Automobile body design method, device, program, and automobile body manufacturing method

Abstract

To provide an automobile body designing method, an apparatus and a program for designing an automobile body in which a vibration damping property of a white body structure of an automobile body is improved by bonding a sheet member to the surface of an automobile body part constituting the white body structure, and a method for manufacturing the automobile body.SOLUTION: The automobile body designing method according to the present invention is an automobile body designing method in which a vibration damping property of a white body structure 100 is improved by bonding a sheet member to the surface of an automobile body part constituting the white body structure 100 of an automobile body. The method includes: automobile body part selection step S1 for performing sensitivity analysis of automobile body parts to vibration characteristics used for evaluating vibration resistance of the white body structure 100 and selecting an automobile body part to be bonded to the sheet member; and sheet member optimization analysis step S3 for performing optimization analysis on a shape of the sheet member to be bonded to the selected automobile body part.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an automobile body design method, an apparatus, and a program for designing an automobile body having high vibration damping properties, and a method for manufacturing an automobile body. [Background technology]

[0002] In recent years, there is an ever-increasing demand for the development of efficient design methods for automobile bodies with excellent vibration damping. One of the major factors behind this is the widespread use of electric vehicles. Electric vehicles do not have the vibration and noise generated by the internal combustion engines that are installed in conventional gasoline vehicles, etc., and therefore passengers are more sensitive to vibration and noise from other vibration sources. In addition, since electric vehicles need to be equipped with large-capacity batteries, the body frame structure of electric vehicles, combined with the protective structure for the battery, may differ significantly from the body frame structure of conventional gasoline vehicles, etc. In such cases, the vibration transmission path in electric vehicles is different from that of conventional gasoline vehicles, etc., and conventional rules of thumb regarding the vibration damping structure of automobile bodies do not apply.

[0003] Conventionally, as a technology for efficiently designing high-performance automobile bodies, for example, Patent Document 1 applies optimization analysis to obtain the optimal shape of an automobile body part using a computer. This technology is a method for obtaining the optimal shape of an automobile body part by setting a design space, constraint conditions, and load conditions for the automobile body part to be optimized, and deleting unnecessary parts in the design space so as to satisfy target conditions related to the automobile body performance such as rigidity and weight. Moreover, Patent Document 2 discloses a method for determining an optimal plate thickness of a frame part for reducing vibration noise of a panel part of an automobile. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5585672 [Patent Document 2] Patent No. 6769536 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the method disclosed in Patent Document 1, it is possible to obtain the optimal three-dimensional shape of an autobody part that achieves objective functions such as minimizing strain energy, minimizing generated stress, and maximizing collision absorption energy for multiple set input loads.

[0006] Therefore, in order to improve the vibration damping of the entire body-in-white structure of an automobile body, it is conceivable to apply the optimization analysis technology described in Patent Document 1 to the optimization of frequency response in the vibration and acoustic fields to obtain the optimal shape of the body parts that improves the vibration damping. However, as a result of attempting this, the optimal shapes of the body parts were sparsely scattered in three dimensions, and no shape useful for the actual body-in-white structure was obtained. Therefore, even if the optimal three-dimensional shape was obtained by the optimization analysis technology, it was not possible to obtain a part shape that can be manufactured by press molding or the like from the obtained optimal shape.

[0007] Also, according to the method disclosed in Patent Document 2, it is possible to optimize the plate thickness distribution of the vehicle body parts that are configured as an automobile body in terms of acoustic performance. However, since this method is premised on the reconstruction of the plate thickness distribution in the vehicle body parts, although vibration damping performance is improved, there are cases where it is difficult to improve vibration damping performance while maintaining other vehicle body performance, for example, the vehicle body rigidity is reduced.

[0008] The present invention has been made to solve the above-mentioned problems, and has an object to provide an automobile body design method, device, and program for designing an automobile body with improved vibration-damping performance of a body-in-white structure while maintaining vehicle body performance other than vibration-damping performance such as rigidity. Furthermore, the present invention has an object to provide an automobile body manufacturing method for manufacturing an automobile body with improved vibration-damping performance of a body-in-white structure while maintaining vehicle body performance other than vibration-damping performance such as rigidity. [Means for solving the problem]

[0009] In order to solve the above problems, the inventors have earnestly studied a method for designing an automobile body that can improve vibration damping while maintaining the body performance such as the rigidity of the original automobile body. As a result, they came up with the idea of ​​selecting an automobile body part that is effective in improving the vibration damping of the entire body-in-white structure, and adjusting the mass distribution of the automobile body part by attaching a plate-like part without changing the shape and plate thickness of the selected automobile body part. Then, for the plate-like parts to be attached to the selected body parts, from the standpoint of vibration-damping and weight reduction of the body-in-white structure, the team decided to use topology optimization to find the optimal shape for the plate-like parts by removing parts that do not affect the vibration characteristics. In this way, by selecting body parts that are effective in improving vibration damping and determining the optimal shape of plate-like parts to be attached to the selected body parts, we have come up with the idea of ​​improving the vibration damping of the entire body-in-white structure while maintaining vehicle performance such as rigidity.

[0010] Furthermore, the researchers also conducted intensive research into methods for making the shape of the plate-like parts remaining after optimization analyses such as topology optimization into shapes that are easy to manufacture as actual plate-like parts. As a result, the two-dimensional space along the surface of the selected body part was set as the design space, a plate-like part model made of shell elements was generated and attached to the body part, and topology optimization was performed to find the optimal shape of the plate-like part model. This led to the discovery that the optimal shape of the plate-like part model remaining after topology optimization is a shape that is easy to manufacture as an actual plate-like part.

[0011] The present invention has been made based on such findings, and specifically comprises the following configurations.

[0012] (1) An automobile body design method according to the present invention is a method for designing an automobile body having improved vibration damping performance by attaching plate-shaped parts to surfaces of body parts constituting a body-in-white structure of the automobile body, the method comprising the steps of: a vehicle body part selection step of performing a sensitivity analysis of the vehicle body part with respect to vibration characteristics used in an evaluation of vibration damping performance of the body-in-white structure, and selecting a vehicle body part to which the plate-like part is to be attached; a plate-like part optimization analysis step of performing optimization analysis on the shape of a plate-like part to be attached to the selected vehicle body part, The vehicle body part selection step includes: a sensitivity analysis condition setting step of setting, as sensitivity analysis conditions, an objective function related to vibration characteristics of the body-in-white structure, constraint conditions related to the weight of the body-in-white structure and the plate thicknesses of the vehicle body parts, and vibration input conditions related to vibrations applied to the body-in-white structure; a sensitivity analysis step of performing the sensitivity analysis under the set sensitivity analysis conditions to obtain a sensitivity of each of the vehicle body parts to the vibration characteristics of the body-in-white structure; and a plate-like part attachment target vehicle body part selection step of selecting a vehicle body part to which the plate-like part is to be attached based on the sensitivity obtained for each vehicle body part, The plate-shaped part optimization analysis step includes: a design space setting step of setting a two-dimensional space along the surface of the vehicle body part selected in the vehicle body part selection step as a design space to be subjected to the optimization analysis; a plate-like part model generating step of generating a plate-like part model that is modeled with shell elements in the set design space and is subjected to optimization analysis processing; a coupling process step of coupling the generated plate-like part model to the vehicle body part selected in the vehicle body part selection step; an optimization analysis condition setting step of setting the objective function and the vibration input condition set as the sensitivity analysis conditions, and a constraint condition related to a weight of the body-in-white structure, as optimization analysis conditions for performing the optimization analysis; and an optimization analysis step of performing the optimization analysis to find an optimal shape of the plate-like part model under the set optimization analysis conditions.

[0013] (2) In the above (1), In the sensitivity analysis condition setting step, An objective function that minimizes a frequency response value of either acceleration, inertance, or equivalent radiated power in a predetermined frequency band; A constraint condition that the plate thickness of each of the vehicle body parts is equal to or greater than the original plate thickness of each of the vehicle body parts; The present invention is characterized in that a vibration input condition is set for inputting a predetermined vibration to one or more parts of the body-in-white structure.

[0014] (3) The automobile body designing device according to the present invention is for designing an automobile body having improved vibration damping properties of a body-in-white structure by attaching a plate-shaped part to a surface of a body part constituting the body-in-white structure of the automobile body, a vehicle body part selection unit that performs a sensitivity analysis of the vehicle body part with respect to vibration characteristics used in evaluating the vibration damping property of the body-in-white structure, and selects a vehicle body part to which the plate-like part is to be attached; a plate-like part optimization analysis unit that performs optimization analysis on the shape of a plate-like part to be attached to the selected vehicle body part, The vehicle body part selection unit includes: a sensitivity analysis condition setting unit that sets, as sensitivity analysis conditions, an objective function related to vibration characteristics of the body-in-white structure, constraint conditions related to the weight of the body-in-white structure and the plate thicknesses of the vehicle body parts, and vibration input conditions related to vibrations applied to the body-in-white structure; a sensitivity analysis unit that performs the sensitivity analysis under the set sensitivity analysis conditions and obtains a sensitivity of each of the vehicle body parts to the vibration characteristics of the body-in-white structure; a plate-like part attachment target vehicle body part selection unit that selects a vehicle body part to which the plate-like part is to be attached based on the sensitivity obtained for each of the vehicle body parts, The plate-shaped part optimization analysis unit includes: a design space setting unit that sets a two-dimensional space along a surface of the vehicle body part selected by the vehicle body part selection unit as a design space to be subjected to the optimization analysis; a plate-like part model generation unit that generates a plate-like part model that is modeled with shell elements in the set design space and that performs optimization analysis processing; a combining processing unit that combines the generated plate-like part model with the body part selected by the body part selection unit; an optimization analysis condition setting unit that sets the objective function and the vibration input condition that are set as the sensitivity analysis conditions, and a constraint condition related to a weight of the body-in-white structure, as optimization analysis conditions for performing the optimization analysis; and an optimization analysis unit that performs the optimization analysis to find an optimal shape of the plate-like part model under the set optimization analysis conditions.

[0015] (4) The automobile body design program according to the present invention is for designing an automobile body having improved vibration damping properties of a body-in-white structure by attaching a plate-shaped part to a surface of a body part constituting the body-in-white structure of the automobile body, a vehicle body part selection unit that performs sensitivity analysis of the vehicle body parts with respect to vibration characteristics used in evaluating the vibration damping performance of the body-in-white structure and selects a vehicle body part to which the plate-like part is to be attached; a plate-shaped part optimization analysis unit that performs optimization analysis on the shape of a plate-shaped part to be attached to the selected vehicle body part; and The vehicle body part selection unit, a sensitivity analysis condition setting unit that sets, as sensitivity analysis conditions, an objective function related to vibration characteristics of the body-in-white structure, constraint conditions related to the weight of the body-in-white structure and the plate thicknesses of the vehicle body parts, and vibration input conditions related to vibrations applied to the body-in-white structure; a sensitivity analysis unit that performs the sensitivity analysis under the set sensitivity analysis conditions and obtains a sensitivity of each of the vehicle body parts to the vibration characteristics of the body-in-white structure; a plate-like part attachment target vehicle body part selection unit that selects a vehicle body part to which the plate-like part is to be attached based on the sensitivity obtained for each vehicle body part; The plate-shaped part optimization analysis unit, a design space setting unit that sets a two-dimensional space along a surface of the vehicle body part selected by the vehicle body part selection unit as a design space to be subjected to the optimization analysis; a plate-like part model generation unit that generates a plate-like part model that is modeled with shell elements in the set design space and that performs optimization analysis processing; a combining processing unit that combines the generated plate-like part model with the body part selected by the body part selection unit; an optimization analysis condition setting unit that sets the objective function and the vibration input condition that are set as the sensitivity analysis conditions, and a constraint condition related to a weight of the body-in-white structure, as optimization analysis conditions for performing the optimization analysis; The optimization analysis unit is characterized in that it functions as an optimization analysis unit that performs the optimization analysis to find an optimal shape for the plate-like part model under the set optimization analysis conditions.

[0016] (5) A method for manufacturing an automobile body according to the present invention is for manufacturing an automobile body having improved vibration damping properties of a body-in-white structure by attaching a plate-shaped part to a surface of a body part constituting the body-in-white structure of the automobile body, Using the automobile body design method described in (1) or (2) above, an optimal shape of a plate-like part model to be attached to the vehicle body part selected in the body-in-white structure is obtained; determining a shape and a position of the plate-like part to be attached to the selected vehicle body part based on the obtained optimal shape of the plate-like part model; manufacturing the plate-shaped part based on the determined shape of the plate-shaped part; The method is characterized in that the manufactured plate-like part is attached to the selected body part in the body-in-white structure using the determined position of the plate-like part. Effect of the Invention

[0017] According to the present invention, by appropriately selecting the vehicle body part to which a plate-like part is attached and by determining the optimal shape of the plate-like part model through optimization analysis, it is possible to design an automobile body with improved vibration-damping properties of the body-in-white structure. Furthermore, according to the present invention, a two-dimensional space along the surface of a selected vehicle body part is set as a design space, and optimization analysis is performed to determine the optimal shape of a plate-like part model, thereby making it possible to obtain a shape that is easy to manufacture as an actual plate-like part by press molding or the like. Furthermore, according to the present invention, it is possible to manufacture an automobile body with improved vibration damping properties of the body-in-white structure while maintaining vehicle body performance other than vibration damping properties such as rigidity. [Brief description of the drawings]

[0018] [Figure 1] 1 is a block diagram showing a configuration of an automobile body designing device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a body-in-white structure of an automobile body that is an analysis target in the first embodiment. [Diagram 3] 3A and 3B are diagrams showing specific examples of portions for determining vibration characteristics used in evaluating the vibration damping performance of a body-in-white structure in the first embodiment ((a) roof panel, (b) roof center RF and floor cross member). [Figure 4] In the first embodiment, this shows the frequency response of the inertance of the roof center RF, which is obtained as an example of vibration characteristics used for evaluating the vibration damping performance of the body-in-white structure. [Diagram 5] FIG. 11 is a diagram showing the plate thickness change rate for each body part obtained by sensitivity analysis in the present embodiment 1, Example 2 and Example 6, and the body part selected as the target to which the plate-shaped part is attached based on the plate thickness change rate ((a) sensitivity analysis result, (b) selected body part). [Figure 6] FIG. 11 is a diagram showing the results of determining an optimal shape of a plate-like part model to be attached to a vehicle body part selected based on the results of sensitivity analysis in the first and second embodiments and in the second and sixth examples. [Figure 7]3 is a flowchart showing a process flow of the automobile body design method according to the first embodiment. FIG. [Figure 8] FIG. 11 is a diagram showing the plate thickness change rate for each vehicle body part obtained by sensitivity analysis in Example 1, and the vehicle body part selected as the target to which a plate-shaped part is attached based on the plate thickness change rate ((a) sensitivity analysis result, (b) selected vehicle body part). [Figure 9] 10 is a diagram showing the results of determining an optimal shape of a plate-like part model to be attached to a vehicle body part selected based on the result of a sensitivity analysis in Example 1. FIG. [Figure 10] FIG. 11 is a diagram showing the plate thickness change rate for each vehicle body part obtained by sensitivity analysis in Example 3, and the vehicle body part selected as the target to which a plate-shaped part is attached based on the plate thickness change rate ((a) sensitivity analysis result, (b) selected vehicle body part). [Figure 11] FIG. 11 is a diagram showing the results of determining an optimal shape of a plate-like part model to be attached to a vehicle body part selected based on the results of sensitivity analysis in Example 3. [Figure 12] FIG. 11 is a diagram showing the plate thickness change rate for each body part obtained by sensitivity analysis in Example 4, and the body part selected as the target to which a plate-shaped part is attached based on the plate thickness change rate ((a) sensitivity analysis result, (b) selected body part). [Figure 13] FIG. 13 is a diagram showing the results of determining an optimal shape of a plate-like part model to be attached to a vehicle body part selected based on the result of sensitivity analysis in Example 4. [Figure 14] FIG. 11 is a diagram showing the plate thickness change rate for each element of a body part obtained by sensitivity analysis in Example 5, and the body part selected as the target to which a plate-shaped part is attached based on the plate thickness change rate ((a) sensitivity analysis result, (b) selected body part). [Figure 15] FIG. 13 is a diagram showing the results of determining an optimal shape of a plate-like part model to be attached to a vehicle body part selected based on the result of a sensitivity analysis in Example 5. [Figure 16] FIG. 23 is a diagram showing the results of determining an optimal shape of a plate-like part model to be attached to a vehicle body part selected based on the result of sensitivity analysis in Example 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Prior to describing the first and second embodiments of the present invention, a body-in-white structure of an automobile body to which the present invention is applied will be described. In the drawings of the present application, the X direction, the Y direction, and the Z direction respectively indicate the front-rear direction, the width direction, and the up-down direction of the vehicle body.

[0020] <Body-in-white structure> A body-in-white structure 100 of an automobile body is composed of body parts such as body frame parts and panel parts, as shown in Fig. 2. Examples of the body frame parts include a center pillar 101, a roof center RF 103, a floor cross member 105, and a rear side sill 107. Examples of the panel parts include a roof panel 109 and a door panel 111.

[0021] As described below, the present invention performs sensitivity analysis of the body parts with respect to the vibration characteristics of the body-on-white structure 100, and optimization analysis to obtain the optimal shape of a plate-like part model to be attached to the body parts. For this reason, the body parts constituting the body-on-white structure 100 are assumed to be modeled using shell elements and / or solid elements. Furthermore, element information and material properties of the body parts constituting the body-on-white structure 100 are assumed to be stored in a body-on-white structure model file 21 (FIG. 1) described below.

[0022] [Embodiment 1] <Automobile body design device> The automobile body designing device according to the first embodiment of the present invention is for attaching plate-shaped parts to the surfaces of body parts constituting a body-in-white structure 100 of an automobile body, thereby designing an automobile body with improved vibration damping performance of the body-in-white structure 100. As shown in FIG. 1 as an example, the automobile body designing device 1 is configured by a PC (personal computer) or the like, and includes a display device 3, an input device 5, a storage device 7, a working data memory 9, and a calculation processing unit 11. The display device 3, the input device 5, the storage device 7, and the working data memory 9 are connected to the calculation processing unit 11, and each function is executed by a command from the calculation processing unit 11. Each component of the automobile body designing device 1 will be described below.

[0023] The display device 3 is used to display the analysis results and is configured with a liquid crystal monitor or the like. The input device 5 is used for issuing display instructions for the body-in-white structural model file 21 and inputting conditions by an operator, and is composed of a keyboard, a mouse, and the like. The storage device 7 is used for storing various files such as the body-in-white structural model file 21, and is configured with a hard disk or the like. The working data memory 9 is used for temporary storage of data used by the arithmetic processing unit 11 and for calculations, and is composed of a RAM (Random Access Memory) or the like.

[0024] 1, the calculation processing unit 11 has a body part selection unit 13 and a plate-like part optimization analysis unit 15, and is configured by a CPU (Central Processing Unit) such as a PC. Each of these units functions by the CPU executing a predetermined program. The functions of each of the above units in the arithmetic processing unit 11 will be described below.

[0025] <Body parts selection unit> The body part selection unit 13 performs sensitivity analysis of each body part with respect to vibration characteristics used in evaluating the vibration damping performance of the body-in-white structure 100, and selects the body part to which the plate-like part is to be attached. As shown in Fig. 1, the body part selection unit 13 has a sensitivity analysis condition setting unit 13a, a sensitivity analysis unit 13b, and a plate-like part attachment target body part selection unit 13c.

[0026] (Sensitivity analysis condition setting section) The sensitivity analysis condition setting unit 13a sets sensitivity analysis conditions in sensitivity analysis of body parts for vibration characteristics used in evaluating the vibration damping performance of the body-on-white structure 100. The sensitivity analysis condition setting unit 13a sets, as the sensitivity analysis conditions, an objective function related to the vibration characteristics of the body-on-white structure 100 and constraint conditions related to the weight of the body-on-white structure 100 and the plate thickness of each body part. Furthermore, the sensitivity analysis condition setting unit 13a sets, as the sensitivity analysis conditions, vibration input conditions related to vibrations applied to the body-on-white structure 100.

[0027] The objective function is set according to the vibration characteristics used to evaluate the vibration damping performance of the body-in-white structure 100. The vibration characteristics include frequency response values ​​such as acceleration, inertance, or equivalent radiation power in a predetermined frequency band at a predetermined part of the body-in-white structure 100.

[0028] Inertance is the ratio of the force input to an object to the acceleration generated by it, and is also called the vibration transfer function. Inertance I can be calculated using the following formula (1).

number

[0029] Equivalent radiated power is an index that simply expresses the sound level emitted by a structure, and is based on the idea that the perpendicular component of the vibration velocity of a structure gives energy to the acoustic space. Equivalent radiated power ERP can be calculated using the following formula (2), and represents the acoustic radiation energy per unit time.

number

[0030] FIG. 3 shows an example of a portion for evaluating vibration characteristics. FIG. 3(a) is a diagram showing a roof panel 109 for evaluating equivalent radiated power as a vibration characteristic. FIG. 3(b) is a diagram showing a roof center RF 103 and a floor cross member 105, the inertance of which is evaluated as a vibration characteristic.

[0031] FIG. 4 shows a frequency response of the vertical inertance at the center of the roof center RF103 as an example of vibration characteristics.

[0032] In the first embodiment, minimization of the vertical inertance in the frequency band of 95 Hz to 115 Hz in the central portion of the roof center RF 103 in the body-in-white structure 100 is set as the objective function.

[0033] The location of the body-in-white structure 100 for evaluating vibration characteristics is appropriately set according to instructions from the operator.

[0034] The constraint conditions are restrictions imposed when performing sensitivity analysis of the vehicle body parts with respect to the vibration characteristics of the body-in-white structure 100. In this embodiment 1, the sensitivity analysis condition setting unit 13a sets the total weight of the white body structure 100 to be less than a predetermined weight as a constraint condition regarding the weight of the white body structure 100, and sets the original thickness of each body part or more as a constraint condition regarding the plate thickness of each body part.

[0035] The vibration input conditions are conditions related to vibrations applied to the body-in-white structure 100 in a sensitivity analysis of each vehicle part with respect to the vibration characteristics of the body-in-white structure 100. As vibration conditions, the amplitude (magnitude of vibration), frequency (number of vibrations), and part to which vibration is applied are set. Examples of parts to which vibration is applied include the front subframe 113 and the suspension tower 115 indicated by triangle marks in FIG.

[0036] The sensitivity analysis condition setting unit 13a sets vibration input conditions for applying predetermined vibrations to one or more locations of the body-in-white structure 100. As an example of a mode for applying a predetermined vibration to one location, a vibration input condition is set to apply a predetermined vibration to either the front subframe 113 or the suspension tower 115. As an example of a mode for applying a predetermined vibration to two parts, vibration input conditions are set to apply a predetermined vibration to both the front subframe 113 and the suspension tower 115, or to these parts as well as other parts.

[0037] When vibrations are applied to a plurality of parts, the vibrations may be of the same amplitude and frequency to these parts, or may be of different amplitudes or frequencies at least.

[0038] (Sensitivity analysis section) The sensitivity analysis unit 13b performs sensitivity analysis under the sensitivity analysis conditions set by the sensitivity analysis condition setting unit 13a, and obtains the sensitivity of each vehicle body part to the vibration characteristics of the body-in-white structure 100.

[0039] In the first embodiment, the sensitivity analysis by the sensitivity analysis unit 13b performs a plate thickness optimization analysis of each vehicle body part. 0 The thickness change rate (=(tt 0 )×100 / t 0 Calculate the percentage.

[0040] However, the sensitivity analysis unit 13b may use, for example, the optimum plate thickness t and the original plate thickness t 0 The difference between (=tt 0 ) and the optimum plate thickness t and the original plate thickness t 0 Ratio to (=t / t 0 ) may be calculated.

[0041] In addition, the sensitivity analysis unit 13b may be either a plate thickness optimization analysis that finds the optimal plate thickness for the entire body part, or a plate thickness optimization analysis that finds the optimal plate thickness for each shell element used to model the body part.

[0042] FIG. 5(a) shows an example of the results of a sensitivity analysis performed to obtain the sensitivity of each vehicle body part of the body-in-white structure 100 shown in FIG. 5(a) shows the results when an objective function for minimizing the inertance of the central portion of the roof center RF 103 and constraints for limiting the increase in weight of the body-in-white structure 100 to 5 kg and for limiting the plate thickness of the vehicle body parts to the original plate thickness or more are given as sensitivity analysis conditions. Furthermore, a vibration input condition for applying a predetermined vibration to the front subframe 113 is given as a sensitivity analysis condition.

[0043] As shown in FIG. 5( a ), the thickness change rate is large in body parts such as the roof center RF 103 , the roof rail 117 , and the wheel house 119 , and therefore it can be seen that these body parts are highly sensitive to the vibration characteristics of the body-in-white structure 100 .

[0044] (Selection of vehicle body parts to which plate-shaped parts are attached) The plate-like part attachment target vehicle body part selection unit 13c selects a vehicle body part to which the plate-like part is to be attached, based on the sensitivity obtained for each vehicle body part by the sensitivity analysis unit 13b.

[0045] When the sensitivity analysis unit 13b performs a plate thickness optimization analysis to find sensitivity for each vehicle body part, the plate-like part attachment target vehicle body part selection unit 13c selects vehicle body parts whose sensitivity is greater than a predetermined value set in advance. On the other hand, when the sensitivity analysis unit 13b performs a plate thickness optimization analysis to obtain sensitivity for each shell element of the body part, the ratio of shell elements having a sensitivity equal to or greater than a predetermined value is calculated among the shell elements included in each body part. Then, the body part having a large ratio of the calculated shell elements is selected.

[0046] FIG. 5(b) shows a roof center RF 103, a roof rail 117, a wheel house 119, etc., which have a large thickness change rate of 5% or more and have been selected as targets for attaching plate-like parts.

[0047] <Plate-shaped Parts Optimization Analysis Unit> The plate-like part optimization analysis unit 15 performs optimization analysis on the shape of a plate-like part to be attached to the vehicle body part selected by the vehicle body part selection unit 13. As shown in Fig. 1, the plate-like part optimization analysis unit 15 has a design space setting unit 15a, a plate-like part model generation unit 15b, a connection processing unit 15c, a material property setting unit 15d, an optimization analysis condition setting unit 15e, and an optimization analysis unit 15f.

[0048] (Design space setting department) The design space setting unit 15a sets a two-dimensional space along the surface of the body part selected by the body part selection unit 13 as a design space to be subjected to optimization analysis.

[0049] (Plate-shaped part model generation unit) The plate-like part model generating unit 15b generates a plate-like part model that is modeled with shell elements and performs optimization analysis processing in the design space set by the design space setting unit 15a.

[0050] (Combination processing section) The merging processing unit 15c is configured to merge the plate-like part model generated by the plate-like part model generating unit 15b with the vehicle body part selected by the vehicle body part selecting unit 13.

[0051] The plate-like part model and the vehicle body part may be connected, for example, by connecting the nodes of the plate-like part model and the nodes of the vehicle body part with elements (rigid elements, elastic elements, or elasto-plastic elements) (rigid connections or elastic connections).

[0052] (Material property setting section) The material property setting unit 15d sets material properties for the plate-like part model. The material properties to be set may be set according to the type of material (steel plate, etc.) of the plate-like part to be attached to the actual vehicle body part. The material properties set in the plate-shaped part model by the material property setting unit 15d may be set according to the type of material (steel plate, etc.) of the plate-shaped part to be attached to the actual vehicle body part. The plate thickness set in the plate-shaped part model may be the plate thickness of the material to be actually applied. There is no particular restriction on the plate thickness value, but it is preferable that it is within the range that can be regarded as a plate material (approximately 0.5 mm to 10 mm). The setting of the material properties of the plate-like part model by the joining processing unit 15c may be performed either before or after the joining processing unit 15c joins the plate-like part model to the vehicle body part.

[0053] (Optimization analysis condition setting section) The optimization analysis condition setting unit 15e sets the objective function and vibration input conditions set as the sensitivity analysis conditions by the sensitivity analysis condition setting unit 13a, and the constraint conditions related to the weight of the body-in-white structure 100, as optimization analysis conditions.

[0054] The optimization analysis condition setting unit 15e can set an objective function for minimizing the frequency response value of any of the acceleration, inertance, or equivalent radiated power in a predetermined frequency band at a predetermined portion of the body-in-white structure 100. Furthermore, the optimization analysis condition setting unit 15e can set vibration input conditions for inputting predetermined vibrations to one or more parts of the body-in-white structure 100.

[0055] In the present embodiment 1, the optimization analysis condition setting unit 15e sets an objective function for minimizing the inertance of the central portion of the roof center RF103 in a predetermined frequency band, and a constraint condition on the weight of the body-in-white structure 100. Furthermore, in the present embodiment 1, the optimization analysis condition setting unit 15e sets a vibration input condition for inputting a predetermined vibration to the front subframe 113 of the body-in-white structure 100.

[0056] (Optimization Analysis Section) The optimization analysis unit 15f performs optimization analysis to find the optimal shape of the plate-like part model under the optimization analysis conditions set by the optimization analysis condition setting unit 15e.

[0057] For example, topology optimization of shell elements may be applied to the optimization analysis by the optimization analysis unit 15f. In topology optimization using the density method, optimization analysis processing is performed using the density of the shell elements of the plate-like part model as a design variable, and the optimal shape of the plate-like part model is obtained by retaining and eliminating the shell elements. Furthermore, the optimal position of the plate-like part model can be obtained from the positions of the shell elements that remain in the optimization analysis processing.

[0058] In addition, when there are many intermediate densities in topology optimization using the density method, it is preferable to discretize by giving a penalty coefficient as an optimization parameter. In this case, the value of the penalty coefficient can be set appropriately.

[0059] The optimization analysis unit 15f is not limited to the one that performs topology optimization as described above, and may perform optimization analysis using other calculation methods. In addition, the optimization analysis unit 15f may use, for example, commercially available analysis software using the finite element method.

[0060] FIG. 6 shows an example of an optimal shape of a plate-like part model obtained by performing optimization analysis by the optimization analysis unit 15f. As shown in FIG. 6, an optimal shape 121 of the plate-like part model to be attached to the roof center RF 103, an optimal shape 123 of the plate-like part model to be attached to the roof rail 117, and an optimal shape 125 of the plate-like part model to be attached to the wheel house 119 were obtained.

[0061] <Automobile body design method> The automobile body design method according to the first embodiment is for designing an automobile body with improved vibration damping performance of the body-in-white structure 100 by attaching plate-like parts to the surfaces of the body parts constituting the body-in-white structure 100 of the automobile body. The automobile body design method according to the first embodiment is performed by a computer to execute the steps shown in Fig. 7, and includes a body part selection step S1 and a plate-like part optimization analysis step S3.

[0062] <Body part selection steps> The vehicle body part selection step S1 is a step of performing sensitivity analysis of the vehicle body parts with respect to vibration characteristics used in evaluating the vibration damping property of the body-in-white structure 100, and selecting the vehicle body parts to which the plate-like parts are to be attached. As shown in Fig. 7, the vehicle body part selection step S1 includes a sensitivity analysis condition setting step S1a, a sensitivity analysis step S1b, and a vehicle body part selection step S1c to which the plate-like parts are to be attached. In the first embodiment, the vehicle body part selection step S1 is executed by the vehicle body part selection unit 13 of the automobile body design device 1.

[0063] (Sensitivity analysis condition setting process) The sensitivity analysis condition setting process S1a is a process for setting sensitivity analysis conditions in a sensitivity analysis of vehicle body parts with respect to vibration characteristics used in evaluating the vibration damping performance of the body-on-white structure 100. Then, as the sensitivity analysis conditions, an objective function related to the vibration characteristics of the body-on-white structure 100, constraint conditions related to the weight of the body-on-white structure 100 and the plate thickness of each vehicle body part, and vibration input conditions related to vibrations applied to the body-on-white structure 100 are set.

[0064] In the first embodiment, the sensitivity analysis condition setting step S1a is executed by the sensitivity analysis condition setting unit 13a of the automobile body design device 1.

[0065] In the sensitivity analysis condition setting step S1a, an objective function can be set to minimize the frequency response value of any of the acceleration, inertance, or equivalent radiated power in a predetermined frequency band at a predetermined portion of the body-in-white structure 100. Here, the inertance can be calculated by the above-mentioned formula (1), and the equivalent radiated power can be calculated by the above-mentioned formula (2).

[0066] In the sensitivity analysis condition setting process S1a, the constraint condition regarding the weight of the white body structure 100 can be set to a total weight of the white body structure 100 being less than a predetermined weight, and the constraint condition regarding the plate thickness of each body part can be set to be greater than or equal to the original plate thickness of each body part.

[0067] Furthermore, in the sensitivity analysis condition setting step S1a, vibration input conditions for inputting predetermined vibrations to one or more parts of the body-in-white structure 100 can be set.

[0068] As an example of a mode for applying a predetermined vibration to one location, a vibration input condition is set to apply a predetermined vibration to either the front subframe 113 or the suspension tower 115, as shown by a triangle mark in FIG. As an example of a mode for applying a predetermined vibration to two parts, for example, in FIG. 2, both the front subframe 113 and the suspension tower 115, or these parts plus other parts, are set as the parts to be vibrated, and vibration input conditions are set to apply the predetermined vibration to these multiple parts.

[0069] When vibrations are applied to a plurality of parts, the vibrations may be of the same amplitude and frequency to these parts, or may be of different amplitudes or frequencies at least.

[0070] (Sensitivity analysis process) The sensitivity analysis step S1b is a step of performing a sensitivity analysis under the sensitivity analysis conditions set in the sensitivity analysis condition setting step S1a, and determining the sensitivity of each vehicle body part to the vibration characteristics of the body-in-white structure 100. In the first embodiment, the sensitivity analysis step S1b is executed by the sensitivity analysis unit 13b of the automobile body design device 1.

[0071] The sensitivity analysis in the sensitivity analysis step S1b can be applied to the thickness optimization analysis of each vehicle body part. In this case, the original thickness t 0 The thickness change rate (=(tt 0 )×100 / t 0 [%]) can be calculated. For example, the optimum plate thickness t and the original plate thickness t 0 The difference between (=tt 0 ) and the optimum plate thickness t and the original plate thickness t 0 Ratio to (=t / t 0 ) may be calculated as the sensitivity.

[0072] In addition, the sensitivity analysis in the sensitivity analysis process S1b may be either a thickness optimization analysis that determines the optimal thickness for the entire body part, or a thickness optimization analysis that determines the optimal thickness for each shell element used to model the body part.

[0073] (Process for selecting vehicle body parts to which plate-shaped parts are attached) The plate-shaped part attachment target vehicle body part selection step S1c is a step of selecting a vehicle body part to which the plate-shaped part is to be attached, based on the sensitivity obtained for each vehicle body part in the sensitivity analysis step S1b. In the first embodiment, the plate-like part affixed target vehicle body part selection step S1c is executed by the plate-like part affixed target vehicle body part selection unit 13c of the automobile body designing device 1.

[0074] When a plate thickness optimization analysis is performed in the sensitivity analysis step S1b to find sensitivity for each vehicle body part, a vehicle body part having a sensitivity greater than a predetermined value set in advance is selected in the plate-shaped part attachment target vehicle body part selection step S1c. On the other hand, when a plate thickness optimization analysis is performed to obtain sensitivity for each shell element of the body part in the sensitivity analysis step S1b, the ratio of shell elements whose sensitivity is equal to or greater than a predetermined value is calculated among the shell elements included in each body part. Then, the body part with the highest ratio of calculated shell elements is selected.

[0075] <Plate part optimization analysis step> The plate-like part optimization analysis step S3 is a step of performing optimization analysis on the shape of a plate-like part to be attached to the vehicle body part selected in the vehicle body part selection step S1. The plate-like part optimization analysis step S3 includes a design space setting step S3a, a plate-like part model generation step S3b, a joining processing step S3c, a material property setting step S3d, an optimization analysis condition setting step S3e, and an optimization analysis step S3f, as shown in Fig. 7. In the first embodiment, the plate part optimization analysis step S3 is executed by the plate part optimization analysis unit 15 of the automobile body design device 1.

[0076] (Design space setting process) The design space definition step S3a is a step of defining a two-dimensional space along the surface of the vehicle body part selected in the vehicle body part selection step S1 as a design space to be subjected to optimization analysis. In the first embodiment, the design space setting step S3a is executed by the design space setting unit 15a of the automobile body design device 1.

[0077] (Plate part model generation process) The plate-like part model generating step S3b is a step of generating a plate-like part model that is modeled with shell elements and subjected to optimization analysis processing in the design space set in the design space setting step S3a. In the first embodiment, the plate part model generating step S3b is executed by the plate part model generating unit 15b of the automobile body design device 1.

[0078] (Bonding process) The combining process step S3c is a step of combining the plate-like part model generated in the plate-like part model generating step S3b with the vehicle body part selected in the vehicle body part selecting step S1. In the first embodiment, the combining process step S3c is executed by the combining processing unit 15c of the automobile body designing apparatus 1.

[0079] In the joining processing step S3c, the joining between the plate-like part model and the vehicle body part may be, for example, by joining the nodes of the plate-like part model and the nodes of the vehicle body part with elements (rigid elements, elastic elements, or elasto-plastic elements) (rigid joining or elastic joining).

[0080] (Material property setting process) The material property setting step S3d is a step of setting material properties for the plate-like part model. In the first embodiment, the material property setting step S3d is executed by the material property setting unit 15d of the automobile body designing apparatus 1. The material properties set in the material property setting step S3d may be set according to the type of material (steel plate, etc.) of the plate-shaped part to be attached to the actual vehicle body part. The plate thickness set in the plate-shaped part model may be the plate thickness of the material to be actually applied. There are no particular restrictions on the plate thickness value, but it is preferable that it is within the range that can be regarded as a plate material (approximately 0.5 mm to 10 mm). The material properties of the plate-like part model in the material property setting step S3d may be set either before or after the plate-like part model is bonded to the vehicle body part in the bonding processing step S3c.

[0081] (Optimization analysis condition setting process) The optimization analysis condition setting step S3e is a step of setting, as optimization analysis conditions, the objective function and vibration input conditions set as the sensitivity analysis conditions in the sensitivity analysis condition setting step S11, and a constraint condition related to the weight of the body-in-white structure. In the first embodiment, the optimization analysis condition setting step S3e is executed by the optimization analysis condition setting unit 15e of the automobile body design device 1.

[0082] In the optimization analysis condition setting process S3e, an objective function can be set to minimize the frequency response value of any of the acceleration, inertance, or equivalent radiated power in a specified frequency band at a specified portion of the body-in-white structure 100. Furthermore, in the optimization analysis condition setting step S3e, vibration input conditions for inputting predetermined vibrations to one or more parts of the body-in-white structure 100 can be set.

[0083] The objective function and vibration input conditions set as the optimization analysis conditions are the same as the objective function and vibration input conditions set in the sensitivity analysis condition setting step. In contrast, the constraint condition regarding the weight of the body-in-white structure 100 set as the optimization analysis condition should be the same as the constraint condition regarding the weight of the body-in-white structure 100 set as one of the constraint conditions in the sensitivity analysis condition setting process. The constraint condition on the weight of the body-in-white structure 100 is a constraint that limits the weight increase due to the attachment of the plate-like parts to a predetermined value or less. Therefore, the constraint condition on the weight of the body-in-white structure 100 is synonymous with the constraint condition on the weight of the plate-like part model.

[0084] (Optimization analysis process) The optimization analysis step S3f is a step of performing an optimization analysis to find an optimal shape of the plate-like part model under the optimization analysis conditions set in the optimization analysis condition setting step S3e. In the first embodiment, the optimization analysis step S3f is executed by the optimization analysis unit 15f of the automobile body design device 1.

[0085] For example, topology optimization can be applied to the optimization analysis in the optimization analysis step S3f. In topology optimization using the density method, optimization analysis processing is performed using the density of the shell elements of the plate-like part model as a design variable, and the optimal shape of the plate-like part model is obtained by retaining and eliminating the shell elements. Furthermore, the optimal position of the plate-like part model can be obtained from the positions of the shell elements of the plate-like part model that remain in the optimization analysis processing.

[0086] In addition, when there are many intermediate densities in topology optimization using the density method, it is preferable to discretize by giving a penalty coefficient as an optimization parameter. In this case, the value of the penalty coefficient can be set appropriately.

[0087] The optimization analysis step S3f is not limited to the topology optimization as described above, and may be an optimization analysis using other calculation methods. In addition, the optimization analysis step S3f may use, for example, commercially available analysis software using the finite element method.

[0088] <Automobile body design program> The above description of the first embodiment relates to a load transfer structure optimization analysis device and method. However, the first embodiment can be configured as an automobile body design program that causes each unit in the arithmetic processing unit 11 of the automobile body design device 1 (FIG. 1) configured by a computer to function.

[0089] The automobile body design program according to the first embodiment is for designing an automobile body with improved vibration damping of the body-in-white structure by attaching plate-like parts to the surfaces of the body parts constituting the body-in-white structure of the automobile body. The automobile body design program according to the first embodiment causes a computer to function as a body part selection unit 13 and a plate-like part optimization analysis unit 15, as in the arithmetic processing unit 11 shown in FIG.

[0090] Here, the automobile body design program according to the first embodiment causes a computer to function as the body part selection unit 13, thereby causing each section of the body part selection unit 13 to function. As shown in Fig. 1 described above, the body part selection unit 13 has a sensitivity analysis condition setting section 13a, a sensitivity analysis section 13b, and a plate-like part affixed target body part selection section 13c.

[0091] Furthermore, the automobile body design program according to the first embodiment causes the computer to function as the plate part optimization analysis unit 15, thereby causing each unit of the plate part optimization analysis unit 15 to function. As shown in Fig. 1 described above, the plate part optimization analysis unit 15 has a design space setting unit 15a, a plate part model generating unit 15b, a connection processing unit 15c, a material property setting unit 15d, an optimization analysis condition setting unit 15e, and an optimization analysis unit 15f.

[0092] As described above, according to the automobile body design device, method, and program of the first embodiment, it is possible to design an automobile body with improved vibration damping of the body-in-white structure by appropriately selecting the body part to which the plate-like part is attached and determining the optimal shape of the plate-like part. Furthermore, according to the first embodiment, a two-dimensional space along the surface of the selected vehicle body part is set as the design space, and the optimal shape of a plate-like part modeled with shell elements is obtained, thereby making it possible to obtain a shape that is easy to manufacture as an actual plate-like part by press molding or the like. The effect of improving vibration damping performance by the automobile body design device, method, and program according to the first embodiment will be verified in examples described later.

[0093] The automobile body design device, method, and program according to the first embodiment are for improving the vibration damping of the body-in-white structure of an automobile body by attaching plate-like parts to the body parts to change the mass distribution of the body parts. However, the vibration characteristics related to the vibration damping of an automobile body are affected by the rigidity as well as the mass distribution of the body parts. Therefore, when applying topology optimization as an optimization analysis for finding the optimal shape of a plate-like part model, it is considered to directly give the Young's modulus of the material (e.g., steel plate, etc.) used in the actual plate-like part as the material property of the plate-like part modeled with shell elements.

[0094] In addition, the shape of the plate-like part model remaining after topology optimization is easily affected by the rigidity of the vehicle body part. In other words, it was found that when a plate-like part model is combined with a vehicle body part and topology optimization is performed, the plate-like part model may tend to remain porous in parts where the rigidity improvement effect is likely to be obtained, such as ridges of the vehicle body part. It is considered that the optimal shape of such a plate-like part model remaining porous is a shape that is difficult to actually manufacture into a plate-like part.

[0095] When obtaining such an optimal shape for a plate-like part model, it is preferable to set the material properties of the plate-like part model as they are, except for the Young's modulus of the material actually used, and set the Young's modulus to a minimum value. This eliminates the effect of rigidity due to the plate-like part model, and obtains an optimal shape that remains concentrated mainly in the planar portion of the vehicle body part, thereby obtaining a shape that is easy to manufacture the plate-like part.

[0096] [Embodiment 2] The automobile body design method according to the first embodiment described above is for designing an automobile body with improved vibration damping performance of the body-in-white structure by attaching plate-shaped parts to the surfaces of the body parts constituting the body-in-white structure of the automobile body.

[0097] However, the present invention can be configured as a method for manufacturing an automobile body by attaching a plate-shaped part to the surface of a body part that constitutes a body-in-white structure of the automobile body, thereby manufacturing an automobile body having improved vibration damping properties of the body-in-white structure.

[0098] That is, in the manufacturing method of an automobile body in this embodiment 2, first, the automobile body design method related to the above-mentioned embodiment 1 is used to determine the optimal shape of a plate-like part model to be attached to the body part selected in the body-in-white structure. Next, the shape and position of the plate-like part to be attached to the selected vehicle body part are determined based on the optimum shape of the plate-like part model thus obtained. Next, the plate-shaped part is manufactured based on the determined shape of the plate-shaped part. Then, using the determined position of the plate-like part, the manufactured plate-like part is attached to a selected body part in the body-in-white structure.

[0099] As an example, the automobile body manufacturing method according to the second embodiment will be described for the case where optimal shapes 121, 123 and 125 shown in FIG. 6 are obtained as optimal shapes of a plate-shaped part model using the automobile body design method according to the first embodiment described above.

[0100] In the automobile body design method according to the first embodiment, the roof center RF103, the roof rail 117, and the wheel house 119 are selected as the vehicle body parts to which the plate-like parts are to be attached. First, the shapes and attachment positions of each plate-like part to be attached to the roof center RF103, the roof rail 117, and the wheel house 119 are determined based on the optimal shapes 121, 123, and 125 of the plate-like part models.

[0101] Here, the optimal shapes 121, 123, and 125 of the plate-like part models are obtained by retaining and deleting shell elements in the topology optimization of the shell elements in the optimization analysis step S3f of the automobile body design method according to embodiment 1. Therefore, the positions at which the plate-like parts are attached can be determined from the positions of the plate-like part models that remain in the optimization analysis.

[0102] Next, each plate-shaped part is designed and manufactured according to the shape of each plate-shaped part determined based on the optimum shapes 121, 123, and 125. The plate thickness and material type of the plate-shaped part are set to the plate thickness and material type set for each plate-shaped part model in the material property setting process S3d. Since the plate-shaped parts are manufactured by press working, they are designed to have a shape that can be manufactured by press working based on the optimum shapes 121, 123, and 125 of the plate-shaped part models. For example, taking into consideration the blank workability of the plate-shaped part, the unevenness of the contour is smoothed while maintaining the weight of the plate-shaped part model. In addition, when the plate-shaped part models are scattered in a certain range area, they are replaced with one plate-shaped part with the same weight and center of gravity position.

[0103] Next, using the positions of each plate-like part determined based on the optimum shapes 121, 123, and 125, the manufactured plate-like parts are attached to the selected vehicle body parts, namely, the roof center RF 103, the roof rail 117, and the wheel house 119. The attachment of the plate-like parts to the vehicle body parts may be performed by welding such as resistance spot welding, arc welding, or laser welding, or by adhesion using an industrial adhesive, or by a weld bond method that combines spot welding and adhesion.

[0104] The plate-like parts may be attached in the following manner. First, position data of three-dimensional coordinates in the body-in-white structure 100 is obtained as the position of the plate-like part to be attached to each selected vehicle body part. Next, the obtained 3D coordinate position data is converted into assembly data, which is in a format used by assembly robots in the manufacturing process of automobile bodies, and the converted assembly data is read into the NC unit. Then, using an NC unit that has read the converted assembly data, component assembly is performed in which plate-like components are attached to each vehicle component selected in the body-in-white structure 100.

[0105] The manufacturing method of the automobile body according to the present invention may also be used for modifying an already manufactured automobile body to improve the vibration damping performance of the body-in-white structure. In this case, first, the positions of the obtained optimum shapes 121, 123, and 125 of the plate-like part model are displayed on a display device. Then, plate-like parts may be attached by a spot gun or the like to positions on the automobile body (roof center RF 103, roof rail 117, and wheel house 119) that correspond to the positions of the displayed optimum shapes 121, 123, and 125 of the plate-like part model.

[0106] In this way, according to the manufacturing method of the automobile body of the second embodiment, it is possible to manufacture an automobile body with improved vibration damping of the body-in-white structure while maintaining vehicle body performance other than vibration damping such as rigidity. EXAMPLES

[0107] An analysis was carried out to verify the effects of the automobile body design method, device, and program according to the present invention, which will be described below.

[0108] In the analysis, first, in step A, a sensitivity analysis was performed to obtain the sensitivity of each vehicle body part to vibration characteristics related to vibration damping, using the vehicle body-in-white structure 100 shown in Fig. 2 as the analysis target, as in the above-described first embodiment. Furthermore, vehicle body parts to which plate-like parts were attached were selected based on the sensitivity obtained by the sensitivity analysis.

[0109] Next, in Step B, an optimization analysis was conducted to determine the optimal shape of the plate-shaped parts to be attached to the body parts selected in Step A.

[0110] Furthermore, in Step C, the vibration characteristics of a body-in-white structure in which the plate-like part model with the optimal shape obtained in Step B was attached to the vehicle body part selected in Step A were obtained as an example of the invention. Then, the vibration characteristics of the original body-in-white structure in which the plate-like part model with the optimal shape was not attached were obtained as a comparative example, and the vibration damping properties of the body-in-white structure according to the example of the invention were evaluated.

[0111] In the analysis, as shown in Tables 1 and 2, sensitivity analysis, selection of body parts, and optimization analysis of the plate-like parts were performed for Examples 1 to 6 in which the sensitivity analysis conditions, sensitivity analysis method, and material of the plate-like parts were changed, and the vibration damping improvement effects of these were compared.

[0112] [Table 1] [Table 2]

[0113] First, for each of Examples 1 to 6, in step A, a vehicle body part to which a plate-like part was to be attached was selected, and in step B, the optimal shape of the plate-like part model was obtained.

[0114] In Example 1, as sensitivity analysis conditions, an objective function for minimizing the inertance of the floor cross member 105 in the frequency band of 115 Hz to 135 Hz and constraints for limiting the weight increase of the body-in-white structure 100 to 5 kg or less and to be equal to or greater than the plate thickness of the original body part were set. The inertance was calculated using the above-mentioned formula (1).

[0115] As a vibration input condition in the sensitivity analysis and optimization analysis, the front subframe 113 was set as a part to which vibration was applied. In the sensitivity analysis of Example 1, a plate thickness optimization analysis was performed for each vehicle body part, and the plate thickness change rate for each vehicle body part was obtained as the sensitivity. Furthermore, in the optimization analysis of the plate-shaped part model of Example 1, the material properties of the steel plate shown in Table 3 were set for the plate-shaped part model.

[0116] [Table 3]

[0117] FIG. 8 shows a contour diagram of the plate thickness change rate for each vehicle body part obtained by sensitivity analysis in Example 1, and the vehicle body part selected as the target to which the plate-shaped part is attached based on the plate thickness change rate. In the first embodiment, as shown in FIG. 8, the wheel house 119, the fuel tank 127, and the like have a large thickness change rate of 8% or more, and therefore were selected as the vehicle body parts to which the plate-like parts were attached.

[0118] Fig. 9 shows the optimum shape of the plate-like part model found in Example 1. In Fig. 9, the parts displayed in dark grey are the optimum shape of the plate-like part model. As shown in FIG. 9, an optimum shape 129 of a plate-like part model to be attached to a wheel house 119, an optimum shape 131 of a plate-like part model to be attached to a fuel tank 127, etc. were obtained.

[0119] In Example 2, similarly to the above-described embodiment 1, the vibration input condition is set to the front subframe 113 as a part to which vibration is applied, and the objective function is set to minimize the inertance in the frequency band of 95 Hz to 115 Hz at the central part of the roof center RF 103. The inertance is calculated using the above-described formula (1).

[0120] In addition, in Example 2, in the sensitivity analysis, a plate thickness optimization analysis was performed for each vehicle body part, and the plate thickness change rate for each vehicle body part was obtained as the sensitivity. Furthermore, in Example 2, in the optimization analysis of the plate-shaped part model, the material properties of the steel plate shown in Table 3 above were set for the plate-shaped part model.

[0121] FIG. 5 mentioned above shows a contour diagram of the plate thickness change rate for each vehicle body part obtained by sensitivity analysis in Example 2, and the vehicle body part selected as the target to which the plate-shaped part is attached based on the plate thickness change rate. In Example 2, the roof center RF 103, roof rail 117, wheel house 119, etc. had a large thickness change rate of 5% or more, and were therefore selected as the vehicle body parts to which the plate-like parts were attached.

[0122] The above-mentioned Fig. 6 shows the results of determining the optimum shape of the plate-like part model to be attached to the body part selected based on the result of the sensitivity analysis in Example 2. In Fig. 6, the parts displayed in dark grey are the optimum shape of the plate-like part model. As shown in FIG. 6, an optimal shape 121 of the plate-like part to be attached to the roof center RF 103, an optimal shape 123 of the plate-like part model to be attached to the roof rail 117, an optimal shape 125 of the plate-like part model to be attached to the wheel house 119, etc. were obtained.

[0123] In the third embodiment, the vibration input condition is set to the front subframe 113 as a part to which vibration is applied, and the objective function is set to minimize the equivalent radiated power (ERP) of the roof panel 109 in a frequency band of 110 Hz to 130 Hz. The above-mentioned formula (2) is used to calculate the equivalent radiated power ERP.

[0124] In addition, in the third embodiment, in the sensitivity analysis, a plate thickness optimization analysis was performed for each vehicle body part, and the plate thickness change rate for each vehicle body part was obtained as the sensitivity. Furthermore, in Example 3, in the optimization analysis of the plate-shaped part model, the material properties of the steel plate shown in Table 3 above were set for the plate-shaped part model.

[0125] FIG. 10 shows a contour diagram of the plate thickness change rate for each vehicle body part obtained by sensitivity analysis in Example 3, and vehicle body parts selected as targets to which plate-like parts are attached based on the plate thickness change rate. In Example 3, the door panel 111, the radiator support 133, etc. had a large thickness change rate of 5% or more, and were therefore selected as the vehicle body parts to which the plate-like parts were attached.

[0126] Fig. 11 shows the results of determining the optimal shape of the plate-like part model to be attached to the vehicle body part selected based on the result of the sensitivity analysis in Example 3. In Fig. 11, the parts displayed in dark gray are the optimal shape of the plate-like part model. As shown in FIG. 11, an optimum shape 135 of a plate-like part model to be attached to a door panel 111 and an optimum shape 135 of a plate-like part model to be attached to a radiator support 133 were obtained.

[0127] In the fourth embodiment, the vibration input condition is set to the front subframe 113 and the suspension tower 115 as parts to which vibration is applied, and the objective function is set to minimize the inertance in the frequency band of 95 Hz to 115 Hz at the central part of the roof center RF 103. The inertance is calculated using the above-mentioned formula (1).

[0128] In addition, in Example 4, in the sensitivity analysis, a plate thickness optimization analysis was performed for each vehicle body part, and the plate thickness change rate for each vehicle body part was obtained as the sensitivity. Furthermore, in Example 4, in the optimization analysis of the plate-shaped part model, the material properties of the steel plate shown in Table 3 above were set for the plate-shaped part model.

[0129] FIG. 12 shows a contour diagram of the plate thickness change rate for each vehicle body part obtained by sensitivity analysis in Example 4, and the vehicle body parts selected as targets to be attached to the plate-like part. In Example 4, the roof center RF 103, the radiator support 133, etc. had a large thickness change rate of 8% or more, and were therefore selected as the vehicle body parts to which the plate-like parts were attached.

[0130] Fig. 13 shows the results of determining the optimal shape of the plate-like part model to be attached to the vehicle body part selected based on the result of the sensitivity analysis in Example 4. In Fig. 13, the parts displayed in dark gray are the optimal shape of the plate-like part model. As shown in FIG. 13, an optimal shape 139 of the plate-like part model to be attached to the roof center RF 103 and an optimal shape 141 of the plate-like part model to be attached to the radiator support 133 were obtained.

[0131] In the fifth embodiment, the vibration input condition is set to a part to which vibration is applied to the front subframe 113, and the objective function is set to minimize the inertance in a frequency band of 95 Hz to 115 Hz at the central part of the roof center RF 103. The inertance is calculated using the above-mentioned formula (1).

[0132] In addition, in Example 5, in the sensitivity analysis, a plate thickness optimization analysis was performed for each element of the vehicle body part, and the plate thickness change rate for each element of the vehicle body part was obtained as the sensitivity. Furthermore, in Example 5, in the optimization analysis of the plate-shaped part model, the material properties of the steel plate shown in Table 3 above were set for the plate-shaped part model.

[0133] FIG. 14 shows a contour diagram of the plate thickness change rate for each vehicle body part obtained by sensitivity analysis in Example 5, and vehicle body parts selected as targets to which plate-like parts are attached based on the plate thickness change rate. In Example 5, the roof center RF103 and the like had a large sheet thickness change rate of 8% or more, and therefore these were selected as the vehicle body parts to which the plate-like parts were attached.

[0134] Fig. 15 shows the results of determining the optimal shape of the plate-like part model to be attached to the vehicle body part selected based on the result of the sensitivity analysis in Example 5. In Fig. 15, the parts displayed in dark gray are the optimal shape of the plate-like part model. From the results shown in FIG. 15, an optimum shape 143 of the plate-like part model to be attached to the roof center RF 103, etc., was obtained.

[0135] In the sixth embodiment, the vibration input condition is set to a part to which vibration is applied to the front subframe 113, and the objective function is set to minimize the inertance in a frequency band of 95 Hz to 115 Hz at the central part of the roof center RF 103. The inertance is calculated using the above-mentioned formula (1). In addition, in Example 6, in the sensitivity analysis, a plate thickness optimization analysis was performed for each vehicle body part, and the plate thickness change rate for each vehicle body part was obtained as the sensitivity. Furthermore, in Example 6, in the optimization analysis of the plate-like part model, the material properties of the lead plate shown in Table 3 above were set for the plate-like part model.

[0136] FIG. 5 shown above shows a contour diagram of the plate thickness change rate for each body part obtained by sensitivity analysis in Example 6, and the body parts selected as targets to which plate-shaped parts are attached based on the plate thickness change rate. The sensitivity analysis conditions in Example 6 were the same as those in Example 2, and therefore the roof center RF 103, the roof rail 117, the wheel house 119, and the like were selected as the vehicle body parts to which the plate-like parts were attached.

[0137] Fig. 16 shows the results of determining the optimal shape of the plate-like part model to be attached to the vehicle body part selected based on the result of the sensitivity analysis in Example 6. In Fig. 16, the parts displayed in dark gray are the optimal shape of the plate-like part model. As shown in FIG. 16, an optimum shape 121 of the plate-like part model attached to the roof center RF 103, an optimum shape 123 of the plate-like part model attached to the roof rail 117, and an optimum shape 125 of the plate-like part model attached to the wheel house 119 were obtained.

[0138] Next, in step C, an evaluation value of the vibration characteristics of the body-in-white structure 100 in which the plate-like part models of the optimal shapes obtained in Examples 1 to 6 were attached to each vehicle body part was calculated. Furthermore, an evaluation value of the vibration characteristics was similarly calculated for the original body-in-white structure 100 before the plate-like part models were attached. Then, improvement in vibration damping of the body-in-white structure by attaching the plate-like part models of the optimal shapes was examined.

[0139] In evaluating the improvement in vibration damping performance, the vibration characteristic values ​​of the original body-in-white structure were used as the standard, and the reduction rate of the evaluation value of the vibration characteristics of the body-in-white structure to which the optimally shaped plate-shaped part was attached was calculated.

[0140] The evaluation values ​​of the vibration characteristics in each of Examples 1 to 6 were set to be the same as the vibration characteristics set as the target conditions of the sensitivity analysis conditions described above. Furthermore, in calculating the vibration characteristic evaluation value, the vibration input conditions given to the body-in-white structure 100 were the same as the vibration input conditions given as the sensitivity analysis conditions in each of Examples 1 to 6.

[0141] Table 4 shows the vibration characteristic evaluation values ​​(invention examples) of the body-in-white structure to which the plate-shaped parts of the optimal shapes obtained in Examples 1 to 6 are attached, the vibration characteristic evaluation values ​​of the original body-in-white structure (comparison example), and the reduction rate of the vibration characteristic evaluation values.

[0142] [Table 4]

[0143] It can be seen that in all of Examples 1 to 6, by attaching a plate-like part with an optimum shape to a vehicle body part, the evaluation value of the vibration characteristics is significantly reduced (43% to 90%). This shows that the automobile body design method according to the present invention makes it possible to design an automobile body having improved vibration damping properties of the body-in-white structure. [Explanation of symbols]

[0144] 1. Automobile body design equipment 3 Display device 5 Input Devices 7 Storage device 9 Working Data Memory 11 Processing unit 13 Body Parts Selection Unit 13a Sensitivity analysis condition setting section 13b Sensitivity analysis section 13c Body part selection section for attaching plate-shaped parts 15 Plate-shaped Parts Optimization Analysis Unit 15a Design space setting section 15b Plate-shaped part model generation unit 15c Joint processing section 15d Material property setting section 15e Optimization analysis condition setting section 15f Optimization Analysis Section 21 Body-in-white structure model file 100 Body-in-white structure 101 Center pillar 103 Roof Center RF 105 Floor cross member 107 Rear side sill 109 Roof Panel 111 Door Panel 113 Front subframe 115 Suspension Tower 117 Roof rail 119 Wheelhouse 121 Optimal Shape 123 Optimal Shape 125 Optimal Shape 127 Fuel Tank 129 Optimal Shape 131 Optimal Shape 133 Radiator Support 135 Optimal Shape 137 Optimal Shape 139 Optimal Shape 141 Optimal Shape 143 Optimal Shape 145 Optimal Shape

Claims

1. A method for designing an automobile body in which a plate-shaped part is attached to a surface of a body part constituting a body-in-white structure of the automobile body, thereby improving the vibration damping performance of the body-in-white structure, the method comprising the steps of: a vehicle body part selection step of performing a sensitivity analysis of the vehicle body part with respect to vibration characteristics used in an evaluation of vibration damping performance of the body-in-white structure, and selecting a vehicle body part to which the plate-like part is to be attached; a plate-like part optimization analysis step of performing optimization analysis on the shape of a plate-like part to be attached to the selected vehicle body part, The vehicle body part selection step includes: a sensitivity analysis condition setting step of setting, as sensitivity analysis conditions, an objective function related to vibration characteristics of the body-in-white structure, constraint conditions related to the weight of the body-in-white structure and the plate thicknesses of the vehicle body parts, and vibration input conditions related to vibrations applied to the body-in-white structure; a sensitivity analysis step of performing the sensitivity analysis under the set sensitivity analysis conditions to obtain a sensitivity of each of the vehicle body parts to the vibration characteristics of the body-in-white structure; and a plate-like part attachment target vehicle body part selection step of selecting a vehicle body part to which the plate-like part is to be attached based on the sensitivity obtained for each vehicle body part, The plate-shaped part optimization analysis step includes: a design space setting step of setting a two-dimensional space along the surface of the vehicle body part selected in the vehicle body part selection step as a design space to be subjected to the optimization analysis; a plate-like part model generating step of generating a plate-like part model that is modeled with shell elements in the set design space and is subjected to optimization analysis processing; a coupling process step of coupling the generated plate-like part model to the vehicle body part selected in the vehicle body part selection step; an optimization analysis condition setting step of setting the objective function and the vibration input condition set as the sensitivity analysis conditions, and a constraint condition related to a weight of the body-in-white structure, as optimization analysis conditions for performing the optimization analysis; and an optimization analysis step of performing the optimization analysis to find an optimal shape of the plate-like part model under the set optimization analysis conditions.

2. In the sensitivity analysis condition setting step, An objective function that minimizes a frequency response value of either acceleration, inertance, or equivalent radiated power in a predetermined frequency band; A constraint condition that the plate thickness of each of the vehicle body parts is equal to or greater than the original plate thickness of each of the vehicle body parts; 2. The automobile body design method according to claim 1, further comprising the step of: setting a vibration input condition for inputting a predetermined vibration to one or more portions of the body-in-white structure.

3. An automobile body designing device that designs an automobile body having improved vibration damping properties of a body-in-white structure by attaching a plate-shaped part to a surface of a body part that constitutes a body-in-white structure of the automobile body, comprising: a vehicle body part selection unit that performs a sensitivity analysis of the vehicle body part with respect to vibration characteristics used in evaluating the vibration damping property of the body-in-white structure, and selects a vehicle body part to which the plate-like part is to be attached; a plate-like part optimization analysis unit that performs optimization analysis on the shape of a plate-like part to be attached to the selected vehicle body part, The vehicle body part selection unit includes: a sensitivity analysis condition setting unit that sets, as sensitivity analysis conditions, an objective function related to vibration characteristics of the body-in-white structure, constraint conditions related to the weight of the body-in-white structure and the plate thicknesses of the vehicle body parts, and vibration input conditions related to vibrations applied to the body-in-white structure; a sensitivity analysis unit that performs the sensitivity analysis under the set sensitivity analysis conditions and obtains a sensitivity of each of the vehicle body parts to the vibration characteristics of the body-in-white structure; a plate-like part attachment target vehicle body part selection unit that selects a vehicle body part to which the plate-like part is to be attached based on the sensitivity obtained for each vehicle body part, The plate-shaped part optimization analysis unit includes: a design space setting unit that sets a two-dimensional space along a surface of the vehicle body part selected by the vehicle body part selection unit as a design space to be subjected to the optimization analysis; a plate-like part model generation unit that generates a plate-like part model that is modeled with shell elements in the set design space and that performs optimization analysis processing; a combining processing unit that combines the generated plate-like part model with the body part selected by the body part selection unit; an optimization analysis condition setting unit that sets the objective function and the vibration input condition that are set as the sensitivity analysis conditions, and a constraint condition related to a weight of the body-in-white structure, as optimization analysis conditions for performing the optimization analysis; an optimization analysis unit that performs the optimization analysis to find an optimal shape of the plate-like part model under the set optimization analysis conditions.

4. A vehicle body design program for designing a vehicle body having improved vibration damping properties of a white body structure by attaching a plate-shaped part to a surface of a vehicle body part constituting a white body structure of the vehicle body, the program comprising: a vehicle body part selection unit that performs sensitivity analysis of the vehicle body parts with respect to vibration characteristics used in evaluating the vibration damping performance of the body-in-white structure and selects a vehicle body part to which the plate-like part is to be attached; a plate-shaped part optimization analysis unit that performs optimization analysis on the shape of a plate-shaped part to be attached to the selected vehicle body part; and The vehicle body part selection unit, a sensitivity analysis condition setting unit that sets, as sensitivity analysis conditions, an objective function related to vibration characteristics of the body-in-white structure, constraint conditions related to the weight of the body-in-white structure and the plate thicknesses of the vehicle body parts, and vibration input conditions related to vibrations applied to the body-in-white structure; a sensitivity analysis unit that performs the sensitivity analysis under the set sensitivity analysis conditions and obtains a sensitivity of each of the vehicle body parts to the vibration characteristics of the body-in-white structure; a plate-like part attachment target vehicle body part selection unit that selects a vehicle body part to which the plate-like part is to be attached based on the sensitivity obtained for each vehicle body part; The plate-shaped part optimization analysis unit, a design space setting unit that sets a two-dimensional space along a surface of the vehicle body part selected by the vehicle body part selection unit as a design space to be subjected to the optimization analysis; a plate-like part model generation unit that generates a plate-like part model that is modeled with shell elements in the set design space and that performs optimization analysis processing; a combining processing unit that combines the generated plate-like part model with the body part selected by the body part selection unit; an optimization analysis condition setting unit that sets the objective function and the vibration input condition that are set as the sensitivity analysis conditions, and a constraint condition related to a weight of the body-in-white structure, as optimization analysis conditions for performing the optimization analysis; an optimization analysis unit that performs the optimization analysis to find an optimal shape of the plate-like part model under the set optimization analysis conditions.

5. A method for manufacturing an automobile body, comprising the steps of: attaching a plate-shaped part to a surface of a body part constituting a body-in-white structure of an automobile body; and manufacturing an automobile body having improved vibration damping properties of the body-in-white structure, comprising:

3. Using the automobile body design method according to claim 1 or 2, an optimal shape of a plate-like part model to be attached to the selected vehicle body part in the body-in-white structure is obtained; determining a shape and a position of the plate-like part to be attached to the selected vehicle body part based on the obtained optimal shape of the plate-like part model; manufacturing the plate-shaped part based on the determined shape of the plate-shaped part; A method for manufacturing an automobile body, comprising the steps of: attaching the manufactured plate-like part to the selected body part in the body-in-white structure using the determined position of the plate-like part.

Images