Method, device and program for designing automobile body, and method for manufacturing automobile body

Abstract

The method for designing an automobile body according to the present invention is a method for designing an automobile body in which a plate-shaped member is attached to the surface of a body member constituting a body-in-white structure (100) to improve the damping properties of the body-in-white structure (100), the method comprising: a body member selection step (S1); a sensitivity analysis step for analyzing the sensitivity of the vehicle body member with respect to the vibration characteristics used for evaluating the damping properties of the body-in-white structure (100), and selecting a vehicle body member to be attached to the plate-shaped member; and a plate-like member optimization analysis step S3 for performing optimization analysis on the shape of the plate-like member attached to the selected vehicle body member.

Description

Technical Field

[0001] The present invention relates to an automobile body design method, an apparatus and a program for designing an automobile body with high shock absorption performance, and a method for manufacturing an automobile body. Background Art

[0002] In recent years, there is a greater demand than ever before for developing efficient design methods for automotive bodies with excellent vibration-damping properties. One of the major factors is the widespread expansion of electric vehicles (battery powered vehicles). This is because electric vehicles do not generate the vibrations and noises caused by internal combustion engines carried in previous gasoline vehicles (gasoline powered automobiles), so the sensitivity of passengers to vibrations and noises from other vibration sources increases. In addition, since electric vehicles need to carry large-capacity batteries, there are examples such as the following: the body frame structure of electric vehicles is combined with the protective structure of the battery, which is significantly different from the body frame structure of previous gasoline vehicles. In this case, the vibration transfer path in electric vehicles is different from that of previous gasoline vehicles, and the previous empirical rules related to the vibration damping structure of the automobile body are no longer valid.

[0003] In the past, as a technology for efficiently designing a high-performance automobile body, for example, Patent Document 1 discloses an optimization analysis using a computer to find the optimal shape of an automobile body part. This technology is a method of finding the optimal shape of an automobile body part by setting the design space, constraint conditions, and loading conditions of the automobile body part to be optimized, and eliminating unnecessary parts in the design space in a manner that satisfies the objective conditions related to the vehicle body performance, such as the stiffness and weight of the automobile body. In addition, Patent Document 2 discloses a method for finding the optimal plate thickness of a frame part for reducing the vibration noise of a panel part of an automobile.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 5585672

[0007] Patent Document 2: Japanese Patent No. 6769536 Summary of the invention

[0008] Problems to be solved by the invention

[0009] According to the method disclosed in Patent Document 1, it is possible to find the optimum three-dimensional shape of a vehicle body component that achieves objective functions such as minimizing strain energy, minimizing generated stress, and maximizing impact absorption energy for a plurality of set input loads.

[0010] Therefore, in order to improve the overall shock absorption of the body-in-white structure of the automobile body, it is considered to apply the optimization analysis technology described in Patent Document 1 to optimize the frequency response related to the vibration and acoustic fields to find the optimal shape of the body parts that improves the shock absorption. However, after trying it, the optimal shape of the body parts is a three-dimensional scattered shape, and a shape useful for the actual body-in-white structure cannot be obtained. Therefore, even if the optimal three-dimensional shape is obtained using the optimization analysis technology, it is impossible to find a part shape that can be manufactured by press forming or the like based on the obtained optimal shape.

[0011] In addition, according to the method disclosed in Patent Document 2, the plate thickness distribution of the body parts constituting the automobile body can be optimized with respect to the vibration noise reduction performance. However, since this method assumes the reconstruction of the plate thickness distribution in the body parts, although the shock absorption performance is improved, there are cases where it is difficult to improve the shock absorption performance while maintaining other body performances, such as a decrease in body rigidity.

[0012] The present invention has been made in view of the above problems, and its object is to provide an automobile body design method, device and program for designing an automobile body that improves the shock absorption of the body-in-white structure while maintaining the vehicle body performance other than shock absorption such as rigidity. Moreover, another object of the present invention is to provide an automobile body manufacturing method for manufacturing an automobile body that improves the shock absorption of the body-in-white structure while maintaining the vehicle body performance other than shock absorption such as rigidity.

[0013] Means for solving problems

[0014] In order to solve the above-mentioned problems, the inventors have studied hard to design a method for improving the shock absorption of an automobile body while maintaining the original automobile body's rigidity and other body performance. As a result, the inventors have come up with the following idea: select a body part that is effective in improving the shock absorption of the entire body-in-white structure, and adjust the mass distribution of the body part by bonding and joining a sheet-like part without changing the shape and thickness of the selected body part. Then, regarding the sheet-like part attached to the selected body part, the inventors use topology optimization to remove the part that does not affect the vibration characteristics from the perspective of the shock absorption and weight reduction of the body-in-white structure, thereby obtaining the optimal shape of the sheet-like part. In this way, the inventors have come up with the idea that by selecting a body part that is effective in improving the shock absorption and obtaining the optimal shape of the sheet-like part attached to the selected body part, the shock absorption of the entire body-in-white structure can be improved while maintaining the body performance such as rigidity.

[0015] Furthermore, the inventors have also diligently studied a method for making the shape of the plate-like component remaining after optimization analysis such as topology optimization become a shape that is easy to manufacture as an actual plate-like component. As a result, the inventors set the two-dimensional space along the surface of the selected body part as the design space, generated a plate-like component model composed of shell elements, and connected it to the body part, and performed topology optimization to find the optimal shape of the plate-like component model. As a result, the following insight was obtained: the optimal shape of the plate-like component model remaining after topology optimization becomes a shape that is easy to manufacture as an actual plate-like component.

[0016] The present invention has been made based on this finding, and specifically comprises the following structure.

[0017] The automobile body design method of the present invention is a method for designing an automobile body, wherein the automobile body is an automobile body in which a plate-like component is attached to a surface of a body component of a body-in-white structure constituting the automobile body so as to improve the shock absorption property of the body-in-white structure, wherein a computer executes a body component selection step and a plate-like component optimization analysis step, wherein in the body component selection step, a sensitivity analysis (sensitivity) of the body component with respect to a vibration characteristic used for evaluating the shock absorption property of the body-in-white structure is performed. analysis), selecting a body part to be attached with the plate-like part, in the plate-like part optimization analysis step, performing an optimization analysis on the shape of the plate-like part attached to the selected body part, the body part selection step comprising: a sensitivity analysis condition setting step, setting an objective function (objectives) related to the vibration characteristics of the body-in-white structure, a constraint condition related to the weight of the body-in-white structure and the plate thickness of each body part, and a vibration input condition related to the vibration applied to the body-in-white structure as sensitivity analysis conditions; a sensitivity analysis step, performing the sensitivity analysis under the set sensitivity analysis conditions to obtain the sensitivity (sensitivity) of each body part relative to the vibration characteristics of the body-in-white structure; and a body part selection step for attaching the plate-like part, based on the sensitivity analysis of the The sensitivity of each body part is obtained, and a body part set as an object to attach the plate-like part is selected, and the plate-like part optimization analysis step includes: a design space setting step, setting a two-dimensional space along the surface of the body part selected in the body part selection step as a design space as an object of the optimization analysis; a plate-like part model generation step, generating a plate-like part model that is modeled with shell elements and optimized in the set design space; a combination processing step, combining the generated plate-like part model with the body part selected in the body part selection step; an optimization analysis condition setting step, setting the objective function set as the sensitivity analysis condition and the vibration input condition, and the restriction condition related to the weight of the body-in-white structure as the optimization analysis condition for performing the optimization analysis; and an optimization analysis step, performing the optimization analysis to obtain the optimal shape of the plate-like part model under the set optimization analysis condition.

[0018] Alternatively, in the sensitivity analysis condition setting process, the following are set: an objective function to minimize the frequency response value of any one of acceleration, inertance or equivalent radiated power in a specified frequency band; a constraint condition to set the plate thickness of each body component to be greater than the original plate thickness of each body component; and a vibration input condition to input a specified vibration to one or more parts of the body-in-white structure.

[0019] The automobile body design device of the present invention is a device for designing an automobile body, wherein the automobile body is an automobile body in which a plate-like component is attached to a surface of a body component of a body-in-white structure constituting the automobile body so that the shock absorption property of the body-in-white structure is improved, wherein the automobile body design device comprises: a body component selection unit, which performs a sensitivity analysis of the body component with respect to a vibration characteristic used for evaluating the shock absorption property of the body-in-white structure, and selects a body component set as an object for attaching the plate-like component; and a plate-like component optimization analysis unit, which performs an optimization analysis of the shape of the plate-like component attached to the selected body component, wherein the body component selection unit comprises: a sensitivity analysis condition setting unit, which sets as a sensitivity analysis condition an objective function related to the vibration characteristic of the body-in-white structure, a constraint condition related to the weight of the body-in-white structure and the plate thickness of each body component, and a vibration input condition related to the vibration applied to the body-in-white structure; and a sensitivity analysis unit, which performs the sensitivity analysis under the set sensitivity analysis condition, and obtains a vibration characteristic with respect to the body-in-white structure. The method comprises the following steps: a first step of determining the sensitivity of each body part of the vehicle body; and a body part selection unit for attaching a plate-like part, which selects a body part to be attached to the plate-like part based on the sensitivity obtained for each body part. The plate-like part optimization analysis unit comprises: a design space setting unit, which sets a two-dimensional space along the surface of the body part selected in the body part selection unit as a design space as an object of the optimization analysis; a plate-like part model generation unit, which generates a plate-like part model that is modeled with shell elements and performs an optimization analysis process in the set design space; a combination processing unit, which combines the generated plate-like part model with the body part selected in the body part selection unit; an optimization analysis condition setting unit, which sets the objective function set as the sensitivity analysis condition and the vibration input condition, and the restriction condition related to the weight of the body-in-white structure as the optimization analysis condition for performing the optimization analysis; and an optimization analysis unit, which performs the optimization analysis for obtaining the optimal shape of the plate-like part model under the set optimization analysis condition.

[0020] The automobile body design program of the present invention is a program for designing an automobile body, wherein the automobile body is an automobile body in which the shock absorbing property of the body-in-white structure is improved by attaching plate-like components to the surfaces of body components of the body-in-white structure constituting the automobile body, wherein the automobile body design program causes a computer to function as a body component selection unit and a plate-like component optimization analysis unit, wherein the body component selection unit performs sensitivity analysis of the body component with respect to vibration characteristics used for evaluating the shock absorbing property of the body-in-white structure, and selects a body component to be attached with the plate-like components; and the plate-like component optimization analysis unit performs sensitivity analysis of the body component with respect to vibration characteristics used for evaluating the shock absorbing property of the body-in-white structure, and selects a body component to be attached with the plate-like components; The shape of the plate-like component on the body part is optimized and analyzed, and the automobile body design program enables the body part selection unit to function as a sensitivity analysis condition setting unit, a sensitivity analysis unit, and a body part selection unit for attaching the plate-like component. The sensitivity analysis condition setting unit sets the objective function related to the vibration characteristics of the body-in-white structure, the restriction conditions related to the weight of the body-in-white structure and the plate thickness of each body part, and the vibration input conditions related to the vibration applied to the body-in-white structure as sensitivity analysis conditions; the sensitivity analysis unit performs the sensitivity analysis under the set sensitivity analysis conditions to obtain the sensitivity analysis relative to the body-in-white structure. The sensitivity of each body part in terms of the vibration characteristics of the body structure; the body part selection unit for attaching the plate-like part selects the body part as the object for attaching the plate-like part based on the sensitivity calculated for each body part; the automobile body design program enables the plate-like part optimization analysis unit to function as a design space setting unit, a plate-like part model generating unit, a combination processing unit, an optimization analysis condition setting unit and an optimization analysis unit, the design space setting unit sets the two-dimensional space along the surface of the body part selected in the body part selection unit as the design space as the object of the optimization analysis; the plate-like part The component model generating unit generates a plate-like component model which is modeled by shell elements and performs an optimized analytical process in the set design space; the combining processing unit combines the generated plate-like component model with the body component selected in the body component selecting unit; the optimization analytical condition setting unit sets the objective function and the vibration input condition set as the sensitivity analytical condition, and the restriction condition related to the weight of the body-in-white structure as the optimization analytical condition for performing the optimization analysis; the optimization analytical unit performs the optimization analysis to obtain the optimal shape of the plate-like component model under the set optimization analytical condition.

[0021] The method for manufacturing an automobile body of the present invention is a method for manufacturing an automobile body, wherein the automobile body is an automobile body in which the shock absorption of the body-in-white structure is improved by attaching a plate-like component to the surface of a body component constituting the body-in-white structure of the automobile body, wherein the automobile body design method of the present invention is used to obtain the optimal shape of a plate-like component model attached to the body component selected in the body-in-white structure, and based on the obtained optimal shape of the plate-like component model, the shape and attachment position of the plate-like component attached to the selected body component are determined, the plate-like component is manufactured based on the determined shape of the plate-like component, and the manufactured plate-like component is attached to the selected body component in the body-in-white structure using the determined position of the plate-like component.

[0022] Effects of the Invention

[0023] According to the present invention, by appropriately selecting a vehicle body part to which a plate-like component is attached and finding the optimal shape of the plate-like component model through optimization analysis, an automobile body can be designed with improved shock absorption of the body-in-white structure. In addition, according to the present invention, by setting a two-dimensional space along the surface of the selected vehicle body part as a design space and performing optimization analysis to find the optimal shape of the plate-like component model, a shape that is easy to manufacture by stamping or the like as an actual plate-like component can be obtained. Furthermore, according to the present invention, an automobile body can be manufactured while maintaining vehicle body performance other than shock absorption such as rigidity and improving the shock absorption of the body-in-white structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a block diagram showing the structure of the automobile body design device according to the first embodiment.

[0025] Figure 2 This is a diagram showing a body-in-white structure of an automobile body that is an analysis target in the first embodiment.

[0026] Figure 3 The figures show specific examples of the parts of the vibration characteristics used for evaluating the vibration damping performance of the body-in-white structure in the first embodiment ((a) is the roof panel, (b) is the roof center RF (roof center reinforcement) and the floor cross member).

[0027] Figure 4 This is the frequency responsiveness of the inertia of the roof center RF obtained as an example of vibration characteristics used for evaluating the vibration damping performance of the body-in-white structure in the first embodiment.

[0028] Figure 5This is a diagram showing the thickness change rate of each body part obtained by sensitivity analysis in the present embodiment 1, example 2 and example 6, and the body part selected as the object for attaching the plate-like part based on the thickness change rate ((a) is the sensitivity analysis result, (b) is the selected body part).

[0029] Figure 6 The diagram shows the results of obtaining the optimum shape of the plate-like member model to be attached to the vehicle body member selected based on the result of the sensitivity analysis in the first and second embodiments and the second and sixth examples.

[0030] Figure 7 This is a flowchart showing the flow of processing of the automobile body design method according to the first embodiment.

[0031] Figure 8 The figure shows the thickness change rate of each body part obtained by sensitivity analysis in Example 1 and the body part selected as the object to attach the plate-like part based on the thickness change rate ((a) is the sensitivity analysis result, (b) is the selected body part).

[0032] Fig. 9 This is a diagram showing the result of obtaining the optimum shape of the plate-shaped member model to be attached to the vehicle body member selected based on the result of the sensitivity analysis in the first embodiment.

[0033] Fig.10 This figure shows the thickness change rate of each body part obtained by sensitivity analysis in Example 3 and the body part selected as the object to attach the plate-like part based on the thickness change rate ((a) is the sensitivity analysis result, (b) is the selected body part).

[0034] Fig.11 This is a diagram showing the result of obtaining the optimum shape of the plate-shaped member model to be attached to the vehicle body member selected based on the result of the sensitivity analysis in the third embodiment.

[0035] Fig.12 This is a diagram showing the thickness change rate of each body part obtained by sensitivity analysis in Example 4, and the body part selected as the object to attach the plate-like part based on the thickness change rate ((a) is the sensitivity analysis result, (b) is the selected body part).

[0036] Fig.13 This is a diagram showing the result of obtaining the optimum shape of the plate-shaped member model to be attached to the vehicle body member selected based on the result of the sensitivity analysis in the fourth embodiment.

[0037] Fig.14This is a diagram showing the thickness change rate of each element of the body component obtained by sensitivity analysis in Example 5, and the body component selected as the object for attaching the plate-like component based on the thickness change rate ((a) is the sensitivity analysis result, and (b) is the selected body component).

[0038] Fig.15 This is a diagram showing the result of obtaining the optimum shape of the plate-shaped member model to be attached to the vehicle body member selected based on the result of the sensitivity analysis in the fifth embodiment.

[0039] Fig.16 This is a diagram showing the result of obtaining the optimum shape of the plate-shaped member model to be attached to the vehicle body member selected based on the result of the sensitivity analysis in the sixth embodiment. DETAILED DESCRIPTION

[0040] Before describing the first and second embodiments of the present invention, the body-in-white structure of the automobile body to which the present invention is applied is described. In the drawings of the present application, the X direction, the Y direction, and the Z direction respectively indicate the body front-rear direction, the body width direction, and the body up-down direction.

[0041] <Body-in-white structure>

[0042] As an example, Figure 2 As shown, the body-in-white structure 100 of the automobile body is composed of body parts such as body frame parts and panel parts. 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. In addition, examples of the panel parts include a roof panel 109, a door panel 111, and the like.

[0043] As described later, the present invention performs sensitivity analysis of the body parts with respect to the vibration characteristics of the body-in-white structure 100 and optimization analysis to find the optimal shape of the plate-shaped part model attached to the body parts. Therefore, the body parts constituting the body-in-white structure 100 are modeled using shell elements and / or solid elements. In addition, the element information, material properties, etc. of the body parts constituting the body-in-white structure 100 are stored in the body-in-white structure model file 21 ( Figure 1 ).

[0044] [Implementation Method 1]

[0045] <Automobile body design device>

[0046] The automobile body design device according to the first embodiment of the present invention designs an automobile body in which the shock absorbing property of the body-in-white structure 100 is improved by attaching plate-shaped members to the surfaces of body parts of the body-in-white structure 100 constituting the automobile body. Figure 1 As shown, the automobile body design device 1 is composed of a PC (personal computer) and the like, and includes a display device 3, an input device 5, a memory storage 7, a working data memory 9, and an arithmetic processing unit 11. The display device 3, the input device 5, the memory storage 7, and the working data memory 9 are connected to the arithmetic processing unit 11, and perform their respective functions according to instructions from the arithmetic processing unit 11. The following describes the various structures of the automobile body design device 1.

[0047] The display device 3 is used for displaying the analysis results, etc., and is composed of a liquid crystal monitor (LCD monitor) or the like. The input device 5 is used for displaying the body-in-white structure model file 21, inputting conditions by the operator, etc., and is composed of a keyboard, a mouse, etc. The storage device 7 is used for storing various files such as the body-in-white structure model file 21, etc., and is composed of a hard disk, etc. The working data memory 9 is used for temporary storage and calculation of data used in the calculation processing unit 11, and is composed of a RAM (Random Access Memory), etc.

[0048] like Figure 1 As shown, the calculation processing unit 11 includes a vehicle body component selection unit 13 and a plate-shaped component optimization analysis unit 15, and is composed of a CPU (central processing unit) of a PC or the like. These units function by the CPU executing a predetermined program. The functions of the above-mentioned units in the calculation processing unit 11 are described below.

[0049] 《Body Parts Selection Unit》

[0050] The vehicle body component selection unit 13 performs sensitivity analysis of each vehicle body component with respect to vibration characteristics for evaluating the shock absorption performance of the vehicle body structure 100, and selects a vehicle body component to which the plate-shaped component is to be attached. Figure 1 As shown, the vehicle body component selecting means 13 includes a sensitivity analysis condition setting unit 13a, a sensitivity analysis unit 13b, and a plate-like component attachment target vehicle body component selecting unit 13c.

[0051] (Sensitivity analysis condition setting section)

[0052] The sensitivity analysis condition setting unit 13a sets sensitivity analysis conditions in the sensitivity analysis of the body parts with respect to the vibration characteristics for evaluating the shock absorption performance of the body-in-white structure 100. Furthermore, the sensitivity analysis condition setting unit 13a sets the objective function related to the vibration characteristics of the body-in-white structure 100 and the constraint conditions related to the weight of the body-in-white structure 100 and the plate thickness of each body part as the sensitivity analysis conditions. Furthermore, the sensitivity analysis condition setting unit 13a sets the vibration input conditions related to the vibration applied to the body-in-white structure 100 as the sensitivity analysis conditions.

[0053] The objective function is set based on 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, inertia, or equivalent radiated power in a predetermined frequency band at a predetermined location of the body-in-white structure 100.

[0054] Inertia is a value obtained by taking the ratio of the force input to an object and the acceleration generated thereby, and is also called a vibration transfer function. Inertia I can be calculated using the following formula (1).

[0055] [Mathematical formula 1]

[0056]

[0057] a is the acceleration amplitude at the evaluation point of the vibration characteristics, and F is the load amplitude of the vibration input to the body-in-white structure.

[0058] The equivalent radiated power (ERP) is a simple indicator that expresses the level of sound emitted by a structure. It is based on the idea that the component of the vibration speed of the structure that is perpendicular to the surface provides energy to the acoustic space. The equivalent radiated power (ERP) can be calculated using the following formula (2) and represents the energy in acoustic emission per unit time.

[0059] [Mathematical formula 2]

[0060]

[0061] lf is the loss coefficient, c is the acoustic velocity, ρ is the medium density, v is the component of the velocity perpendicular to the plane, and ∫ds is the area of ​​the target surface.

[0062] exist Figure 3 An example of a location for evaluating vibration characteristics is shown in FIG. Figure 3 (a) is a diagram showing the roof panel 109 in which the equivalent radiated power is evaluated as a vibration characteristic. Figure 3 (b) is a diagram showing the roof center RF103 and the floor cross member 105 whose inertia is evaluated as vibration characteristics.

[0063] exist Figure 4 , as an example of vibration characteristics, the frequency response of the inertia in the vertical direction of the central portion of the roof center RF103 is shown.

[0064] In the first embodiment, minimization of the inertia in the vertical direction in the frequency band of 95 Hz to 115 Hz at the center portion of the roof center RF103 in the body-in-white structure 100 is set as the objective function.

[0065] The portion of the vehicle body structure 100 where the vibration characteristics are evaluated is appropriately set in accordance with the instruction of the operator.

[0066] The restriction condition is a restriction imposed on the sensitivity analysis of the body parts with respect to the vibration characteristics of the body-in-white structure 100. In the first embodiment, the sensitivity analysis condition setting unit 13a sets the total weight of the body-in-white structure 100 to a predetermined weight or less as a restriction condition related to the weight of the body-in-white structure 100, and sets the original plate thickness of each body part to be greater than or equal to the plate thickness of each body part as a restriction condition related to the plate thickness of each body part.

[0067] The vibration input condition is a condition related to the vibration applied to the body-in-white structure 100 in the sensitivity analysis of each body component with respect to the vibration characteristics of the body-in-white structure 100. As the conditions related to the vibration, the amplitude (magnitude of the vibration), the frequency (vibration frequency) (frequency), and the location where the vibration is applied are set. Examples of the location where the vibration is applied include, for example, Figure 2 A front sub-frame 113 and a suspension tower 115 are indicated by triangle marks.

[0068] The sensitivity analysis condition setting unit 13a sets a vibration input condition for applying a predetermined vibration to one or two or more locations of the vehicle body structure 100. As a scheme for applying the predetermined vibration to one location, for example, a vibration input condition for applying the predetermined vibration to either the front subframe 113 or the suspension support tower 115 is set. As a scheme for applying the predetermined vibration to two locations, for example, a vibration input condition for applying the predetermined vibration to both the front subframe 113 and the suspension support tower 115, or to other locations to which the vibration is applied in addition to these locations, is set.

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

[0070] (Sensitivity Analysis Section)

[0071] The sensitivity analysis unit 13 b performs sensitivity analysis under the sensitivity analysis conditions set by the sensitivity analysis condition setting unit 13 a , and obtains the sensitivity of each vehicle body component with respect to the vibration characteristics of the vehicle body structure 100 .

[0072] In the first embodiment, as the sensitivity analysis performed by the sensitivity analysis unit 13b, sheet thickness optimization analysis of each vehicle body component is performed. Then, as the sensitivity of each vehicle body component, the ratio of change of the optimal sheet thickness t based on the original sheet thickness t0, that is, the sheet thickness change rate (=(t-t0)×100 / t0[%]) is calculated.

[0073] Of course, the sensitivity analysis unit 13b may calculate, for example, the difference between the optimum thickness t and the original thickness t0 (= t-t0) or the ratio between the optimum thickness t and the original thickness t0 (= t / t0) as the sensitivity.

[0074] The sensitivity analysis unit 13 b may perform either a thickness optimization analysis for finding the optimum thickness of the entire vehicle body component or a thickness optimization analysis for finding the optimum thickness for each shell element used for modeling the vehicle body component.

[0075] exist Figure 5 (a) shows that Figure 2 An example of the results of sensitivity analysis of the sensitivity of each vehicle body component of the body-in-white structure 100 is shown. Figure 5 The result shown in (a) provides an objective function and a constraint condition as a sensitivity analysis condition, wherein the objective function is set to minimize the inertia of the central portion of the roof center RF103, and the constraint condition is set to set the weight increase of the body-in-white structure 100 to within 5 kg and the plate thickness of the body parts to be greater than the original plate thickness. In addition, as a sensitivity analysis condition, a vibration input condition of applying a predetermined vibration to the front subframe 113 is provided.

[0076] like Figure 5 As shown in (a), since the thickness variation rate of the vehicle body parts such as the roof center RF103, the roof rail 117, and the wheel house 119 is large, it can be seen that these vehicle body parts are highly sensitive to the vibration characteristics of the body-in-white structure 100.

[0077] (Part for selecting body parts to be attached with plate-shaped parts)

[0078] The plate-like member affixing target vehicle body component selecting unit 13c selects a vehicle body component to be affixed with the plate-like member based on the sensitivity of each vehicle body component obtained by the sensitivity analyzing unit 13b.

[0079] When the sensitivity analysis unit 13b performs a thickness optimization analysis to find the sensitivity of each body part, the body part selection unit 13c selects a body part having a sensitivity greater than a predetermined value to which the plate-shaped part is attached. On the other hand, when the sensitivity analysis unit 13b performs a thickness optimization analysis to find the sensitivity of each shell element of the body part, first, the ratio of the shell elements of the shell elements included in each body part having a sensitivity greater than the predetermined value is calculated. Then, the body part having a larger ratio of the calculated shell elements is selected.

[0080] exist Figure 5 (b) shows the roof center RF103, roof side rail 117, wheel house 119, etc., which have a plate thickness variation rate of 5% or more for each vehicle body component and are selected as targets for attaching plate-shaped components.

[0081] 《Analysis unit for optimizing plate-shaped parts》

[0082] The plate-shaped component optimization analysis unit 15 optimizes the shape of the plate-shaped component to be attached to the vehicle body component selected by the vehicle body component selection unit 13. Figure 1 As shown, the plate-like component optimization analysis unit 15 includes a design space setting unit 15a, a plate-like component model generating unit 15b, a combination processing unit 15c, a material property setting unit 15d, an optimization analysis condition setting unit 15e, and an optimization analysis unit 15f.

[0083] (Design space setting department)

[0084] The design space setting unit 15 a sets a two-dimensional space along the surface of the vehicle body component selected by the vehicle body component selecting unit 13 as a design space to be subjected to optimization analysis.

[0085] (Plate-like component model generation unit)

[0086] The plate-like component model generating unit 15 b generates a plate-like component model by modeling it with shell elements in the design space set by the design space setting unit 15 a and performing an optimized analytical process.

[0087] (Combination Processing Unit)

[0088] The combination processing unit 15 c combines the plate-shaped component model generated by the plate-shaped component model generating unit 15 b with the vehicle body component selected by the vehicle body component selecting unit 13 .

[0089] The plate-like component model and the vehicle body component can be combined by, for example, using elements (rigid body element, elastic body element or elastic-plastic body element) to connect the nodes of the plate-like component model with the nodes of the vehicle body component (rigid joint or elastic joint).

[0090] (Material property setting section)

[0091] The material property setting unit 15d sets material properties in the plate-like component model. The set material properties can be set according to the type of material (steel sheet, etc.) of the plate-like component attached to the actual body component. In addition, the plate thickness set in the plate-like component model can be set to the plate thickness of the material actually used. There is no particular restriction on the value of the plate thickness, but it is preferably within the range that can be regarded as a plate material (about 0.5mm to 10mm). The setting of the material properties of the plate-like component model by the joining processing unit 15c can be performed either before or after the plate-like component model is joined to the body component by the joining processing unit 15c.

[0092] (Optimization analysis condition setting section)

[0093] The optimization analysis condition setting unit 15 e sets the objective function and vibration input conditions set as sensitivity analysis conditions by the sensitivity analysis condition setting unit 13 a , and the constraint conditions related to the weight of the body-in-white structure 100 as optimization analysis conditions.

[0094] The optimization analysis condition setting unit 15e can set an objective function that minimizes a frequency response value of any one of acceleration, inertia, 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 a vibration input condition for inputting a predetermined vibration to one or more portions of the body-in-white structure 100.

[0095] In the first embodiment, the optimization analysis condition setting unit 15e sets an objective function for minimizing the inertia of the center portion of the roof center RF103 in a predetermined frequency band and a constraint condition related to the weight of the body-in-white structure 100. Furthermore, in the first embodiment, the optimization analysis condition setting unit 15e sets a vibration input condition for inputting a predetermined vibration to the front subframe 113 for the body-in-white structure 100.

[0096] (Optimization Analysis Department)

[0097] The optimization analysis unit 15f performs optimization analysis to obtain the optimal shape of the plate-like member model under the optimization analysis conditions set by the optimization analysis condition setting unit 15e.

[0098] In the optimization analysis performed by the optimization analysis unit 15f, for example, topology optimization of shell elements can be applied. In the topology optimization using the density method, the density of the shell elements of the plate-like component model is used as a design variable for optimization analysis processing, and the optimal shape of the plate-like component model is obtained by leaving or removing shell elements. In addition, the optimal position of the plate-like component model can be obtained based on the position of the shell elements remaining in the optimization analysis processing.

[0099] In topology optimization using the density method, when there are many intermediate densities, it is preferable to assign a penalty coefficient as an optimization parameter for discretization. In this case, the value of the penalty coefficient can be appropriately set.

[0100] The optimization analysis unit 15f is not limited to performing the topology optimization as described above, and may be an optimization analysis using other calculation methods. In addition, the optimization analysis unit 15f may use commercially available analysis software using the finite element method, for example.

[0101] exist Figure 6 An example of the optimal shape of the plate-like component model obtained by the optimization analysis performed by the optimization analysis unit 15f is shown in FIG. Figure 6 As shown, an optimal shape 121 of the plate-shaped component model attached to the roof center RF103, an optimal shape 123 of the plate-shaped component model attached to the roof side rail 117, and an optimal shape 125 of the plate-shaped component model attached to the wheel house 119 are obtained.

[0102] <Automobile Body Design Method>

[0103] The automobile body design method of the first embodiment is used to design an automobile body in which a plate-shaped member is attached to the surface of the body member of the body-in-white structure 100 constituting the automobile body so as to improve the shock absorption performance of the body-in-white structure 100. Figure 7 The method of each step shown includes a vehicle body component selection step S1 and a plate-shaped component optimization analysis step S3.

[0104] 《Body Parts Selection Steps》

[0105] The vehicle body component selection step S1 is a step of performing sensitivity analysis of each vehicle body component with respect to vibration characteristics for evaluating the shock absorption performance of the vehicle body structure 100, and selecting a vehicle body component to which the plate-shaped component is to be attached. Figure 7 As shown, the body part selection step S1 includes a sensitivity analysis condition setting step S1a, a sensitivity analysis step S1b, and a plate-like part attachment target body part selection step S1c. In the first embodiment, the body part selection step S1 is executed by the body part selection unit 13 of the automobile body design device 1.

[0106] (Sensitivity analysis condition setting process)

[0107] The sensitivity analysis condition setting step S1a is a step of setting sensitivity analysis conditions in the sensitivity analysis of the vehicle body parts with respect to the vibration characteristics for evaluating the shock absorption performance of the vehicle body structure 100. In addition, an objective function related to the vibration characteristics of the vehicle body structure 100, constraint conditions related to the weight of the vehicle body structure 100 and the plate thickness of each vehicle body part, and vibration input conditions related to the vibration applied to the vehicle body structure 100 are set as the sensitivity analysis conditions.

[0108] In the first embodiment, the sensitivity analysis condition setting step S1 a is executed by the sensitivity analysis condition setting unit 13 a of the automobile body design device 1 .

[0109] In the sensitivity analysis condition setting step S1a, an objective function can be set to minimize the frequency response value of any one of acceleration, inertia, or equivalent radiated power in a predetermined frequency band at a predetermined location of the vehicle body structure 100. Inertia can be calculated using the above equation (1), and equivalent radiated power can be calculated using the above equation (2).

[0110] In the sensitivity analysis condition setting step S1a, the total weight of the body-in-white structure 100 can be set to a predetermined weight or less as a restriction condition related to the weight of the body-in-white structure 100, and the original thickness of each body component can be set to be greater than or equal to the original thickness of each body component as a restriction condition related to the thickness of each body component.

[0111] Furthermore, in the sensitivity analysis condition setting step S1 a , a vibration input condition for inputting a predetermined vibration to one or two or more locations in the vehicle body structure 100 can be set.

[0112] As a method of applying a predetermined vibration to a certain part, for example, Figure 2 As shown by the △ mark in FIG. 1 , a vibration input condition is set to apply a predetermined vibration to either the front subframe 113 or the suspension support tower 115. As a scheme for applying a predetermined vibration to two locations, for example, Figure 2 In the embodiment, both the front subframe 113 and the suspension tower 115 or other sites in addition to these sites are used as sites to which vibration is applied, and vibration input conditions for applying predetermined vibration to these multiple sites are set.

[0113] When vibration is applied to a plurality of locations, vibrations having the same amplitude and frequency may be applied to these locations, or vibrations having at least different amplitudes or frequencies may be applied to these locations.

[0114] (Sensitivity analysis process)

[0115] The sensitivity analysis step S1b is a step of performing sensitivity analysis under the sensitivity analysis conditions set in the sensitivity analysis condition setting step S1a to obtain the sensitivity of each vehicle body component with respect to the vibration characteristics of the vehicle body structure 100. In the first embodiment, the sensitivity analysis step S1b is performed by the sensitivity analysis unit 13b of the automobile body design device 1.

[0116] In the sensitivity analysis in the sensitivity analysis step S1b, the thickness optimization analysis of each body component can be applied. In this case, as the sensitivity of each body component, the ratio of the change of the optimal plate thickness t when the original plate thickness t0 is used as the reference, that is, the plate thickness change rate (= (t-t0) × 100 / t0 [%]) can be calculated. Of course, for example, the difference between the optimal plate thickness t and the original plate thickness t0 (= t-t0) or the ratio of the optimal plate thickness t to the original plate thickness t0 (= t / t0) can also be calculated as the sensitivity.

[0117] In the sensitivity analysis in the sensitivity analysis step S1b, either a thickness optimization analysis for finding the optimum thickness of the entire body component or a thickness optimization analysis for finding the optimum thickness for each shell element used in modeling the body component may be performed.

[0118] (Step of selecting the body parts to be attached with the plate-shaped parts)

[0119] The plate-like component attachment target vehicle body part selection step S1c is a step of selecting a vehicle body part to be attached to the plate-like component based on the sensitivity of each vehicle body part obtained in the sensitivity analysis step S1b. In the first embodiment, the plate-like component attachment target vehicle body part selection step S1c is performed by the plate-like component attachment target vehicle body part selection unit 13c of the automobile body design device 1.

[0120] When the plate thickness optimization analysis for finding the sensitivity of each body part is performed in the sensitivity analysis step S1b, a body part having a sensitivity greater than a predetermined value is selected in the plate-like part attachment target body part selection step S1c. On the other hand, when the plate thickness optimization analysis for finding the sensitivity of each shell element of the body part is performed in the sensitivity analysis step S1b, first, the ratio of the shell elements having a sensitivity greater than the predetermined value among the shell elements included in each body part is calculated. Then, the body part having a larger ratio of the calculated shell elements is selected.

[0121] 《Analysis steps for optimizing plate-shaped parts》

[0122] The plate-like component optimization analysis step S3 is a step of optimizing the shape of the plate-like component attached to the body component selected in the body component selection step S1. Figure 7 As shown, the plate-like component optimization analysis step S3 includes a design space setting step S3a, a plate-like component model generation step S3b, a combination processing step S3c, a material property setting step S3d, an optimization analysis condition setting step S3e, and an optimization analysis step S3f. In the first embodiment, the plate-like component optimization analysis step S3 is executed by the plate-like component optimization analysis unit 15 of the automobile body design device 1.

[0123] (Design space setting process)

[0124] The design space setting step S3a is a step of setting a two-dimensional space along the surface of the vehicle body component selected in the vehicle body component 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.

[0125] (Plate-like component model generation process)

[0126] The plate-like component model generation step S3b is a step of generating a plate-like component model that is modeled with shell elements and subjected to an optimized analytical process in the design space set in the design space setting step S3a. In the first embodiment, the plate-like component model generation step S3b is executed by the plate-like component model generation unit 15b of the automobile body design device 1.

[0127] (Combined processing steps)

[0128] The combining process S3c combines the plate-shaped component model generated in the plate-shaped component model generating process S3b with the vehicle body component selected in the vehicle body component selecting process S1. In the first embodiment, the combining process S3c is executed by the combining process unit 15c of the vehicle body designing device 1.

[0129] In the combining process step S3c, the plate-like component model and the body component are combined by, for example, combining the nodes of the plate-like component model and the nodes of the body component using elements (rigid elements, elastic elements or elastoplastic elements) (rigid combination or elastic combination).

[0130] (Material property setting process)

[0131] The material property setting step S3d is a step of setting material properties in the plate-like component model. In the present first embodiment, the material property setting step S3d is executed by the material property setting unit 15d of the automobile body design device 1. The material properties set in the material property setting step S3d can be set according to the type of material (steel plate, etc.) of the plate-like component attached to the actual body component. In addition, the plate thickness set in the plate-like component model can be set to the plate thickness of the material actually used. There is no particular restriction on the value of the plate thickness, and it is preferably within the range that can be regarded as a plate material (about 0.5mm to 10mm). The setting of the material properties to the plate-like component model in the material property setting step S3d can be performed either before or after the plate-like component model is combined with the body component in the combining process step S3c.

[0132] (Optimization analysis condition setting process)

[0133] The optimization analysis condition setting step S3e is a step of setting the objective function and vibration input conditions set as sensitivity analysis conditions in the sensitivity analysis condition setting step S11, and the constraint conditions related to the weight of the body-in-white structure as optimization analysis conditions. 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.

[0134] In the optimization analysis condition setting step S3e, an objective function can be set, wherein the objective function is set to minimize a frequency response value of any one of acceleration, inertia, or equivalent radiated power in a predetermined frequency band at a predetermined portion of the vehicle body structure 100. In addition, in the optimization analysis condition setting step S3e, a vibration input condition for inputting a predetermined vibration to one or more portions of the vehicle body structure 100 can be set.

[0135] The objective function and vibration input condition set as the optimization analysis condition are the same as the objective function and vibration input condition set in the sensitivity analysis condition setting step. In contrast, the constraint condition related to the weight of the body-in-white structure 100 set as the optimization analysis condition is preferably the same as the constraint condition related to the weight of the body-in-white structure 100 set as one constraint condition in the sensitivity analysis condition setting step. In addition, the constraint condition related to the weight of the body-in-white structure 100 is a constraint that sets the weight increase caused by attaching the plate-like component to a specified value or less. Therefore, the constraint condition related to the weight of the body-in-white structure 100 and the constraint condition related to the weight of the plate-like component model are synonymous.

[0136] (Optimization analysis process)

[0137] The optimization analysis step S3f is a step of performing optimization analysis to find the optimal shape of the plate-like member 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 performed by the optimization analysis unit 15f of the automobile body design device 1.

[0138] In the optimization analysis in the optimization analysis step S3f, for example, topology optimization can be applied. In the topology optimization using the density method, the density of the shell element of the plate-like component model is used as a design variable for the optimization analysis process, and the optimal shape of the plate-like component model is obtained by leaving or removing the shell element. In addition, the optimal position of the plate-like component model can be obtained based on the position of the shell element of the plate-like component model that remains in the optimization analysis process.

[0139] In topology optimization using the density method, when there are many intermediate densities, it is preferable to assign a compensation coefficient as an optimization parameter for discretization. In this case, the value of the compensation coefficient can be appropriately set.

[0140] 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, in the optimization analysis step S3f, for example, commercially available analysis software using the finite element method may be used.

[0141] <Automobile body design program>

[0142] The description of the first embodiment is a description of a load transfer structure optimization analysis device and method. Of course, the first embodiment can be configured so that the automobile body design device 1 ( Figure 1 )'s automobile body design program in which each unit in the calculation processing unit 11 functions.

[0143] The automobile body design program of the first embodiment designs an automobile body in which a plate-shaped member is attached to the surface of a body member of a body-in-white structure constituting the automobile body so as to improve the shock absorption performance of the body-in-white structure. Figure 1 The vehicle body component selection unit 13 and the plate-shaped component optimization analysis unit 15 function as the calculation processing unit 11 shown in FIG.

[0144] Since the automobile body design program of the first embodiment makes the computer function as the body part selection unit 13, each part of the body part selection unit 13 is made to function. Figure 1 As shown, the vehicle body component selecting means 13 includes a sensitivity analysis condition setting unit 13a, a sensitivity analysis unit 13b, and a plate-like component attachment target vehicle body component selecting unit 13c.

[0145] Furthermore, since the automobile body design program of the first embodiment makes the computer function as the plate-like component optimization analysis unit 15, each unit of the plate-like component optimization analysis unit 15 is made to function. Figure 1 As shown, the plate-like component optimization analysis unit 15 includes a design space setting unit 15a, a plate-like component model generating unit 15b, a combination processing unit 15c, a material property setting unit 15d, an optimization analysis condition setting unit 15e, and an optimization analysis unit 15f.

[0146] 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 that improves the shock absorption of the body-in-white structure by appropriately selecting the body part to which the plate-like part is attached and finding the optimal shape of the plate-like part. Furthermore, according to the first embodiment, by setting the two-dimensional space along the surface of the selected body part as the design space and finding the optimal shape of the plate-like part model modeled by the shell element, it is possible to obtain a shape that is easy to manufacture by stamping or the like as an actual plate-like part. The effect of improving the shock absorption of the automobile body design device, method, and program of the first embodiment is verified in the examples described later.

[0147] The automobile body design device, method and program of the present embodiment 1 improve the shock absorption of the body-in-white structure of the automobile body by attaching a plate-like component to the body component to change the mass distribution of the body component. However, the vibration characteristics related to the shock absorption of the automobile body also affect the rigidity in addition to the mass distribution of the body component. Therefore, when applying topology optimization as an optimization analysis to find the optimal shape of the plate-like component model, it is possible to consider directly providing the Young's modulus of the material (such as a steel plate, etc.) used in the actual plate-like component as the material property of the plate-like component model modeled by the shell element.

[0148] In addition, the shape of the plate-like component model remaining after topology optimization is easily affected by the rigidity of the body part. In other words, it has been found that when the plate-like component model is combined with the body part and topology optimization is performed, the plate-like component model is sometimes easily left in a porous shape in the ridge line part of the body part where the rigidity improvement effect is easy to obtain. Moreover, it is generally believed that the optimal shape of the plate-like component model remaining in a porous shape is a shape that is difficult to actually manufacture the plate-like component.

[0149] When obtaining the optimal shape of such a plate-like component model, the material properties set in the plate-like component model are directly set except for the Young's modulus of the material actually used, and the Young's modulus is preferably set to a minimum value. In this way, the influence of the rigidity caused by the plate-like component model is eliminated, and the optimal shape mainly concentrated on the surface part of the body component and remaining is obtained, and a shape that is easier to manufacture of the plate-like component is obtained.

[0150] [Implementation Method 2]

[0151] The automobile body design method of the first embodiment designs an automobile body in which the vibration-damping properties of the body-in-white structure are improved by attaching plate-like members to surfaces of body members constituting the body-in-white structure of the automobile body.

[0152] Of course, the present invention can be configured as a method for manufacturing an automobile body in which the vibration damping property of the body-in-white structure is improved by attaching plate-like members to the surfaces of body members constituting the body-in-white structure of the automobile body.

[0153] That is, in the second embodiment, the method for manufacturing an automobile body first uses the automobile body design method of the first embodiment to obtain the optimal shape of a plate-shaped component model to be attached to the selected body component in the body-in-white structure. Next, based on the obtained optimal shape of the plate-shaped component model, the shape and attachment position of the plate-shaped component to be attached to the selected body component are determined. Next, the plate-shaped component is manufactured based on the determined shape of the plate-shaped component. Then, using the determined position of the plate-shaped component, the manufactured plate-shaped component is attached to the selected body component in the body-in-white structure.

[0154] As an example, the automobile body design method using the above-mentioned embodiment 1 is used to obtain Figure 6 The method for manufacturing the automobile body according to the second embodiment will be described with reference to the case where the optimum shapes 121 , 123 , and 125 are shown as the optimum shapes of the plate-shaped member model.

[0155] In the automobile body design method of the first embodiment, the roof center RF103, the roof side rail 117 and the wheel house 119 are selected as the body parts to which the plate-shaped parts are attached. Therefore, first, based on the optimal shapes 121, 123 and 125 of the plate-shaped part model, the shapes and attachment positions of the plate-shaped parts to be attached to the roof center RF103, the roof side rail 117 and the wheel house 119 are determined.

[0156] The optimal shapes 121, 123, and 125 of the plate-like component model are obtained by retaining and removing shell elements in the topology optimization of the shell elements in the optimization analysis step S3f of the automobile body design method of embodiment 1. Therefore, the position of attaching the plate-like component can be determined based on the position of the plate-like component model remaining in the optimization analysis.

[0157] Next, each plate-like component is designed and manufactured according to the shape of each plate-like component determined based on the optimal shapes 121, 123 and 125. The plate thickness and material type of the plate-like component are set to the plate thickness and material type set in each plate-like component model in the material property setting step S3d. Since the plate-like components are manufactured by stamping, the shape based on the optimal shapes 121, 123 and 125 of the plate-like component model is designed to be a shape that can be made by stamping. For example, considering the blank processability of the plate-like component, the weight of the plate-like component model is maintained while the bumps and depressions of the contour are smoothed. In addition, in the case where the plate-like component models are scattered in a certain range area, they are replaced with a plate-like component with the same weight and center of gravity position.

[0158] Next, the manufactured plate-like components are attached to the selected vehicle body components, namely, the roof center RF103, the roof rail 117, and the wheel housing 119, using the positions of the plate-like components determined based on the optimal shapes 121, 123, and 125. The attachment of the plate-like components to the vehicle body components may be welding such as resistance spot welding, electric arc welding, and laser beam welding, or may be bonding using a structural adhesive or a combination of spot welding and bonding.

[0159] As a scheme for attaching plate-like components, the following schemes can be listed. First, the position data of the three-dimensional coordinates in the body-in-white structure 100 is obtained as the position of the plate-like component attached to each selected body component. Next, the obtained three-dimensional coordinate position data is converted into assembly data. Assembly data refers to data in a format used by an assembly robot in the manufacturing process of the body of an automobile (NC data (numerical control data)), and the converted assembly data is read into an NC unit (numerical control unit). Then, using the NC unit that has read the converted assembly data, the component combination of attaching the plate-like component to each selected body component in the body-in-white structure 100 is performed.

[0160] In addition, the manufacturing method of the automobile body of the present invention can modify the already manufactured automobile body to improve the shock absorption of the body-in-white structure. In this case, first, the positions of the optimal shapes 121, 123 and 125 of the plate-like component model are displayed on the display device. Then, the plate-like component can be attached to the position of the automobile body (roof center RF103, roof rail 117 and wheel cover 119) corresponding to the position of the displayed optimal shapes 121, 123 and 125 of the plate-like component model using a spot welding gun or the like.

[0161] As described above, according to the method for manufacturing an automobile body of the second embodiment, it is possible to manufacture an automobile body that improves the vibration damping property of the body-in-white structure while maintaining vehicle body performance other than vibration damping property such as rigidity.

[0162] [Example]

[0163] Since an analysis was performed to verify the effects of the automobile body design method, device, and program of the present invention, this will be described below.

[0164] In the analysis, first, as step A, similarly to the above-mentioned embodiment 1, Figure 2 The body-in-white structure 100 of the automobile body shown is used as the analysis object, and sensitivity analysis is performed to obtain the sensitivity of each body component with respect to the vibration characteristics related to the shock absorption performance. Then, the body component to which the plate-shaped component is attached is selected based on the sensitivity obtained by the sensitivity analysis.

[0165] Next, as step B, an optimization analysis is performed to determine the optimum shape of the plate-shaped member to be attached to the vehicle body member selected in step A.

[0166] Then, as step C, the vibration characteristics of the body-in-white structure formed by attaching the plate-like component model of the optimal shape obtained in step B to the body component selected in step A are obtained as an invention example. Then, the vibration characteristics of the original body-in-white structure to which the plate-like component model of the optimal shape is not attached are obtained as a comparative example, and the shock absorbing performance of the body-in-white structure of the invention example is evaluated.

[0167] In the analysis, as shown in Tables 1 and 2, sensitivity analysis, selection of body parts and optimization analysis of plate-like parts were performed on Examples 1 to 6 which were formed by changing the sensitivity analysis conditions, sensitivity analysis methods and materials of plate-like parts, and a comparative study was conducted on their effects of improving shock absorption.

[0168] [Table 1]

[0169]

[0170] [Table 2]

[0171]

[0172] First, in each of Examples 1 to 6, as step A, a vehicle body component to be attached to a plate-like component is selected, and as step B, an optimal shape of a plate-like component model is obtained.

[0173] In Example 1, an objective function and a constraint condition are set as sensitivity analysis conditions. The objective function minimizes the inertia of the floor cross member 105 in the frequency band of 115 Hz to 135 Hz. The constraint condition sets the weight increase of the body-in-white structure 100 to be less than 5 kg and to be greater than the original thickness of the body member. It should be noted that the above formula (1) is used in the calculation of the inertia.

[0174] In addition, as the vibration input condition in the sensitivity analysis and the optimization analysis, the front subframe 113 is set as the part to which vibration is applied. In the sensitivity analysis of Example 1, the thickness optimization analysis of each body component is performed, and the thickness change rate of each body component is obtained as the sensitivity. In addition, in the optimization analysis of the plate-shaped component model of Example 1, the material properties of the steel plate shown in Table 3 are set in the plate-shaped component model.

[0175] [Table 3]

[0176] Plate thickness [mm] <![CDATA[Density [kg / cm 3 > Young's modulus [GPa] Steel Plate 2.0 7.85 210 stereotype 3.0 11.34 16.1

[0177] exist Figure 8 FIG. 2 shows a contour diagram of the thickness change rate of each body component obtained by sensitivity analysis in Example 1, and body components selected as targets for attaching plate-shaped components based on the thickness change rate. Figure 8 As shown, since the plate thickness variation rate of the wheel house 119 and the fuel tank 127 is as large as 8% or more, they are selected as the vehicle body parts to which the plate-shaped parts are attached.

[0178] exist Fig. 9 The optimal shape of the plate-like component model obtained in Example 1 is shown in FIG. Fig. 9 In the figure, the area shown in dark gray is the optimal shape of the plate-like component model. Fig. 9 As shown, an optimal shape 129 of the plate-like component model attached to the wheel house 119, an optimal shape 131 of the plate-like component model attached to the fuel tank 127, and the like are obtained.

[0179] In Example 2, similarly to the first embodiment, the front subframe 113 is set as the vibration input condition as the location to which vibration is applied, and the minimization of inertia in the frequency band of 95 Hz to 115 Hz at the center of the roof center RF103 is set as the objective function. The above formula (1) is used to calculate the inertia.

[0180] In Example 2, in the sensitivity analysis, the thickness optimization analysis of each body component is performed, and the thickness change rate of each body component is obtained as the sensitivity. In addition, in Example 2, in the optimization analysis of the plate-like component model, the material properties of the steel plate shown in Table 3 above are set in the plate-like component model.

[0181] In the above Figure 5 1 shows a distribution diagram of the plate thickness change rate of each body part obtained by sensitivity analysis in Example 2, and body parts selected as targets for attaching plate-shaped parts based on the plate thickness change rate. In Example 2, the roof center RF103, the roof side rail 117, the wheel arch 119, etc. are selected as targets for attaching plate-shaped parts because the plate thickness change rate is as large as 5% or more.

[0182] In the above Figure 6 , the results of obtaining the optimal shape of the plate-shaped component model attached to the vehicle body component selected based on the results of the sensitivity analysis in Example 2 are shown. Figure 6 In the figure, the area shown in dark gray is the optimal shape of the plate-like component model. Figure 6 As shown, an optimal shape 121 of the plate-shaped member attached to the roof center RF103, an optimal shape 123 of the plate-shaped member model attached to the roof side rail 117, and an optimal shape 125 of the plate-shaped member model attached to the wheel house 119 are obtained.

[0183] In Example 3, the front subframe 113 is set as the vibration input condition as the location where vibration is applied, and the objective function is set to minimize the equivalent radiated power (ERP) in the frequency band of 110 Hz to 130 Hz of the roof panel 109. The above-mentioned formula (2) is used to calculate the equivalent radiated power ERP.

[0184] In Example 3, in the sensitivity analysis, the thickness optimization analysis of each body component is performed, and the thickness change rate of each body component is obtained as the sensitivity. In addition, in Example 3, in the optimization analysis of the plate-like component model, the material properties of the steel plate shown in Table 3 above are set in the plate-like component model.

[0185] exist Fig.10 2 shows a distribution diagram of the plate thickness change rate of each vehicle body component obtained by sensitivity analysis in Example 3, and the vehicle body components selected as targets for attaching the plate-shaped component based on the plate thickness change rate. In Example 3, the door panel 111, the radiator support 133, etc. are selected as vehicle body components for attaching the plate-shaped component because the plate thickness change rate is as large as 5% or more.

[0186] exist Fig.11 , the results of obtaining the optimal shape of the plate-shaped component model attached to the vehicle body component selected based on the results of the sensitivity analysis in Example 3 are shown. Fig.11 In the figure, the area shown in dark gray is the optimal shape of the plate-like component model. Fig.11 As shown, the optimal shape 135 of the plate-shaped component model attached to the door panel 111 and the optimal shape 135 of the plate-shaped component model attached to the radiator support 133 are obtained.

[0187] In Example 4, as vibration input conditions, the front subframe 113 and the suspension support tower 115 are set as the locations where vibration is applied, and as the objective function, the inertia in the frequency band of 95 Hz to 115 Hz in the center of the roof center RF103 is minimized. The above formula (1) is used to calculate the inertia.

[0188] In Example 4, in the sensitivity analysis, the thickness optimization analysis of each body component is performed, and the thickness change rate of each body component is obtained as the sensitivity. In addition, in Example 4, in the optimization analysis of the plate-like component model, the material properties of the steel plate shown in Table 3 above are set in the plate-like component model.

[0189] exist Fig.122 shows the distribution diagram of the plate thickness change rate of each body part obtained by sensitivity analysis in Example 4, and the body parts selected as the objects to be attached to the plate-like parts. In Example 4, the roof center RF103, the radiator support 133, etc., have a plate thickness change rate as large as 8% or more, so they are selected as the body parts to be attached to the plate-like parts.

[0190] exist Fig.13 , the results of obtaining the optimal shape of the plate-shaped component model attached to the vehicle body component selected based on the results of the sensitivity analysis in Example 4 are shown. Fig.13 In the figure, the area shown in dark gray is the optimal shape of the plate-like component model. Fig.13 As shown, the optimal shape 139 of the plate-shaped component model attached to the roof center RF103 and the optimal shape 141 of the plate-shaped component model attached to the radiator support 133 are obtained.

[0191] In Example 5, the front subframe 113 is used as the vibration input condition as the site to which vibration is applied, and the objective function is set to minimize the inertia in the frequency band of 95 Hz to 115 Hz at the center of the roof center RF103. The above equation (1) is used to calculate the inertia.

[0192] In Example 5, in the sensitivity analysis, the plate thickness optimization analysis of each element of the body component is performed, and the plate thickness change rate of each element of the body component is obtained as the sensitivity. In addition, in Example 5, in the optimization analysis of the plate-like component model, the material properties of the steel plate shown in Table 3 above are set in the plate-like component model.

[0193] exist Fig.14 2 shows a distribution diagram of the plate thickness change rate of each body part obtained by sensitivity analysis in Example 5, and body parts selected as targets for attaching plate-shaped parts based on the plate thickness change rate. In Example 5, since the plate thickness change rate of the roof center RF103 is as large as 8% or more, it is selected as the body part to which the plate-shaped part is attached.

[0194] exist Fig.15 , the results of obtaining the optimal shape of the plate-shaped component model attached to the vehicle body component selected based on the results of the sensitivity analysis in Example 5 are shown. Fig.15 In the figure, the dark gray area is the optimal shape of the plate-like component model. Fig.15 As shown in the result, the optimum shape 143 of the plate-shaped member model attached to the roof center RF103 and the like are obtained.

[0195] In Example 6, as a vibration input condition, the front subframe 113 is set as the part to which vibration is applied, and as an objective function, the minimization of inertia in the frequency band of 95 Hz to 115 Hz at the center of the roof center RF103 is set. The above formula (1) is used to calculate the inertia. In addition, in Example 6, in the sensitivity analysis, the plate thickness optimization analysis of each body component is performed, and the plate thickness change rate of each body component is calculated as the sensitivity. Moreover, in Example 6, in the optimization analysis of the plate-like component model, the material properties of the lead plate shown in Table 3 above are set in the plate-like component model.

[0196] In the above Figure 5 , a distribution diagram of the plate thickness change rate of each body part obtained by sensitivity analysis in Example 6, and body parts selected as targets for attaching plate-like parts based on the plate thickness change rate are shown. Since the sensitivity analysis conditions in Example 6 are the same as those in Example 2, the roof center RF103, the roof rail 117, and the wheel house 119 are selected as body parts for attaching plate-like parts.

[0197] exist Fig.16 , the results of obtaining the optimal shape of the plate-shaped component model attached to the vehicle body component selected based on the results of the sensitivity analysis in Example 6 are shown. Fig.16 In the figure, the area shown in dark gray is the optimal shape of the plate-like component model. Fig.16 As shown, an optimal shape 121 of the plate-shaped component model attached to the roof center RF103, an optimal shape 123 of the plate-shaped component model attached to the roof side rail 117, and an optimal shape 125 of the plate-shaped component model attached to the wheel house 119 are obtained.

[0198] Next, as step C, the evaluation value of the vibration characteristics of the body-in-white structure 100 in which the plate-like component models of the optimal shapes obtained in Examples 1 to 6 are attached to each body component is calculated. In addition, the evaluation value of the vibration characteristics is similarly calculated for the original body-in-white structure 100 before the plate-like component models are attached. Then, the improvement of the vibration damping performance of the body-in-white structure by attaching the plate-like component models of the optimal shapes is studied.

[0199] In the evaluation of the improvement in the vibration damping performance, the vibration characteristic value of the original body-in-white structure was used as a reference, and the reduction rate of the evaluation value of the vibration characteristic of the body-in-white structure to which the plate-shaped member of the optimal shape was attached was calculated.

[0200] The evaluation value of the vibration characteristics in each of Examples 1 to 6 is set to be the same as the vibration characteristics of the target condition set as the sensitivity analysis condition. In addition, in calculating the vibration characteristic evaluation value, the vibration input condition applied to the body-in-white structure 100 is set to be the same as the vibration input condition applied as the sensitivity analysis condition of each of Examples 1 to 6.

[0201] Table 4 shows the vibration characteristic evaluation values ​​of the body-in-white structure to which the plate-shaped components of the optimal shape obtained in Examples 1 to 6 are attached (invention example), the vibration characteristic evaluation values ​​of the original body-in-white structure (comparative example), and the reduction rate of the vibration characteristic evaluation values.

[0202] [Table 4]

[0203]

[0204] It can be seen that in any of Examples 1 to 6, by attaching the optimally shaped plate-shaped member to the vehicle body member, the evaluation value of the vibration characteristic is greatly reduced (43% to 90%). This shows that according to the automobile body design method of the present invention, it is possible to design an automobile body with improved shock absorption of the body-in-white structure.

[0205] Industrial Applicability

[0206] According to the present invention, it is possible to provide an automobile body design method, device, and program for designing an automobile body that improves the shock absorption of the body-in-white structure while maintaining the vehicle body performance other than shock absorption such as rigidity. Furthermore, according to the present invention, it is possible to provide an automobile body manufacturing method for manufacturing an automobile body that improves the shock absorption of the body-in-white structure while maintaining the vehicle body performance other than shock absorption such as rigidity.

[0207] Description of Reference Numerals

[0208] 1. Car body design device

[0209] 3 Display device

[0210] 5 Input Devices

[0211] 7 Storage Devices

[0212] 9 Data storage for operation

[0213] 11. Calculation Processing Unit

[0214] 13 Body Parts Selection Unit

[0215] 13a Sensitivity analysis condition setting section

[0216] 13b Sensitivity analysis section

[0217] 13c Plate-like component attachment target vehicle body component selection section

[0218] 15 Plate-like component optimization analysis unit

[0219] 15a Design space setting section

[0220] 15b Plate-like component model generation unit

[0221] 15c Combined processing unit

[0222] 15d Material property setting section

[0223] 15e Optimization analysis condition setting section

[0224] 15f Optimization Analysis Department

[0225] 21 Body-in-white structure model file

[0226] 100 Body-in-white construction

[0227] 101 Middle Column

[0228] 103 Roof Center RF

[0229] 105 Floor beam

[0230] 107 Rear side beam

[0231] 109 Roof Panel

[0232] 111 Door Panel

[0233] 113 Front subframe

[0234] 115 Suspension support tower

[0235] 117 Upper side beam

[0236] 119 wheel cover

[0237] 121 Optimal Shape

[0238] 123 Optimal Shape

[0239] 125 Optimal Shape

[0240] 127 Fuel Tank

[0241] 129 Optimal Shape

[0242] 131 Optimal Shape

[0243] 133 Radiator support

[0244] 135 Optimal Shape

[0245] 137 Optimal Shape

[0246] 139 Optimal Shape

[0247] 141 Optimal Shape

[0248] 143 Optimal Shape

[0249] 145 Optimal Shape

Claims

1. A method for designing an automobile body, the method comprising: attaching a plate-like member to a surface of a body member constituting a body-in-white structure of the automobile body so as to improve the shock absorption of the body-in-white structure; wherein: The computer performs the steps of selecting the body parts and optimizing the plate parts. In the vehicle body component selection step, sensitivity analysis of the vehicle body component with respect to vibration characteristics for evaluating the vibration damping performance of the body-in-white structure is performed to select a vehicle body component to which the plate-shaped component is to be attached. In the plate-like component optimization analysis step, the shape of the plate-like component attached to the selected vehicle body component is optimized. The vehicle body component selection step comprises: 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 thickness of each body component, and vibration input conditions related to vibration applied to the body-in-white structure; a sensitivity analysis step of performing the sensitivity analysis under the set sensitivity analysis conditions to obtain the sensitivity of each of the vehicle body components with respect to the vibration characteristics of the vehicle body structure; and a step of selecting a vehicle body part to be attached with the plate-like member, based on the sensitivities found for the respective vehicle body parts, selecting a vehicle body part to be attached with the plate-like member, The plate-like component optimization analysis step comprises: 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 component model generating step of generating a plate-like component model by modeling with shell elements and performing an optimized analytical process in the set design space; A combining step of combining the generated plate-shaped component model with the vehicle body component selected in the vehicle body component selecting step; an optimization analysis condition setting step of setting the objective function and the vibration input condition set as the sensitivity analysis condition, and a constraint condition related to the weight of the body-in-white structure as optimization analysis conditions for performing the optimization analysis; and The optimization analysis step performs the optimization analysis to obtain the optimal shape of the plate-like member model under the set optimization analysis conditions.

2. The automobile body design method according to claim 1, wherein: In the sensitivity analysis condition setting step, the following are set: The objective function is to minimize the frequency response value of any one of acceleration, inertia or equivalent radiated power in a specified frequency band; The restriction condition is to set the plate thickness of each body component to be greater than the original plate thickness of each body component; and The vibration input condition is to input a predetermined vibration to one or more locations in the body-in-white structure.

3. An automobile body design device for designing an automobile body, wherein the automobile body is an automobile body in which the shock absorbing property of the body-in-white structure is improved by attaching a plate-like member to a surface of a body member constituting the body-in-white structure of the automobile body, wherein: The automobile body design device comprises: a body component selecting unit that performs sensitivity analysis of the body component with respect to vibration characteristics for evaluating the vibration damping performance of the body-in-white structure, and selects a body component to which the plate-like component is to be attached; and The plate-shaped component optimization analysis unit optimizes the shape of the plate-shaped component attached to the selected vehicle body component. The vehicle body component selection unit comprises: 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 thickness of each body component, and vibration input conditions related to vibration applied to the body-in-white structure; a sensitivity analysis unit that performs the sensitivity analysis under the set sensitivity analysis conditions to obtain the sensitivity of each of the vehicle body components with respect to the vibration characteristics of the vehicle body structure; and The plate-shaped member affixed vehicle body member selection unit selects a vehicle body member to be affixed to the plate-shaped member based on the sensitivities obtained for the respective vehicle body members. The plate-like component optimization analysis unit has: a design space setting unit that sets a two-dimensional space along the surface of the vehicle body component selected by the vehicle body component selecting unit as a design space to be subjected to the optimization analysis; A plate-like component model generating unit generates a plate-like component model by modeling it with shell elements and performing an optimized analytical process in the set design space; A combination processing unit combines the generated plate-shaped component model with the vehicle body component selected in the vehicle body component selection unit; an optimization analysis condition setting unit that sets the objective function set as the sensitivity analysis condition and the vibration input condition, and a constraint condition related to the weight of the body-in-white structure as optimization analysis conditions for performing the optimization analysis; and The optimization analysis unit performs the optimization analysis to obtain the optimal shape of the plate-like member model under the set optimization analysis conditions.

4. An automobile body design program for designing an automobile body, wherein the automobile body is an automobile body in which the shock absorbing property of the body-in-white structure is improved by attaching a plate-like member to a surface of a body member constituting the body-in-white structure of the automobile body, wherein: The automobile body design program causes the computer to function as a body part selection unit and a plate-like part optimization analysis unit, wherein the body part selection unit performs sensitivity analysis of the body part with respect to vibration characteristics for evaluating the shock absorption performance of the body-in-white structure and selects a body part to which the plate-like part is to be attached. The plate-like component optimization analysis unit optimizes the shape of the plate-like component attached to the selected vehicle body component. Furthermore, the automobile body design program causes the body part selection unit to function as a sensitivity analysis condition setting unit, a sensitivity analysis unit, and a plate-like part attachment target body part selection unit. The sensitivity analysis condition setting unit 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 thickness of each body component, and vibration input conditions related to vibration applied to the body-in-white structure. The sensitivity analysis unit performs the sensitivity analysis under the set sensitivity analysis conditions to obtain the sensitivity of each of the vehicle body components with respect to the vibration characteristics of the vehicle body structure. The plate-like member affixing target vehicle body component selecting unit selects a vehicle body component to be affixed to the plate-like member based on the sensitivities found for the respective vehicle body components. The automobile body design program enables the plate-like component optimization analysis unit to function as a design space setting unit, a plate-like component model generating unit, a combination processing unit, an optimization analysis condition setting unit, and an optimization analysis unit. The design space setting unit sets a two-dimensional space along the surface of the vehicle body part selected by the vehicle body part selecting unit as a design space to be subjected to the optimization analysis. The plate-like component model generation unit generates a plate-like component model that is modeled using shell elements and subjected to an optimized analytical process in the set design space. The combining processing unit combines the generated plate-shaped component model with the vehicle body component selected by the vehicle body component selecting unit. The optimization analysis condition setting unit sets the objective function and the vibration input condition set as the sensitivity analysis condition, and a constraint condition related to the weight of the body-in-white structure as optimization analysis conditions for performing the optimization analysis. The optimization analysis unit performs the optimization analysis to obtain the optimal shape of the plate-like member model under the set optimization analysis conditions.

5. A method for manufacturing an automobile body, the method comprising: manufacturing an automobile body, wherein the automobile body is an automobile body in which the shock absorbing property of the body-in-white structure is improved by attaching a plate-like member to a surface of a body member constituting the body-in-white structure of the automobile body, wherein: Using the automobile body design method according to claim 1 or 2, the optimum shape of the plate-shaped component model attached to the body component selected in the body-in-white structure is obtained, Based on the obtained optimal shape of the plate-like component model, the shape and attachment position of the plate-like component to be attached to the selected vehicle body component are determined; manufacturing the plate-like component based on the determined shape of the plate-like component, The manufactured plate-shaped component is attached to the selected vehicle body component in the body-in-white structure using the determined position of the plate-shaped component.

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