the flow of processing in the optimization analysis method of the joining position of the vehicle body according to the first embodiment of the present invention. Fig.12 This is a block diagram of a vehicle body joint position optimization analysis device according to a second embodiment of the present invention. Fig.13 This is a flowchart showing the flow of processing in the optimization analysis method of the joining position of the vehicle body according to the second embodiment of the present invention. Fig.14 This is an explanatory diagram of rigidity evaluation points in the rear subframe model which is a part of the vehicle body model to be analyzed in the first embodiment. Fig.15 The diagram shows the optimal arrangement of the joint lines obtained by the optimization analysis in Comparative Example 1 in which the optimization analysis conditions regarding the rigidity and the joint length were set, using the rear subframe model as the analysis object in Example 1. Fig.16 This is a graph showing the length of the bonding wire (welding length) obtained by optimization analysis in Examples 1 to 3. Fig.17 This is a graph showing the shortest fatigue life of the joining lines in the rear subframe model in which the optimal arrangement of the joining lines is set in Examples 1 to 3. Fig.18 This is a graph showing the rigidity improvement rate in the rear subframe model in which the optimal arrangement of the joining line is set in Examples 1 to 3. DETAILED DESCRIPTION

[0027] Before describing the optimization analysis method, device and program of the joint position of the vehicle body involved in the first and second embodiments of the present invention, and the vehicle body manufacturing method involved in the third embodiment, the vehicle body model as the object of the present invention is described. In the specification and drawings of the present application, the front-back direction of the vehicle body, the left-right direction of the vehicle body and the up-down direction of the vehicle body are respectively represented as the X direction, the Y direction and the Z direction. In the specification and drawings, for units having substantially the same function and structure, repeated description is omitted by marking the same reference numerals.

[0028] <Body model and analysis object model>

[0029] The automotive body model used as an object in the present invention is composed of a plurality of component models such as body frame parts and chassis components, and these component models are modeled using beam elements, plane elements, and / or solid elements.

[0030] Generally, vehicle body frame components, chassis components, and the like are mainly formed of metal sheets with a relatively thin sheet thickness, and therefore, component models constituting the vehicle body model may be constituted by only planar units.

[0031] The vehicle body model has an initial joint line for joining a plurality of component models as a component assembly. The initial joint line is obtained by modeling a joint line of arc welding or laser welding for joining a plurality of automobile components as a component assembly using a plane unit or a three-dimensional unit.

[0032] For example, when two component models composed of planar cells are joined by an initial joining line modeled by the planar cells, the planar cells of the initial joining line are connected to both planar cells of the two component models.

[0033] Furthermore, when the initial joint line is modeled by solid elements, in order to distribute the translational force acting on the initial joint line to the component model, the planar elements of the component model and the solid elements of the initial joint line are combined by rigid body elements.

[0034] The present invention analyzes the deformation caused by the variable load acting on the analysis target model (described later) as the whole or a part of the vehicle body model, so each component model in the vehicle body model is modeled as an elastic body, a viscoelastic body, or an elastic-plastic body. In addition, the material properties of each component model constituting the vehicle body model, element information, and information related to the initial joint line in each component assembly are stored in the vehicle body model file 101 (refer to Figure 1 , Fig.12 ).

[0035] [Implementation Method 1]

[0036] <Analysis device for optimizing the joint position of a vehicle body>

[0037] Hereinafter, the configuration of an optimization analysis device for a joining position of a vehicle body according to the first embodiment of the present invention (hereinafter simply referred to as “optimization analysis device”) will be described.

[0038] The optimization analysis device is a device that uses the entire or a part of the vehicle body model as an analysis object model and performs optimization analysis on the analysis object model. The optimization analysis finds the optimal configuration of the joining line. The optimal configuration of the joining line is achieved with the purpose of improving the rigidity of the vehicle body model, improving the fatigue life of the joining line that joins the component assembly in the vehicle body model, and minimizing the length of the joining line.

[0039] exist Figure 1 FIG. 1 shows an example of the structure of the optimization analysis device 1 according to the first embodiment. The optimization analysis device 1 is composed of a PC (personal computer) and the like. Figure 1 As shown, the optimization analysis device 1 according to the first embodiment has a display device 3, an input device 5, a memory storage 7, a work data memory 9, and an arithmetic processing unit 11. The display device 3, the input device 5, the memory storage 7, and the work data memory 9 are connected to the arithmetic processing unit 11, and perform their respective functions according to the instructions from the arithmetic processing unit 11. The functions of the components of the optimization analysis device 1 according to the first embodiment are described below.

[0040] Display Device

[0041] The display device 3 is used to display the vehicle body model, the analysis target model, and the analysis results, and is composed of a liquid crystal monitor (LCD monitor) or the like.

[0042] Input Device

[0043] The input device 5 is used by the operator to input the vehicle body model file 101 ( Figure 1 ), the reading of the vehicle body model, the display of the analysis object model, etc., and the input of instructions, etc., are composed of a keyboard, a mouse, etc.

[0044] Storage Device

[0045] The storage device 7 is used for the vehicle body model file 101 ( Figure 1 ) and other files, and saves analysis results, etc., and is composed of a hard disk, etc.

[0046] 《Data storage for operation》

[0047] The working data memory 9 is used for temporary storage and calculation of data used by the calculation processing unit 11 , and is composed of a RAM (Random Access Memory) or the like.

[0048] 《Calculation Processing Department》

[0049] like Figure 1 As shown in FIG. 1 , the calculation processing unit 11 includes an analysis object model setting unit 13, an optimization analysis model generating unit 15, a variable load condition setting unit 17, a target fatigue life setting unit 19, an optimization analysis condition setting unit 21, and an optimization analysis unit 23, and is composed of a CPU (central processing unit) of a PC or the like. The above-mentioned units function by executing a predetermined program by the CPU. The functions of the units of the calculation processing unit 11 are described below.

[0050] (Analysis object model setting section)

[0051] The analysis target model setting unit 13 acquires a vehicle body model from the vehicle body model file 101 , and sets the entire or a part of the acquired vehicle body model as an analysis target model.

[0052] An example of the processing performed by the analysis target model setting unit 13 is described below. First, the operator instructs the vehicle body model to be read from the vehicle body model file 101 using the input device 5, and the vehicle body model is read from the storage device 7. Next, according to the operator's instruction, the vehicle body model is displayed on the display device 3. In addition, according to the operator's instruction, a part to be the object of optimization analysis is specified in the vehicle body model displayed on the display device 3. The analysis target model setting unit 13 sets the specified part as the analysis target model.

[0053] exist Figure 2 , an example is shown in which a rear subframe model 111 obtained by simplifying a rear suspension subframe (hereinafter referred to as a rear subframe) as a chassis member is set as an analysis target model.

[0054] exist Figure 2 In the rear subframe model 111 shown, as a component model, the side frame upper portion (subframe upper) 112 and the side frame lower portion (subframe lower) 113 on the right side are joined by arc welding to form a side frame R211. Similarly, the side frame upper portion 114 and the side frame lower portion 115 on the left side are joined by arc welding to form a side frame L212. The cross member upper portion (cross member upper) 116 and the cross member lower portion (cross member lower) 117 on the front side of the vehicle body are joined by arc welding to form a cross member front portion (cross member front) 213. The cross member front portion 118 and the cross member rear portion (cross member rear) 119 on the rear side of the vehicle body are joined by arc welding to form a rear cross member (rear cross member) 214. These side frame R211, side frame L212, cross member front portion 213 and rear cross member 214 are further joined by arc welding to form a parallel cross member structure (parallel cross member) In addition, brackets 120, 121, and 122 are connected by arc welding in the tic-tac-toe structure. The brackets 120, 121, and 122 are used to install components supporting the suspension or components connecting the link mechanism to the tire (in Figure 2 Only the right side is shown, but the same bracket is also installed on the left side). The above-mentioned component models are modeled by plane units. Figure 2 In FIG. 1 , the components connecting the tire input point 100 with the brackets 120 , 121 , 122 and the rear cross member 214 are simplified by straight lines representing bar elements.

[0055] And, if Figure 3 As shown, the rear subframe model 111 is pre-set with an initial joining line 131 for joining each component model as a component assembly. Figure 4 As shown, the initial joint line 131 is modeled by a plane unit connected to the plane unit of the component model by sharing nodes, and the length of the initial joint line is 6540 mm. The thickness of the initial joint line 131 is the thickness of the thinner plate of the component model to be joined. In addition, the material property value of the initial joint line 131 is the same as that of the component model.

[0056] In addition, in order to set the variable load conditions and restriction conditions given to the rear subframe model 111 by the variable load condition setting unit 17 described later, as shown in FIG. Figure 5 As shown, the brackets 120, 121, 122 and the rear cross beam 214 are connected to the tire input point 100 (refer to Figure 2 ) are connected by a rod unit. The tire input point 100 is set as the load input point A, and the four points of the mounting bushing a, b, c, and d in the figure are set as complete restraint points.

[0057] (Optimization analysis model generation department)

[0058] like Figure 6 As shown, the optimization analysis model generation unit 15 generates an optimization analysis model 151 obtained by setting all the candidate joining lines that are candidates for the optimally arranged joining lines, that is, the largest number of candidate joining lines that can be set, to the analysis target model.

[0059] exist Figure 6 2 shows an optimized analytical model 151 generated by setting a joint candidate line 155 in the rear subframe model 111 . Figure 6 (b) is a diagram showing a part of the optimized analytical model 151 in an enlarged manner, where the solid line represents the initial joint line 131 and the dotted line represents the additional joint line 153. Figure 6 In (a), these initial joining lines 131 and additional joining lines 153 are indicated as candidate joining lines 155. Additional joining lines 153 may be added by connecting initial joining lines 131 that are set intermittently, or may be set by extending the ends of initial joining lines 131, or may be set by changing the shape of a component when there is no space for setting additional joining lines 153. Similar to the initial joining lines 131 described above, additional joining lines 153 may be modeled by planar units or by three-dimensional units.

[0060] (Variable load condition setting section)

[0061] The variable load condition setting unit 17 sets variable load conditions that divide the variable loads applied to the optimization analysis model into load conditions of a plurality of different vibration modes and combine the load conditions of the vibration modes into one sequence for a predetermined number of cycles.

[0062] The so-called variable load is a load obtained by dividing the magnitude, position and direction of the load input to the analysis target model into one or more different vibration modes, and combining each vibration mode for a predetermined number of cycles. It is a load obtained by simulating the variable load input to the vehicle body that changes with time when the actual vehicle is running. In addition, the variable load condition is given in the calculation of the fatigue life of the initial joint line 131 and the joint candidate line described later.

[0063] The variable load condition setting unit 17 may set a variable load condition that divides the variable load into loads of a plurality of different vibration modes and combines them, and a restriction condition that restricts the analysis target model for each variable load condition.

[0064] In the first embodiment, the variable load condition is set as the load condition of the first vibration mode and the condition of the second vibration mode. The load condition of the first vibration mode and the condition of the second vibration mode are completely restricted in the rear subframe model 111, and the tire input point 100 on the right side of the vehicle body is used as the load input point A. The load condition of the first vibration mode is as follows: Figure 5 As shown in (a), a variable load of ±2.5 kN is input in the forward and backward direction (input 1). The conditions of the second vibration mode are as follows: Figure 5 As shown in (b), a variable load of ±6.0 kN is input in the inner / outer direction (input 2).

[0065] Furthermore, the changing load conditions such as Figure 7 As shown in the schematic diagram of the variable load history, the load condition of the first vibration mode / one cycle and the load condition of the second vibration mode / five cycles are combined to form a series of variable load conditions. In addition, the fatigue life under the loaded variable conditions is considered. Figure 7 The graph shown is a graph schematically showing a variable load in which the magnitude of the load of each of the load conditions of the first vibration mode and the load conditions of the second vibration mode is reversed as an amplitude in order to represent the number of cycles of each of the load conditions of the first vibration mode and the load conditions of the second vibration mode under a sequence of variable load conditions.

[0066] (Target fatigue life setting department)

[0067] The target fatigue life setting unit 19 sets the target fatigue life of the optimization analysis model 151 according to the order of the above-mentioned variable load condition.

[0068] As the target fatigue life of the optimized analytical model 151, the load condition of the vibration mode under the variable load condition set by the variable load condition setting unit 17 is given to the analytical object model and stress analysis is performed separately, fatigue life is calculated using commercially available fatigue life prediction software, and the target fatigue life is set based on the shortest fatigue life. In addition, a predetermined number of sequences may be set as the target fatigue life of the above-mentioned optimized analytical model 151 based on a conventional empirical rule.

[0069] In general, since the load input to the body of an actual automobile is not constant over time, it can be considered as a stress state in which stresses of various amplitudes are randomly generated in the initial joint line 131. In order to evaluate the fatigue life of the initial joint line 131 under such a stress state, the linear cumulative damage rule is used.

[0070] In the cumulative fatigue damage rule, first, a state in which stresses of various amplitudes are randomly generated is considered as σ1, σ2, σ3, ... σ m Next, let each stress amplitude be σ1, σ2, σ3, ... σ m Produced individually, from Figure 8 The SN graph shown reads the number of repetitions (fracture repetitions) N1, N2, N3, ... N at each stress amplitude until fracture (fatigue fracture). m These stress amplitudes are repeated for n1, n2, n3, ... n m The damage degree is considered to be n1 / N1, n2 / N2, n3 / N3...n m / N m .

[0071] In the cumulative fatigue damage law, as shown in formula (1), the sum of the damage degrees under each stress amplitude is calculated, that is, the cumulative damage degree dm. And when the cumulative damage degree dm ≥ 1, fatigue failure occurs. Under the condition of variable loads subjected to irregular repeated variable loads, the Rainflow Counting method can also be used to determine the stress amplitudes σ1, σ2, σ3, ... σ m and the number of repetitions n1, n2, n3...n m .

[0072] [Mathematical formula 1]

[0073] The specific procedure of calculating the target cumulative damage degree of the initial joint line 131 under the variable load condition by the target fatigue life setting unit 19 is as follows.

[0074] First, the stress acting on each initial bonding line 131 obtained by performing stress analysis according to the load conditions of each vibration mode under the variable load condition is defined as different stress amplitudes σ1, σ2, σ3, ..., σ generated on the initial bonding line 131 under the variable load condition. m .

[0075] Next, the target fatigue life setting unit 19 sets the target fatigue life according to the SN diagram ( Figure 8 ) Calculate the number of repetitions (fracture repetition number) N1, N2, N3, ... N until the initial bonding line 131 breaks when each stress amplitude is generated independently in the initial bonding line 131. m .

[0076] Next, the number of repetitions until fracture (fracture repetition number) N1, N2, N3, ... N m and the number of cycles n1, n2, n3, ... n of the load conditions of each vibration mode in a sequence of varying load conditions m Substituting into formula (1), the cumulative damage degree dm in one sequence is calculated. Furthermore, the cumulative damage degree DM when one sequence of variable load conditions is repeated K times (K sequences) is calculated by formula (2). Then, the number of sequences K when the cumulative damage degree DM is greater than 1 is calculated as the fatigue life of the initial joint line 131 under the variable load condition.

[0077] [Mathematical formula 2]

[0078] Based on the fatigue life of each initial joint line 131 calculated in this way, the target fatigue life setting unit 19 sets the target fatigue life of the optimization analysis model 151. The target fatigue life is a fatigue life that the candidate joint lines 155 (described later) remaining after the optimization analysis should satisfy. In the first embodiment, the target fatigue life is set to be at least a fatigue life greater than the shortest fatigue life (shortest fatigue life) among the initial joint lines 131 calculated by the target fatigue life setting unit 19.

[0079] exist Fig. 9 The rear subframe model 111 is shown in FIG. Figure 7 The varying load conditions and Figure 5 An example of the results of the positions and fatigue lives of three initial joining lines 131 from the shortest one among the fatigue lives of the initial joining lines 131 obtained from the results of the stress analysis under the constraint conditions shown.

[0080] Fig. 9 The fatigue life of the initial joint line 131 shown is calculated under the variable load conditions as a sequence in which the mounting bushings a to d mounted relative to the vehicle body are completely restrained in the rear subframe model 111, the tire input point 100 on the right side of the vehicle body is used as the load input point A, the first vibration mode in which a variable load of ±2.5 kN is input in the front-rear direction (input 1) is combined with one cycle, and the second vibration mode in which a variable load of ±6.0 kN is input in the inner / outer direction (input 2) is combined with five cycles.

[0081] Regarding the fatigue life calculated for the initial joint line 131 of the rear subframe model 111, Fig. 9 As shown in FIG. 1 , the joints between the side frame lower portion 113 and the bracket 122 are 44,000 sequences and 53,000 sequences, and the joints between the side frame upper portion 112 and the bracket 120 are 64,000 sequences, which are three joint lines from the side with the shorter fatigue life. Based on this result, the target fatigue life setting unit 19 sets the fatigue life of 44,000 sequences or more of the initial joint line 131 joining the side frame lower portion 113 and the bracket 122 as the target fatigue life.

[0082] As described above, in the calculation of the fatigue life by the target fatigue life setting unit 19, it is sufficient to use commercially available fatigue life prediction analysis software. For example, when the fatigue life of the initial joint line 131 modeled by the plane unit is calculated using the commercially available fatigue life prediction analysis software, the fatigue life of the initial joint line 131 can be calculated by inputting the conditions such as the stress of the initial joint line 131 into the fatigue life prediction analysis software. As the stress of the initial joint line 131, the stress value of the plane unit of each component model connected to the plane unit of the initial joint line 131, or the normal structure stress (normal structure stress) obtained from the force and moment acting on both ends of the plane unit of the initial joint line 131 can be used.

[0083] In addition, the SN diagram sometimes changes depending on the load state of the load. For example, even if the stress amplitude is the same, it changes depending on whether the average stress is compressive stress or tensile stress. However, it is sufficient to refer to the values ​​of fatigue life prediction analysis software or experimental values. Alternatively, when using nominal structural stress to calculate fatigue life, an SN diagram that includes different load states can also be used. In addition, if Figure 8As shown, the SN diagram can also be expressed by applying various rules such as Miner's rule that does not determine fracture below the fatigue limit on the low stress side, and modified Miner's rule that counts damage even below the fatigue limit.

[0084] (Optimization analysis condition setting section)

[0085] In order to perform optimization analysis with the optimization analysis model as the optimization object, the optimization analysis condition setting unit 21 calculates the number of fracture repetitions of each joining candidate line 155 according to the load conditions of each vibration mode set by the variable load condition setting unit 17, and calculates the ratio of the number of cycles of the load conditions of each vibration mode to the number of fracture repetitions, and the sum of the number of sequence times of the variable load conditions set by the target fatigue life setting unit 19 as the cumulative damage degree DM of the said each joining candidate line 155, and sets the conditions related to the cumulative damage degree of the joining candidate line 155 remaining after the optimization analysis, the conditions related to the rigidity of the optimization analysis model, and the conditions related to the length of the joining candidate line 155 remaining after the optimization analysis as the objective function or constraint conditions of the optimization analysis conditions.

[0086] There are two types of optimization analysis conditions: objective function and constraint conditions. Only one objective function is set according to the purpose of optimization analysis. As objective functions, conditions related to rigidity, conditions related to fatigue life, and conditions related to joint length can be cited.

[0087] As a condition related to rigidity, for example, a predetermined position in the analytical object model can be used as a rigidity evaluation point, and the displacement (displacement) or strain (strain) of the rigidity evaluation point can be used as an index. In addition, in the variable load condition, for example, the condition related to rigidity can be set as the minimization of the value obtained by adding the displacement of the rigidity evaluation point A under the load conditions of each vibration mode, or the minimization of the displacement of the rigidity evaluation point A under the load conditions of each vibration mode. As a condition related to fatigue life, it can be set as a condition greater than the target fatigue life set by the target fatigue life setting unit 19. In addition, regarding the joint length, for example, it can be set as a ratio relative to the total joint length.

[0088] The constraint condition is a constraint given after performing the optimization analysis, and a plurality of constraints may be set as needed.

[0089] In the first embodiment, the condition that the fatigue life of the candidate bonding wire 155 is greater than the target fatigue life set by the target fatigue life setting unit 19 can be set as a constraint condition. The number of fracture repetitions of the candidate bonding wire 155 is the same as the number of fracture repetitions of the initial bonding wire 131 under the variable load condition described above, and can be used. Figure 8 The SN line diagram shown is used for calculation.

[0090] The conditions related to fatigue life are not limited to directly assigning the target fatigue life set by the target fatigue life setting unit 19 as a constraint condition. The constraint condition that the cumulative damage degree DM of the number of sequence times set as the target fatigue life by the target fatigue life setting unit 19 of the joining candidate line 155 under variable load conditions is DM<1 which does not cause fatigue failure can also be assigned.

[0091] The cumulative damage degree DM of the candidate joint line 155 can be calculated using, for example, the stress of the plane unit of the component model to which the plane unit of the candidate joint line 155 is connected, the nominal structural stress calculated from the force and moment (moment of force, moment) acting on both ends of the plane unit, and the like. Figure 8 The SN line diagram shown and formula (2) are used to calculate.

[0092] Furthermore, regarding the condition related to the length of the candidate joining line 155 , the length of the remaining candidate joining line 155 can be set to a predetermined value. In the first embodiment, a constraint condition is set such that the length of the remaining candidate joining line 155 is equal to or less than the length of the initial joining line 131 .

[0093] Regarding the optimization analysis conditions related to the line length of the joining candidate line 155, when the density method is applied in the topology optimization in the optimization analysis performed by the optimization analysis unit 23, the volume of the joining candidate line 155 calculated based on the density of the units (planar units, three-dimensional units, etc.) modeled as the joining candidate line 155 can also be assigned as a constraint condition.

[0094] (Optimization Analysis Department)

[0095] The optimization analysis unit 23 assigns the variable load conditions set by the variable load condition setting unit 17 to the optimization analysis model, performs optimization analysis under the optimization analysis conditions, and obtains the configuration of the bonding candidate line 155 that achieves any one of the following objectives: reducing the cumulative damage degree of the bonding candidate line 155, improving the rigidity of the optimization analysis model, and minimizing the length of the remaining bonding candidate line 155, as the optimal configuration of the bonding line.

[0096] As the optimization analysis performed by the optimization analysis unit 23, topology optimization can be applied. When the density method is used in the topology optimization, a normalized virtual density taking a value of 0 to 1 is assigned as a design variable to the cell (plane cell, solid cell, etc.) modeled as the joining candidate line 155, and the value of the density that satisfies the optimization analysis condition is calculated.

[0097] If the calculated density value is 1, the candidate bonding line 155 completely exists; if it is 0, the candidate bonding line 155 does not exist; and if it is an intermediate value, the bonding of the component assembly based on the candidate bonding line 155 is in an intermediate state.

[0098] Therefore, when there are many intermediate densities in the topology optimization to which the density method is applied, it is preferable to discretize using a penalty coefficient as shown in Formula (3).

[0099] [Mathematical formula 3]

[0100] in, K M is the stiffness matrix obtained by assigning a penalty to the stiffness matrix of the unit. K is the rigidity matrix of the element ρ is the normalized density, p is the penalty coefficient.

[0101] The penalty coefficient often used in discretization is 2 or more, but in the optimization analysis of the joining position according to the present invention, the penalty coefficient is preferably 4 or more.

[0102] The optimization analysis unit 23 may perform optimization analysis based on topology optimization as described above, or may perform optimization analysis based on other calculation methods.

[0103] exist Fig.10 1 shows an example of the optimal arrangement of the bonding wires 157 obtained by the optimization analysis unit 23 using the density method in the topology optimization. The effects of the optimal arrangement of the bonding wires obtained in the first embodiment will be described in Example 1 described later.

[0104] <Analysis method for optimizing the joint position of the vehicle body>

[0105] The optimization analysis method for the joint position of the vehicle body involved in the first embodiment of the present invention (hereinafter referred to as "the optimization analysis method") performs optimization analysis on all or part of the vehicle body model of a vehicle having a plurality of component models including beam units, plane units and / or three-dimensional units and having an initial joint line 131 for joining the plurality of component models as a component assembly by executing the following steps by a computer. The optimization analysis finds the optimal configuration of the joint line for the purpose of improving the rigidity of the vehicle body model, improving the fatigue life near the joint line for joining the component assembly in the vehicle body model, and minimizing the length of the joint line. Fig.11 As shown in FIG. 1 , the optimization analysis method includes an analysis object model setting step S1, an optimization analysis model generation step S3, a variable load condition setting step S5, a target fatigue life setting step S7, an optimization analysis condition setting step S9, and an optimization analysis step S11. The above steps are described below. The following steps are performed by an optimization analysis device 1 ( Figure 1 )conduct.

[0106] 《Analysis object model setting steps》

[0107] In the analysis target model setting step S1 , all or part of the vehicle body model is set as the analysis target model.

[0108] In the first embodiment, in the analysis target model setting step S1 , the analysis target model setting unit 13 sets the rear subframe model 111 , which is a part of the vehicle body model, as the analysis target model.

[0109] 《Optimization analysis model generation steps》

[0110] The optimized analytical model generating step S3 sets all the candidate joining lines 155 that are candidates for the optimally arranged joining lines to the analysis target model, and generates an optimized analytical model.

[0111] In the first embodiment, in the optimization analysis model generation step S3 , the optimization analysis model generation unit 15 generates additional joint lines 153 between the initial joint lines 131 preset in the rear subframe model 111 , and sets both the initial joint lines 131 and the additional joint lines 153 as joint candidate lines 155 .

[0112] 《Steps for Setting Variable Load Conditions》

[0113] In the variable load condition setting step S5 , variable load conditions are set in which the variable loads applied to the optimized analytical model are divided into load conditions of a plurality of different vibration modes and the load conditions of the vibration modes are combined for a predetermined number of cycles as one sequence.

[0114] In the first embodiment, in the variable load condition setting step S5, the variable load condition setting unit 17 of the optimization analysis device 1 sets Figure 5 (a) Loading conditions for the first vibration mode / one cycle and Figure 5 (b) The load condition of the second vibration mode shown / five cycles are combined as a series of variable load conditions (refer to Figure 7 ), and further, if Figure 5 As shown in FIG. 1 , the restriction conditions for restricting the restriction points a to d are set.

[0115] 《Steps for Setting Target Fatigue Life》

[0116] In the target fatigue life setting step S7, the target fatigue life of the optimized analytical model 151 is set with the sequence number of the variable load condition set in the variable load condition setting step S5. As the target fatigue life of the optimized analytical model 151, the load condition of the vibration mode under the variable load condition set in the variable load condition setting step S5 may be assigned to the analytical target model and stress analysis may be performed separately. The sequence number of the variable load condition that becomes the fatigue life under the variable load condition of the initial joint line 131 of the analytical target model may be calculated using the result of the stress analysis, and the sequence number of the variable load condition that becomes the target fatigue life may be set based on the calculated sequence number of the variable load condition that becomes the fatigue life of the initial joint line 131. Alternatively, the sequence number of the variable load condition that is specified may be used as the target fatigue life based on a conventional empirical rule.

[0117] The target fatigue life is the fatigue life that the candidate joining line 155 to be optimized should satisfy, and at least the number of sequences of the variable load conditions that become the shortest fatigue life (shortest fatigue life) of each initial joining line 131 calculated in the target fatigue life setting step S7 is set as the target fatigue life.

[0118] 《Steps for setting optimal analysis conditions》

[0119] In the optimization analysis condition setting step S9, in order to perform optimization analysis with the optimization analysis model 151 as the optimization object, the number of fracture repetitions of each joining candidate line 155 is calculated according to the different load conditions of each vibration mode in the variable load condition setting step S5, and the ratio of the number of cycles of the load conditions of each vibration mode to the number of fracture repetitions is calculated, and the sum of the number of sequence times of the variable load conditions set by the target fatigue life setting step S7 is taken as the cumulative damage degree DM of each joining candidate line 155, and the conditions related to the cumulative damage degree of the joining candidate line 155 remaining after the optimization analysis, the conditions related to the rigidity of the optimization analysis model 151, and the conditions related to the length of the joining candidate line 155 remaining after the optimization analysis are set as the objective function or constraint conditions as the optimization analysis conditions.

[0120] In the first embodiment, in the optimization analysis condition setting step S9, the optimization analysis condition setting unit 21 sets the maximization of the rigidity of the optimization analysis model 151 (minimization of the displacement of the rigidity evaluation point A) as the objective function, and sets the constraint conditions that the fatigue life of the candidate joining line 155 is greater than the target fatigue life and the constraint conditions that the length of the remaining candidate joining line 155 is less than the length of the initial joining line 131 as the optimization analysis conditions.

[0121] As a condition related to rigidity, for example, a predetermined position in the analysis target model may be used as a rigidity evaluation point, and the displacement or strain of the rigidity evaluation point may be used as an index. Furthermore, in the variable load condition, for example, the variable load may be divided into each vibration mode, and the value obtained by adding the displacement of the rigidity evaluation point A under the load condition of each vibration mode may be minimized, or the displacement of the rigidity evaluation point A under the variable load condition may be minimized as a condition related to rigidity.

[0122] In addition, the condition related to fatigue life is not limited to directly assigning the target fatigue life set in the target fatigue life setting step S7 as a constraint condition. For example, a constraint condition that the cumulative damage degree DM of the joining candidate line 155 is less than the cumulative damage degree equivalent to the target fatigue life can also be assigned.

[0123] 《Optimization analysis steps》

[0124] In the optimization analysis step S11, the variable load condition set in the variable load condition setting step S5 is assigned to the optimization analysis model 151, and the optimization analysis is performed under the optimization analysis condition. The configuration of the bonding candidate line 155 that aims to achieve any one of reducing the cumulative damage degree of the bonding candidate line 155, improving the rigidity of the optimization analysis model 151, and minimizing the length of the remaining bonding candidate line 155 is obtained as the optimal configuration of the bonding line.

[0125] In the first embodiment, in the optimization analysis step S11, the optimization analysis unit 23 performs optimization analysis on the joint candidate line 155 set in the rear subframe model 111 as an optimization target, such as Fig.10 As shown, the arrangement of the candidate bonding lines 155 that satisfies the optimization analysis conditions is obtained as the optimal arrangement of the bonding lines 157 .

[0126] <Analysis program for optimizing the joint position of the vehicle body>

[0127] Embodiment 1 of the present invention can be configured as an optimization analysis program for the joint position of a vehicle body, which is composed of a computer and enables various parts of the optimization analysis device 1 for the joint position of a vehicle body to function. That is, the optimization analysis program for the joint position of a vehicle body involved in embodiment 1 of the present invention uses the whole or a part of the vehicle body model as an analysis object model, and performs optimization analysis on the analysis object model. The optimization analysis finds the optimal configuration of the joint line for the purpose of improving the rigidity of the vehicle body model, improving the fatigue life of the joint line for joining the component assembly in the vehicle body model, and minimizing the length of the joint line. Figure 1 As shown in the figure as an example, the optimization analysis program for the joining position of the vehicle body involved in embodiment 1 of the present invention enables the computer to function as an analysis object model setting unit 13, an optimization analysis model generation unit 15, a variable load condition setting unit 17, a target fatigue life setting unit 19, an optimization analysis condition setting unit 21 and an optimization analysis unit 23.

[0128] As described above, according to the optimization analysis method, device and program for the joining position of the vehicle body involved in the present embodiment 1, the whole or part of the vehicle body model is used as the analysis object model, and an optimized analysis model 151 is generated by setting the candidate joining line 155 as the component assembly to be joined for the analysis object model, and the optimization analysis conditions (objective function or constraint conditions) related to the residual line length, fatigue life and rigidity of the candidate joining line 155 as the optimization object and the optimization analysis model 151 are set to perform optimization analysis on the candidate joining line 155. As a result, when a variable load whose amplitude, direction, etc. changes with time is input to the vehicle body, the optimal configuration of the joining line can be obtained to achieve any one of the following purposes: minimizing the line length of the candidate joining line 155, improving the rigidity of the analysis object model, and improving the fatigue life of the joining line for joining the component assembly.

[0129] [Implementation Method 2]

[0130] In the above-mentioned first embodiment of the present invention, topology optimization based on the density method is applied in optimization analysis to obtain the candidate joining lines 155 that satisfy the optimization analysis conditions. Whether the candidate joining lines 155 remain or disappear in the topology optimization is determined based on the density value of the candidate joining lines 155.

[0131] As described above, the density in the topology optimization based on the density method is a normalized virtual density taking values ​​from 0 to 1. If the density value is 1, it indicates a state where the joining candidate line 155 remains completely. If it is 0, it indicates a state where the joining candidate line 155 disappears. If it is an intermediate value between 0 and 1, it indicates a state between the remaining and disappearance of the joining candidate line 155.

[0132] Therefore, as described above, when there are many intermediate densities to which the density method is applied in topology optimization, it is preferable to discretize using a penalty coefficient as shown in Formula (1).

[0133] Furthermore, when discretization is performed by assigning a penalty coefficient in topology optimization, the configuration of the candidate bonding line 155 of a specified length remaining after the optimization analysis is set as the optimal configuration of the bonding line, and the fatigue life of the bonding line in the analytical object model and the rigidity of the analytical object model both satisfy the target performance of fatigue life and rigidity.

[0134] However, when discretization is performed without assigning a penalty coefficient in topology optimization, the intermediate density of the candidate joining lines 155 remains in the optimization analysis model 151 after the optimization analysis. In addition, in order to obtain the optimal configuration of the joining lines of a predetermined length based on the results of the optimization analysis, for example, the configuration of the candidate joining lines 155 with a density greater than a certain threshold is selected as the optimal configuration of the joining lines, and the configuration of the candidate joining lines 155 with an intermediate density value less than the threshold is not selected as the optimal configuration of the joining lines.

[0135] If the optimal configuration of the bonding line thus obtained is newly set as the analysis target model to calculate the fatigue life of the analysis target model, the following problems may occur: stress is concentrated on a specific bonding line, resulting in a reduction in fatigue life than the target, or the rigidity of the analysis target model is reduced, or the fatigue life and / or rigidity do not satisfy the specified performance.

[0136] Therefore, in order to solve the above-mentioned problem, in-depth research was conducted, and the following insights were obtained: by determining whether the fatigue life and rigidity of the analysis object model obtained by configuring the selected bonding candidate line 155 instead of the initial bonding line 131 meet the specified performance, and if it is determined that they do not meet the requirements, changing the optimization analysis conditions (for example, the density threshold) and performing the optimization analysis again, thereby obtaining the optimal configuration of the bonding line whose rigidity and fatigue life meet the specified performance.

[0137] The method, device and program for optimizing the joint position of the vehicle body involved in the second embodiment are completed based on the above-mentioned insights, and their specific structures are described below. For the same components as the method, device and program for optimizing the joint position of the vehicle body involved in the second embodiment, repeated descriptions are omitted.

[0138] <Analysis device for optimizing the joint position of a vehicle body>

[0139] Hereinafter, the configuration of a vehicle body joint position optimization analysis device according to a second embodiment of the present invention will be described.

[0140] The optimization analysis device 31 is a device that uses the entire body model or a part thereof as an analysis target model, and performs optimization analysis on the entire body model or a part thereof of a vehicle body model having a plurality of component models including beam units, plane units, and / or solid units, and having an initial joint line 131 for joining the plurality of component models as a component assembly, and the optimization analysis finds the optimal arrangement of the joint line for the purpose of improving the rigidity of the body model, improving the fatigue life of the joint line for joining the component assembly in the body model, or minimizing the length of the joint line. The optimization analysis device 31 is composed of a PC (personal computer) or the like, such as Fig.12 As shown, the display device 3, the input device 5, the storage device 7, the work data memory 9 and the operation processing unit 33 are provided. Furthermore, the display device 3, the input device 5, the storage device 7 and the work data memory 9 are connected to the operation processing unit 33, and perform their respective functions according to the instructions from the operation processing unit 33.

[0141] 《Calculation Processing Department》

[0142] like Fig.12 As shown, the calculation processing unit 33 includes an analysis object model setting unit 13, an optimization analysis model generation unit 15, a variable load condition setting unit 17, a target fatigue life setting unit 19, an optimization analysis condition setting unit 21, and an optimization analysis unit 34, and also includes a joint candidate line selection setting analysis object model generation unit 35, a joint candidate line selection performance calculation unit 37, a determination unit 39, and an optimal joint line determination unit 41, and is composed of a CPU (central processing unit) such as a PC. These units function by executing a predetermined program by the CPU.

[0143] Regarding the analysis object model setting unit 13, the optimization analysis model generation unit 15, the variable load condition setting unit 17, the target fatigue life setting unit 19, and the optimization analysis condition setting unit 21 in the operation processing unit 33, since they are the same functions as those of the above-mentioned present embodiment 1, the functions of the optimization analysis unit 34, the analysis object model generation unit 35 for selecting the joining candidate line, the performance calculation unit 37 for selecting the joining candidate line, the judgment unit 39, and the optimal joining line determination unit 41 are described below.

[0144] (Optimization Analysis Department)

[0145] The optimization analysis unit 34 assigns the variable load condition set by the variable load condition setting unit 17 to the optimization analysis model 151, and performs optimization analysis under the optimization analysis condition, so that the configuration of the joining candidate line 155 achieved for any one of the purposes of reducing the cumulative damage degree of the joining candidate line 155, improving the rigidity of the optimization analysis model 151, and minimizing the length of the remaining joining candidate line 155 remains as a temporary optimal configuration of the joining line.

[0146] As the optimization analysis performed by the optimization analyzing unit 34 , topology optimization can be applied similarly to the optimization analyzing unit 23 in the first embodiment described above.

[0147] (Selection of joint candidate lines and setting of analysis target model generation unit)

[0148] The selected joining candidate line setting analysis object model generation unit 35 selects a joining candidate line 155 of a specified length from the joining candidate lines 155 remaining as a temporary optimal configuration after the optimization analysis in the optimization analysis unit 34, and sets the selected joining candidate line 155 in the analysis object model instead of the initial joining line 131, thereby generating a selected joining candidate line setting analysis object model.

[0149] In topological optimization based on the density method, the density of units (e.g., planar units, etc.) modeled as joining candidate lines 155 is calculated. Therefore, the joining candidate lines are selected and set to the analysis object model generation unit 35. For example, a specified length can be selected from the joining candidate lines 155 whose unit density is above a specified threshold and set as the analysis object model.

[0150] (Selection of bonding candidate line performance calculation section)

[0151] The selected joining candidate line performance calculation unit 37 performs stress analysis on the selected joining candidate line setting analysis object model by assigning the load conditions and restriction conditions of each vibration mode under the variable load conditions set by the variable load condition setting unit 17, and uses the results of the stress analysis to calculate the fatigue life of the selected joining candidate line 155 under the variable load conditions and the rigidity of the selected joining candidate line setting analysis object model.

[0152] Regarding the fatigue life under the variable load conditions of the candidate joining line 155 set in the selected candidate joining line setting analysis object model, it is sufficient to use the stress of the candidate joining line 155 obtained by stress analysis of the selected candidate joining line setting analysis object model in the same way as the above-mentioned target fatigue life setting unit 19, and calculate the cumulative damage degree DM (refer to formula (2)) based on the cumulative fatigue damage law, which can be obtained by commercially available fatigue life prediction analysis software.

[0153] Furthermore, the stress of the candidate joining line 155 used for calculating the cumulative damage degree DM can be, for example, the stress of the planar unit of the component model to which the planar unit of the candidate joining line 155 is modeled, the nominal structural stress calculated based on the force and moment acting on both ends of the planar unit of the candidate joining line 155, or the like.

[0154] In addition, the rigidity of the analysis object model can be set by selecting the candidate joining line. For example, a specified position can be used as a rigidity evaluation point and its displacement or strain can be used as an indicator. The displacement of the rigidity evaluation point under the variable load condition, the variable load is divided into each vibration mode, and the value obtained by adding the displacement of the rigidity evaluation point under the load condition of each vibration mode can be used as an indicator.

[0155] (Judgment Department)

[0156] The determination unit 39 determines whether the fatigue life under variable load conditions of the candidate joining line 155 in the selected candidate joining line setting analysis target model and the rigidity of the selected candidate joining line setting analysis target model satisfy the prescribed performance exceeding that of the analysis target model in which the initial joining line 131 is set.

[0157] The predetermined performance related to the fatigue life can be set, for example, to be within a predetermined range of the target fatigue life set by the target fatigue life setting unit 19 .

[0158] (Optimal bonding line determination section)

[0159] The optimal joining line determination unit 41 determines the configuration of the joining candidate line 155 selected by the joining candidate line selection and analysis object model generation unit 35 as the optimal configuration of the joining line when the determination unit 39 determines that the specified performance is satisfied. When the determination unit 39 determines that the specified performance is not satisfied, the optimal joining line determination unit 41 changes the condition related to the cumulative damage degree of the joining candidate line 155 remaining after the optimization analysis, the condition related to the rigidity of the optimization analysis model 151, or the condition related to the length of the joining candidate line 155 remaining after the optimization analysis set by the optimization analysis condition setting unit 21, and repeatedly performs the processing performed by the optimization analysis unit 34, the joining candidate line selection and analysis object model generation unit 35, the joining candidate line performance calculation unit 37 and the determination unit 39 until the specified performance is satisfied, and determines the configuration of the joining candidate line 155 selected when the specified performance is satisfied as the optimal configuration of the joining line.

[0160] When the determination unit 39 does not determine that the rigidity and fatigue life satisfy the specified performance, the optimal bonding line determination unit 41 can utilize the optimization analysis condition setting unit 21 to change the optimization analysis conditions such as the threshold for selecting the bonding candidate line 155, so as to increase the length of the bonding candidate line 155 remaining in the optimization analysis.

[0161] When changing the condition related to the cumulative damage degree of the joining candidate line 155, the condition related to the rigidity of the optimization analysis model 151, or the condition related to the length of the remaining joining candidate line 155 in the optimization analysis condition setting unit 21, any one condition may be changed, or two or three conditions may be changed simultaneously.

[0162] <Analysis method for optimizing the joint position of the vehicle body>

[0163] The method for optimizing the joint position of a vehicle body according to the second embodiment of the present invention performs optimization analysis on all or part of a vehicle body model having a plurality of component models including beam units, plane units and / or three-dimensional units and having an initial joint line 131 for joining the plurality of component models as a component assembly by executing the following steps by a computer, and the optimization analysis is performed to find the optimal configuration of the joint line for the purpose of improving the rigidity of the vehicle body model, improving the fatigue life of the joint line for joining the component assembly in the vehicle body model, or minimizing the length of the joint line. Fig.13As shown, the optimization analysis method of the joining position of the vehicle body involved in embodiment 2 of the present invention includes an analysis object model setting step S1, an optimization analysis model generation step S3, a variable load condition setting step S5, a target fatigue life setting step S7, an optimization analysis condition setting step S9, an optimization analysis step S12, a joining candidate line selection analysis object model generation step S13, a joining candidate line selection performance calculation step S15, a judgment step S17 and an optimal joining line determination step S19.

[0164] The above steps of the analysis object model setting step S1, the optimization analysis model generation step S3, the variable load condition setting step S5, the target fatigue life setting step S7, and the optimization analysis condition setting step S9 are the same as those of the first embodiment described above. Therefore, the optimization analysis step S12, the joint candidate line selection analysis object model generation step S13, the joint candidate line selection performance calculation step S15, the determination step S17, and the optimal joint line determination step S19 are described below. The steps of the optimization analysis method according to the second embodiment are performed by the optimization analysis device 31 ( Fig.12 )conduct.

[0165] 《Optimization analysis steps》

[0166] In the optimization analysis unit S12, the variable load condition set in the variable load condition setting step S5 is assigned to the optimization analysis model 151, and the optimization analysis is performed under the optimization analysis condition, so that the configuration of the joining candidate line 155 achieved for the purpose of reducing the cumulative damage degree of the joining candidate line 155, improving the rigidity of the optimization analysis model 151, and minimizing the length of the remaining joining candidate line 155 remains as a temporary optimal configuration of the joining line.

[0167] In the second embodiment, in the optimization analysis step S12, the optimization analysis unit 34 performs optimization analysis on the joint candidate line 155 set in the rear subframe model 111 as an optimization target, such as Fig.10 As shown, the arrangement of the candidate bonding lines 155 that satisfies the optimization analysis conditions is left as a temporary optimal arrangement of the bonding lines 157 .

[0168] 《Selecting the candidate joint line and setting the analysis target model generation steps》

[0169] In the step S13 of generating the analysis object model for selecting the joining candidate line setting, a joining candidate line 155 of a specified length is selected from the joining candidate lines 155 remaining as a temporary optimal configuration through the optimization analysis in the optimization analysis step S12, and the selected joining candidate line 155 is set in the analysis object model instead of the initial joining line 131, thereby generating the analysis object model for selecting the joining candidate line setting.

[0170] In the second embodiment, the joint candidate line selection and analysis target model setting generation step S13 is performed by the joint candidate line selection and analysis target model setting generation unit 35 .

[0171] 《Performance calculation steps for selecting bonding candidate lines》

[0172] In the selected bonding candidate line performance calculation step S15, the selected bonding candidate line setting analysis object model is given the load conditions and restriction conditions of each vibration mode under the variable load conditions set in the variable load condition setting step S5 to perform stress analysis, and the fatigue life of the selected bonding candidate line 155 under the variable load conditions and the rigidity of the selected bonding candidate line setting analysis object model are calculated using the results of the stress analysis. In the present second embodiment, the selected bonding candidate line performance calculation step S15 is performed by the selected bonding candidate line performance calculation unit 37.

[0173] 《Determination Steps》

[0174] In the determination step S17, it is determined whether the fatigue life under the variable load condition of the candidate bonding line 155 in the selected candidate bonding line setting analysis target model and the rigidity of the selected candidate bonding line setting analysis target model satisfy the prescribed performance exceeding that of the analysis target model set with the initial bonding line 131. In the second embodiment, the determination step S17 is performed by the determination unit 39.

[0175] As described above, the predetermined performance related to the fatigue life may be set within the predetermined range of the target fatigue life set by the target fatigue life setting unit 19 , for example.

[0176] 《Steps to determine the optimal joining line》

[0177] In the optimal joining line determination step S19, if it is determined in the determination step S17 that the specified performance is satisfied, the configuration of the joining candidate line 155 selected in the step S13 for generating the analysis object model for selecting the joining candidate line is determined as the optimal configuration of the joining line. If it is determined in the determination step S17 that the specified performance is not satisfied, the condition related to the cumulative damage degree of the joining candidate line 155 remaining after the optimization analysis, the condition related to the rigidity of the optimization analysis model 151, or the condition related to the length of the joining candidate line 155 remaining after the optimization analysis set in the optimization analysis condition setting step S9 is changed, and the optimization analysis step S12, the step S13 for generating the analysis object model for selecting the joining candidate line, the step S15 for calculating the performance of the joining candidate line and the determination step S17 are repeated until the specified performance is satisfied, and the configuration of the joining candidate line 155 selected when the specified performance is satisfied is determined as the optimal configuration of the joining line. In the determination step S17 , the reason why the predetermined performance is not satisfied is that there are a large number of intermediate density candidate joining lines 155 , and the performance obtained by combining these is determined. In the second embodiment, the optimum joining line determination step S19 is performed by the optimum joining line determination unit 41 .

[0178] When changing the condition related to the cumulative damage degree of the candidate joining line 155, the condition related to the rigidity of the optimization analysis model 151, or the condition related to the length of the remaining candidate joining line 155 in the optimization analysis condition setting step S9, any one condition may be changed, or two or three conditions may be changed simultaneously.

[0179] <Analysis program for optimizing the joint position of the vehicle body>

[0180] Embodiment 2 of the present invention can be configured as an optimization analysis program for the joint position of the vehicle body, which is configured by a computer and enables various parts of the optimization analysis device 31 for the joint position of the vehicle body to function. That is, the optimization analysis program for the joint position of the vehicle body involved in embodiment 2 of the present invention takes the whole or part of the vehicle body model as the analysis object model, and performs optimization analysis on the whole or part of the vehicle body model having multiple component models including beam units, plane units and / or three-dimensional units and having an initial joint line 131 for joining the multiple component models as a component assembly. The optimization analysis finds the optimal configuration of the joint line for any one of the purposes of improving the rigidity of the vehicle body model, improving the fatigue life of the joint line for joining the component assembly in the vehicle body model, and minimizing the length of the joint line. Fig.12As shown in the figure as an example, the optimization analysis program of the joining position of the vehicle body involved in the second embodiment of the present invention enables the computer to function as an analysis object model setting unit 13, an optimization analysis model generation unit 15, a variable load condition setting unit 17, a target fatigue life setting unit 19, an optimization analysis condition setting unit 21 and an optimization analysis unit 34, and also functions as a setting analysis object model generation unit 35 for selecting a joining candidate line, a selection of a joining candidate line performance calculation unit 37, a judgment unit 39 and an optimal joining line determination unit 41.

[0181] As described above, in the optimization analysis method, device and program for the joining position of the vehicle body involved in the present embodiment 2, even when discretization is not performed in the topological optimization based on the density method, it is possible to appropriately determine the optimal configuration of the joining line to achieve any one of the following purposes: minimizing the line length of the joining candidate line 155, improving the rigidity of the analysis object model, and improving the fatigue life of the joining line for joining the component assembly, taking the situation where the load that varies with time is input to the vehicle body as in the actual driving process of the automobile as the object.

[0182] In the above description, a vehicle body model obtained by modeling the entire vehicle body is obtained, and the rear subframe model 111, which is a part of the vehicle body model, is used as the analysis target model. However, the present invention may use the entire vehicle body model as the analysis target model, or may use a part of the vehicle body model other than the rear subframe model 111 as the analysis target model. In addition, a vehicle body partial model, which is a part of the vehicle body model, may be obtained, and the obtained vehicle body partial model may be used as the analysis target model.

[0183] In addition, in the above description, an example is given in which the initial joint line 131 having a length of 6540 mm is preset in the rear subframe model 111 , but the length of the initial joint line 131 is not limited thereto.

[0184] Furthermore, the initial joint line 131 is set in advance in the rear subframe model 111 by an operator or other means. However, in the present invention, the initial joint line 131 may be set by the operator in the analysis target model setting unit or in the analysis target model setting step, or may be set by adding the initial joint line 131 to the analysis target model in which the initial joint line 131 has already been set.

[0185] In the first embodiment, the rear subframe model 111 is set Figure 5 The load conditions and restriction conditions shown in the figure are not specific, but the present invention only needs to appropriately set the variable load conditions and restriction conditions by assuming the variable load acting on the part of the vehicle body to be analyzed or the actual vehicle body.

[0186] In the examples of the first and second embodiments, the target performance of the fatigue life of the candidate joining line 155 is set based on the shortest fatigue life (shortest fatigue life) of the initial joining lines 131 set in the analysis target model.

[0187] However, in the present invention, the initial joint line 131 before the optimization analysis can be calculated to set the additional joint line 153 (see Figure 6 ) and the fatigue life of the candidate bonding line 155 in the optimized analysis model 151 obtained by the calculation, determine the shortest fatigue life among the calculated fatigue lives of the candidate bonding line 155, and set the target fatigue life in the optimization analysis to satisfy the following relationship.

[0188] (The shortest fatigue life of the initial bonding wire) ≤ (the target fatigue life of the bonding candidate wire) ≤ (the shortest fatigue life of the bonding candidate wire for which the bonding wire before the optimization analysis is set)

[0189] Moreover, in the above description, both the initial bonding line 131 and the additional bonding line 153 are used as the bonding candidate line 155 for optimization analysis, but only the additional bonding line 153 can be used as the bonding candidate line 155, and the initial bonding line 131 is not used as the object of optimization analysis to find the optimal configuration of the bonding line added to the initial bonding line 131.

[0190] Furthermore, if the optimization analysis is performed by setting the initial weld line 131 to be included in the candidate weld line 155, the candidate weld line 155 to be welded as the component assembly disappears during the optimization analysis, and the component assembly becomes scattered, and the optimization analysis may not be performed. In such a case, at least one fixed weld line that is not the subject of the optimization analysis may be set in each component assembly.

[0191] The fixed weld line may be arbitrarily selected from the initial weld lines 131 , or a candidate fixed weld line may be set as a candidate fixed weld line and stress analysis or optimization analysis of the analysis target model may be performed separately, and the fixed weld line may be selected from the candidate fixed weld lines based on the results.

[0192] In the above description, the fatigue life of the candidate bonding line 155 or the rigidity of the optimized analytical model 151 is used as the objective function. However, the length of the candidate bonding line 155 may be used as the objective function, and the fatigue life and rigidity may be used as the constraints.

[0193] [Implementation method 3]

[0194] The above-mentioned optimization analysis method of the joint position of the vehicle body according to the first embodiment and the second embodiment performs optimization analysis to obtain the optimal arrangement of the joint line for the purpose of improving the rigidity of the vehicle body model having the initial joint line 131 for joining a plurality of component models as a component assembly, improving the fatigue life of the joint line for joining the component assembly in the vehicle body model, and minimizing the length of the joint line. However, the present invention can be configured as a vehicle body manufacturing method for manufacturing a vehicle body in which the rigidity of the vehicle body and the fatigue life of the joint line are improved by optimally arranging the joint line for joining the component assembly in the vehicle body.

[0195] In the method for manufacturing a vehicle body according to the third embodiment, first, the optimal arrangement of the joining lines is obtained for all or part of a vehicle body model having initial joining lines for joining a plurality of component models as a component assembly using the above-mentioned method for analyzing the joining positions of the vehicle body according to the first or second embodiment. Next, the joining positions of the component assemblies in the vehicle body are determined based on the obtained optimal arrangement of the joining lines of the vehicle body model. Then, the component assemblies in the vehicle body are joined at the determined joining positions. As a method for determining the joining positions of the component assemblies in the vehicle body, the following method can be exemplified.

[0196] As a specific example of a method for determining a joining position, the position data of the three-dimensional coordinates of the optimal arrangement of the joining line of the vehicle body model obtained by using the optimization analysis method of the joining position of the vehicle body is input into a CAD / CAM program that cooperates with the NC unit of the welding robot configured in the vehicle body welding process, and is converted into NC data (NC program) for the welding robot. In addition, as a specific example of a method for joining component assemblies in the vehicle body, the welding robot configured in the vehicle body welding process is operated by using the converted NC data, so that the component assemblies of the vehicle body are joined at the determined joining position. In this way, according to the vehicle body manufacturing method involved in the third embodiment, it is possible to achieve the optimal arrangement of welding positions such as arc welding in the vehicle body structure, improve the fatigue life near the joining line, and improve the rigidity of the vehicle body, and it is possible to achieve a reduction in welding costs and a high rigidity and light weight of the vehicle body.

[0197] Example 1

[0198] Since an analysis was performed to confirm the effect of the present invention, this will be described below. Fig.14 As shown, the rear subframe model 111 obtained by modeling the rear subframe is used as an object, and the optimal arrangement of the joining lines for joining the component models constituting the rear subframe model 111 as a component assembly is obtained by optimization analysis.

[0199] As for the rear subframe model 111, as described in Embodiment 1, as a component model, the side frame upper portion 112 and the side frame lower portion 113 are joined by arc welding to form a side frame R211. The side frame upper portion 114 and the side frame lower portion 115 are joined by arc welding to form a side frame L212. The cross beam upper portion 116 and the cross beam lower portion 117 are joined by arc welding to form a cross beam front portion 213. The cross beam front portion 118 and the cross beam rear portion 119 are joined by arc welding to form a rear cross beam 214. These side frame R211, side frame L212, cross beam front portion 213 and rear cross beam 214 are further joined by arc welding to form a tic-tac-toe structure. These component models are modeled by plane units.

[0200] The rear subframe model 111 is also pre-set with an initial joint line 131 for joining the component models as a component assembly. The initial joint line 131 is modeled by a plane element joining nodes of the plane elements of the component model, and the length of the initial joint line 131 is 6540 mm.

[0201] In Example 1, first, based on Figure 7 The fatigue life of the initial bond line 131 under the varying load conditions shown sets the target fatigue life.

[0202] Figure 7 The variable load condition shown is the load condition of the first vibration mode in which a variable load of ±2.5 kN is input in the forward and backward direction (input 1) (refer to Figure 5 (a)) and the conditions of the second vibration mode with a variable load of ±6.0 kN input in the inner / outer direction (input 2) (refer to Figure 5 (b)) The variable load condition is a combination of the load condition of the first vibration mode and one cycle, and the load condition of the second vibration mode and five cycles, to form a series of variable load conditions.

[0203] Next, according to the load condition of the first vibration mode ( Figure 5 A) and the load conditions of the second vibration mode ( Figure 5 (b) A stress analysis of the rear subframe model 111 is performed to determine the stress generated at the initial joint line 131 under the load conditions of each vibration mode.

[0204] Next, according to the SN line diagram ( Figure 8 ) Calculate the number of repetitions N1 and N2 of different stress amplitudes σ1 and σ2 generated at the initial bonding line 131 under the variable load condition, from when they are generated at the initial bonding line 131 to when the initial bonding line 131 breaks.

[0205] Then, the number of repetitions N1 and N2 until fracture at each stress amplitude and the number of cycles n1 (= 1 cycle) and n2 (= 20 cycles) of the load conditions of the first vibration mode and the load conditions of the second vibration mode under a sequence of variable load conditions are substituted into formula (1) to calculate the cumulative damage degree dm in a sequence.

[0206] Furthermore, the sequence number K when the cumulative damage degree DM calculated using equation (2) becomes greater than 1 is calculated as the fatigue life of the initial joint line 131 under the variable load condition, and the target fatigue life is set based on the shortest fatigue life among the fatigue lives of the initial joint lines 131.

[0207] After setting the target fatigue life, an optimization analysis is performed to determine the optimal arrangement of the joint line in the rear subframe model 111. In the optimization analysis, first, Figure 6 As shown, additional joint lines 153 are set between the initial joint lines 131 in the rear subframe model 111 , and the optimized analytical model 151 is generated in which the initial joint lines 131 and the additional joint lines 153 are set as joint candidate lines 155 .

[0208] Next, give Figure 5 The optimization analysis is performed under the load conditions and constraint conditions shown, and the candidate joining line 155 satisfying the optimization analysis conditions is obtained. In the optimization analysis, topology optimization based on the density method is applied, and the penalty coefficient is set to 4 in the topology optimization to perform discretization.

[0209] Table 1 shows combinations of objective functions and constraint functions for optimization analysis conditions.

[0210] [Table 1]

[0211] The objective function and constraint conditions related to rigidity are set as the rigidity evaluation point A (refer to Fig.14 ) is less than the displacement of the rigidity evaluation point A when stress analysis is performed on the rear subframe model 111 in which the initial joint line 131 is set.

[0212] In addition, regarding the objective function and constraint conditions related to fatigue life, the cumulative damage degree DM of the candidate bonding line 155 under the variable load condition is calculated in the same manner as the initial bonding line 131 described above. And, it is set as a condition that the fatigue life calculated based on the cumulative damage degree DM of each candidate bonding line 155 is greater than the target fatigue life.

[0213] Furthermore, the objective function and constraint conditions related to the length of the candidate joining line 155 , that is, the joining length, are set such that the length of the candidate joining line 155 remaining after the optimization analysis is equal to or less than the length of the initial joining line 131 .

[0214] exist Fig.10 The result of the remaining bonding candidate line 155 in the invention example 1 in the embodiment 1 is shown in FIG. Fig.15 The result of the remaining bonding candidate line 155 in Comparative Example 1 is shown in FIG. Fig.10 As shown, the joint lines are densely arranged around the brackets 120, 121, and 122, and the joints between the side frame upper parts 112, 114 and the side frame lower parts 113, 115, and the joints between the cross beam upper part 116 and the cross beam lower part 117 are sparsely arranged. Fig.15 As shown, in Comparative Example 1, the joints between the cross beam upper portion 116 and the cross beam lower portion 117 and the joints between the side frame upper portion 112 and the side frame lower portion 113 are arranged more sparsely than in Example 1 of the Invention.

[0215] The analysis results of Examples 1 to 3, that is, the weld lengths (weld lengths) after the optimization analysis are shown in Table 2, and a graph of Table 2 is shown in FIG. Fig.16 .

[0216] [Table 2]

[0217] Next, in order to perform performance evaluation based on the optimized weld line, an optimal weld line rear subframe model 161 (refer to Fig.10 ), the rigidity and fatigue life of the joint line 157 are calculated.

[0218] In the calculation of rigidity and fatigue life, Figure 5 The load conditions of the first vibration mode and the load conditions of the second vibration mode and the constraint conditions are applied to the optimal joint line rear subframe model 161 to perform stress analysis.

[0219] Regarding the rigidity of the optimal joint line rear subframe model 161, the rigidity evaluation point A (see Figure 5 )’s displacements are used as indicators respectively.

[0220] Regarding the fatigue life of the joint line 157 , the shortest fatigue life among fatigue lives calculated using the stress of the joint line 157 obtained by stress analysis of the optimal joint line rear subframe model 161 is used as an index.

[0221] The evaluation results are shown in Table 3, and a graph obtained by graphing the fatigue life and the improvement rate of stiffness in Table 3 is shown in Fig.17 , Fig.18 Table 3 also records the welding lengths shown in Table 2.

[0222] [Table 3]

[0223] The rigidity improvement rate in inputs 1 and 2 is calculated by the following formula.

[0224] [Formula 4]

[0225] Inventive Examples 1 to 3 and Comparative Examples 2 and 3-2 all use fatigue life as an objective function or constraint, so fatigue life is improved compared to the original parts. In addition, in any of Examples 1 to 3, fatigue life of the inventive examples is greatly improved compared to the comparative examples.

[0226] In addition, in the invention examples 1 to 3, the comparative examples 1 and 3-1, the rigidity is improved compared with the original part because the rigidity is used as the objective function or constraint condition. In addition, in the invention example 1 and the comparative example 1 in the embodiment 1, the rigidity improvement rate is roughly the same, but in the embodiments 2 and 3, the rigidity improvement rate of the invention example is higher than that of the comparative example.

[0227] Industrial Applicability

[0228] According to the present invention, a method, device and program for optimizing the joint position of a vehicle body, and a method for manufacturing a vehicle body can be provided to find the optimal configuration of the joint line that improves the rigidity of the vehicle body and the fatigue life of the continuous joint line that joins the component assemblies in the vehicle body and minimizes the length of the joint line when a simple or variable load is input to the vehicle body.

[0229] Description of symbols 1 Optimizing the analytical device 3 Display device 5 Input Devices 7 Storage Devices 9 Data storage for operation 11. Calculation Processing Unit 13 Analysis object model setting section 15 Optimization analysis model generation unit 17 Variable load condition setting section 19 Target fatigue life setting section 21 Optimization analysis condition setting section 23 Optimization Analysis Department 31 Optimization analysis device 33. Calculation Processing Unit 34 Optimization Analysis Department 35 Select the candidate joint line and set the analysis target model generation unit 37 Select the bonding candidate line performance calculation section 39 Judgment Department 41 Optimal bonding line determination unit 100 Tire Input Points 101 Car body model file 111 Rear subframe model 112 Upper side frame 113 Side frame lower part 114 Side frame upper part 115 Side frame lower part 116 Upper beam 117 Lower part of beam 118 Front of beam 119 Rear of beam 120, 121, 122 brackets 131 Initial bonding line 141 Arc welding department 151 Optimization Analysis Model 153 Additional bonding line 155 Joining candidate lines 157 Bonding Wire 161 Optimal joint line rear subframe model 201 Car body model 203 Side frame 211 Side frame R 212 Side frame L 213 Front of beam 214 Rear cross member.

Claims

1. A method for optimizing the joint position of a vehicle body, wherein a computer executes the following steps to perform optimization analysis on all or part of a vehicle body model having a plurality of component models including beam units, plane units and / or solid units and having initial joint lines for joining the plurality of component models as component assemblies, wherein the optimization analysis is performed to obtain an optimal arrangement of the joint lines for any one of improving the rigidity of the vehicle body model, improving the fatigue life near the joint lines for joining the component assemblies in the vehicle body model, and minimizing the length of the joint lines, wherein: The optimization analysis method of the joint position of the vehicle body includes: An analysis object model setting step of setting all or part of the vehicle body model as an analysis object model; an optimized analytical model generating step of generating an optimized analytical model obtained by setting all candidate joining lines that are candidates for the optimally arranged joining lines to the analysis target model; a variable load condition setting step of setting a variable load condition, wherein the variable load condition is divided into load conditions of a plurality of different vibration modes, and the load conditions of the respective vibration modes are combined for a predetermined number of cycles as one sequence; a target fatigue life setting step of setting the target fatigue life of the optimized analytical model according to the sequence number of the variable load condition; an optimization analysis condition setting step, in order to perform an optimization analysis taking the optimization analysis model as an optimization object, the number of fracture repetitions near each joining candidate line is calculated according to the load conditions of each vibration mode, and the ratio of the number of cycles of the load conditions of each vibration mode to the number of fracture repetitions is calculated, and the sum of the number of sequence times of the variable load conditions set by the target fatigue life setting step is calculated as the cumulative damage degree of each joining candidate line, and the conditions related to the cumulative damage degree of the joining candidate line remaining after the optimization analysis, the conditions related to the rigidity of the optimization analysis model, and the conditions related to the length of the joining candidate line remaining after the optimization analysis are set as objective functions or constraints as optimization analysis conditions; and An optimization analysis step, assigning the variable load condition set in the variable load condition setting step to the optimization analysis model, performing optimization analysis under the optimization analysis condition, and finding the configuration of the bonding candidate line that achieves any one of reducing the cumulative damage degree of the bonding candidate line, improving the rigidity of the optimization analysis model, and minimizing the remaining length of the bonding candidate line as the optimal configuration of the bonding line.

2. The method for optimizing the joint position of a vehicle body according to claim 1, wherein: The optimization analysis step performs topology optimization based on a density method, and in the topology optimization, a penalty coefficient is set to 4 or more to perform discretization.

3. A method for optimizing the joint position of a vehicle body, wherein a computer executes the following steps to perform optimization analysis on all or part of a vehicle body model having a plurality of component models including beam units, plane units and / or solid units and having an initial joint line for joining the plurality of component models as a component assembly, wherein the optimization analysis is performed to obtain an optimal arrangement of the joint line for any one of improving the rigidity of the vehicle body model, improving the fatigue life near the joint line for joining the component assembly in the vehicle body model, and minimizing the length of the joint line, wherein: The optimization analysis method of the joint position of the vehicle body includes: An analysis object model setting step of setting all or part of the vehicle body model as an analysis object model; an optimized analytical model generating step of generating an optimized analytical model obtained by setting all candidate joining lines that are candidates for the optimally arranged joining lines to the analysis target model; a variable load condition setting step of setting a variable load condition, wherein the variable load condition is divided into load conditions of a plurality of different vibration modes, and the load conditions of the respective vibration modes are combined for a predetermined number of cycles as one sequence; a target fatigue life setting step of setting the target fatigue life of the optimized analytical model according to the sequence number of the variable load condition; an optimization analysis condition setting step, in order to perform an optimization analysis taking the optimization analysis model as an optimization object, the number of fracture repetitions near each of the candidate joining lines is calculated according to the load conditions of each vibration mode, and the sum of the number of sequence times of the variable load conditions set by the target fatigue life setting step, which is the ratio of the number of cycles of the load conditions of each vibration mode to the number of fracture repetitions, is calculated as the cumulative damage degree of each of the candidate joining lines, and a condition related to the cumulative damage degree of the candidate joining lines remaining after the optimization analysis, a condition related to the rigidity of the optimization analysis model, and a condition related to the length of the candidate joining lines remaining after the optimization analysis are set as an objective function or constraint condition as an optimization analysis condition; an optimization analysis step of assigning the variable load condition set in the variable load condition setting step to the optimization analysis model, performing optimization analysis under the optimization analysis condition, and allowing the configuration of the candidate bonding line achieved for any one of reducing the cumulative damage degree of the candidate bonding line, improving the rigidity of the optimization analysis model, and minimizing the remaining length of the candidate bonding line to remain as a temporary optimal configuration of the candidate bonding line; A step of selecting a candidate joining line and setting an analysis target model, selecting a candidate joining line of a predetermined length from the candidate joining lines remaining as a temporary optimal configuration through the optimization analysis, and setting the selected candidate joining line in the analysis target model instead of the initial joining line, thereby generating a selected candidate joining line setting analysis target model; A step of calculating the performance of a selected candidate joining line, assigning the load conditions and restriction conditions of the vibration modes under the variable load conditions set in the variable load condition setting step to the selected candidate joining line setting analysis object model to perform stress analysis, and using the result of the stress analysis, calculating the fatigue life under the variable load conditions near the selected candidate joining line and the rigidity of the selected candidate joining line setting analysis object model; A determination step of determining whether the fatigue life under the variable load condition near the candidate joining line in the selected candidate joining line setting analysis object model and the rigidity of the selected candidate joining line setting analysis object model satisfy the performance exceeding the prescribed performance of the analysis object model in which the initial joining line is set; and An optimal joining line determination step, when it is determined in the determination step that the specified performance is satisfied, the configuration of the selected joining candidate line is determined as the optimal configuration of the joining line, and when it is determined in the determination step that the specified performance is not satisfied, the condition related to the cumulative damage degree of the joining candidate line remaining after the optimization analysis, the condition related to the rigidity of the optimization analysis model, or the condition related to the length of the joining candidate line remaining after the optimization analysis set in the optimization analysis condition setting step is changed, and the optimization analysis step, the step of generating the selected joining candidate line setting analysis object model, the step of calculating the performance of the selected joining candidate line and the determination step are repeated until the specified performance is satisfied, and the configuration of the joining candidate line selected when the specified performance is satisfied is determined as the optimal configuration of the joining line.

4. An optimization analysis device for a joint position of a vehicle body, which performs optimization analysis on all or part of a vehicle body model having a plurality of component models including beam units, plane units and / or solid units and having an initial joint line for joining the plurality of component models as a component assembly, wherein the optimization analysis finds an optimal arrangement of the joint line for any one of improving the rigidity of the vehicle body model, improving the fatigue life near the joint line for joining the component assembly in the vehicle body model, and minimizing the length of the joint line, wherein: The optimization analysis device for the joint position of the vehicle body comprises: an analysis target model setting unit that sets all or part of the vehicle body model as an analysis target model; an optimized analytical model generating unit that generates an optimized analytical model obtained by setting all candidate joining lines that are candidates for the optimally arranged joining lines to the analysis target model; a variable load condition setting unit for setting a variable load condition that divides a variable load applied to the optimized analytical model into load conditions of a plurality of different vibration modes and combines the load conditions of the vibration modes into one sequence by a predetermined number of cycles; a target fatigue life setting unit that sets a target fatigue life of the optimized analytical model according to the sequence number of the variable load condition; an optimization analysis condition setting unit, which, in order to perform an optimization analysis taking the optimization analysis model as an optimization object, obtains the number of fracture repetitions near each of the candidate joining lines according to the load conditions of each vibration mode, obtains the ratio of the number of cycles of the load conditions of each vibration mode to the number of fracture repetitions, and obtains the sum of the number of sequence times of the variable load conditions set by the target fatigue life setting unit as the cumulative damage degree of each of the candidate joining lines, and sets conditions related to the cumulative damage degree of the candidate joining lines remaining after the optimization analysis, conditions related to the rigidity of the optimization analysis model, and conditions related to the length of the candidate joining lines remaining after the optimization analysis as objective functions or constraints of optimization analysis conditions; and An optimization analysis unit assigns the variable load condition set by the variable load condition setting unit to the optimization analysis model, performs optimization analysis under the optimization analysis condition, and obtains a configuration of the bonding candidate line that achieves any one of reducing the cumulative damage degree of the bonding candidate line, improving the rigidity of the optimization analysis model, and minimizing the remaining length of the bonding candidate line as the optimal configuration of the bonding line.

5. The optimization analysis device for the joint position of the vehicle body according to claim 4, wherein: The optimization analysis unit performs topology optimization based on a density method, and discretizes the topology by setting a penalty coefficient to 4 or more.

6. An optimization analysis device for a joint position of a vehicle body, which performs optimization analysis on all or part of a vehicle body model having a plurality of component models including beam units, plane units and / or solid units and having an initial joint line for joining the plurality of component models as a component assembly, wherein the optimization analysis finds the optimal arrangement of the joint line for any one of improving the rigidity of the vehicle body model, improving the fatigue life near the joint line for joining the component assembly in the vehicle body model, and minimizing the length of the joint line, wherein: The optimization analysis device for the joint position of the vehicle body comprises: an analysis target model setting unit that sets all or part of the vehicle body model as an analysis target model; an optimized analytical model generating unit that generates an optimized analytical model obtained by setting all candidate joining lines that are candidates for the optimally arranged joining lines to the analysis target model; a variable load condition setting unit for setting a variable load condition that divides a variable load applied to the optimized analytical model into load conditions of a plurality of different vibration modes and combines the load conditions of the respective vibration modes into one sequence by a predetermined number of cycles; a target fatigue life setting unit that sets a target fatigue life of the optimized analytical model according to the sequence number of the variable load condition; an optimization analysis condition setting unit, which, in order to perform an optimization analysis taking the optimization analysis model as an optimization object, obtains the number of fracture repetitions near each of the candidate joining lines according to the load conditions of each vibration mode, obtains the ratio of the number of cycles of the load conditions of each vibration mode to the number of fracture repetitions, and obtains the sum of the number of sequence times of the variable load conditions set by the target fatigue life setting unit as the cumulative damage degree of each of the candidate joining lines, and sets a condition related to the cumulative damage degree of the candidate joining lines remaining after the optimization analysis, a condition related to the rigidity of the optimization analysis model, and a condition related to the length of the candidate joining lines remaining in the optimization analysis as an objective function or constraint condition as an optimization analysis condition; an optimization analysis unit that assigns the variable load condition set by the variable load condition setting unit to the optimization analysis model, performs optimization analysis under the optimization analysis condition, and causes the configuration of the candidate bonding line achieved for the purpose of reducing the cumulative damage degree near the candidate bonding line, improving the rigidity of the optimization analysis model, and minimizing the length of the candidate bonding line that remains to remain as a temporary optimal configuration of the candidate bonding line; a selected joining candidate line setting analysis object model generating unit, which selects a joining candidate line of a predetermined length from the joining candidate lines remaining as a temporary optimal arrangement through the optimization analysis, and sets the selected joining candidate line in the analysis object model instead of the initial joining line, thereby generating a selected joining candidate line setting analysis object model; A selected bonding candidate line performance calculation unit is configured to perform stress analysis by assigning the load conditions and restriction conditions of the vibration modes under the variable load conditions set by the variable load condition setting unit to the selected bonding candidate line setting analysis object model, and calculate the fatigue life under the variable load conditions near the selected bonding candidate line and the rigidity of the selected bonding candidate line setting analysis object model using the result of the stress analysis; a determination unit that determines whether the fatigue life under the variable load condition near the candidate joining line in the selected candidate joining line setting analysis object model and the rigidity of the selected candidate joining line setting analysis object model satisfy the performance exceeding the prescribed performance of the analysis object model in which the initial joining line is set; and An optimal joining line determination unit determines the configuration of the selected joining candidate line as the optimal configuration of the joining line when the determination unit determines that the specified performance is satisfied, and changes the condition related to the cumulative damage degree of the joining candidate line remaining after the optimization analysis, the condition related to the rigidity of the optimization analysis model, or the condition related to the length of the joining candidate line remaining after the optimization analysis set by the optimization analysis condition setting unit when the specified performance is not satisfied, and repeatedly performs the processing performed by the optimization analysis unit, the selected joining candidate line setting analysis object model generation unit, the selected joining candidate line performance calculation unit and the determination unit until the specified performance is satisfied, and determines the configuration of the joining candidate line selected when the specified performance is satisfied as the optimal configuration of the joining line.

7. An optimization analysis program for a joint position of a vehicle body, which performs optimization analysis on all or part of a vehicle body model having a plurality of component models including beam units, plane units and / or solid units and having an initial joint line for joining the plurality of component models as a component assembly, wherein the optimization analysis finds the optimal arrangement of the joint line for any one of improving the rigidity of the vehicle body model, improving the fatigue life near the joint line for joining the component assembly in the vehicle body model, and minimizing the length of the joint line, wherein: Make the computer function as: an analysis target model setting unit that sets all or part of the vehicle body model as an analysis target model; an optimized analytical model generating unit that generates an optimized analytical model obtained by setting all candidate joining lines that are candidates for the optimally arranged joining lines to the analysis target model; a variable load condition setting unit for setting a variable load condition that divides a variable load applied to the optimized analytical model into load conditions of a plurality of different vibration modes and combines the load conditions of the vibration modes into one sequence by a predetermined number of cycles; a target fatigue life setting unit that sets a target fatigue life of the optimized analytical model according to the sequence number of the variable load condition; an optimization analysis condition setting unit, which, in order to perform an optimization analysis taking the optimization analysis model as an optimization object, obtains the number of fracture repetitions near each of the candidate joining lines according to the load conditions of each vibration mode, obtains the ratio of the number of cycles of the load conditions of each vibration mode to the number of fracture repetitions, and obtains the sum of the number of sequence times of the variable load conditions set by the target fatigue life setting unit as the cumulative damage degree of each of the candidate joining lines, and sets conditions related to the cumulative damage degree of the candidate joining lines remaining after the optimization analysis, conditions related to the rigidity of the optimization analysis model, and conditions related to the length of the candidate joining lines remaining after the optimization analysis as objective functions or constraints of optimization analysis conditions; and An optimization analysis unit assigns the variable load condition set by the variable load condition setting unit to the optimization analysis model, performs optimization analysis under the optimization analysis condition, and obtains a configuration of the bonding candidate line that achieves any one of reducing the cumulative damage degree of the bonding candidate line, improving the rigidity of the optimization analysis model, and minimizing the remaining length of the bonding candidate line as the optimal configuration of the bonding line.

8. The optimization analysis program for the joint position of the vehicle body according to claim 7, wherein: The optimization analysis unit performs topology optimization based on a density method, and discretizes the topology by setting a penalty coefficient to 4 or more.

9. An optimization analysis program for a joint position of a vehicle body, which performs optimization analysis on all or part of a vehicle body model having a plurality of component models including beam units, plane units and / or solid units and having an initial joint line for joining the plurality of component models as a component assembly, wherein the optimization analysis finds the optimal arrangement of the joint line for any one of improving the rigidity of the vehicle body model, improving the fatigue life near the joint line for joining the component assembly in the vehicle body model, and minimizing the length of the joint line, wherein: Make the computer function as: an analysis target model setting unit that sets all or part of the vehicle body model as an analysis target model; an optimized analytical model generating unit that generates an optimized analytical model obtained by setting all candidate joining lines that are candidates for the optimally arranged joining lines to the analysis target model; a variable load condition setting unit for setting a variable load condition that divides a variable load applied to the optimized analytical model into load conditions of a plurality of different vibration modes and combines the load conditions of the vibration modes into one sequence by a predetermined number of cycles; a target fatigue life setting unit that sets a target fatigue life of the optimized analytical model according to the sequence number of the variable load condition; an optimization analysis condition setting unit, which, in order to perform an optimization analysis taking the optimization analysis model as an optimization object, obtains the number of fracture repetitions near each of the candidate joining lines according to the load conditions of each vibration mode, obtains the ratio of the number of cycles of the load conditions of each vibration mode to the number of fracture repetitions, and obtains the sum of the number of sequence times of the variable load conditions set by the target fatigue life setting unit as the cumulative damage degree near each of the candidate joining lines, and sets a condition related to the cumulative damage degree near the candidate joining lines remaining after the optimization analysis, a condition related to the rigidity of the optimization analysis model, and a condition related to the length of the candidate joining lines remaining in the optimization analysis as an objective function or constraint condition as an optimization analysis condition; an optimization analysis unit that assigns the variable load condition set by the variable load condition setting unit to the optimization analysis model, performs optimization analysis under the optimization analysis condition, and causes the configuration of the candidate bonding line achieved for the purpose of reducing the cumulative damage degree near the candidate bonding line, improving the rigidity of the optimization analysis model, and minimizing the length of the candidate bonding line that remains to remain as a temporary optimal configuration of the candidate bonding line; a selected joining candidate line setting analysis object model generating unit, which selects a joining candidate line of a predetermined length from the joining candidate lines remaining as a temporary optimal arrangement through the optimization analysis, and sets the selected joining candidate line in the analysis object model instead of the initial joining line, thereby generating a selected joining candidate line setting analysis object model; A selected bonding candidate line performance calculation unit is configured to perform stress analysis by assigning the load conditions and restriction conditions of the vibration modes under the variable load conditions set by the variable load condition setting unit to the selected bonding candidate line setting analysis object model, and calculate the fatigue life under the variable load conditions near the selected bonding candidate line and the rigidity of the selected bonding candidate line setting analysis object model using the result of the stress analysis; a determination unit that determines whether the fatigue life under the variable load condition near the candidate joining line in the selected candidate joining line setting analysis object model and the rigidity of the selected candidate joining line setting analysis object model satisfy the performance exceeding the prescribed performance of the analysis object model in which the initial joining line is set; and An optimal joining line determination unit determines the configuration of the selected joining candidate line as the optimal configuration of the joining line when the determination unit determines that the specified performance is satisfied, and changes the condition related to the cumulative damage degree near the joining candidate line remaining after the optimization analysis, the condition related to the rigidity of the optimization analysis model, or the condition related to the length of the joining candidate line remaining after the optimization analysis set by the optimization analysis condition setting unit when the specified performance is not satisfied, and repeatedly performs the processing performed by the optimization analysis unit, the selected joining candidate line setting analysis object model generation unit, the selected joining candidate line performance calculation unit and the determination unit until the specified performance is satisfied, and determines the configuration of the joining candidate line selected when the specified performance is satisfied as the optimal configuration of the joining line.

10. A method for manufacturing a vehicle body, wherein the vehicle body has a joint line optimally arranged to improve the rigidity of the vehicle body and the fatigue life of the joint line, wherein the joint line joins component assemblies in the vehicle body, Using the optimization analysis method for the joining position of the vehicle body described in any one of claims 1 to 3, the optimal configuration of the joining line is obtained, and the joining position of the component assembly in the vehicle body is determined based on the obtained optimal configuration of the joining line, and the component assembly of the vehicle body is joined at the determined joining position.

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