Motor vehicle body design method, motor vehicle body design device, motor vehicle body design program, and motor vehicle body manufacturing method

Abstract

To provide a motor vehicle body design method, a device and a program for designing a motor vehicle body improved in the damping property of a vibration noise reduction object part by providing a damping member of a two-layer structure of a resin material and a sheet metal component on the surface of a motor vehicle body component, and a motor vehicle body manufacturing method.SOLUTION: A motor vehicle body design method according to the present invention includes: an optimization analysis model generation step S1 of generating an optimization analysis model for performing optimization analysis on the optimal shape of a vibration control member; and an optimization analysis step S3 of performing optimization analysis for determining the optimal shape of a vibration control member model in the generated optimization analysis model. In the optimization analysis model generation step S1, a vibration control member model having a one-layer structure is generated. In the optimization analysis step S3, the density, thickness, and rigidity of the vibration control member model are set so that the vibration characteristics of a vehicle body component provided with the vibration control member model are equivalent to the vibration characteristics of the vehicle body component provided with the vibration control member having a two-layer structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an automobile body design method, an automobile body design device, an automobile body design program, and an automobile body manufacturing method for designing an automobile body with improved vibration damping properties in areas of the body-in-white structure that are targets for vibration noise reduction. [Background technology]

[0002] In recent years, there has been an ever-increasing demand for the development of efficient design methods for automobile bodies with excellent vibration damping. One major factor behind this is the widespread use of electric vehicles. Because electric vehicles do not generate vibrations or noise from internal combustion engines, occupants are more sensitive to vibrations and noise from other sources. In addition, electric vehicles must be equipped with large-capacity batteries, and in some cases, the body frame structure, coupled with the protective structure for these batteries, is significantly different. As a result, the vibration transmission paths of electric vehicles are different from those of conventional gasoline-powered vehicles, and conventional rules of thumb regarding vibration damping structures that reduce vibration and noise are no longer applicable.

[0003] Computer-based optimization analysis techniques have been proposed as a means of obtaining design guidelines for high-performance vibration-damping structures without the need for empirical rules for the design of automobile bodies. For example, Patent Document 1 discloses a technology for dividing a vibration-transmitting skeletal component into multiple regions and determining the optimum plate thickness for each divided region in order to reduce vibration noise caused by vibrations transmitted from a vibration source in an automobile to a panel component via the vibration-transmitting skeletal component. Furthermore, Patent Document 2 discloses a technology for improving the vibration damping properties of an automobile part having a metal plate-shaped member by applying or attaching a resin layer to the inner surface of the plate-shaped member and adhering a metal plate vibration damping member to the surface opposite the resin layer. Furthermore, Patent Document 3 discloses an optimization analysis that uses a computer to find the optimal shape of a vehicle body part as a technology for efficiently designing a high-performance automobile body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6769536 [Patent Document 2] Japanese Patent Publication No. 2022-132725 [Patent Document 3] Patent No. 5585672 Summary of the Invention [Problem to be solved by the invention]

[0005] The technology of Patent Document 1 changes the plate thickness for each region of a vibration-transmitting skeletal component, and therefore although it improves the vibration-damping properties of the panel component targeted for vibration noise reduction, other vehicle body performance (e.g., vehicle body rigidity) may be reduced, making it difficult to achieve both vibration-damping properties and other vehicle body performance.

[0006] Furthermore, the technology of Patent Document 2 does not specify any specifics regarding the position or range of the resin layer and vibration-damping member to be provided on the plate-shaped member of the automotive part, so in order to sufficiently improve the vibration-damping performance of the automotive part, it was necessary to determine the position and range of the resin layer and vibration-damping member by trial and error. Furthermore, the technology of Patent Document 2 was aimed at improving vibration damping when a single automobile part was vibrated. Therefore, when vibration was input to the entire automobile body, it was unclear whether the technology of Patent Document 2 would efficiently improve vibration damping in the part of the automobile body that was the target of vibration noise reduction (referred to as the "target part of vibration noise reduction" in this application).

[0007] Furthermore, the technology of Patent Document 3 determines the optimal shape of a vehicle body part by setting a design space for the vehicle body part to be optimized and eliminating unnecessary parts in the design space so as to satisfy target conditions related to vehicle body performance, such as the rigidity and weight of the vehicle body. However, the technology of Patent Document 3 generates an optimization block model made of a single material in the design space and determines its optimal shape through optimization analysis processing. Therefore, the technology of Patent Document 3 cannot determine the optimal shape of a two-layer vibration-damping member made of a resin layer (corresponding to the resin material in the present application) and a vibration-damping member (corresponding to the sheet metal part in the present application), as in the technology of Patent Document 2.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide an automobile body design method, device, and program for designing an automobile body that effectively improves the vibration damping properties of areas in the body-in-white structure of the automobile body that require vibration and noise reduction, by determining the optimal shape for a two-layer vibration damping member made of a resin material and a sheet metal part to be attached to the automobile body part. Furthermore, the present invention aims to provide a method for manufacturing an automobile body that uses a vibration-damping member with a two-layer structure of a resin material and a sheet metal part to improve the vibration-damping properties of areas where vibration noise is to be reduced. [Means for solving the problem]

[0009] (1) The automobile body design method of the present invention is a method in which a computer executes the following steps to design an automobile body in which vibration and noise reduction target portions in a body-in-white structure of the automobile body are improved by providing a vibration-damping member having a two-layer structure of a resin material and a sheet metal part on the surface of the body part in the body-in-white structure of the automobile body, an optimization analysis model generation step of generating an optimization analysis model for performing optimization analysis on the optimal shape of the vibration damping member; an optimization analysis step of performing the optimization analysis using the generated optimization analysis model, The optimization analysis model generation step includes: a design space setting step of setting a design space to be subjected to the optimization analysis along the surfaces of all or some of the body parts in the body-in-white structure; a vibration-damping member model generation step of generating a vibration-damping member model of a single layer structure, which is modeled using shell elements or solid elements in the set design space and subjected to optimization analysis processing; a coupling process step of coupling the generated vibration-damping member model to the vehicle body part in the body-in-white structure to generate an optimized analysis model, The optimization analysis step includes: a material property setting step of setting density, thickness, and rigidity as material properties of the vibration-damping member model in the optimization analysis model so that the vibration characteristics of the vehicle body part provided with the vibration-damping member model are equivalent to the vibration characteristics of the vehicle body part provided with the vibration-damping member having a two-layer structure; a vibration input condition setting step of setting vibration input conditions related to vibrations to be applied to the optimization analysis model in the optimization analysis; an optimization analysis condition setting step of setting, as optimization analysis conditions, an objective function related to vibration characteristics used in evaluating the vibration-damping performance of the vibration noise reduction target portion in the optimization analysis model and a constraint condition related to the weight or volume of the vibration-damping member model; and an optimization analysis step of performing an optimization analysis to determine the optimal shape of the vibration-damping member model in the optimization analysis model under the vibration input conditions and the optimization analysis conditions.

[0010] (2) In the above (1), In the design space setting step, the design space is set in a gap between the vehicle body parts.

[0011] (3) In the above (1), In the design space setting step, a two-dimensional space along only one surface of the vehicle body part is set as the design space; The vibration-damping member model generating step is characterized in that the vibration-damping member model is generated by using shell elements.

[0012] (4) In any one of (1) to (3) above, In the optimization analysis condition setting step, the objective function is set to minimize the frequency response value of any one of acceleration, inertance, or equivalent radiation power in a predetermined frequency band of the target part for vibration noise reduction, or to minimize a function having these as variables.

[0013] (5) The automobile body design device according to the present invention designs an automobile body in which vibration damping properties of target parts for vibration and noise reduction in a body-in-white structure are improved by providing a two-layer damping member made of a resin material and a sheet metal part on the surface of a body part in the body-in-white structure of the automobile body, an optimization analysis model generation unit that generates an optimization analysis model for performing optimization analysis on the optimal shape of the vibration damping member; an optimization analysis unit that performs the optimization analysis using the generated optimization analysis model, The optimization analysis model generation unit a design space setting unit that sets a design space to be subjected to the optimization analysis along surfaces of all or some of the vehicle body parts in the body-in-white structure; a vibration-damping member model generation unit that generates a single-layer vibration-damping member model that is modeled using shell elements or solid elements in the set design space and that performs optimization analysis processing; a coupling processing unit that couples the generated vibration-damping member model to the vehicle body part in the body-in-white structure to generate an optimized analysis model, The optimization analysis unit a material property setting unit that sets density, thickness, and rigidity as material properties of the vibration-damping member model in the optimization analysis model so that vibration properties of the vehicle body part provided with the vibration-damping member model are equivalent to vibration properties of the vehicle body part provided with the vibration-damping member having a two-layer structure; a vibration input condition setting unit that sets vibration input conditions related to vibrations to be applied to the optimization analysis model in the optimization analysis; an optimization analysis condition setting unit that sets, as optimization analysis conditions, an objective function related to vibration characteristics used in evaluating the vibration-damping performance of the vibration noise reduction target portion in the optimization analysis model and a constraint condition related to the weight or volume of the vibration-damping member model; and an optimization analysis unit that performs optimization analysis to determine the optimal shape of the vibration-damping member model in the optimization analysis model under the vibration input conditions and the optimization analysis conditions.

[0014] (6) The automobile body design program of the present invention designs an automobile body in which vibration damping properties of target parts for vibration and noise reduction in a body-in-white structure are improved by providing a two-layer damping member made of a resin material and a sheet metal part on the surface of a body part in the body-in-white structure of the automobile body, Computer, an optimization analysis model generation unit that generates an optimization analysis model for performing optimization analysis on the optimal shape of the vibration damping member; an optimization analysis unit that performs the optimization analysis using the generated optimization analysis model; moreover, The optimization analysis model generation unit, a design space setting unit that sets a design space to be subjected to the optimization analysis along surfaces of all or some of the vehicle body parts in the body-in-white structure; a vibration-damping member model generation unit that generates a single-layer vibration-damping member model that is modeled using shell elements or solid elements in the set design space and that performs optimization analysis processing; a coupling processing unit that couples the generated vibration-damping member model to the vehicle body parts in the body-in-white structure and generates an optimized analysis model; The optimization analysis unit a material property setting unit that sets density, thickness, and rigidity as material properties of the vibration-damping member model in the optimization analysis model so that vibration properties of the vehicle body part provided with the vibration-damping member model are equivalent to vibration properties of the vehicle body part provided with the vibration-damping member having a two-layer structure; a vibration input condition setting unit that sets vibration input conditions related to vibrations to be applied to the optimization analysis model in the optimization analysis; an optimization analysis condition setting unit that sets, as optimization analysis conditions, an objective function related to vibration characteristics used in evaluating the vibration-damping performance of the vibration noise reduction target portion in the optimization analysis model and a constraint condition related to the weight or volume of the vibration-damping member model; The optimization analysis unit functions as an optimization analysis unit that performs optimization analysis to determine the optimal shape of the vibration-damping member model in the optimization analysis model under the vibration input conditions and the optimization analysis conditions.

[0015] (7) The manufacturing method of an automobile body according to the present invention is for manufacturing an automobile body in which a vibration-damping member having a two-layer structure of a resin material and a sheet metal part is provided on the surface of a body part in a body-in-white structure of the automobile body, thereby improving the vibration-damping properties of a part in the body-in-white structure that is a target for vibration and noise reduction, determining an optimal shape of the vibration-damping member using the automobile body design method described in any one of (1) to (4) above; determining a shape and a position of the vibration-damping member to be provided on the vehicle body part based on the optimum shape of the vibration-damping member that has been found; The vibration-damping member is provided on the vehicle body part based on the determined shape and position of the vibration-damping member. [Effects of the Invention]

[0016] In this invention, the optimal shape of a vibration-damping member with a two-layer structure of resin material and sheet metal parts that is applied to the surface of a body part that constitutes the body-in-white structure of an automobile body is determined. This allows the application locations of a multi-material structure of resin material and sheet metal parts (a sandwich structure in which resin material is sandwiched between a body part and a sheet metal part) to be determined, making it possible to design an automobile body with improved vibration-damping performance in areas of the body-in-white structure where vibration noise reduction is targeted. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a block diagram showing an automobile body design device according to a first embodiment of the present invention. [Figure 2] 1 is a diagram showing an example of a body-in-white structure of an automobile body that is the subject of analysis in the first embodiment, a portion to which vibration is input in optimization analysis, and a portion to which vibration noise is to be reduced. FIG. [Figure 3] FIG. 1 is a diagram illustrating a laminated structure in which a two-layer vibration-damping member is provided on a metal plate vehicle body part, and a laminated structure in which a one-layer vibration-damping member model is provided so that the vibration characteristics are equivalent, and how to calculate the bending moment for each structure, in the present invention. [Figure 4] 1 is a flowchart showing a processing flow in an automobile body design method according to a first embodiment of the present invention. [Figure 5] 10 is a graph showing the frequency response of the equivalent radiation power of a floor cross member in a body-in-white structure that is the subject of analysis in the examples. [Figure 6] FIG. 10 is a diagram showing a design space set for a vehicle body part provided with a two-layer vibration-damping member in an embodiment, and a model of a one-layer vibration-damping member generated in the design space. [Figure 7] FIG. 10 is a diagram showing an optimal shape vibration-damping member model obtained by optimization analysis in the example. [Figure 8] 1 is a graph showing the frequency response of the equivalent radiation power of a floor cross member in a body-in-white structure equipped with an optimal-shape damping member model in an embodiment (dashed line: original body-in-white structure, solid line: body-in-white structure equipped with an optimal-shape damping member model). [Figure 9] 10 is a graph showing the frequency response of the equivalent radiation power of a floor cross member in a body-in-white structure in which an optimal-shape damping member model is provided only at the tip of the side sill in an example (dashed line: original body-in-white structure, solid line: body-in-white structure in which an optimal-shape damping member model is provided only at the tip of the side sill). [Figure 10] 1A and 1B are diagrams showing a body-in-white structure in which an optimally shaped vibration-damping member model obtained by optimization analysis is replaced with a two-layer vibration-damping member and set at the tip of a side sill in an embodiment ((a) body-in-white structure, (b) two-layer vibration-damping member provided at the tip of a side sill). [Figure 11] This is a graph showing the frequency response of the equivalent radiation power of a floor cross member in a body-in-white structure in which a two-layer vibration-damping member is provided at the tip of the side sill in an example (dashed line: original body-in-white structure, solid line: body-in-white structure with two-layer vibration-damping member). DETAILED DESCRIPTION OF THE INVENTION

[0018] Before describing the first and second embodiments of the present invention, we will explain the body-in-white structure of an automobile body to which the present invention is applied and how the present invention was arrived at. In the drawings of the present application, the X-axis direction, the Y-axis direction, and the Z-axis direction respectively indicate the front-rear direction, the width direction, and the up-down direction of the vehicle body.

[0019] <Body-in-white structure> As shown in FIG. 2, a body-in-white structure 100 of an automobile body is made up of body parts such as body frame parts, reinforcing parts, and panel parts. The body frame parts are parts that constitute the body frame of an automobile, and examples thereof include side sills 101, front subframes 103, floor cross members 105, and the like. The reinforcing parts are parts that are provided on each body frame part to reinforce it, and examples thereof include reinforcements (not shown). The panel parts are outer panels and inner panels that are thin plate structure parts, and examples thereof include a floor panel 107 and the like.

[0020] In the body-in-white structure 100, examples of the parts that are subject to vibration and noise reduction include the floor cross member 105 and the floor panel 107.

[0021] The body-in-white structure 100 is assumed to be configured with body parts modeled using shell elements and / or solid elements. Element information, material properties, etc. of each body part modeled using shell elements and / or solid elements are assumed to be stored in a body-in-white structure model file 21 (FIG. 1) described later.

[0022] <Background to the invention> The inventors thought that in order to effectively improve the vibration-damping properties of target vibration and noise reduction areas in the body-in-white structure of an automobile body, it might be possible to determine the optimal shape of a two-layer vibration-damping member using the optimization analysis technology disclosed in Patent Document 3. Here, the two-layer vibration-damping member is assumed to be one in which a resin material is attached or applied to the surface of a body part made of metal plate, and a sheet metal part is bonded to the surface of the resin material opposite the body part. However, as mentioned above, the optimization analysis technology of Patent Document 3 is designed to optimize body parts made of a single material, and therefore cannot optimize vibration-damping members with a two-layer structure made of multiple materials, such as resin material and sheet metal parts.

[0023] The inventors therefore conducted extensive research into solving this problem, and came up with the idea of ​​performing optimization analysis by replacing vibration-damping member 115, which has a two-layer structure made of resin material 115a and sheet metal part 115b, with vibration-damping member model 123 having a single layer structure, as shown in Fig. 3. They then discovered that in order to perform optimization analysis by replacing vibration-damping member 115 having a two-layer structure with vibration-damping member model 123 having a single layer structure, the material properties to be set for vibration-damping member model 123 having a single layer structure should be determined as follows:

[0024] When considering how to determine the material properties to be set in the vibration-damping member model 123 of a single-layer structure, first consider simple harmonic motion, which is the most basic vibration expressed by the following equation.

number

[0025] The equation that expresses vibration will differ if the target structure becomes more complex, but the material properties that affect vibration in that structure are the mass m and modulus of elasticity k, as shown in the above equation.

[0026] The vibration problem of plate-like members such as car body parts can be considered as being divided into longitudinal waves that propagate due to in-plane deformation and transverse waves that propagate due to out-of-plane deformation. In order for laminated structure 111, in which two-layer vibration-damping member 115 is provided on car body part 113 made of metal plate, and laminated structure 121, in which one-layer vibration-damping member model 123 is provided on car body part 113, to exhibit equivalent behavior (vibration characteristics), it is necessary for the rigidity in the in-plane direction with respect to longitudinal waves to be equal, and the bending rigidity with respect to transverse waves to be equal.

[0027] From the above, it can be considered that the material properties of the single-layer vibration-damping member model 123 that should be set so that the vibration characteristics of the laminated structure 111 provided with the two-layer vibration-damping member 115 and the laminated structure 121 provided with the single-layer vibration-damping member model 123 are equivalent to each other are weight (density), in-plane rigidity, and bending rigidity.

[0028] First, if the weight of the laminated structure 121 provided with the one-layer vibration-damping member model 123 is equivalent to the weight of the laminated structure 111 provided with the two-layer vibration-damping member 115, the following formula (1) holds.

number

[0029] Next, if the in-plane stiffness of the laminated structure 121 to which the single-layer vibration-damping member model 123 is applied is equivalent to the in-plane stiffness of the laminated structure 111 to which the two-layer vibration-damping member 115 is provided, the following equation (2) holds true.

number

[0030] Furthermore, if the bending rigidity of the laminated structure 121 provided with the single-layer vibration-damping member model 123 is equivalent to the bending rigidity of the laminated structure 111 provided with the two-layer vibration-damping member 115, it can be considered that the bending moments when they are bent with the same curvature are equal. Below, the bending moments of the laminated structure 111 and the laminated structure 121 will be explained with reference to Fig. 3.

[0031] The bending moment M of the laminated structure 111 provided with the two-layered vibration-damping member 115 is expressed by the formula (3) (see FIG. 3(a)).

number

number

[0032] On the other hand, the bending moment M' of the laminated structure 121 provided with the vibration damping member model 123 of a single layer structure is expressed by equation (5) (see FIG. 3(b)).

number

number

[0033] Then, assuming that the bending moment M of the laminated structure 111 is equal to the bending moment M' of the laminated structure 121, the Young's modulus E' and the thickness t' of the vibration-damping member model 123 can be found by simultaneously solving equations (2), (3), and (5). Furthermore, by substituting the found thickness t' into equation (1), the density ρ' of the vibration-damping member model 123 can be found.

[0034] In this way, by using the above method to determine the density ρ', Young's modulus E', and thickness t' of the single-layer vibration-damping member model 123 and setting them as material properties, and then performing optimization analysis, it was discovered that it is possible to determine the optimal shape of the two-layer vibration-damping member 115 that can effectively improve the vibration-damping properties of the target areas for vibration and noise reduction in the body-in-white structure. The present invention was completed based on these findings and has the following configuration.

[0035] [Embodiment 1] <Automobile body design device> The automobile body design device according to the first embodiment of the present invention designs an automobile body in which the vibration damping performance of target parts for vibration and noise reduction in the body-in-white structure is improved by providing a two-layer damping member made of a resin material and a sheet metal part on the surface of the body part in the body-in-white structure of the automobile body.

[0036] 1, the automobile body designing device 1 is configured by a PC (personal computer) or the like, and includes a display device 3, an input device 5, a storage device 7, a working data memory 9, and an arithmetic processing unit 11. Furthermore, in the automobile body designing device 1, the display device 3, the input device 5, the storage device 7, and the working data memory 9 are connected to the arithmetic processing unit 11, and each function is executed by a command from the arithmetic processing unit 11. Each component of the automobile body design device 1 will be described below.

[0037] The display device 3 is used to display the analysis results and is configured with a liquid crystal monitor or the like. The input device 5 is used to instruct the display of the body-in-white structural model file 21 and to input conditions by the operator, and is composed of a keyboard, a mouse, and the like. The storage device 7 is used to store various files such as the body-in-white structural model file 21, and is configured with a hard disk or the like. The working data memory 9 is used for temporary storage of data used by the arithmetic processing unit 11 and for calculations, and is composed of RAM (Random Access Memory) and the like.

[0038] 1, the calculation processing unit 11 has an optimization analysis model generation unit 13 and an optimization analysis unit 15, and is configured by a CPU (Central Processing Unit) such as a PC. Each of these units functions when the CPU executes a predetermined program. The functions of the above units in the arithmetic processing unit 11 will be explained below.

[0039] <Optimization Analysis Model Generation Unit> The optimization analysis model generation unit 13 generates an optimization analysis model for performing optimization analysis on the optimal shape of a vibration-damping member. As shown in Fig. 1, the optimization analysis model generation unit 13 includes a design space setting unit 13a, a vibration-damping member model generation unit 13b, and a connection processing unit 13c.

[0040] (Design space setting department) The design space setting unit 13a sets a design space to be subjected to optimization analysis along the surfaces of all or some of the body parts in the body-in-white structure 100.

[0041] Here, the body parts for which the design space is set should preferably be body parts on which a vibration-damping member can be installed without damaging the appearance of the automobile body, or body parts for which space is secured for installing a vibration-damping member.

[0042] The design space setting unit 13a may set the design space in the gap between the vehicle body parts, or may set the design space as a two-dimensional space along the surface of the vehicle body part. This makes it easy to secure space for installing the vibration-damping member and to prevent the installation of the vibration-damping member from damaging the appearance of the automobile body.

[0043] When setting a design section for the gap between vehicle body parts, it is advisable to target a space with a thickness of 25 mm or less as a guideline for the space in which a vibration-damping member can be installed. Examples of gaps between body parts that define the design space include the spaces formed between body frame parts such as side sills, front side members, tunnels, and front pillars, and reinforcements that are placed inside the body frame parts as reinforcing parts.

[0044] Examples of surfaces of vehicle body parts for which the design space is set include inner or outer surfaces of vehicle body frame parts such as side sills, A-pillar lowers, front side members, tunnels, front pillars, center pillars, etc. Furthermore, examples include the inner surfaces of panel parts such as door panels, roof panels, and floor panels.

[0045] (Vibration damping member model generation section) The vibration-damping member model generation unit 13b generates a single-layer vibration-damping member model that is modeled using shell elements or solid elements in the design space set by the design space setting unit 13a and that performs optimization analysis processing.

[0046] (Combination processing section) The connection processing unit 13c connects the vibration-damping member model generated by the vibration-damping member model generating unit 13b to the vehicle body parts in the body-in-white structure 100, and generates an optimized analysis model.

[0047] The vibration-damping member model and the vehicle body part in the body-in-white structure 100 may be coupled, for example, by coupling (rigid coupling or elastic coupling) the nodes of the vibration-damping member model and the nodes of the vehicle body part with elements (rigid elements, elastic elements, or elasto-plastic elements). Alternatively, the vibration-damping member model and the vehicle body part may be coupled by sharing the nodes of the vibration-damping member model and the nodes of the vehicle body part.

[0048] Optimization Analysis Unit The optimization analysis unit 15 performs optimization analysis using the optimization analysis model generated by the optimization analysis model generation unit 13. As shown in Fig. 1, the optimization analysis unit 15 includes a material property setting unit 15a, a vibration input condition setting unit 15b, an optimization analysis condition setting unit 15c, and an optimization analysis unit 15d.

[0049] (Material property setting section) The material property setting unit 15a sets the density, thickness, and rigidity as the material properties of the vibration-damping member model in the optimization analysis model so that the vibration characteristics of the vehicle body part on which the vibration-damping member model is provided are equivalent to the vibration characteristics of the vehicle body part on which a two-layer vibration-damping member is provided.

[0050] The density, thickness, and rigidity (Young's modulus) of the vibration-damping member model are calculated using the formulas (1) to (6) as described above. First, the bending moment M of the laminated structure 111 provided with the two-layer vibration-damping member 115 is assumed to be equal to the bending moment M' of the laminated structure provided with the single-layer vibration-damping member model 123, and the Young's modulus E' and thickness t' of the vibration-damping member model 123 are found by simultaneously solving equations (2), (3), and (5).

[0051] In equation (3), n is the position of the neutral plane in the laminated structure 111, and is given by equation (4). In equation (5), n' is the position of the neutral plane in the laminated structure 121, and is given by equation (6). Note that equations (2), (3), and (5) can be solved using a numerical method such as a solver in a spreadsheet software. Then, the density ρ′ of the vibration-damping member model 123 is calculated by substituting the calculated thickness t′ of the vibration-damping member model 123 into equation (1).

[0052] In this way, when the density ρ′, stiffness (Young's modulus E′) and thickness t′ of the vibration-damping member model 123 are calculated by the material property setting unit 15a, the material properties (density ρ r and ρ S , Young's modulus E r and E S , thickness t r and t S ) are assumed to be given and known in advance.

[0053] (Vibration input condition setting section) The vibration input condition setting unit 15b sets vibration input conditions relating to vibrations to be applied to the optimization analysis model in the optimization analysis.

[0054] The vibration input condition setting unit 15b sets, as vibration input conditions, amplitude (vibration magnitude), frequency, and a part (vibration input part) to which vibration is applied in the body-in-white structure 100. The vibration input conditions may be set appropriately assuming, for example, vibrations input to the body-in-white structure 100 when a car is running.

[0055] In the case of assuming road noise when the vehicle is running, an example of a portion to which vibration is applied is the joint (indicated by a triangle in the drawing) of the front subframe 103 with the lower arm (not shown), as shown in FIG.

[0056] (Optimization analysis condition setting section) The optimization analysis condition setting unit 15c sets, as optimization analysis conditions, an objective function related to vibration characteristics used to evaluate the vibration damping properties of the target vibration noise reduction portion in the optimization analysis model, and constraint conditions related to the weight or volume of the vibration damping member model.

[0057] The objective function is a condition set according to the vibration characteristics used to evaluate the vibration-damping ability of the target portion for vibration and noise reduction. The vibration characteristics may be, for example, the vibration intensity of the target portion for vibration and noise reduction.

[0058] The target area for vibration noise reduction can be set as appropriate by the operator. In the case of road noise while the vehicle is running, an example of the target area for vibration noise reduction is the floor cross member 105 where the seat is attached, as shown in Figure 2.

[0059] Examples of the vibration intensity of a target portion for vibration noise reduction include frequency response values ​​such as acceleration, inertance, or equivalent radiated power (ERP) in a predetermined frequency band, or functions with these as variables.

[0060] Inertance is a vibration characteristic expressed as the ratio of the force input to an object to the acceleration generated by the force, and is also called the vibration transfer function.

[0061] Equivalent radiated power is an index that simply expresses the sound level emitted by a vibrating structure, and is a vibration characteristic expressed based on the idea that the perpendicular component of the vibration velocity of a structure provides energy to the acoustic space.

[0062] Examples of functions that use acceleration, inertance, or equivalent radiation power as variables include functions that give the average or maximum value of acceleration, etc. at multiple positions on a vehicle body part (panel part, etc.) that is the target area for vibration and noise reduction.

[0063] The constraint condition is a constraint on the weight or volume of the vibration-damping member model when performing optimization analysis of the vibration-damping member model for improving the vibration-damping performance of the target portion for vibration and noise reduction using the optimization analysis model.

[0064] As a constraint condition regarding weight, for example, a constraint that the weight of the vibration-damping member model must be equal to or less than a predetermined weight can be set. Furthermore, as a constraint on volume, a constraint can be set that the ratio of the volume of the vibration-damping member model based on the volume of the design space set in the body-in-white structure 100 must be equal to or less than a predetermined value. The constraints on the weight and volume of the vibration-damping member model 123 may be set based on the total weight and volume of the optimization analysis model.

[0065] (Optimization Analysis Department) The optimization analysis unit 15d performs optimization analysis to determine the optimal shape of the vibration-damping member model in the optimization analysis model under the vibration input conditions set by the vibration input condition setting unit 15b and the optimization analysis conditions set by the optimization analysis condition setting unit 15c.

[0066] The optimization analysis performed by the optimization analysis unit 15d may be, for example, topology optimization. In topology optimization using the density method, the virtual material density of the elements (shell elements or solid elements) of the vibration-damping member model 123 is used as a design variable, and an optimization analysis process is performed to determine whether elements remain or are eliminated, thereby obtaining the optimal shape of the vibration-damping member model. Furthermore, the optimal position of the vibration-damping member model 123 can be obtained from the positions of the elements that remain in the optimization analysis process.

[0067] <Automobile body design method> The automobile body design method according to the first embodiment is for designing an automobile body in which the vibration damping performance of the body-in-white structure is improved by providing the body-in-white structure with a vibration damping member having a two-layer structure of a resin material and a sheet metal part. As shown in Fig. 4, the automobile body design method according to the first embodiment includes an optimization analysis model generation step S1 and an optimization analysis step S3, and these steps are executed by a computer. Each of the above steps will be described below based on the flow diagram shown in Fig. 4. In the following description, each of the above steps is executed using an automobile body design device 1 (Fig. 1) according to the first embodiment configured by a computer.

[0068] <Optimization analysis model generation step> The optimization analysis model generation step S1 is a step of generating an optimization analysis model for performing optimization analysis on the optimal shape of a two-layer vibration-damping member to be provided on a vehicle body part in the body-in-white structure 100. The optimization analysis model generation step S10 includes a design space setting process S1a, a vibration-damping member model generation process S1b, and a connection processing process S1c, as shown in FIG. In the first embodiment, the optimization analysis model generating step S1 is executed by the optimization analysis model generating unit 13 of the automobile body design device 1.

[0069] (Design space setting process) The design space setting step S1a is a step of setting a design space to be subjected to optimization analysis along the surfaces of all or some of the body parts in the body-in-white structure 100. In the first embodiment, the design space setting step S1a is executed by the design space setting unit 13a of the automobile body design device 1.

[0070] In the design space definition step S1a, the design space may be defined in the gap between the vehicle body parts, or a two-dimensional space along the surface of the vehicle body part. This makes it easy to secure space for applying a two-layered vibration-damping member and to prevent the application of the vibration-damping member from damaging the appearance of the automobile body.

[0071] (Vibration damping member model generation process) The vibration-damping member model generation step S1b is a step of generating a vibration-damping member model that is modeled using shell elements or solid elements in the design space set in the design space setting step S1a and that undergoes optimization analysis processing. In the first embodiment, the vibration-damping member model generating step S1b is executed by the vibration-damping member model generating unit 13b of the automobile body design device 1.

[0072] If a two-dimensional space along the surface of the vehicle body part is set as the design space in the design space setting step S1a, a vibration-damping member model modeled using shell elements is generated in the vibration-damping member model generation step S1b. This is to obtain a shape of the vibration-damping member that is easy to manufacture from the optimal shape of the vibration-damping member model obtained by the optimization analysis process.

[0073] (Bonding process) The coupling process step S1c is a step of coupling the vibration-damping member model generated in the vibration-damping member model generation step S1b to the vehicle body parts in the body-in-white structure 100 to generate an optimized analysis model. In the first embodiment, the combining process step S1c is executed by the combining processing unit 13c of the automobile body design device 1.

[0074] In the connection processing step S1c, the connection between the vibration damping member model 123 and the vehicle body part in the body-in-white structure 100 may be achieved, for example, by connecting the nodes of the vibration damping member model and the nodes of the vehicle body part with elements (rigid elements, elastic elements, or elasto-plastic elements) (rigid connection or elastic connection). Alternatively, the nodes of the vibration damping member model and the nodes of the vehicle body part may be connected by sharing them.

[0075] <Optimization analysis step> The optimization analysis step S3 is a step of performing optimization analysis using the optimization analysis model generated in the optimization analysis model generation step S1. The optimization analysis step S3 includes a material property setting step S3a, a vibration input condition setting step S3b, an optimization analysis condition setting step S3c, and an optimization analysis step S3d, as shown in Fig. 4 . In the first embodiment, the optimization analysis step S3 is executed by the optimization analysis unit 15 of the automobile body design device 1.

[0076] (Material property setting process) The material property setting process S3a is a process of setting the density, thickness, and rigidity as the material properties of the vibration-damping member model in the optimization analysis model so that the vibration characteristics of the vehicle body part equipped with the vibration-damping member model 123 are equivalent to the vibration characteristics of the vehicle body part equipped with the two-layer vibration-damping member 115. In the first embodiment, the material property setting step S3a is executed by the material property setting unit 15a of the automobile body design device 1 described above.

[0077] The density, thickness, and rigidity (Young's modulus) of the vibration-damping member model can be calculated by the above-mentioned method (see formulas (1) to (6) and FIG. 3). To do so, the material properties (density ρ r and ρ S , Young's modulus E r and E S , thickness t r and t S ) is given in advance.

[0078] (Vibration input condition setting process) The vibration input condition setting step S3b is a step of setting vibration input conditions related to vibrations to be applied to the optimization analysis model in the optimization analysis. In the first embodiment, the vibration input condition setting step S3b is executed by the vibration input condition setting unit 15b of the automobile body design device 1.

[0079] In the vibration input condition setting step S3b, the amplitude (vibration magnitude), frequency (frequency of vibration), and part to which vibration is applied are set as vibration input conditions. The vibration input conditions may be set appropriately assuming, for example, vibration input to the body-in-white structure 100 when the automobile is running.

[0080] As shown in FIG. 2, the portion to which vibration is applied can be exemplified by the joint (indicated by the triangle mark in the drawing) between the front subframe 103 and the lower arm (not shown).

[0081] (Optimization analysis condition setting process) The optimization analysis condition setting process S3c is a process of setting, as optimization analysis conditions, an objective function related to the vibration characteristics used to evaluate the vibration-damping properties of the target vibration noise reduction area in the optimization analysis model, and constraints related to the weight or volume of the vibration-damping member model. In the first embodiment, the optimization analysis condition setting step S3c is executed by the optimization analysis condition setting unit 15c of the automobile body design device 1.

[0082] In the optimization analysis condition setting step S3c, the objective function can be minimization of the vibration intensity of the target vibration noise reduction portion in the optimization analysis model. Examples of the vibration intensity include acceleration, inertance, or frequency response value of equivalent radiated power (ERP) in a predetermined frequency band, or a function with these as variables.

[0083] (Optimization analysis process) The optimization analysis process S3d is a process of performing an optimization analysis to determine the optimal shape of the vibration-damping member model 123 in the optimization analysis model under the vibration input conditions set in the vibration input condition setting process S3b and the optimization analysis conditions set in the optimization analysis condition setting process S3c. In the first embodiment, the optimization analysis step S3d is executed by the optimization analysis unit 15d of the automobile body design device 1.

[0084] The optimization analysis in the optimization analysis step S3d may be performed by applying topology optimization, for example. When topology optimization is applied, the optimal position of the vibration-damping member model can be obtained from the positions of elements that remain in the optimization analysis process.

[0085] <Automobile body design program> The above description of the first embodiment has been about an automobile body design device and an automobile body design method. However, the first embodiment can be configured as an automobile body design program that causes each unit in the arithmetic processing unit 11 of the automobile body design device 1 (FIG. 1) configured by a computer to function.

[0086] In other words, the automobile body design program according to the first embodiment designs an automobile body that improves the vibration damping performance of the target areas for vibration and noise reduction in the body-in-white structure by providing a two-layer vibration damping member made of a resin material and a sheet metal part on the surface of the body part in the body-in-white structure of the automobile body. The automobile body design program according to the first embodiment causes a computer to function as an optimization analysis model generation unit 13 and an optimization analysis unit 15, like the calculation processing unit 11 shown in FIG.

[0087] Here, the automobile body design program according to the first embodiment causes a computer to function as the optimization analysis model generation unit 13, thereby causing each unit included in the optimization analysis model generation unit 13 to function. As shown in Fig. 1 described above, the optimization analysis model generation unit 13 includes a design space setting unit 13a, a vibration damping member model generation unit 13b, and a connection processing unit 13c.

[0088] Furthermore, the automobile body design program according to the first embodiment causes the computer to function as the optimization analysis unit 15, thereby causing each unit included in the optimization analysis unit 15 to function. As shown in FIG. 1, the optimization analysis unit 15 includes a material property setting unit 15a, a vibration input condition setting unit 15b, an optimization analysis condition setting unit 15c, and an optimization analysis unit 15d.

[0089] As described above, in the first embodiment, the optimal shape of a vibration-damping member with a two-layer structure of resin material and sheet metal parts to be applied to the surface of a body part that constitutes the body-in-white structure of an automobile body is determined. This allows the application locations of a multi-material structure of resin material and sheet metal parts (a sandwich structure in which resin material is sandwiched between a body part and a sheet metal part) to be determined, making it possible to design an automobile body with improved vibration-damping performance in areas of the body-in-white structure that require noise and vibration reduction.

[0090] Although the above description has been given with respect to a case where the design space is set either in the gap between the body parts or on only one side of the body part, the present invention is not limited to this, and the design space may be set in both the gap between the body parts and on one side of the body part, or on both sides of the body part.

[0091] Furthermore, in the first embodiment, the material properties (density, rigidity, and thickness) of the vibration-damping member model are set for the optimization analysis model in which the vibration-damping member model is coupled to the body-in-white structure 100, but the material properties of the vibration-damping member model may also be set before coupling to the body-in-white structure 100.

[0092] Furthermore, in the first embodiment, as shown in Fig. 2, the optimization analysis is performed with vibration applied to one location on the optimization analysis model, but in the present invention, vibration may be applied to two or more locations. When vibration is applied to multiple locations, these locations may be vibrations with the same amplitude and frequency, or vibrations with different amplitudes or frequencies may be applied, and the vibrations may be applied with phases shifted from each other.

[0093] Furthermore, the present invention does not limit the optimization analysis for determining the optimal shape of the vibration-damping member model to topology optimization, but may also use optimization analysis using other calculation methods. Furthermore, the optimization analysis can also be performed using commercially available analysis software that uses the finite element method, for example.

[0094] [Embodiment 2] The automobile body design method according to the first embodiment described above was for designing an automobile body with improved vibration damping properties in areas targeted for vibration and noise reduction by providing a two-layer damping member made of a resin material and a sheet metal part in the body parts that make up the body-in-white structure 100 of the automobile body.

[0095] However, the present invention can also be configured as a manufacturing method for an automobile body in which a two-layer vibration-damping member is provided in the body parts that make up the body-in-white structure of the automobile body, thereby manufacturing an automobile body in which the vibration-damping properties of the target areas for vibration and noise reduction in the body-in-white structure are improved.

[0096] In the automobile body manufacturing method according to the second embodiment, first, the automobile body design method according to the first embodiment described above is used to determine the optimal shape of a single-layer vibration-damping member model to be attached to all or some of the body parts in the optimization analysis model. Next, based on the optimum shape of the vibration-damping member model thus obtained, the optimum shape and position of the two-layered vibration-damping member to be provided on the vehicle body part are determined. Then, based on the determined optimum shape and position of the vibration-damping member, a two-layered vibration-damping member is provided on the surface of the vehicle body part.

[0097] Examples of ways to provide a two-layer vibration-damping member on the surface of a vehicle body part include a way in which a resin is attached or applied to the surface of the vehicle body part and then a sheet metal part is adhered to the surface of the resin material, and a way in which a two-layer vibration-damping member is produced and attached to the vehicle body part.

[0098] When applying a resin material to a vehicle body part, first, an injection molding mold is fabricated based on the optimal shape of the vibration-damping member model obtained by optimization analysis, and the resin material is produced by injection molding. Alternatively, a sheet-shaped resin material can be clamped in a mold and press-molded into the desired shape, or other methods can be used as appropriate. Then, based on the position of the vibration-damping member model with the optimal shape, the manufactured resin material can be attached to a vehicle body part in a body-in-white structure.

[0099] Furthermore, when applying resin material to a vehicle body part, the optimal shape and position of the vibration-damping member model are converted into NC data. The converted NC data is then used to operate a robot that applies the resin material, thereby applying the resin material to the vehicle body part in the body-in-white structure. The applied resin material may be liquid resin or foam resin.

[0100] When a sheet metal part is bonded to a resin material applied or affixed to a vehicle body part, it is simply arranged so as to cover the resin material applied or affixed to the vehicle body part, and then adhered to the surface of the resin material. The method for producing the sheet metal part is not particularly limited, but for example, it may be possible to clamp a sheet-like metal material in a mold and press-form it into the desired shape. The sheet metal part is preferably made larger than the resin material, and the portion other than the portion bonded to the resin material may be joined (by welding, etc.) to the vehicle body part. In this case, the position at which the sheet metal part is joined to the vehicle body part is not particularly limited, and may be determined appropriately so as not to impair the appearance of the vehicle body part or to avoid interfering with other vehicle body parts.

[0101] When manufacturing a two-layer vibration-damping member, a plate-shaped resin material may be manufactured based on the optimal shape of the vibration-damping member model, sheet metal parts may be attached to its surface to manufacture the vibration-damping member, and the manufactured vibration-damping member may then be attached to a vehicle body part based on the position of the vibration-damping member model with the optimal shape.

[0102] In this way, in the automobile body manufacturing method according to the second embodiment, the optimum shape of the vibration-damping member with a two-layer structure of resin material and sheet metal parts to be applied to the surface of the body parts that make up the body-in-white structure of the automobile body is determined. This allows the application locations of the vibration-damping members made of resin material and sheet metal parts to be determined, making it possible to manufacture an automobile body with improved vibration-damping performance in the target areas of the body-in-white structure for vibration and noise reduction. [Example]

[0103] Using the automobile body design method, device, and program according to the present invention, an analysis was conducted to verify the effect of improving vibration damping performance in target vibration and noise reduction areas in the body-in-white structure of an automobile body, and this analysis will be described below.

[0104] The analysis was performed on the body-in-white structure 100 shown in Figure 2, with the floor cross member 105 in the body-in-white structure 100 being the target area for vibration and noise reduction. To improve the vibration damping performance of the floor cross member 105, an optimization analysis was performed to determine the optimal shape for a two-layer vibration damping member made of a resin material and a sheet metal part that is attached to the body part of the body-in-white structure 100.

[0105] In the optimization analysis, road noise while the vehicle is running was assumed, and vibration input conditions were set to input vibrations of amplitude 1N and frequency 1Hz to 200Hz to the joint between the front subframe 103 and the lower arm (the part indicated by the triangle in Fig. 2).The frequency response of the equivalent radiated power (ERP) of the floor cross member 105 in the frequency band between 40Hz and 80Hz was then used to evaluate vibration damping performance.

[0106] Fig. 5 shows the frequency response results of the equivalent radiation power of floor cross member 105 obtained under the above vibration input conditions. As shown in Fig. 5, the maximum value of the equivalent radiation power in the frequency band of 40 Hz to 80 Hz was 176.7 dB (48.0 Hz).

[0107] Next, an optimization analysis was performed to determine the optimum shape of the vibration-damping member that improves the vibration-damping performance of the floor cross member 105 using the method according to the first embodiment described above. In the optimization analysis, first, a design space 133 was set for the side sill 101 and the floor cross member 105 as shown in FIG. Then, for the set design space 133, a single-layer vibration-damping member model 135 was created using solid elements, and the vibration-damping member model 135 and each vehicle body part (side sill 101, floor cross member 105) were connected with rigid beam elements to create the optimization analysis model 131 shown in Figure 6.

[0108] Next, the material properties of the vibration-damping member model 135 were set. As described above, the density, rigidity, and thickness of the material properties were set so that the vibration characteristics of the vehicle body part provided with the vibration-damping member model 135 would be equivalent to the vibration characteristics of the vehicle body part 113 provided with the two-layer vibration-damping member 115. In setting the material properties of the vibration-damping member model 135, the density, Young's modulus, and thickness of the vehicle body part 113, and the resin material 115a and sheet metal part 115b used in the two-layer vibration-damping member 115 were set as follows:

[0109] [Resin material] density ρ r :1.4g / cm 3 Young's Modulus E r :6GPa Thickness t r :1.0mm [Sheet metal parts] density ρ s :7.85g / cm 3 Young's Modulus E s :210GPa Thickness t s :0.6mm

[0110] Furthermore, the density ρ0, Young's modulus E0, and thickness t0 of the side sill 101 and floor cross member 105 as the vehicle body parts were set as follows. [Body parts] Density ρ0:7.85g / cm 3 Young's modulus E0: 210GPa Thickness t0: 0.6 mm

[0111] The density ρ', Young's modulus E', and thickness t' of the vibration-damping member model 135 calculated by substituting these values ​​into the above-mentioned equations (1) to (8) are as follows, and these values ​​were set as the material properties of the vibration-damping member model 135. [Vibration damping member model] Density ρ':4.1g / cm 3 Young's modulus E': 146.8GPa Thickness t': 1.0 mm

[0112] Next, vibration input conditions for the optimization analysis were set. The vibration input conditions were set to the portion of the front subframe 103 where it is connected to the lower arm (the portion marked with a triangle in FIG. 2), and vibrations of amplitude 1N and frequency 1 Hz to 200 Hz were input.

[0113] Next, an objective function and constraint conditions were set as optimization analysis conditions in the optimization analysis. The objective function was set to minimize the maximum value of the equivalent radiation power of the floor cross member 105 in the frequency band from 40 Hz to 80 Hz. On the other hand, the constraint was that the volume of the vibration-damping member model 135 be 10% or less of the volume of the design space 133 set in the body-in-white structure 100.

[0114] Then, under the vibration input conditions and optimization analysis conditions set as described above, an optimization analysis was performed to find the optimal shape of the vibration-damping member model 135 in the optimization analysis model 131. Topology optimization using the density method was applied to the optimization analysis. 7 shows the optimal shape (optimal shape vibration-damping member model 137) of the vibration-damping member model 135 obtained by optimization analysis. As shown in FIG. 7, the optimal shape vibration-damping member model 137 has a shape that remains at the tip of the side sill 101 and the floor cross member 105.

[0115] Therefore, the optimal shape vibration-damping member model 137 shown in Figure 7 was connected to each vehicle body part in the body-in-white structure 100, and vibration analysis was performed under the same vibration input conditions as in the optimization analysis, and the frequency characteristics of the equivalent radiation power of the floor cross member 105 were obtained. Fig. 8 shows a graph of the frequency response of the equivalent radiation power of the floor cross member 105 in the body-in-white structure 100 to which the optimal shape vibration-damping member model 137 has been coupled. For comparison, Fig. 8 also shows (dashed line) the frequency response of the equivalent radiation power of the floor panel 107 (see Fig. 5) obtained for the original body-in-white structure 100 before the optimal shape vibration-damping member model 137 has been coupled.

[0116] As shown in Figure 8, when the optimal shape vibration-damping member model 137 is used in the body-in-white structure 100, the maximum value of the equivalent radiation power ERP of the floor cross member 105 in the frequency band from 40 Hz to 80 Hz is 152.8 dB (43.5 Hz), which is a reduction of 23.9 dB compared to the original body-in-white structure. This result shows that the vibration-damping performance of the floor cross member 105, which is the target part for vibration and noise reduction, has improved.

[0117] In addition, of the optimal shape vibration-damping member model 137 obtained by the optimization analysis, the optimal shape vibration-damping member model 137 was applied only to the tip of the side sill 101, and vibration analysis was performed under the same vibration input conditions as in the optimization analysis, and the frequency characteristics of the equivalent radiation power of the floor cross member 105 were obtained. Figure 9 shows the frequency response of the equivalent radiation power of the floor cross member 105 when the optimal shape vibration-damping member model 137 is applied only to the tip of the side sill 101. The maximum value of the equivalent radiation power ERP of the floor cross member 105 in the frequency band from 40 Hz to 80 Hz is 148.0 dB (43.5 Hz), a reduction of 28.7 dB compared to the original body-in-white structure. This result shows that the vibration-damping performance of the floor cross member 105, which is the target area for vibration and noise reduction, has improved.

[0118] Furthermore, as shown in Figure 10, a vibration-damping evaluation model 141 in which a vibration-damping member 143 having a two-layer structure of a resin material 143a and a sheet metal part 143b is applied to the tip of the side sill 101 was also evaluated for the improvement in vibration-damping performance provided by the vibration-damping member 143.

[0119] The vibration damping evaluation model 141 is formed by providing a resin material 143a and a sheet metal part 143b on the surface at the tip of the side sill 101, bonding (adhering) the surface of the resin material 143a to the sheet metal part 143b, and bonding (joining) the other portion of the sheet metal part 143b to the side sill 101.

[0120] The vibration damping performance of the vibration damping performance evaluation model 141 was evaluated by executing a vibration analysis under the same vibration input conditions as in the optimization analysis described above, and determining the frequency characteristics of the equivalent radiation power of the floor cross member 105. Furthermore, in the vibration damping evaluation model 141, the material properties (density, Young's modulus, thickness) of the resin material 143a and the sheet metal part 143b constituting the two-layer vibration damping member 143 were set to the values ​​used when determining the material properties of the single-layer vibration damping member model 123 in the optimization analysis described above.

[0121] Figure 11 shows a graph of the frequency response of the equivalent radiation power of the floor cross member 105 in the body-in-white structure 100 in which the two-layer vibration-damping member 143 is provided at the tip of the side sill 101. For comparison, Figure 11 also shows (broken line) the frequency response of the equivalent radiation power of the floor cross member 105 obtained for the original body-in-white structure 100 (see Figure 5).

[0122] As shown in Figure 11, in the body-in-white structure 100 to which the two-layer vibration-damping member 143 is attached, the maximum value of the equivalent radiation power ERP of the floor cross member 105 in the frequency band from 40 Hz to 80 Hz is 155.9 dB (43.5 Hz), which is a reduction of 20.8 dB compared to the original body-in-white structure.

[0123] These results show that even when the shape and position of the two-layer vibration-damping member 143 are determined based on the optimal shape of the single-layer vibration-damping member model 135 obtained by optimization analysis, it is possible to improve the vibration-damping performance of the target vibration and noise reduction areas in the white body structure 100. [Explanation of symbols]

[0124] 1. Automobile body design equipment 3 Display device 5 Input Devices 7 Storage device 9 Working data memory 11 Processing unit 13 Optimization Analysis Model Generation Unit 13a Design space setting section 13b Vibration damping member model generation section 13c Joint processing section 15 Optimization Analysis Unit 15a Material property setting section 15b Vibration input condition setting section 15c Optimization analysis condition setting section 15d Optimization Analysis Section 21 Body-in-White structural model files 100 Body-in-White Structure 101 Side sill 103 Front subframe 105 Floor cross member 107 Floor Panel 111 Laminated structure 113 Body Parts 115 Vibration-damping members 115a Resin material 115b Sheet metal parts 121 Laminated structure 123 Vibration-damping member model 131 Optimization Analysis Model 133 Design space 135 Vibration-damping member model 137 Optimal Shape Damping Member Model 141 Vibration Damping Evaluation Model 143 Vibration-damping members 143a Resin material 143b Sheet metal parts

Claims

1. 1. An automobile body design method in which a computer executes the following steps to design an automobile body in which vibration and noise reduction target portions in a body-in-white structure of an automobile are improved by providing a vibration-damping member having a two-layer structure of a resin material and a sheet metal part on the surface of the body part in the body-in-white structure of the automobile body, an optimization analysis model generation step of generating an optimization analysis model for performing optimization analysis on the optimal shape of the vibration damping member; an optimization analysis step of performing the optimization analysis using the generated optimization analysis model, The optimization analysis model generation step includes: a design space setting step of setting a design space to be subjected to the optimization analysis along the surfaces of all or some of the body parts in the body-in-white structure; a vibration-damping member model generation step of generating a vibration-damping member model of a single layer structure, which is modeled using shell elements or solid elements in the set design space and subjected to optimization analysis processing; a coupling process step of coupling the generated vibration-damping member model to the vehicle body part in the body-in-white structure to generate an optimized analysis model, The optimization analysis step includes: a material property setting step of setting density, thickness, and rigidity as material properties of the vibration-damping member model in the optimization analysis model so that the vibration characteristics of the vehicle body part provided with the vibration-damping member model are equivalent to the vibration characteristics of the vehicle body part provided with the vibration-damping member having a two-layer structure; a vibration input condition setting step of setting vibration input conditions related to vibrations to be applied to the optimization analysis model in the optimization analysis; an optimization analysis condition setting step of setting, as optimization analysis conditions, an objective function related to vibration characteristics used in evaluating the vibration-damping performance of the vibration noise reduction target portion in the optimization analysis model and a constraint condition related to the weight or volume of the vibration-damping member model; an optimization analysis step of performing an optimization analysis to determine an optimal shape of the vibration-damping member model in the optimization analysis model under the vibration input conditions and the optimization analysis conditions.

2. 2. The automobile body design method according to claim 1, wherein the design space is set in a gap between the body parts in the design space setting step.

3. In the design space setting step, a two-dimensional space along only one surface of the vehicle body part is set as the design space; 2. The automobile body design method according to claim 1, wherein the vibration-damping member model generation step generates the vibration-damping member model that is modeled using shell elements.

4. 4. The automobile body design method according to claim 1, wherein in the optimization analysis condition setting step, the objective function is the minimization of a frequency response value of any one of acceleration, inertance, or equivalent radiation power in a predetermined frequency band of the target portion for vibration and noise reduction, or the minimization of a function having these as variables.

5. 1. An automobile body design device for designing an automobile body in which vibration damping properties of target parts for vibration and noise reduction in a body-in-white structure are improved by providing a two-layer damping member made of a resin material and a sheet metal part on a surface of a body part in the body-in-white structure of the automobile body, an optimization analysis model generation unit that generates an optimization analysis model for performing optimization analysis on the optimal shape of the vibration damping member; an optimization analysis unit that performs the optimization analysis using the generated optimization analysis model, The optimization analysis model generation unit a design space setting unit that sets a design space to be subjected to the optimization analysis along surfaces of all or some of the vehicle body parts in the body-in-white structure; a vibration-damping member model generation unit that generates a single-layer vibration-damping member model that is modeled using shell elements or solid elements in the set design space and that performs optimization analysis processing; a coupling processing unit that couples the generated vibration-damping member model to the vehicle body part in the body-in-white structure to generate an optimized analysis model, The optimization analysis unit a material property setting unit that sets density, thickness, and rigidity as material properties of the vibration-damping member model in the optimization analysis model so that vibration properties of the vehicle body part provided with the vibration-damping member model are equivalent to vibration properties of the vehicle body part provided with the vibration-damping member having a two-layer structure; a vibration input condition setting unit that sets vibration input conditions related to vibrations to be applied to the optimization analysis model in the optimization analysis; an optimization analysis condition setting unit that sets, as optimization analysis conditions, an objective function related to vibration characteristics used in evaluating the vibration-damping performance of the vibration noise reduction target portion in the optimization analysis model and a constraint condition related to the weight or volume of the vibration-damping member model; an optimization analysis unit that performs optimization analysis to determine the optimal shape of the vibration-damping member model in the optimization analysis model under the vibration input conditions and the optimization analysis conditions.

6. 1. An automobile body design program for designing an automobile body in which vibration and noise reduction target portions in a body-in-white structure of an automobile are improved by providing a vibration-damping member having a two-layer structure of a resin material and a sheet metal part on the surface of a body part in the body-in-white structure of the automobile body, Computer, an optimization analysis model generation unit that generates an optimization analysis model for performing optimization analysis on the optimal shape of the vibration damping member; an optimization analysis unit that performs the optimization analysis using the generated optimization analysis model; moreover, The optimization analysis model generation unit, a design space setting unit that sets a design space to be subjected to the optimization analysis along surfaces of all or some of the vehicle body parts in the body-in-white structure; a vibration-damping member model generation unit that generates a single-layer vibration-damping member model that is modeled using shell elements or solid elements in the set design space and that performs optimization analysis processing; a coupling processing unit that couples the generated vibration-damping member model to the vehicle body parts in the body-in-white structure and generates an optimized analysis model; The optimization analysis unit a material property setting unit that sets density, thickness, and rigidity as material properties of the vibration-damping member model in the optimization analysis model so that vibration properties of the vehicle body part provided with the vibration-damping member model are equivalent to vibration properties of the vehicle body part provided with the vibration-damping member having a two-layer structure; a vibration input condition setting unit that sets vibration input conditions related to vibrations to be applied to the optimization analysis model in the optimization analysis; an optimization analysis condition setting unit that sets, as optimization analysis conditions, an objective function related to vibration characteristics used in evaluating the vibration-damping performance of the vibration noise reduction target portion in the optimization analysis model and a constraint condition related to the weight or volume of the vibration-damping member model; an optimization analysis unit that performs optimization analysis to determine the optimal shape of the vibration-damping member model in the optimization analysis model under the vibration input conditions and the optimization analysis conditions.

7. A method of manufacturing an automobile body in which a vibration-damping member having a two-layer structure of a resin material and a sheet metal part is provided on a surface of a body part in a body-in-white structure of the automobile body, thereby improving the vibration-damping properties of a target part for vibration and noise reduction in the body-in-white structure, The optimum shape of the vibration damping member is determined using the automobile body design method according to any one of claims 1 to 3, determining a shape and a position of the vibration-damping member to be provided on the vehicle body part based on the optimum shape of the vibration-damping member that has been found; and providing the vibration-damping member on the vehicle body part based on the determined shape and position of the vibration-damping member.

Images