Automotive component design method, device, and program, and automotive component manufacturing method

Abstract

An automotive component design method according to the present invention comprises: obtaining an automotive component model that models an automotive component that receives a compressive load in the longitudinal direction during an automotive collision (S1); setting a design space for a to-be-designed portion, which is a portion to be designed (S3); generating a to-be-designed-portion model by modeling the set design space with shell elements and / or solid elements (S5); setting, in the automotive component model, an objective function that maximizes the buckling load of the primary buckling mode obtained by linear buckling analysis (S7); performing optimization analysis to find the optimal shape of the to-be-designed-portion model that satisfies the set objective function (S9); and determining the shape of the to-be-designed portion on the basis of the optimal shape of the to-be-designed-portion model (S11).

Description

Automotive part design method, device, and program, and automotive part manufacturing method

[0001] The present invention relates to a method, an apparatus, and a program for designing an auto part so as to improve the crashworthiness of the auto part that receives a compressive load in the longitudinal direction during a vehicle collision.Furthermore, the present invention relates to a method for manufacturing an auto part that manufactures an auto part that receives a compressive load in the longitudinal direction during a vehicle collision so as to improve the crashworthiness of the auto part.

[0002] While there is an increasing demand for improved crashworthiness of automobile bodies, there is also a need to reduce the weight of automobile bodies in order to reduce CO2 emissions. To meet these demands simultaneously, it is important to design automobile parts with improved crashworthiness while increasing the strength and thinning of materials (e.g., steel plates) used in automobile bodies.

[0003] The knowledge accumulated over many years has been extremely useful for designing automobile bodies and automobile parts with consideration for crash performance. However, electric vehicles are equipped with large-capacity batteries, which require space to accommodate them, and their body frame structure differs significantly from that of conventional gasoline-powered vehicles. Furthermore, collision safety for these batteries must also be considered. As electric vehicles become more widespread, more efficient design methods for automobile bodies and automobile parts are required than ever before.

[0004] As a technology for efficiently designing high-performance automobile bodies, for example, Patent Document 1 discloses an optimization method for finding an optimal shape for a portion of a structural model (automotive body) using a computer. This method first sets a design space for the portion of the vehicle body to be optimized, and then sets loading conditions and constraint conditions to be applied to the vehicle body, as well as objectives (corresponding to "objective functions" in this application; hereinafter, referred to as "objective functions") and constraints related to vehicle body performance such as stiffness and weight. Then, under the set loading conditions and constraint conditions, an optimization analysis process is performed to remove unnecessary parts from the design space so as to satisfy the objective function and constraint conditions, thereby finding the optimal shape for the portion of the vehicle body.

[0005] Patent No. 5585672

[0006] According to the method disclosed in Patent Document 1, by setting an objective function such as maximizing rigidity, minimizing displacement and stress, or minimizing strain energy, it is possible to determine the optimal shape of a part of an automobile body so as to satisfy the objective function.

[0007] Therefore, the inventors of the present application attempted to use the method of Patent Document 1 to determine the optimal shape of an automobile part that is subjected to a compressive load in the longitudinal direction so as to improve the crashworthiness of the automobile part. However, the optimal shape of the automobile part that was determined did not necessarily improve the crashworthiness. This was because, while an optimization analysis process that sets maximization of stiffness or minimization of stress as an objective function is appropriate as an index for determining stiffness, stiffness does not necessarily correlate with crashworthiness. Therefore, the method described in Patent Document 1, in particular, was unable to determine the optimal shape for improving the crashworthiness of an automobile part that is subjected to a compressive load in the longitudinal direction, and thus was unable to design the automobile part.

[0008] The present invention has been made to solve the above-mentioned problems, and its object is to provide an automobile part design method, device, and program that can design automobile parts so as to improve the collision performance of automobile parts that receive a compressive load in the longitudinal direction during an automobile collision. Another object of the present invention is to provide an automobile part manufacturing method that can improve the collision performance of automobile parts that receive a compressive load in the longitudinal direction during an automobile collision.

[0009] a design space setting step of setting a design space for a design target portion to be designed in the acquired automobile part model; a design target portion model generation step of generating a design target portion model for performing optimization analysis processing in the set design space; an optimization analysis condition setting step of setting optimization analysis conditions including load conditions for inputting a compressive load in the longitudinal direction of the automobile part model, an objective function for maximizing the buckling load of a primary buckling mode obtained by linear buckling analysis, and predetermined constraints on the design target portion model; an optimization analysis step of performing an optimization analysis to determine an optimal shape of the design target portion model generated in the automobile part model under the optimization analysis conditions; and a design target portion shape determination step of determining the shape of the design target portion based on the optimal shape of the design target portion model.

[0010] In the optimization analysis condition setting step, the objective function may be set to maximize the smallest eigenvalue among eigenvalues ​​that are solutions to the eigen equation shown in the following equation (1).

[0011]

[0012] The automobile part is assumed to have a stiffened member affixed to it that reinforces the automobile part so as to improve collision performance, and in the design space setting step, a two-dimensional space that follows the surface of the automobile part model is set as the design space, and in the design target portion model generation step, the design space is modeled using shell elements to generate the design target portion model and the design target portion model is combined with the automobile part model, and in the design target portion shape determination step, the shape and position of the stiffened member to be affixed to the automobile part are determined based on an optimal shape of the design target portion model in the automobile part model.

[0013] In the design space setting step, the design space may be set by using the automobile part model itself as the design target portion.

[0014] In the optimization analysis step, topology optimization may be performed as the optimization analysis to find an optimal shape for the model of the design target portion.

[0015] In the optimization analysis step, thickness optimization is performed as an optimization analysis of the design target portion model, and the thickness distribution of the design target portion model obtained by the thickness optimization is determined as the optimal shape of the design target portion model.

[0016] In the optimization analysis condition setting step, the load conditions may be set based on a load to be input in the longitudinal direction of the automobile part, which is determined in advance by a collision analysis in which all or part of the automobile including the automobile part is the analysis target.

[0017] an optimization analysis condition setting unit that sets optimization analysis conditions including load conditions for inputting a load in the longitudinal direction of the automobile part model, an objective function that maximizes the buckling load of a primary buckling mode obtained by linear buckling analysis of the automobile part model, and predetermined constraint conditions for the design target part model; an optimization analysis unit that performs optimization analysis on the automobile part model from which the design target part model has been generated under the optimization analysis conditions, and determines an optimal shape of the design target part model; and a design target part shape determination unit that determines the shape of the design target part based on the optimal shape of the design target part model.

[0018] An automotive part design program according to the present invention is for designing an automotive part so as to improve the collision performance of the automotive part that receives a compressive load in the longitudinal direction during an automotive collision, and causes a computer to function as an automotive part model acquisition unit that acquires an automotive part model that models the automotive part; a design space setting unit that sets a design space for a design target portion that is to be designed in the acquired automotive part model; a design target portion model generation unit that generates a design target portion model that performs optimization analysis processing in the set design space; an optimization analysis condition setting unit that sets optimization analysis conditions including load conditions for inputting a load in the longitudinal direction of the automotive part model, an objective function that maximizes the buckling load of a primary buckling mode obtained by linear buckling analysis of the automotive part model, and predetermined constraint conditions for the design target portion model; an optimization analysis unit that performs an optimization analysis to determine an optimal shape of the design target portion model under the optimization analysis conditions; and a design target portion shape determination unit that determines the shape of the design target portion based on the optimal shape of the design target portion model.

[0019] The manufacturing method of an automobile part according to the present invention manufactures an automobile part so as to improve the collision performance of the automobile part that receives a compressive load in the longitudinal direction during an automobile collision, and manufactures the automobile part by manufacturing a plate-shaped reinforcing member by press forming according to the shape of the reinforcing member determined by the design method of an automobile part according to the present invention, and attaching the manufactured plate-shaped reinforcing member to the determined position of the reinforcing member on the automobile part.

[0020] The manufacturing method of an automobile part according to the present invention manufactures an automobile part so as to improve the collision performance of the automobile part that is subjected to a compressive load in the longitudinal direction during an automobile collision, and is characterized in that the automobile part is manufactured based on the shape of the automobile part determined by the design method of an automobile part according to the present invention.

[0021] In the present invention, in an optimization analysis of an automotive part that receives a compressive load in the longitudinal direction during a vehicle collision, an objective function is set that maximizes the buckling load of the primary buckling mode. This makes it possible to design an automotive part that has excellent crash performance in the axial crush deformation mode, whose performance is determined by the buckling load. Furthermore, according to the present invention, it is possible to manufacture an automotive part that has excellent crash performance in the axial crush deformation mode.

[0022] FIG. 1 is a block diagram showing the configuration of an automobile part design apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating an automobile part that is subjected to a longitudinal compressive load during an automobile collision, which is the subject of the present invention. FIG. 3 is a diagram showing a rectangular cylindrical automobile part model that simulates an automobile part that is subjected to a longitudinal compressive load during an automobile collision, which was an example of a subject of study in the process leading to the present invention. FIG. 4 is an example graph of a load-stroke curve when a load is input in the longitudinal direction of the rectangular cylindrical automobile part model. FIG. 5 is a diagram showing a rectangular cylindrical automobile part model used in the process leading to the present invention to compare the relationship between stiffness and load-bearing capacity (load capacity / load-bearing capacity). ((a) An automobile part model with a ridge line section of the rectangular cylindrical automobile part model remaining, (b) An automobile part model with a plane portion of the rectangular cylindrical automobile part model remaining). FIG. 6 is a graph plotting the load-stroke curves and the buckling loads obtained by linear buckling analysis when a compressive load is applied in the longitudinal direction to a rectangular cylindrical automobile part model with bend ridges remaining and a rectangular cylindrical automobile part model with flat surfaces remaining, respectively, in the process leading to the present invention. FIG. 7 is a flow diagram illustrating the processing flow of the automobile part design method according to the first embodiment of the present invention. FIG. 8 is a diagram showing the optimal shape of the design target part model obtained by topology optimization in Example 1, where a two-dimensional space along the surface of the automobile part model is set as the design space and a design target part model is generated ((a) Example 1, (b) Comparative Example 1). FIG. 9 is a graph of the load-stroke curves of the automobile part model in Example 1, where the optimal shape of the design target part model obtained by topology optimization in Example 1, where a design space is set as a two-dimensional space along the surface and a design target part model is generated ((a) Example 1, (b) Comparative Example 1). 10A and 10B are diagrams showing the optimal shape of a design target part model obtained by topology optimization in Example 2, with the automobile part model itself being the design target part ((a) Inventive Example 2, (b) Comparative Example 2).FIG. 11 shows graphs of load-stroke curves of optimal shapes of automobile part models obtained by topology optimization in Example 2, with the automobile part model itself being the design target part ((a) Inventive Example 2, (b) Comparative Example 2).

[0023] Before describing the design method, device, and program for an automobile part according to the first embodiment of the present invention and the manufacturing method for an automobile part according to the second embodiment, the automobile part that is the subject of the present invention and the background to the invention will be described.

[0024] <Automobile Parts> The automobile parts targeted by the present invention are those that are expected to receive a longitudinal compressive load during an automobile collision. Examples of such automobile parts include a front side member 101, an upper front pillar / front pillar upper 103, and a roof rail 105 in a frontal collision in an automobile body 100 shown in FIG. 2 . Other examples include a roof center cross member 107 in a side collision and a side sill 109 in a small lap collision. These automobile parts may be composed of a single component or multiple components (e.g., the side sill 109 is composed of a side sill outer and a side sill inner). The present invention is not limited to automobile parts composed of a single component or multiple components; it also targets automobile parts reinforced with reinforcing members to improve collision performance.

[0025] As will be described later, the present invention seeks, through optimization analysis, to find an optimal shape that can improve the crash performance of these automotive parts against a compressive load input in the longitudinal direction. To this end, the automotive parts are assumed to be modeled using shell elements and / or solid elements, and element information, material properties, etc. of the modeled automotive part model are assumed to be stored in an automotive part model file 31 (FIG. 1) that will be described later.

[0026] <Background to the Invention> In order to obtain the optimal shape of an automotive part through optimization analysis with the aim of improving the crashworthiness of the part, it is necessary to appropriately set the objective function in the optimization analysis. As mentioned above, in conventional optimization analysis, the optimal shape of an automotive part is obtained by setting the objective functions of maximizing rigidity, minimizing displacement and stress, and minimizing strain energy. Furthermore, an automotive part with high crashworthiness is one that has high yield strength against loads input in the direction expected during a vehicle collision, i.e., has high load-bearing capacity.

[0027] 3 shows an example of an automobile part model 111 that models an automobile part that is subjected to a compressive load in the longitudinal direction. The automobile part model 111 is formed in a rectangular cylindrical shape with a flat portion 113 and a bending ridge portion 115, and is provided with a flat plate 117 and a flat plate 119 at both ends in the longitudinal direction.

[0028] The relationship between the yield strength and rigidity when the automobile part model 111 is subjected to a compressive load in the longitudinal direction is represented by the load-stroke curve shown in FIG. 4 below. The load-stroke curve shown in FIG. 4 is a graph that shows the relationship between the longitudinal displacement (stroke) of the flat plate 117 provided at one end of the automobile part model 111, where a compressive load is applied to the flat plate 117, and the load input to the automobile part model 111. In FIG. 4, the slope of the load-stroke curve in the elastic deformation phase, where the load and stroke are expressed in a linear relationship, represents the rigidity of the automobile part model 111, and the maximum load in the plastic deformation phase on the load-stroke curve that exceeds the elastic deformation phase represents the yield strength (load capacity) of the automobile part model 111.

[0029] As shown in Figure 4, in order to accurately calculate the load capacity of an automobile part model in the plastic deformation region beyond the elastic deformation region using finite-element method (FEM) analysis or the like, it is necessary to perform a time incremental calculation to determine the time change in the relationship between the load and the stroke (the displacement of the load input point on the automobile part model). However, such a time incremental calculation requires a much longer calculation time than a linear calculation (static analysis) to determine the stiffness of the automobile part model.

[0030] Furthermore, optimization analysis, which determines the optimal shape for an automotive part model that satisfies a specified performance (objective function), requires repeated calculations. Therefore, if the objective function in optimization analysis is to maximize the load-bearing capacity of an automotive part model, the load-bearing capacity must be determined by performing time-incremental calculations at each step of the repeated calculations. However, performing such repeated calculations in optimization analysis is not realistic in terms of calculation time.

[0031] Therefore, in conventional optimization analyses (for example, the aforementioned Patent Document 1), even when the objective was to improve the crashworthiness of an automobile part, maximizing stiffness was set as the objective function in terms of calculation time. Such optimization analyses were effective in determining the optimal shape of an automobile part model in which the load capacity increases according to the stiffness.

[0032] However, it was found that, for example, in the automobile part model 111A shown in FIG. 5(a) and the automobile part model 111B shown in FIG. 5(b), the rigidity and the load capacity when subjected to a compressive load in the longitudinal direction do not correspond.

[0033] Automobile part model 111A is a shape obtained by removing flat portions 113 from automobile part model 111 of the rectangular cylindrical shape shown in Fig. 3 and leaving bent ridge portions 115. On the other hand, automobile part model 111B is a shape obtained by removing bent ridge portions 115 from automobile part model 111 of the rectangular cylindrical shape shown in Fig. 3 and leaving flat portions 113.

[0034] FIG. 6 shows a graph comparing the relationship between load and stroke (load-stroke curve) when a compressive load is applied in the longitudinal direction for each of the automobile part models 111A and 111B.

[0035] The automobile part model 111A in which the bend ridgeline portion 115 remains has a smaller slope (rigidity) in the elastic region of the load-stroke curve (solid line in FIG. 6 ) but a larger maximum load than the automobile part model 111B in which the flat portion 113 remains. In contrast, the automobile part model 111B in which the flat portion 113 remains has a larger slope (rigidity) in the elastic deformation region of the load-stroke curve (solid line in FIG. 6 ) but a smaller maximum load than the automobile part model 111A in which the bend ridgeline portion 115 remains.

[0036] Therefore, when optimization analysis was performed on automobile part model 111 (Figure 3) with maximizing rigidity as the objective function, a shape with high rigidity like automobile part model 111B was obtained, but a shape with high load-bearing capacity like automobile part model 111A could not be obtained.

[0037] The inventors have therefore conducted extensive research into this issue, focusing on the load (buckling load) at which an automobile component that undergoes axial crushing when subjected to a compressive load in the longitudinal direction buckles.

[0038] The crashworthiness of an automotive part can be evaluated by the maximum load (load capacity) applied to the part. However, at the point where the load reaches the maximum, the part is often in a buckling deformation mode. In particular, for automotive parts with complex shapes, when the compressive load applied in the longitudinal direction is gradually increased, the deformation mode changes due to buckling at the initial stage of deformation, and buckling occurs continuously, causing the deformation of the automotive part to progress. Furthermore, at the point where the compressive load applied to the automotive part reaches its maximum (maximum load), the part generally experiences an even larger deformation mode.

[0039] While it is difficult to predict such a state in a large deformation mode using linear calculations (static analysis) to determine the rigidity of automotive parts, the limit load (= buckling load) at which a longitudinal compressive load changes from axial compression mode to another deformation mode, such as bending mode, can be determined using linear buckling analysis.

[0040] Linear buckling analysis is a static analysis that determines the balance between load and displacement before buckling occurs under certain load conditions, and specifically, the buckling load is determined as follows: If we consider the case where a load increment is given to an automotive part in a balanced state determined by static analysis, the stiffness equation for the load increment shown in the following equation (2) can be obtained from the principle of virtual work.

[0041]

[0042] {Δδ} is the nodal displacement increment vector, {ΔF} is the load increment vector, [KE ] is the stiffness matrix, [K G ] represents the initial stress matrix (geometric stiffness matrix). And the initial stress matrix [K G ] is a matrix generated from the stress state before buckling, and can be generated, for example, by the method described in the following reference:

[0043] (References) Tadahiko Kawai, edited by the Japanese Society of Steel Construction, "Computer-Based Structural Engineering Course II-6-B: Analysis of Buckling Problems," Baifukan, October 1974, pp. 52-67.

[0044] When an automobile part buckles under a load condition where the load is λ times the load under balanced stress, {ΔF} can be set to 0, and therefore equation (3) can be obtained from the relationship in equation (2).

[0045]

[0046] Equation (3) is a generalized eigenvalue problem, and by solving this by numerical analysis, the eigenvalue {λ} and the corresponding eigenmode (natural mode) {Δδ} can be obtained.

[0047] The smallest eigenvalue {λ} among the eigenvalues ​​{λ} is the load multiplier that gives the load at the time of buckling relative to the load in a balanced stress state, so {K G The initial buckling load is calculated by multiplying the input load under the load conditions when} is calculated by the smallest eigenvalue λ.

[0048] In this way, linear buckling analysis is an analytical method that derives the equilibrium equation at buckling from the principle of virtual work and treats it as a generalized eigenvalue problem, and does not require time increment calculations to determine the changes in load and stroke over time.

[0049] The aforementioned Figure 6 shows the results of plotting the buckling loads obtained by linear buckling analysis on a load-stroke curve for each of the automobile part model 111A (Figure 5(a)) and the automobile part model 111B (Figure 5(b)). As shown in Figure 6, the buckling loads obtained by linear buckling analysis show no correlation with stiffness for either the automobile part model 111A or the automobile part model 111B, but do show a correlation with the maximum load.

[0050] Based on the above considerations, the inventors came up with the idea of ​​performing an optimization analysis to determine the optimal shape of an automotive part in a deformation mode in which axial crush occurs when subjected to a compressive load in the longitudinal direction, with the objective function being maximization of the buckling load obtained by linear buckling analysis. Such an optimization analysis led to the discovery that it is possible to design an automotive part so as to improve the crash performance of the automotive part when subjected to a compressive load in the longitudinal direction, without requiring a significant amount of calculation time. The present invention was made based on this discovery, and its specific configuration is as described below.

[0051] [First Embodiment] <Automotive Component Design Apparatus> An automotive component design apparatus (hereinafter referred to as the "automotive component design apparatus") according to a first embodiment of the present invention designs automotive components so as to improve the crashworthiness of the automotive components that are subjected to longitudinal compressive loads during an automobile collision. As shown in FIG. 1 , the automotive component design apparatus 1 is configured, for example, by a PC or the like, and includes a display device 3, an input device 5, a storage device 7, a working data memory 9, and a 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 processing unit 11, and each function is executed in response to commands from the processing unit 11. Each component of the automotive component design apparatus 1 will now be described.

[0052] The display device 3 is used to display the analysis results, and is composed of an LCD monitor, etc. The input device 5 is used to give display instructions for the automobile part model file 31 and to input conditions by the operator, and is composed of a keyboard, mouse, etc. The storage device 7 is used to store various files such as the automobile part model file 31, and is composed of a hard disk, etc. The working data memory 9 is used to temporarily store data used by the calculation processing unit 11 and for calculations, and is composed of a RAM (Random Access Memory), etc.

[0053] 1, the calculation processing unit 11 includes an automobile part model acquisition unit 13, a design space setting unit 15, a design target portion model generation unit 17, an optimization analysis condition setting unit 19, an optimization analysis unit 21, and a design target portion shape determination unit 23. The calculation processing unit 11 is configured by a CPU (Central Processing Unit) such as a PC, and the above-mentioned units function when the CPU executes a predetermined program. In the first embodiment, the design target is an automobile part to which a reinforcing member is attached to improve collision performance, and each unit of the above-mentioned automobile part design device 1 will be described.

[0054] <<Automobile Component Model Acquisition Unit>> The automobile component model acquisition unit 13 acquires an automobile component model that models an automobile component (see FIG. 2) that receives a compressive load in the longitudinal direction during an automobile collision.

[0055] In the automotive part design device according to the first embodiment, the automotive part to be designed is assumed to have a reinforcing member attached to it to enhance its crashworthiness. The automotive part model acquisition unit 13 then acquires an automotive part model in which the automotive part is modeled using shell elements and / or solid elements.

[0056] <<Design Space Setting Unit>> The design space setting unit 15 sets a design space for a design target portion that is a design target in the automobile part model acquired by the automobile part model acquisition unit 13. In the first embodiment, the design space setting unit 15 sets a two-dimensional space along the surface of the automobile part model as the design space.

[0057] <<Design target part model generation unit>> The design target part model generation unit 17 generates a design target part model for performing optimization analysis processing in the design space set by the design space setting unit 15. In the first embodiment, the design target part model generation unit 17 generates a design target part model by dividing the design space set in a two-dimensional space along the surface of the automobile part model into elements using shell elements.

[0058] The design target part model generation unit 17 connects the generated design target part model to the automobile part model. The connection between the design target part model and the automobile part model may be achieved, for example, by connecting (rigid joint or elastic joint) the nodes of the design target part model to the nodes of the automobile part model using elements (rigid body elements, elastic body elements, or elastic-plastic body elements). Alternatively, the connection may be achieved by sharing the nodes of the design target part model with the nodes of the automobile part model. Furthermore, the design target part model generation unit 17 sets the material properties, plate thickness, etc. of the generated design target part model according to the material of the reinforcing member that reinforces the automobile part, and, if the reinforcing member is plate-shaped, the plate thickness, etc.

[0059] <Optimization Analysis Condition Setting Unit> The optimization analysis condition setting unit 19 sets load conditions, objective functions, and predetermined constraint conditions as optimization analysis conditions for the automobile part model from which the design target portion model has been generated.

[0060] The load condition is a condition for inputting a compressive load in the longitudinal direction to the automobile part model from which the design target portion model has been generated. In the first embodiment, the optimization analysis condition setting unit 19 sets a load condition for inputting a predetermined load along the longitudinal direction of the automobile part model 111 to the flat plate 117 provided at the tip of the automobile part model 111 in the longitudinal direction (see FIG. 3 ).

[0061] The load conditions include the magnitude and direction of the input load, the load input point, etc. The load conditions are preferably set based on the compressive load input in the longitudinal direction of the automobile part, which is determined in advance by a crash analysis that analyzes all or part of the automobile including the automobile part that is subjected to the compressive load in the longitudinal direction.

[0062] Furthermore, the optimization analysis condition setting unit 19 may set constraint conditions that constrain the displacement of the automobile part model in addition to the load conditions. For example, as in the case of the rectangular cylindrical automobile part model 111 shown in Fig. 3, the constraint conditions may be set to constrain the displacement of a flat plate 119 provided at the tip on the opposite side to a flat plate 117, which is the load input point where the load is input.

[0063] The objective function is to maximize the buckling load of the primary buckling mode obtained by linear buckling analysis. In the first embodiment, the objective function is to maximize the smallest eigenvalue λ, which is the solution of the characteristic equation expressed by the above-mentioned equation (3).

[0064] The constraint conditions impose predetermined constraints on the design target part model in the optimization analysis, and for example, a volume constraint ratio (ratio to the volume of the entire design space) of the design target part model may be set.

[0065] <Optimization Analysis Unit> The optimization analysis unit 21 performs optimization analysis on the automobile part model from which the design target portion model has been generated under the optimization analysis conditions set by the optimization analysis condition setting unit 19, and determines the optimal shape of the design target portion model.

[0066] For example, topology optimization can be applied to the optimization analysis by the optimization analysis unit 21. When using densimetry in topology optimization and there are many intermediate densities, it is preferable to discretize the topology by giving a penalty coefficient (penalty factor) as an optimized parameter. The value of the penalty coefficient can be set appropriately.

[0067] In the first embodiment, the optimal shape of the design target portion model is found by remaining and erasing shell elements that constitute the design target portion model so as to satisfy the optimization analysis conditions set by the optimization analysis condition setting unit 19.

[0068] The optimization analysis by the optimization analysis unit 21 can also be performed by, for example, commercially available analysis software using the finite element method.

[0069] <<Design Subject Portion Shape Determination Unit>> The design subject portion shape determination unit 23 determines the shape of the design subject portion based on the optimal shape of the design subject portion model obtained by the optimization analysis unit 21 .

[0070] In this first embodiment, the design target portion shape determination unit 23 determines the remaining shape, obtained by remaining and eliminating shell elements through a topology optimization analysis process for a design target portion modeled with shell elements, as the shape of a plate-like reinforcing member to be attached to an automobile part model.

[0071] Since plate-shaped reinforcing members are preferably manufactured by, for example, press molding, the design target portion shape determination unit 23 may convert the shape determined for the plate-shaped reinforcing member into a shape that can be manufactured by press molding. For example, the design target portion shape determination unit 23 may smooth contour irregularities in the shape determined for the plate-shaped reinforcing member, taking into account the blank processability of the plate-shaped reinforcing member. Furthermore, if shapes remaining after the optimization analysis process are scattered over a certain range, the design target portion shape determination unit 23 may replace the shapes with the shape of a single plate-shaped reinforcing member that has the same weight and center of gravity.

[0072] Furthermore, in the first embodiment, the design target portion shape determining unit 23 determines the position on the automobile part where the plate-shaped reinforcing member is to be attached, based on the determined or converted shape of the reinforcing member to be attached to the automobile part.

[0073] <Automotive Component Design Method> The automotive component design method according to the first embodiment of the present invention designs an automotive component so as to improve the collision performance of the automotive component that receives a compressive load in the longitudinal direction during a vehicle collision. As shown in FIG. 7 , the automotive component design method according to this embodiment includes an automotive component model acquisition step S1, a design space setting step S3, and a design target portion model generation step S5. Furthermore, as shown in FIG. 7 , the automotive component design method according to this embodiment also includes an optimization analysis condition setting step S7, an optimization analysis step S9, and a design target portion shape determination step S11. In the automotive component design method according to the first embodiment, each of these steps is executed by a computer. Hereinafter, the above steps will be described for the design target of the first embodiment, which is an automotive component to which a reinforcing member is attached to improve collision performance.

[0074] <<Automobile Component Model Acquisition Step>> The automobile component model acquisition step S1 is a step of acquiring an automobile component model that models an automobile component (see FIG. 2 ) that receives a compressive load in the longitudinal direction during an automobile collision. In the first embodiment, the automobile component model acquisition step S1 is executed by the automobile component model acquisition unit 13 of the automobile component design device 1. Then, in the automobile component model acquisition step S1, an automobile component model is acquired in which the automobile component is modeled using shell elements and / or solid elements.

[0075] <<Design Space Setting Step>> The design space setting step S3 is a step of setting a design space for a design target portion to be designed in the automobile part model acquired in the automobile part model acquisition step S1. In the first embodiment, the design space setting step S3 is executed by the design space setting unit 15 of the automobile part design device 1. Then, in the design space setting step S3, a two-dimensional space along the surface of the automobile part model is set as the design space.

[0076] <<Design target part model generation step>> Design target part model generation step S5 is a step of generating a design target part model for performing optimization analysis processing on the design space set in design space setting step S3. In the first embodiment, design target part model generation step S5 is executed by the design target part model generation unit 17 of the automotive part design apparatus 1. Then, in design target part model generation step S5, the design space set in a two-dimensional space along the surface of the automotive part model is divided into elements using shell elements to generate a design target part model.

[0077] Furthermore, in design target portion model generation step S5, the generated design target portion model is connected to the automobile part model. The design target portion model and the automobile part model may be connected, for example, by connecting the nodes of the design target portion model and the nodes of the automobile part model with elements (rigid elements, elastic elements, or elasto-plastic elements) (rigid connection or elastic connection). Alternatively, the design target portion model and the automobile part model may be connected by sharing nodes of the design target portion model and the automobile part model.

[0078] Furthermore, in the design target portion model generation step S5, the material properties and plate thickness of the generated design target portion model are set according to the material of the reinforcing member that reinforces the automobile part, and, if the reinforcing member is plate-shaped, the plate thickness, etc.

[0079] <Optimization Analysis Condition Setting Step> The optimization analysis condition setting step S7 is a step of setting optimization analysis conditions including a load condition for inputting a compressive load in the longitudinal direction of the automotive part model, an objective function for maximizing the buckling load of the primary buckling mode obtained by linear buckling analysis, and predetermined constraint conditions related to the design target portion model. In the first embodiment, the optimization analysis condition setting step S7 is executed by the optimization analysis condition setting unit 19 of the automotive part design device 1. In the optimization analysis condition setting step S7, the load condition, objective function, and constraint conditions are each set in the same way as in the optimization analysis condition setting unit 19 of the automotive part design device 1.

[0080] It is preferable that the load conditions be set based on a load input in the longitudinal direction of the automobile part model, which is determined in advance by a collision analysis that analyzes all or part of an automobile including an automobile part model that is subjected to a compressive load in the longitudinal direction.

[0081] In addition, in the optimization analysis condition setting step S7, similar to the optimization analysis condition setting unit 19 of the automobile part design device 1 described above, it is preferable to set constraint conditions that constrain the displacement of the automobile part model in addition to the load conditions.

[0082] <Optimization Analysis Step> The optimization analysis step S9 is a step of performing optimization analysis to find an optimal shape of the design target portion model generated in the automobile part model under the optimization analysis conditions set in the optimization analysis condition setting step S7. In the present embodiment 1, the optimization analysis step S9 is executed by the optimization analysis unit 21 of the automobile part design device 1.

[0083] For example, topology optimization can be applied to the optimization analysis in the optimization analysis step S9. When using the density method in topology optimization and there are many intermediate densities, it is preferable to discretize the topology by giving a penalty coefficient as an optimization parameter. The value of the penalty coefficient can be set appropriately.

[0084] In the first embodiment, the optimal shape of the design object portion model is found by retaining and eliminating shell elements that constitute the design object portion model so as to satisfy the optimization analysis conditions set in optimization analysis condition setting step S7.

[0085] The optimization analysis in the optimization analysis step S9 can be performed using, for example, commercially available analysis software using the finite element method.

[0086] <<Design target portion shape determination step>> The design target portion shape determination step S11 determines the shape of the design target portion based on the optimal shape of the design target portion model obtained in the optimization analysis step S9. In the first embodiment, the design target portion shape determination step S11 is executed by the design target portion shape determination unit 23 of the automotive part design device 1.

[0087] In this first embodiment, the remaining shape obtained by performing a topology optimization analysis process on a design target portion model modeled using shell elements, whereby shell elements are retained and eliminated, is determined as the shape of a plate-like reinforcing member to be attached to an automobile part model.

[0088] Since plate-shaped reinforcing members are preferably manufactured by press molding, for example, in the design target portion shape determination step S11, the shape determined for the plate-shaped reinforcing member may be converted into a shape that can be manufactured by press molding. For example, taking into consideration the blank processability of the plate-shaped reinforcing member, it may be preferable to smooth out any irregularities in the contour of the determined shape for the plate-shaped reinforcing member. Furthermore, if shapes remaining after the optimization analysis process are scattered over a certain range, it may be preferable to replace them with the shape of a single plate-shaped reinforcing member that has the same weight and center of gravity.

[0089] Furthermore, in the first embodiment, in the design target portion shape determination step S21, the position where the plate-shaped reinforcing member is to be attached to the automobile part is determined based on the determined or converted shape of the reinforcing member to be attached to the automobile part.

[0090] <Automotive Part Design Program> The above description of the first embodiment has been about the automotive part design device and method. However, the first embodiment can also be configured as an automotive part design program that causes each unit in the arithmetic processing unit 11 of the automotive part design device 1 (FIG. 1) configured by a computer to function.

[0091] The design program for an automotive part according to the first embodiment is for designing an automotive part so as to improve the collision performance of the automotive part that receives a compressive load in the longitudinal direction during an automotive collision. The design program for an automotive part according to the first embodiment causes a computer to function as an automotive part model acquisition unit 13, a design space setting unit 15, a design target portion model generation unit 17, an optimization analysis condition setting unit 19, an optimization analysis unit 21, and a design target portion shape determination unit 23, as in the arithmetic processing unit 11 shown in FIG.

[0092] As described above, the design device, method, and program for an automotive part according to the first embodiment perform optimization analysis to determine the optimal shape of a reinforcing member that reinforces an automotive part that receives a compressive load in the longitudinal direction during an automobile collision, thereby improving the collision performance. In this optimization analysis, an objective function is set that maximizes the buckling load in the primary buckling mode. This makes it possible to design an automotive part reinforced with a reinforcing member that improves collision performance in the axial crush deformation mode, in which the buckling load determines performance.

[0093] The above-described first embodiment is directed to designing an automobile part by determining the optimum shape and position of a reinforcing member that is attached to reinforce the automobile part in order to improve the collision performance against a compressive load input in the longitudinal direction during an automobile collision.

[0094] However, as another aspect of the first embodiment, the shape of the automobile part itself may be determined and the automobile part may be designed so as to improve the collision performance of the automobile part that receives a compressive load in the longitudinal direction.

[0095] For example, in a method for designing an automobile part according to another aspect of the first embodiment, the shape of the automobile part may be determined by the following procedure.

[0096] First, in the design space setting step, a design space is set with the automobile part model itself as the design target portion.

[0097] Next, in the design target portion model generation step, a design target portion model is generated using shell elements and / or solid elements. At this time, the design target portion model may be generated using the shell elements and / or solid elements used in modeling the automobile part model.

[0098] Then, the material properties and plate thickness of the generated design target portion model are set according to the material of the automotive part to be designed, and, if the automotive part is manufactured by press-forming a metal plate as described below, the plate thickness, etc.

[0099] Next, in the optimization analysis condition setting step, optimization analysis conditions are set for the automobile part model from which the design target portion model has been generated, with the objective function being maximization of the buckling load in the primary buckling mode. In the optimization analysis condition setting step, the load conditions, constraint conditions, and restriction conditions may be set in the same manner as in the first embodiment described above.

[0100] Next, an optimization analysis is performed on the design object portion model under the set optimization analysis conditions to find the optimal shape of the design object portion model.

[0101] Then, the shape of the automobile part, which is the design target portion, is determined based on the optimum shape of the design target portion model.

[0102] When topology optimization is applied to optimization analysis, three-dimensional coordinate data of the remaining shape (element density distribution above a predetermined threshold) of the design target part is input into a CAD / CAM program. Next, the shape of the automotive part can be determined by performing CAD processing such as smoothing and shape optimization in accordance with the constraints of actual automotive part manufacturing.

[0103] Similarly, the design device and program for an automotive part according to another aspect of the present embodiment 1 may be designed to improve the collision performance of an automotive part by determining the optimal shape of the automotive part itself that is subjected to a compressive load in the longitudinal direction. In this way, also in another aspect of the present embodiment 1, an automotive part that is subjected to a compressive load in the longitudinal direction can be designed to improve the collision performance in an axial crush deformation mode in which the buckling load determines the collision performance.

[0104] In the above description, topology optimization is performed as an optimization analysis to determine the optimal shape of the design target portion model generated in the automobile part model, but the present invention may also perform thickness optimization to determine the optimal thickness distribution of the design target portion model as the optimization analysis. In this case, the shape of the design target portion in the automobile part model can be determined as follows.

[0105] When a two-dimensional space along the surface of an automobile part model is set as the design space, the shape of the design target part model remaining after removing portions of the optimal thickness distribution obtained by thickness optimization that are less than a predetermined thickness is obtained as the optimal shape of the reinforcing member to be affixed to the automobile part. In this case, the predetermined thickness used as the basis for removal may be set appropriately taking into consideration the collision performance and weight.

[0106] Furthermore, when a design space is set with the automobile part model itself as the design target portion, a portion where the plate thickness obtained by the plate thickness optimization analysis is greater than the plate thickness of the original automobile part model is set as a portion where a reinforcing member is attached, and the shape of that portion can be determined as the shape of the reinforcing member. Alternatively, the shape of the design target portion can be determined by deleting portions where the plate thickness is equal to or less than a predetermined value compared to the plate thickness of the automobile part model.

[0107] The automobile part model is not limited to a model of only the automobile part that is the design target, but may also include other automobile parts that are installed around it but are not the design target.

[0108] [Embodiment 2] The method for designing an automobile part according to the first embodiment described above is for designing an automobile part so as to improve the collision performance of the automobile part that receives a compressive load in the longitudinal direction during an automobile collision.

[0109] However, the present invention can be configured to manufacture automobile parts that are subjected to compressive loads in the longitudinal direction during an automobile collision, with improved collision performance.

[0110] In the manufacturing method of the automobile part according to the second embodiment, first, the shape and position of the reinforcing member to be attached to the automobile part so as to improve the collision performance are determined using the design method of the automobile part according to the first embodiment described above. Next, a plate-shaped reinforcing member is produced by press molding according to the determined shape of the reinforcing member.

[0111] Furthermore, the automobile part is manufactured by attaching the manufactured plate-shaped reinforcing member to the determined position of the reinforcing member for the automobile part. Specific examples of modes for attaching the plate-shaped reinforcing member to the automobile part include welding such as resistance spot welding, electric arc welding, and laser beam welding, adhesion using a structural adhesive, and a weld bond method that combines spot welding and adhesion.

[0112] To attach a plate-shaped reinforcing member to an automobile part, first, the three-dimensional coordinate position data of the automobile part is obtained. Next, the obtained three-dimensional coordinate position data of the automobile part is converted into assembly data. The assembly data is data (NC data) in a format used by assembly robots in the automobile body manufacturing process, and the converted assembly data is read into an NC unit. Then, using the NC unit that has read the converted assembly data, the part is assembled to attach the plate-shaped reinforcing member to the automobile part.

[0113] In this way, according to the manufacturing method of an automobile part according to the second embodiment, it is possible to manufacture an automobile part reinforced with a reinforcing member so as to improve the collision performance in the deformation mode of axial crushing when subjected to a compressive load in the longitudinal direction during an automobile collision.

[0114] Furthermore, as a method for manufacturing an automobile part according to another aspect of this embodiment 2, the automobile part may be manufactured based on the shape of the automobile part determined by the design method for an automobile part according to another aspect of this embodiment 1 described above.

[0115] When the shape of an automobile part is determined using a design method for an automobile part according to another aspect of embodiment 1, the automobile part can be manufactured by press-forming a metal plate, as described below as an example.

[0116] First, CAD data of the automobile part is acquired based on the shape of the automobile part determined by the method for designing an automobile part according to another aspect of the first embodiment.

[0117] Next, CAD data for a press-forming die is created based on the acquired CAD data of the automobile part, and a press-forming die (tool of press forming) is created based on the created CAD data of the press-forming die.Then, the automobile part is manufactured using the created press-forming die.

[0118] A specific example of how a press molding die is produced is as follows: CAD data for the press molding die is input into a CAD / CAM program linked to an NC machine tool and converted into NC data (NC program) for NC processing. The NC machine tool performs machining operations on a die model for full mold casting or a steel die (still mold). The acquired NC data (NC program) is then used to produce a mold model for casting or a steel die using the NC machine tool, thereby creating the actual press molding die.

[0119] According to another aspect of the manufacturing method of an automobile part according to the second embodiment described above, it is possible to manufacture an automobile part whose shape is determined so as to improve collision performance against deformation modes such as axial crushing when subjected to a compressive load in the longitudinal direction.

[0120] An analysis was conducted to verify the effect of improving the collision performance of an automobile part subjected to a compressive load in the longitudinal direction using the automobile part design method, device, and program according to the present invention, and this will be described below.

[0121] Example 1: Optimal shape of reinforcing member of automobile part In Example 1, a rectangular cylindrical automobile part model 111 modeled using shell elements, as shown in Figure 3, was used as the analysis target, and the optimal shape of a reinforcing member that reinforces the automobile part model 111 was determined.

[0122] Automobile part model 111 simulates an automobile part that receives a compressive load in the longitudinal direction during an automobile collision, and is formed in a rectangular tube shape with four flat surfaces 113 and bending ridges 115 connecting adjacent flat surfaces 113. Flat plates 117 and 119 are provided at both longitudinal ends of automobile part model 111. Automobile part model 111 has a rectangular tube with a side length of 50 mm, a height of 100 mm, a thickness of 1 mm, and is made of steel plate with a tensile strength of 1,180 MPa.

[0123] In Example 1, as an example of the invention, an optimization analysis was carried out to determine the optimum shape of a reinforcing member that improves the collision performance of an automobile part against a compressive load input in the longitudinal direction.

[0124] In the optimization analysis, first, an automobile part model 111 modeled using shell elements was obtained, and a two-dimensional space along the surfaces of the flat portion 113 and the bend ridge portion 115 of the automobile part model 111 was set as the design space. Then, a design target portion model was generated for the set design space using shell elements. Furthermore, the nodes of the design target portion model and the automobile part model were linked by sharing the nodes.

[0125] Next, loading conditions, constraint conditions, objective function, and constraint conditions were set as optimization analysis conditions for the automobile part model 111. The loading condition was a condition in which a load of 1 kN was input in the longitudinal direction to the flat plate 117 at one end in the longitudinal direction, and the constraint condition was a condition in which the flat plate 119 at the other end was constrained. The objective function was to maximize the eigenvalue of the primary buckling mode of the automobile part model, and the constraint condition was to limit the volume of the design target portion model to 30% or less of the volume of the design space.

[0126] Then, an optimization analysis using topology optimization was performed under the set optimization analysis conditions, and the remaining design target part model was determined as the optimal shape of the reinforcing member.

[0127] In addition, in Example 1, as Comparative Example 1, only the objective function of the optimization analysis conditions set in Invention Example 1 was changed to "minimization of the displacement of the flat plate 117," and an optimization analysis using topology optimization was performed to determine the optimal shape of the model of the part to be designed.

[0128] 8 shows the optimal shapes of the reinforcing member obtained by optimization analysis in Example 1 and Comparative Example 1. As shown in Fig. 8(a), the optimal shape 121 of the reinforcing member in Example 1 was a shape that remained along the longitudinal direction of the bend ridge line 115, with almost no shape remaining on the flat surface 113 of the automobile part model 111. In contrast, as shown in Fig. 8(b), the optimal shape 123 of the reinforcing member in Comparative Example 1 was a shape that remained in a substantially H-shape on the flat surface 113, with almost no shape remaining on the bend ridge line 115.

[0129] The optimal shape 121 of the reinforcing member according to Example 1 of the present invention and the optimal shape 123 of the reinforcing member according to Comparative Example 2 were attached to the automobile part model 111, and an axial compression analysis was performed in which a compressive load was input to the flat plate 117 at one end in the longitudinal direction. The load-stroke curve was calculated and the results are shown in Figure 9.

[0130] As shown in FIG. 9, in Example 1 of the invention and Comparative Example 1, a reinforcing member of the optimal shape 121 or 123 was attached to the original automobile part model 111, and therefore no significant difference was observed in the rigidity (the slope of the load-stroke curve in the elastic region) of the two.

[0131] However, the maximum load was higher in Example 1 of the present invention, which had the objective function of maximizing the buckling load, than in Comparative Example 1, and even in the strokes after the maximum load, the load in Example 1 of the present invention was higher than that in Comparative Example 1.

[0132] This result shows that the automobile part model 111 to which the reinforcing member of the optimum shape 121 according to the invention example 1 is attached has superior collision performance in the deformation mode of axial crushing.

[0133] Example 2: Optimal shape of automobile part In Example 2, a rectangular cylindrical automobile part model 111 modeled using shell elements as shown in FIG. 3 was used as a design target part, and its optimal shape was determined.

[0134] As in Example 1 described above, automobile part model 111 is formed in a rectangular tube shape with four flat surfaces 113 and bending ridges 115 connecting adjacent flat surfaces 113. Flat plates 117 and 119 are provided at both longitudinal ends of automobile part model 111. Automobile part model 111 has a rectangular tube with a side length of 50 mm, a height of 100 mm, a thickness of 1 mm, and is made of steel plate with a tensile strength of 1,180 MPa.

[0135] In Example 2, as an example of the invention, an optimization analysis was performed to find an optimal shape for improving the collision performance of an automobile part model 111 that receives a compressive load in the longitudinal direction.

[0136] In the optimization analysis, first, an automobile part model 111 modeled using shell elements was obtained, and a flat portion 113 and a bend ridge portion 115 in the automobile part model 111 were set as a design space. Then, for the set design space, a design target portion model was generated using the shell elements of the flat portion 113 and the bend ridge portion 115.

[0137] Next, as in Example 1, load conditions, constraint conditions, objective functions, and constraint conditions were set for the automobile part model 111 as optimization analysis conditions. However, in Example 2, the constraint condition was set such that the volume of the design target portion model was 50% or less of the volume of the design space.

[0138] Then, an optimization analysis using topology optimization was performed under the set optimization analysis conditions, and the optimal shape of the remaining design target part model was obtained.

[0139] In addition, in the example, as Comparative Example 2, only the objective function among the optimization analysis conditions set in Invention Example 2 was changed to "minimization of the displacement of the flat plate 117," and optimization analysis was performed using topology optimization to determine the optimal shape of the model of the part to be designed.

[0140] 10 shows the optimal shapes of automobile part model 111 obtained by optimization analysis in invention example 2 and comparative example 2. As shown in Fig. 10(a), optimal shape 131 of the automobile part model in invention example 2 is a shape in which flat portions 113 have almost completely disappeared, remaining in the areas corresponding to bend ridge lines 115 (Fig. 3). In contrast, optimal shape 133 of the automobile part model in comparative example 2 is a shape in which bend ridge lines 115 have almost completely disappeared, remaining in the areas corresponding to bend ridge lines 113 (Fig. 3), as shown in Fig. 10(b).

[0141] For each of the optimal shape 131 according to Example 2 and the optimal shape 133 according to Comparative Example 2, an axial compression analysis was performed in which a load was input to the flat plate 117 at one end in the longitudinal direction, and the load-stroke curves were calculated. The results are shown in Figure 11. As shown in Figure 11, the rigidity (the slope of the load-stroke curve in the elastic region) was higher in Comparative Example 2, which aimed to maximize rigidity. However, the maximum load was higher in Example 2, which used the maximization of buckling load as its objective function, and the maximum load in Comparative Example 2 was significantly lower than that of Example 2.

[0142] These results show that the automobile part having the shape according to Example 2 of the present invention has superior crash performance in the deformation mode of axial crushing.

[0143] The present invention provides a method, device, and program for designing an automobile part that can improve the collision performance of an automobile part that receives a compressive load in the longitudinal direction during a vehicle collision.Furthermore, the present invention provides a method for manufacturing an automobile part that can improve the collision performance of an automobile part that receives a compressive load in the longitudinal direction during a vehicle collision.

[0144] REFERENCE SIGNS LIST 1 Automotive part design device 3 Display device 5 Input device 7 Storage device 9 Working data memory 11 Arithmetic processing unit 13 Automotive part model acquisition unit 15 Design space setting unit 17 Design target portion model generation unit 19 Optimization analysis condition setting unit 21 Optimization analysis unit 23 Design target portion shape determination unit 31 Automotive part model file 100 Automotive body 101 Front side member 103 Front pillar upper 105 Roof rail 107 Roof center cross 109 Side sill 111 Automotive part model 111A Automotive part model 111B Automotive part model 113 Planar portion 115 Bent ridge portion 117 Flat plate 119 Flat plate 121 Optimal shape (reinforcement member, invention example 1) 123 Optimal shape (reinforcement member, comparative example 1) 131 Optimal shape (automotive part, invention example 2) 133 Optimal shape (automotive part, comparative example 2)

Claims

1. A method for designing an automobile part that designs an automobile part that receives a compressive load in its longitudinal direction during an automobile collision so as to improve the collision performance of the automobile part, comprising: an automobile part model acquisition step for acquiring an automobile part model that models the automobile part; a design space setting step for setting a design space for a design target part that is to be designed in the acquired automobile part model; a design target part model generation step for generating a design target part model for performing optimization analysis processing in the set design space; an optimization analysis condition setting step for setting optimization analysis conditions including load conditions for inputting a compressive load in the longitudinal direction of the automobile part model, an objective function that maximizes the buckling load of a primary buckling mode obtained by linear buckling analysis, and predetermined constraint conditions for the design target part model; an optimization analysis step for performing an optimization analysis to determine an optimal shape of the design target part model generated in the automobile part model under the optimization analysis conditions; and a design target part shape determination step for determining the shape of the design target part based on the optimal shape of the design target part model.

2. The method for designing an automotive part according to claim 1, wherein in the optimization analysis condition setting step, the objective function is to maximize the smallest eigenvalue among eigenvalues ​​that are solutions to the characteristic equation shown in the following equation (1).

3. A method for designing an automobile part as described in claim 1 or 2, wherein a reinforcing member is attached to the automobile part to reinforce the automobile part so as to improve collision performance, in the design space setting step, a two-dimensional space along a surface of the automobile part model is set as a design space, in the design target part model generation step, the design space is modeled using shell elements to generate the design target part model and the design target part model is combined with the automobile part model, and in the design target part shape determination step, a shape and position of the reinforcing member to be affixed to the automobile part are determined based on an optimal shape of the design target part model in the automobile part model.

4. A method for designing an automobile part as described in claim 1 or 2, wherein in the design space setting step, the design space is set by setting the automobile part model itself as the design target part.

5. A method for designing an automotive part according to any one of claims 1 to 4, wherein in the optimization analysis step, topology optimization is performed as the optimization analysis to determine an optimal shape of the model of the design target portion.

6. A method for designing an automotive part according to any one of claims 1 to 4, wherein in the optimization analysis step, a plate thickness optimization is performed as an optimization analysis of the model of the design target portion, and the plate thickness distribution of the model of the design target portion obtained by the plate thickness optimization is obtained as an optimal shape of the model of the design target portion.

7. A method for designing an automobile part as claimed in any one of claims 1 to 6, wherein in the optimization analysis condition setting step, the load conditions are set based on a load to be input in the longitudinal direction of the automobile part, which load has been determined in advance by a crash analysis in which all or a part of the automobile including the automobile part is the analysis subject.

8. An automobile part design device that designs automobile parts so as to improve the collision performance of the automobile parts that receive a compressive load in the longitudinal direction during an automobile collision, the automobile part design device comprising: an automobile part model acquisition unit that acquires an automobile part model that models the automobile part; a design space setting unit that sets a design space for a design target part that is to be designed in the acquired automobile part model; a design target part model generation unit that generates a design target part model for performing optimization analysis processing in the set design space; an optimization analysis condition setting unit that sets optimization analysis conditions including load conditions for inputting a load in the longitudinal direction of the automobile part model, an objective function that maximizes the buckling load of a primary buckling mode obtained by linear buckling analysis of the automobile part model, and predetermined constraint conditions for the design target part model; an optimization analysis unit that performs optimization analysis on the automobile part model from which the design target part model has been generated under the optimization analysis conditions, and obtains an optimal shape of the design target part model; and a design target part shape determination unit that determines the shape of the design target part based on the optimal shape of the design target part model.

9. An automobile part design program for designing an automobile part that receives a compressive load in the longitudinal direction during an automobile collision so as to improve the collision performance of the automobile part, the program causing a computer to function as: an automobile part model acquisition unit that acquires an automobile part model that models the automobile part; a design space setting unit that sets a design space for a design target part that is to be designed in the acquired automobile part model; a design target part model generation unit that generates a design target part model for performing optimization analysis processing in the set design space; an optimization analysis condition setting unit that sets optimization analysis conditions including load conditions for inputting a load in the longitudinal direction of the automobile part model, an objective function that maximizes the buckling load of a primary buckling mode obtained by linear buckling analysis of the automobile part model, and specified constraint conditions for the design target part model; an optimization analysis unit that executes an optimization analysis to obtain an optimal shape of the design target part model under the optimization analysis conditions; and a design target part shape determination unit that determines the shape of the design target part based on the optimal shape of the design target part model.

10. A method for manufacturing an automobile part that manufactures an automobile part that receives a compressive load in the longitudinal direction during an automobile collision so as to improve the collision performance of the automobile part, comprising the steps of: manufacturing a plate-shaped reinforcing member by press molding in accordance with the shape of the reinforcing member determined by the automobile part design method described in claim 3; and manufacturing the automobile part by attaching the manufactured plate-shaped reinforcing member to the determined position of the reinforcing member on the automobile part.

11. A method for manufacturing an automobile part, which manufactures an automobile part so as to improve the collision performance of the automobile part that receives a compressive load in the longitudinal direction during an automobile collision, comprising manufacturing the automobile part based on the shape of the automobile part determined by the automobile part design method described in claim 4.

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