Methods for optimizing the geometries of layered composite components, and optimization analysis equipment.

Abstract

DEPCT64 Methods for analyzing and optimizing the geometry of layered composite components. This fabrication, made of layered composite parts, is a replica of a part of a car body model. This includes two-dimensional and / or three-dimensional components, and performs state determination analysis. Suitable for the shape of the composite part, which is a layer of the model being manufactured, the methods include: The design area definition process S1, as a design area, section... The goal is to find the optimal conditions for a car body model; the model building process. The block that is the S3 layer of the building, in the design area, the block model that is a layer that includes... A three-dimensional part in which multiple layers with different material properties are stacked; the process... Process the S5 connection of the layered block model connection to the car body model; And the analysis procedure for finding the optimal condition S7 of the analysis condition input and... Perform optimization analysis to determine the optimal shape of the block model. It is a layer. -----------------------------------------------------------

Description

Shape optimization analysis method and shape optimization analysis device for laminated composite members

[0001] The present invention relates to a method and apparatus for analyzing shape optimization of a layered composite member, and more particularly to a method and apparatus for analyzing shape optimization of a layered composite member in which a portion of a structural body is a laminated composite member formed by stacking multiple layers with different material properties, and the optimal shape of the laminated composite member is determined. Note that, in the present invention, shape optimization does not mean determining an optimal shape based on a predetermined shape, such as a T-shape, but rather means determining an optimal shape that satisfies analytical conditions without assuming a predetermined shape.

[0002] In recent years, the automotive industry, in particular, has been promoting weight reduction of automotive bodies due to environmental issues, and computer-aided engineering (CAE) analysis has become an essential technology for car body design. CAE analysis is known to improve vehicle performance, such as reducing the weight and improving the stiffness of the car body, by using optimization techniques such as mathematical optimization, thickness optimization, shape optimization, and topology optimization. These optimization techniques are often used, for example, in the structural optimization of castings such as engine blocks.

[0003] Among optimization techniques, topology optimization in particular is gaining attention. Topology optimization is a method of determining the optimal shape that satisfies given conditions by creating a design space of a certain size, incorporating three-dimensional elements into that design space, and leaving the minimum necessary three-dimensional element portions. Therefore, topology optimization uses a method of directly constraining and directly applying loads to the three-dimensional elements that make up the design space.

[0004] As a technique relating to such topology optimization, Patent Document 1 discloses a method for topology optimization of components of a complex structure.

[0005] JP 2010-250818 A JP 2013-025533 A

[0006] Yuge, et al., "Optimal Design of Construction Machinery," Seikei University Engineering Research Report, Vol. 41, No. 1, 2004, pp. 1-5

[0007] Structures such as automobile bodies are primarily constructed using thin sheets. When optimizing the shape of a portion of such a thin-sheet vehicle body using optimization technology, conventional methods, such as those described in Non-Patent Document 1, involve extracting the entire vehicle body or a portion of the vehicle body, isolating the portion, and optimizing it while it is still independent. However, with this method, it is difficult to reflect the load and constraint state of the entire vehicle body in the design space, which makes it difficult to apply optimization technology to a portion of the vehicle body. For example, even if an optimization analysis of the entire vehicle body is performed to obtain the optimized shape of the corresponding portion of the vehicle body, the optimized portion may be determined to be unnecessary from the perspective of the entire vehicle body and disappear. Furthermore, even if a portion of the vehicle body is optimized independently, there is also the issue of how to properly incorporate that portion into the vehicle body, which is made of a thin-sheet structure.

[0008] The technology disclosed in Patent Document 1 relates to a mathematical calculation method and a physical system related to optimization analysis using topology optimization, and does not provide any solution to the problem of optimizing the above-mentioned thin plate structure.

[0009] Furthermore, while conventional shape optimization targets have been metal materials such as steel, aluminum alloys (Al alloys), and magnesium alloys, as shown in Patent Document 2, in recent years, the rigidity and strength of automobile bodies have been improved by using composite members (referred to as "laminated composite members" in this application) in which layers of resin or FRP (Fiber-Reinforced Plastics) are laminated and attached to thin plates that make up the body of an automobile. However, there has been no prior art that targets the shape of such laminated composite members, and there has been a need for the development of an optimization technology for determining the optimized shape of laminated composite members.

[0010] The present invention has been made in view of the above-mentioned problems, and its object is to provide a shape optimization analysis method and a shape optimization analysis device for a laminated composite member, which determine the optimal shape of a laminated composite member when the laminated composite member is used in part of a structure such as a vehicle body to improve rigidity.

[0011] A shape optimization analysis method for a laminated composite member according to a first aspect of the present invention is a shape optimization analysis method for a laminated composite member, in which a portion of a structural model of a vehicle body consisting of two-dimensional elements, or planar elements and three-dimensional elements, is modeled using a laminated composite member, and an optimization analysis is performed on the shape of the modeled laminated composite member, in which a computer performs the following steps, including a design space setting step of setting a portion of the structural model of the vehicle body to be optimized as a design space; a laminated block model generation step of generating a laminated block model in which a plurality of layers consisting of three-dimensional elements and having different material properties are stacked within the set design space; a joining processing step of joining the generated laminated block model to a portion of the structural model of the vehicle body; and an optimization analysis step of inputting analysis conditions, performing an optimization analysis using the laminated block model as the optimization analysis target, and determining the optimal shape of the laminated block model.

[0012] A shape optimization analysis method for a laminated composite member according to a second aspect of the present invention involves modeling a portion of a structural model of a vehicle body consisting of planar elements or planar elements and three-dimensional elements using a laminated composite member, and performing an optimization analysis of the shape of the modeled laminated composite member, in which a computer performs the following steps: a design space setting step of setting the portion of the structural model of the vehicle body to be optimized as a plurality of design spaces in which layers are stacked; a laminated block model generation step of generating layered block models consisting of three-dimensional elements by assigning different material properties to each of the set design spaces, and combining the layered block models generated for each design space to generate a laminated block model consisting of the three-dimensional elements; a combining processing step of combining the generated laminated block models with a portion of the structural model of the vehicle body; and an optimization analysis step of inputting analysis conditions, performing an optimization analysis using the laminated block model as the optimization analysis target, and determining the optimal shape of the laminated block model.

[0013] The shape optimization analysis method for a laminated composite member according to the present invention is characterized in that, in the shape optimization analysis method for a laminated composite member according to the first aspect of the present invention, the laminated block model is formed by connecting multiple layers made of three-dimensional elements and having different material properties using rigid elements, beam elements, or planar elements, or by connecting the multiple layers by sharing nodes.

[0014] The shape optimization analysis method for a laminated composite member according to the present invention is characterized in that, in the shape optimization analysis method for a laminated composite member according to the second aspect of the present invention, the laminated block model is formed by connecting layered block models made up of three-dimensional elements generated for each of a plurality of design spaces using rigid elements, beam elements or planar elements, or by connecting the layered block models by sharing nodes of the layered block models.

[0015] The shape optimization analysis method for a laminated composite member according to the present invention is characterized in that, in the shape optimization analysis method for a laminated composite member according to the present invention, the laminated block model consists of a three-dimensional element that is a pentahedron or more and an octahedron or less and has at least one set of two parallel faces.

[0016] The shape optimization analysis method for a laminated composite member according to the present invention is characterized in that, in the shape optimization analysis method for a laminated composite member according to the present invention, the laminated block model is generated so that the surface that is parallel to the surrounding surfaces in which the design space is set in a part of the structural model of the vehicle body has the largest area.

[0017] The shape optimization analysis method for a laminated composite member according to the present invention is characterized in that, in the shape optimization analysis method for a laminated composite member according to the present invention, the laminated block model has nodes placed at joints with planar elements or solid elements of a part of the structural model of the vehicle body, uses hexahedral solid elements as the solid elements of the laminated block model, and is generated by stacking the solid elements along a plane including the nodes placed at the joints.

[0018] The shape optimization analysis method for a laminated composite member according to the present invention is characterized in that, in the shape optimization analysis method for a laminated composite member according to the present invention, the optimization analysis step performs discretization using optimization parameters in the optimization analysis.

[0019] The shape optimization analysis method for a laminated composite member according to the present invention is characterized in that, in the shape optimization analysis method for a laminated composite member according to the present invention, the optimization analysis step performs optimization analysis by topology optimization.

[0020] A shape optimization analysis device for laminated composite members according to a first aspect of the present invention models a portion of a structural model of a vehicle body consisting of planar elements or planar elements and three-dimensional elements using a laminated composite member, and performs optimization analysis of the shape of the modeled laminated composite member. The device comprises: a design space setting unit that sets the portion of the structural model of the vehicle body to be optimized as a design space; a laminated block model generation unit that generates a laminated block model in the set design space, in which a plurality of layers consisting of three-dimensional elements and having different material properties are stacked; a connection processing unit that connects the generated laminated block model to a portion of the structural model of the vehicle body; and an optimization analysis unit that inputs analysis conditions, performs optimization analysis using the laminated block model as the optimization analysis target, and determines the optimal shape of the laminated block model.

[0021] A shape optimization analysis device for laminated composite members according to a second aspect of the present invention models a portion of a structural model of a vehicle body consisting of planar elements or planar elements and three-dimensional elements using a laminated composite member, and performs optimization analysis of the shape of the modeled laminated composite member. The device comprises: a design space setting unit that sets the portion of the structural model of the vehicle body to be optimized as a plurality of design spaces in which layers are laminated; a laminated block model generation unit that assigns different material properties to each of the set design spaces to generate a layered block model consisting of three-dimensional elements and combines the layered block models generated for each design space to generate a laminated block model consisting of the three-dimensional elements; a combination processing unit that combines the generated laminated block model with a portion of the structural model of the vehicle body; and an optimization analysis unit that inputs analysis conditions, performs optimization analysis using the laminated block model as the optimization analysis target, and determines the optimal shape of the laminated block model.

[0022] The shape optimization analysis device for laminated composite members according to the present invention is characterized in that, in the shape optimization analysis device for laminated composite members according to the first aspect of the present invention, the laminated block model is formed by connecting multiple layers made of three-dimensional elements and having different material properties using rigid elements, beam elements, or planar elements, or by connecting the multiple layers by sharing nodes.

[0023] The shape optimization analysis device for a laminated composite member according to the present invention is characterized in that, in the shape optimization analysis device for a laminated composite member according to the second aspect of the present invention, the laminated block model is formed by connecting layered block models made up of three-dimensional elements generated for each of a plurality of design spaces using rigid elements, beam elements or planar elements, or by connecting the layered block models by sharing nodes of the layered block models.

[0024] The shape optimization analysis device for laminated composite members according to the present invention is characterized in that, in the shape optimization analysis device for laminated composite members according to the present invention, the laminated block model is made up of a three-dimensional element that is a pentahedron or more and an octahedron or less and has at least one set of two parallel faces.

[0025] The shape optimization analysis device for laminated composite members according to the present invention is characterized in that, in the shape optimization analysis device for laminated composite members according to the present invention, the laminated block model is generated so that the surface that is parallel to the surrounding surfaces in which the design space is set in a part of the structural model of the vehicle body has the largest area.

[0026] The shape optimization analysis device for laminated composite members according to the present invention is characterized in that, in the shape optimization analysis device for laminated composite members according to the present invention, the laminated block model has nodes placed at joints with planar elements or solid elements of a part of the structural model of the vehicle body, uses hexahedral solid elements as the solid elements of the laminated block model, and is generated by stacking the solid elements along a plane including the nodes placed at the joints.

[0027] The shape optimization analysis device for a laminated composite member according to the present invention is characterized in that, in the shape optimization analysis device for a laminated composite member according to the present invention, the optimization analysis unit performs discretization using optimization parameters in the optimization analysis.

[0028] The shape optimization analysis device for a laminated composite member according to the present invention is characterized in that, in the shape optimization analysis device for a laminated composite member according to the present invention, the optimization analysis unit performs optimization analysis by topology optimization.

[0029] According to the present invention, it is possible to determine the optimal shape of a laminated composite member that becomes part of a vehicle body when an external force acts on the vehicle body structure, thereby making it possible to improve the specified performance of the structure or contribute to reducing the weight of the structure while maintaining the specified performance.

[0030] FIG. 1 is a block diagram of a shape optimization analysis device for a laminated composite member according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a vehicle body model to be analyzed for shape optimization and a design space set for the vehicle body model according to the embodiment. FIG. 3 is a diagram illustrating the design space set for the vehicle body model according to the embodiment (part 1). FIG. 4 is a diagram illustrating the design space set for the vehicle body model according to the embodiment (part 2, (a) outer layer, (b) inner layer). FIG. 5 is a cross-sectional view of the design space set for the vehicle body model according to the embodiment. FIG. 6 is a diagram illustrating the load conditions input in the optimization analysis process according to the embodiment (torsional rigidity). FIG. 7 is a diagram illustrating the load conditions input in the optimization analysis process according to the embodiment (lateral bending rigidity). FIG. 8 is a diagram illustrating an optimal shape obtained by the optimization analysis process for a rear cross member according to the embodiment. FIG. 9 is a flowchart showing the processing flow of a shape optimization analysis method for a laminated composite member according to an embodiment of the present invention. FIG. 10 shows the analysis results of the optimal shape obtained by optimization analysis of a rear cross member in the example (Case 1, outer layer: steel (steel sheet), inner layer: steel). FIG. 11 shows the analysis results of the optimal shape obtained by optimization analysis of a rear cross member in the example (Case 2, outer layer: aluminum alloy (aluminum alloy), inner layer: steel). FIG. 12 shows the analysis results of the optimal shape obtained by optimization analysis of a rear cross member in the example (Case 3, outer layer: steel, inner layer: aluminum alloy). FIG. 13 shows the analysis results of the optimal shape obtained by optimization analysis of a rear cross member in the example (Case 4, outer layer: CFRP, inner layer: steel). FIG. 14 shows the analysis results of the optimal shape obtained by optimization analysis of a rear cross member in the example (Case 5, outer layer: steel, inner layer: CFRP). FIG. 15 is a diagram showing the analysis results of the optimal shape obtained by optimization analysis of a rear cross member in the example (Case 6, outer layer: steel, inner layer: GFRP).FIG. 16 is a diagram showing the analysis results of an optimal shape obtained by optimization analysis of a rear cross member in the example (Case 7, outer layer: steel, inner layer: resin). FIG. 17 is a graph showing the effect of changing the material property combination of a laminated block model on the improvement rate of stiffness of a vehicle body model combined with a rear cross member having an optimal shape obtained by optimization analysis in the example. FIG. 18 is a graph showing the effect of changing the material property combination of a laminated block model on the improvement rate of stiffness per part weight of a vehicle body model combined with a rear cross member having an optimal shape obtained by optimization analysis in the example. FIG. 19 is a diagram showing a design space set for a rear side member of a vehicle body model in the example (Part 1). FIG. 20 is a diagram showing a design space set for a rear side member of a vehicle body model in the example (Part 2, (a) outer layer, (b) inner layer). FIG. 21 is a cross-sectional view of a design space set for a rear side member of a vehicle body model in the example. FIG. 22 shows the analysis results of an optimal shape obtained by optimization analysis of a rear side member in an example (Case 1, outer layer: steel, inner layer: steel). FIG. 23 shows the analysis results of an optimal shape obtained by optimization analysis of a rear side member in an example (Case 2, outer layer: Al alloy, inner layer: steel). FIG. 24 shows the analysis results of an optimal shape obtained by optimization analysis of a rear side member in an example (Case 4, outer layer: CFRP, inner layer: steel). FIG. 25 shows the analysis results of an optimal shape obtained by optimization analysis of a rear side member in an example (Case 5, outer layer: steel, inner layer: CFRP). FIG. 26 shows the analysis results of an optimal shape obtained by optimization analysis of a rear side member in an example (Case 1, constraint: volume constraint ratio of each of the outer layer and inner layer is 10% or less).Fig. 27 is a diagram showing the analysis results of an optimal shape obtained by optimization analysis of a rear side member in an example (Case 4, constraint: volume constraints of 10% or less for each of the outer layer portion and the inner layer portion). Fig. 28 is a graph showing the effect on the rigidity improvement rate of a vehicle body model combined with a rear side member having an optimal shape obtained by optimization analysis by changing the material combination of a laminated block model for the rear side member in an example. Fig. 29 is a graph showing the effect on the rigidity improvement rate per part weight of a vehicle body model combined with a rear side member having an optimal shape obtained by optimization analysis by changing the material combination of a laminated block model for the rear side member in an example.

[0031] Before describing the shape optimization analysis method and shape optimization analysis device for a laminated composite member according to an embodiment of the present invention, an example of a structural model of a vehicle body (hereinafter simply referred to as a "structural model") that is the subject of the present invention will be described.

[0032] <Structural Model> A structural model is a model of a structural body using planar elements and / or three-dimensional elements when a laminated composite member made of a material different from that of the structural body is joined to a part of the structural body. In this embodiment, a vehicle body model 31 shown in Figure 2 is used as an example of a structural model.

[0033] The vehicle body model 31 is composed of a plurality of parts such as automotive body frame members and chassis components, and each part of the vehicle body model 31 is modeled using planar elements and / or three-dimensional elements. Information on the elements (planar elements and three-dimensional elements) and material properties (materials) of each part that constitutes the vehicle body model 31 is stored in the structure model file 21 (see FIG. 1).

[0034] <Shape optimization analysis device for laminated composite member> Next, the configuration of a shape optimization analysis device 1 for laminated composite member according to this embodiment (hereinafter simply referred to as "shape optimization analysis device 1") will be described below with reference to Figs. 1 to 8 .

[0035] A shape optimization analysis device 1 according to this embodiment determines the optimal shape of a laminated composite member when a laminated composite member made of a material different from that of a vehicle body is joined to a portion of the structure to stiffen the structure. As shown in Fig. 1, the shape optimization analysis device 1 according to this embodiment is configured by a computer such as a PC (personal computer), and has 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 each function is executed in response to commands from the arithmetic processing unit 11.

[0036] Hereinafter, each component of the shape optimization analysis device 1 according to this embodiment will be described using an example in which a rear cross member (design space 41), which is part of the vehicle body model 31 shown in FIG. 2, is modeled using a laminated composite member, and the optimal shape of the laminated composite member is determined.

[0037] <Display Device> The display device 3 is used to display the analysis results and is configured with a liquid crystal monitor or the like.

[0038] <<Input Device>> The input device 5 is used for issuing display instructions for the structure model file 21 and inputting conditions by the operator, and is composed of a keyboard, a mouse, and the like.

[0039] <Storage Device> The storage device 7 is used to store various files such as the structure model file 21, and is configured with a hard disk or the like.

[0040] <Working Data Memory> 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.

[0041] 1, the calculation processing unit 11 has a design space setting unit 13, a stacked block model generation unit 15, a connection processing unit 17, and an optimization analysis unit 19, 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 each of the above units in the calculation processing unit 11 are described below.

[0042] (Design Space Setting Unit) The design space setting unit 13 sets a part of the structure model to be optimized as a design space. The design space setting unit 13 deletes the part of the structure model to be optimized, and sets the design space in the deleted part.

[0043] 2 shows an example of a structural model in which a design space 41 of a rear cross member is set in a part of a vehicle body model 31. In FIG. 2, the rear cross member originally included in the vehicle body model 31 has been deleted, and the design space 41 has been set in the deleted part.

[0044] Here, before being removed, the rear cross member is joined at its upper surface in the vehicle height direction to the floor panel 33, and at both left and right ends in the vehicle width direction to the rear side members 35, and when the design space 41 is set, the floor panel 33 and the rear side members 35 are left in place without being removed.

[0045] Therefore, design space 41 can be set as a space surrounded by a surface shaped to fit floor panel 33, a surface shaped to fit rear side member 35, and a surface given by expanding to the limit of the designable range. The designable range can be set appropriately based on, for example, the shape of the original rear cross member and the gap between the rear cross member and other parts around it.

[0046] In the above example, the design space setting unit 13 sets the design space 41 by deleting the rear cross member, which is a part of the vehicle body model 31 acquired from the structure model file 21, but the design space 41 may be set in advance when generating the vehicle body model 31. In this case, the design space setting unit 13 may be provided with a function for generating the vehicle body model 31.

[0047] (Layered Block Model Generator) The layered block model generator 15 generates a layered block model 43 in which multiple layers made of three-dimensional elements and having different material properties are stacked in a set design space 41. Here, the layered block model 43 is a model of a laminated composite member, and is the target of optimization analysis processing.

[0048] The stacked block model generation unit 15 can generate a stacked block model 43 of any shape and size that fits into the design space 41. In generating the stacked block model 43, the stacked block model generation unit 15 first sets a plurality of layers made up of three-dimensional elements, and then connects the plurality of layers using rigid elements, beam elements, or planar elements, or by sharing nodes of the three-dimensional elements of the plurality of layers, thereby connecting and stacking the plurality of layers in a layered manner.

[0049] The three-dimensional elements used in the layered block model 43 are preferably polyhedrons having five or more and octahedrons or less in number of faces, and are preferably three-dimensional elements having at least one pair of two parallel faces.

[0050] The reason for this is that when the portion forming the design space 41 is a layered member such as a laminated composite member, it is desirable to obtain an optimal shape so that it can be reflected in the shape of the laminated composite member when an optimization analysis process is performed on the laminated block model 43. In this regard, such a requirement can be easily met by using a three-dimensional element that is a pentahedron or more and an octahedron or less and has at least one pair of two parallel faces.

[0051] It is also preferable to increase the accuracy of optimization by generating three-dimensional elements of pentahedrons or more and octahedrons or less in size as uniformly as possible in the design space 41. However, the present invention does not exclude the use of three-dimensional elements of less than pentahedrons or more than octahedrons, for example, tetrahedrons.

[0052] Figures 3 to 5 show an example of a laminated block model 43 generated in the design space 41 shown in Figure 2. Figure 3 shows the vehicle body model 31 from below in the vehicle body height direction, Figure 4 shows an outer layer portion 43a and an inner layer portion 43b of the laminated block model 43, and Figure 5 is a cross-sectional view of the laminated block model 43 perpendicular to the vehicle body width direction.

[0053] 4 and 5, the laminated block model 43 is generated from an outer layer portion 43a and an inner layer portion 43b having different material properties, and the outer layer portion 43a and the inner layer portion 43b are laminated in layers. The outer layer portion 43a and the inner layer portion 43b are each composed of three-dimensional elements, and in this embodiment, the outer layer portion 43a and the inner layer portion 43b are connected so as to share the nodes of the three-dimensional elements.

[0054] Examples of material properties to be set for the outer layer portion 43 a and the inner layer portion 43 b of the laminated block model 43 include Young's modulus, Poisson's ratio, and specific gravity. When the material constituting each layer of the laminated composite member to be modeled has in-plane anisotropy, such as FRP, the in-plane anisotropy can be set by assigning a principal axis angle that provides the in-plane anisotropy of the material properties of each of the outer layer portion 43 a and the inner layer portion 43 b of the laminated block model 43 and setting the value of the material property corresponding to the principal axis angle. It is also possible to set the principal axis angle for each layer of the outer layer portion 43 a and the inner layer portion 43 b.

[0055] It is preferable that the stacked block model generation unit 15 generates the stacked block model 43 so as to subdivide the three-dimensional elements along the peripheral surfaces on the vehicle body model 31 where the design space 41 is set and parallel to the surface having the maximum area of ​​the design space 41. Here, the peripheral surfaces on which the design space 41 is set refer to the surfaces of the parts (in this embodiment, the rear cross member) at the location where the design space 41 is to be set, and the surface having the maximum area of ​​the design space refers to the peripheral surface with the largest area.

[0056] For example, when design space 41 is set for the rear cross member of vehicle body model 31, the surrounding surfaces around which design space 41 is set include a surface along floor panel 33 to which the rear cross member is joined and a surface along rear side member 35. Since the surface along floor panel 33 has a larger area than the surface along rear side member 35, the surface along floor panel 33 can be set as the surface with the largest area in design space 41.

[0057] In addition, the stacked block model generation unit 15 may generate the stacked block model 43 by treating the three-dimensional elements that make up the stacked block model 43 as hexahedral three-dimensional elements, arranging the nodes of the hexahedral three-dimensional elements at the joints with the planar elements or three-dimensional elements that make up the vehicle body model 31, and stacking the hexahedral three-dimensional elements along a plane that includes the nodes arranged at the joints.

[0058] For example, if the floor panel 33 of the vehicle body model 31 is composed of planar elements, the stacked block model generation unit 15 may generate the stacked block model 43 by using the nodes of the planar elements of the floor panel 33 as the connection points with the stacked block model 43 and stacking hexahedral three-dimensional elements along the surfaces of the floor panel 33 that include the nodes.

[0059] (Connection Processing Unit) The connection processing unit 17 performs processing to connect the generated stacked block model 43 to other parts of the vehicle body model 31. Rigid elements, plane elements, and beam elements can be used to connect the stacked block model 43 and the vehicle body model 31.

[0060] It is preferable that the connection between the stacked block model 43 and the vehicle body model 31 be made so that the deleted portion of the design space 41 reflects the original connection point between the vehicle body model 31 and the stacked block model 43, so that the load is accurately transmitted from the vehicle body model 31 to the stacked block model 43.

[0061] (Optimization Analysis Unit) The optimization analysis unit 19 applies analysis conditions to the vehicle body model 31 formed by combining stacked block models 43, and performs optimization analysis to find the optimal shape of the stacked block model 43. The analysis conditions include load conditions that specify positions to apply loads and restraint positions, and objective conditions and constraint conditions that are set according to the purpose and constraints of the optimization analysis.

[0062] Examples of loading conditions are shown in Figures 6 and 7. Figure 6 shows the case where optimization analysis is performed for torsional stiffness, and Figure 7 shows the case where optimization analysis is performed for lateral bending stiffness.

[0063] When performing optimization analysis targeting torsional rigidity, as shown in FIG. 6, load input points were set at two locations on the left and right suspension mounting portions on the rear side of the vehicle body model 31, and loads (1000 N) were applied to each load input point in the upward and downward directions along the vehicle height.

[0064] On the other hand, when optimization analysis is performed with lateral bending rigidity as the target, load input points are set at four locations on the rear suspension mounting portion of the vehicle body model 31, and a predetermined load (1000 N) is applied to each load input point in the right direction in the vehicle width direction, as shown in Fig. 7. Note that, although no restraint positions are set under the load conditions shown in Fig. 6 and Fig. 7, in this embodiment, optimization analysis is performed by assuming a state in which the vehicle body model 31 is supported at support points that serve as references for the coordinates of the inertia force acting on the vehicle body model 31, using the inertia relief method.

[0065] However, the load conditions provided by the optimization analysis unit 19 are not limited to those described above, and the position at which the load is input to the vehicle body model 31, the position at which the displacement is constrained, etc. may be set appropriately depending on the purpose of the optimization analysis.

[0066] Target conditions in the optimization analysis include, for example, minimizing the total strain energy in the vehicle body model 31, minimizing displacement, minimizing stress, and maximizing rigidity. Constraint conditions in the optimization analysis include, for example, a volume constraint rate of the laminated block model 43 that is the target of the optimization analysis, and multiple constraint conditions can be set. The volume constraint rate can be applied to the entire laminated block model 43 or individually to each layer of the laminated block model 43 (for example, each of the outer layer portion 43 a and the inner layer portion 43 b shown in FIGS. 4 and 5 ).

[0067] For example, topology optimization can be applied to the optimization analysis process by the optimization analysis unit 19. In topology optimization, it is preferable to discretize by assigning a penalty coefficient as an optimization parameter. It is preferable to limit the penalty coefficient in discretization to a value of 2 or more, or to a value 3 to 20 times the size of the reference three-dimensional element. By assigning a penalty coefficient and discretizing, it becomes possible to reflect the stacked block model obtained as the optimal shape in the structure shape of the thin plate.

[0068] The optimization analysis unit 19 may be one that performs topology optimization as described above, or may perform optimization processing using other calculation methods. For example, commercially available analysis software using the finite element method may be used.

[0069] 8 shows an example of an optimal shape 45 obtained by applying topology optimization to the optimization analysis unit 19, with the rear cross member being the optimization target. The optimal shape 45 was obtained by retaining and eliminating three-dimensional elements for each of the outer layer portion 43a and inner layer portion 43b of the laminated block model 43 so as to satisfy the above-mentioned analysis conditions (load conditions, target conditions, and constraint conditions), and is composed of an optimal shape outer layer portion 45a and an optimal shape inner layer portion 45b, as shown in FIG.

[0070] It is important to note here that a load is transmitted from the vehicle body model 31 to the laminated block model 43 via the portion that connects the vehicle body model 31. In other words, the load is transmitted from the vehicle body model 31 to the laminated block model 43, and as a result, the laminated block model 43 is deformed and the direction of the load changes during the optimization analysis process by the optimization analysis unit 19, but the direction of the load at each time is reflected, and an optimal shape 45 is ultimately obtained in which the shape is optimized.

[0071] In the above description, one design space 41 is set by the design space setting unit 13, and a stacked block model 43 is generated by generating multiple layers in the set design space 41. However, the generation of the stacked block model 43 is not limited to this.

[0072] Another mode for generating the laminated block model 43 may be to set, by the design space setting unit 13, a plurality of design spaces in which the portions of the vehicle body model 31 to be optimized are laminated in layers, and to generate, by the laminated block model generation unit 15, a plurality of layered block models (corresponding to the outer layer portion 43 a and the inner layer portion 43 b shown in FIGS. 4 and 5 ) made up of three-dimensional elements by assigning different material properties to each of the set design spaces, and to combine the plurality of layered block models generated for each of the design spaces to generate a laminated block model made up of the three-dimensional elements.

[0073] In this case, the design space setting unit 13 can set multiple design spaces by deleting a portion to be optimized from a part of the structural model, setting one design space in the deleted portion, and then dividing the design space into two or more design spaces stacked in layers, or by setting one design space and then newly setting another design space so that it is stacked in layers on the set design space.

[0074] The stacked block model generation unit 15 can then combine multiple layered block models by sharing the nodes of the layered block models made up of three-dimensional elements generated for each of the multiple set design spaces, or combine multiple layered block models using rigid elements, beam elements, or plane elements, thereby generating a layered stacked block model.

[0075] <Shape Optimization Analysis Method for Laminated Composite Member> Next, a shape optimization analysis method for a laminated composite member (hereinafter simply referred to as "shape optimization analysis method") according to this embodiment will be described.

[0076] The shape optimization analysis method according to this embodiment models a portion of a structural model using a laminated composite member, and performs optimization analysis of the shape of the modeled laminated composite member. As shown in Fig. 9, the shape optimization analysis method according to this embodiment includes a design space definition step S1, a laminated block model generation step S3, a connection processing step S5, and an optimization analysis step S7. Each of the above steps will be described below for the case of a vehicle body model 31 shown in Fig. 2 as an example of a structural model. Note that the shape optimization analysis method according to this embodiment can execute each of the above steps using a shape optimization analysis device 1 (see Fig. 1) configured by a computer.

[0077] <<Design Space Setting Step>> As shown in FIG. 2 , the design space setting step S1 is a step of setting a design space 41 in which portions of the car body model 31 to be optimized are stacked in layers. In the shape optimization analysis device 1, this step is performed by the design space setting unit 13.

[0078] <<Laminated Block Model Generation Step>> The laminated block model generation step S3 is a step of generating a laminated block model 43 in which a plurality of layers (e.g., an outer layer portion 43 a and an inner layer portion 43 b shown in FIGS. 4 and 5 ) made of three-dimensional elements and having different material properties are laminated in the design space 41 set in the design space setting step S1. In the shape optimization analysis device 1, this step is performed by the laminated block model generation unit 15.

[0079] In the stacked block model generation step S3, for example, the stacked block model generation unit 15 generates a plurality of layers by stacking three-dimensional elements in layers, and connects the plurality of layers using rigid elements, beam elements, or planar elements, or connects the three-dimensional elements of the plurality of layers by sharing nodes, thereby generating the stacked block model 43. Here, the three-dimensional elements used in the stacked block model 43 are preferably polyhedra having five to eight faces, and are preferably configured from three-dimensional elements having at least one pair of two parallel faces.

[0080] In the laminated block model 43, the laminated block model generation unit 15 sets material properties (Young's modulus, Poisson's ratio, specific gravity, etc.) for each layer. If the materials constituting each layer of the laminated composite member include a layer whose material properties are in-plane anisotropic, such as FRP, then a principal axis angle that imparts in-plane anisotropy to that layer can be assigned, and the material property values ​​corresponding to that principal axis angle can be set. In this case, it is also possible to set a principal axis angle for each of the multiple layers in the laminated block model 43.

[0081] In the stacked block model generating step S3, it is preferable to generate the stacked block model 43 so as to subdivide the three-dimensional elements along the peripheral surfaces on which the design space 41 in the vehicle body model 31 is set and parallel to the surface having the maximum area of ​​the design space 41. Here, the peripheral surfaces on which the design space 41 is set refer to the surfaces of the parts in the region where the design space is to be set, and the surface having the maximum area of ​​the design space refers to the peripheral surface with the largest area.

[0082] <<Combining Processing Step>> The combining processing step S5 is a step of combining the stacked block model 43 generated in the stacked block model generating step S3 with the vehicle body model 31, and is performed by the stacked block model generating unit 15 in the shape optimization analysis device 1.

[0083] <Optimization Analysis Step> The optimization analysis step S7 is a step in which analysis conditions are input to the vehicle body model 31 to which the stacked block model 43 is joined in the joining processing step S5, and an optimization analysis is performed to obtain an optimal shape 45 ( FIG. 8 ) in which the shape of the stacked block model 43 is optimized. In the shape optimization analysis device 1, this step is performed by the optimization analysis unit 19.

[0084] Here, in the optimization analysis step S7, the optimization analysis unit 19 provides the following analysis conditions for the optimization analysis: load conditions that indicate the position at which the load is applied to the vehicle body model 31, objective conditions that are set according to the purpose of the optimization analysis, and constraint conditions that are imposed when performing the optimization analysis.

[0085] It should be noted that topology optimization can be applied to the optimization analysis in optimization analysis step S7. Furthermore, when the density method is applied to topology optimization, it is preferable to perform discretization by setting the penalty coefficient of the element to 2 or more.

[0086] However, the optimization analysis in the optimization analysis step S7 can be performed by applying an optimization analysis process using other calculation methods, and for example, commercially available analysis software using finite elements can be used to perform the optimization analysis process.

[0087] In the above description, one design space 41 is set in the design space setting step S1, and multiple layers are generated in the set design space 41 in the stacked block model generation step S3, thereby generating a stacked block model 43 in which multiple layers with different material properties are stacked. However, the manner in which the stacked block model 43 is generated is not limited to this.

[0088] Another mode for generating the laminated block model 43 may be to set, in the design space setting step S1, a plurality of design spaces in which the portions of the vehicle body model 31 to be optimized are layered, and in the laminated block model generation step S3, to generate layered block models (e.g., corresponding to the outer layer portion 43a and the inner layer portion 43b shown in Figures 4 and 5) made of three-dimensional elements by giving different material properties to each of the set design spaces, and to combine the layered block models generated for each design space to generate the laminated block model 43 made of the three-dimensional elements. In this case, the method for setting the plurality of design spaces in the design space setting step S1 may be the same as that used by the design space setting unit 13 described above.

[0089] As described above, the shape optimization analysis method and shape optimization analysis device for a laminated composite member according to the present embodiment make it possible to accurately determine the optimal shape of a laminated composite member when using the laminated composite member to stiffen a part of a structure such as a car body. Furthermore, by using a laminated composite member with the optimal shape, it becomes possible to reduce the weight of the structure. The weight reduction and rigidity improvement effects of a structure using a laminated composite member with the optimal shape will be specifically explained in the examples described below.

[0090] In the above explanation, the structure is the body of an automobile, and the rear cross member, which is a part of the body, is the object of shape optimization analysis. However, the present invention is not limited to rear cross members, and as shown in the examples described below, the object of shape optimization analysis may also be the rear side member of an automobile or other parts, and there are no particular limitations on the structure or part that is the object of analysis.

[0091] An experiment was conducted to confirm the effects of the present invention, and this will now be described. In this example, the rear cross member and rear side member, which are components that make up the vehicle body model 31 shown in Figure 2, were modeled using laminated composite materials, and an optimization analysis was performed to determine the optimal shape.

[0092] In order to perform optimization analysis of the laminated composite member, first, a vehicle body model 31 shown in Fig. 2 was obtained. The vehicle body model 31 was a model of a vehicle body using planar elements and / or three-dimensional elements, and the material of the vehicle body model 31 was steel.

[0093] Then, a design space was set in a part of the acquired vehicle body model 31, and a laminated block model was generated in the set design space. In this example, one design space was set, and a laminated block model in which two layers with different material properties were laminated was generated in the set design space.

[0094] 2 shows a design space 41 set in vehicle body model 31 for a rear cross member. As described in the above embodiment, design space 41 is a space enclosed by a surface shaped to fit floor panel 33, a surface shaped to fit rear side member 35, and a surface defined based on the shape of the original rear cross member, with the rear cross member (not shown) originally included in vehicle body model 31 deleted while leaving floor panel 33 and rear side member 35 to which the rear cross member was joined.

[0095] Next, a layered block model 43 was generated in the set design space 41, in which an outer layer portion 43a and an inner layer portion 43b were layered (see FIGS. 3 to 5). Here, the outer layer portion 43a and the inner layer portion 43b were each generated by stacking three layers of hexahedral three-dimensional elements, and the thickness of each of the outer layer portion 43a and the inner layer portion 43b was set to 5 mm. The outer layer portion 43a and the inner layer portion 43b were connected by sharing the nodes of the hexahedral three-dimensional elements that make up each portion.

[0096] Then, material properties were set for each of the outer layer portion 43a and the inner layer portion 43b of the laminated block model 43. Table 1 shows the materials used in this example and their Young's modulus values.

[0097]

[0098] In Table 1, CFRP stands for carbon fiber reinforced plastics, and GFRP stands for glass fiber reinforced plastics, both of which have isotropic material properties.

[0099] Then, the laminated block model 43 with the set material properties was connected to the vehicle body model 31, and an optimization analysis was performed to determine the optimal shape of the laminated block model 43. Here, the laminated block model 43 and the vehicle body model 31 were connected by the three-dimensional elements of the laminated block model 43. In order to perform the optimization analysis, load conditions and optimization analysis conditions (objective conditions and constraint conditions) were applied as analysis conditions to the vehicle body model 31 connected to the laminated block model 43.

[0100] In this example, the loading conditions were as follows: when optimization analysis was performed on torsional rigidity as shown in FIG. 6, and when optimization analysis was performed on lateral bending rigidity as shown in FIG. 7, a load of 1000 N was applied at the positions and in the directions indicated by the arrows in the figure, which are the rear suspension mounting parts.

[0101] As analysis conditions for the optimization analysis, the target condition was the minimum sum of strain energy, and the constraint condition was the volume constraint rate of the laminated block model 43. Here, the optimization analysis was performed with the volume constraint rate of the entire laminated block model 43 set to 20% or less.

[0102] In this example, topology optimization was used for the optimization analysis, the target condition was the minimization of the total strain energy, and the constraint condition was the volume constraint rate of the laminated block model 43. Here, the volume constraint rate was set for the entire laminated block model 43.

[0103] In this example, optimization analysis was performed by changing the combination of materials for the outer and inner layers of the laminated block model, and the optimal shape of the laminated composite member due to different combinations of materials was examined.

[0104] 10 to 16 show the analysis results of an optimum shape 45 obtained by carrying out optimization analysis on a rear cross member by changing the combination of materials of the laminated block model 43. FIG.

[0105] 10 to 16 show the results of optimization analysis performed by changing the combination of materials of the outer layer portion 43a and the inner layer portion 43b (FIG. 4) (hereinafter, expressed in the format of "(material of the outer layer portion) - (material of the inner layer portion)"). The material combinations in each figure are "steel-steel" (Case 1) in FIG. 10, "Al alloy-steel" (Case 2) in FIG. 11, "steel-Al alloy" (Case 3) in FIG. 12, "CFRP-steel" (Case 4) in FIG. 13, "steel-CFRP" (Case 5) in FIG. 14, "steel-GFRP" (Case 6) in FIG. 15, and "steel-resin" (Case 7) in FIG. 16.

[0106] Here, Case 1 is not included in the present invention because the outer layer portion 43a and the inner layer portion 43b are made of the same material (steel), but Cases 2 to 7 are included in the present invention because the outer layer portion 43a and the inner layer portion 43b are made of different materials. Furthermore, the analysis results shown in Figures 10 to 16 all assume that the constraint condition in the optimization analysis is a volume constraint rate of 20% or less for the entire laminated block model 43. In Figures 10 to 16, (a) shows the remaining state of the optimal-shape outer layer portion 45a and the optimal-shape inner layer portion 45b combined, (b) shows only the optimal-shape outer layer portion 45a, and (c) shows only the optimal-shape inner layer portion 45b.

[0107] In Case 1, where both the outer layer portion 43a and the inner layer portion 43b were made of the same material (steel), the optimal-shape outer layer portion 45a mainly remained, and the optimal-shape inner layer portion 45b mainly remained, as shown in Figure 10. Even in Cases 3, 4, 6, and 7, where the Young's modulus of the outer layer portion 43a was high, the optimal-shape outer layer portion 45a mainly remained, as shown in Figures 12, 13, 15, and 16, resulting in the same results as in Case 1. This is because, in torsion and lateral bending modes, retaining the material of the outer layer portion 43a, which is the outer layer and has a higher Young's modulus than the inner layer portion 43b, increases the rigidity of the corresponding portion of the vehicle body model 31.

[0108] In contrast, in Case 2 and Case 5, in which the Young's modulus of the inner layer portion 43b is high, the optimal shape inner layer portion 45b tends to remain, as shown in Figures 11 and 14, and an optimal shape 45 was obtained in which material remained in both the optimal shape outer layer portion 45a and the optimal shape inner layer portion 45b.

[0109] Figures 17 and 18 show the results of the rigidity improvement rate for each vehicle body model 31 connected to a rear cross member made of a laminated composite material with an optimal shape 45 obtained by optimization analysis under various conditions in which the material combination of the laminated block model 43 was changed.

[0110] 17 and 18, "torsion" and "lateral bending" on the horizontal axis represent the cases where the load conditions shown in Figures 6 and 7 are applied, and "RH" and "LH" indicate the load input positions (see Figures 6 and 7) under each load condition. Also, the "reverse" in "torsion (reverse)" and "lateral bending (reverse)" on the horizontal axis indicates that the load input direction at each load input position is symmetrical to the "torsion" and "lateral bending" loading conditions.

[0111] 17 and 18, the "rigidity improvement rate" on the vertical axis is a value based on the rigidity of the vehicle body model 31 from which the rear cross member that was the subject of the optimization analysis was removed, and the rigidity was calculated by dividing the displacement at each load input point by the value of the input load. Furthermore, the vertical axis in Fig. 18 represents the calculated rigidity improvement rate divided by the weight of the part that was the subject of optimization.

[0112] In Figures 17 and 18, the bar graphs for the load conditions and load input points on the horizontal axis are arranged in the order of the conditions (Case 1 to Case 7) shown in the legend in the figures (the same applies to Figures 28 and 29 described below).

[0113] From the results shown in Figure 17, it can be seen that when the optimal shape 45 is combined with the vehicle body model 31 from which the rear cross member has been removed, within the scope of this embodiment, the rigidity improvement rate was highest for Case 4, in which the material of the optimal shape outer layer portion 45a is CFRP.

[0114] This is because arranging components at the outermost periphery of a structure increases the rigidity of the structure, and placing a material with a high Young's modulus at the outermost periphery improves performance (rigidity). This also coincides with the fact that in order to arrange a material with a high Young's modulus at the outermost periphery, the shape of the material must be large, resulting in increased rigidity. In contrast, Case 2, in which an Al alloy was used for the outer layer portion 43a, resulted in the smallest improvement in rigidity within the scope of this example. This is thought to be due to the use of a material with a low Young's modulus for the outer layer portion, which corresponds to the outer periphery.

[0115] Furthermore, when the rigidity improvement rate per part weight shown in Fig. 18 is viewed from the perspective of weight efficiency, high weight efficiency was achieved by using lightweight, high-rigidity CFRP as the material for the optimal-shape outer layer portion 45a. In other words, when a laminated composite member is applied to a rear cross member of a vehicle body, and the weight of the laminated composite member is reduced while maintaining the rigidity of the original vehicle body, it is suggested that the greatest weight reduction can be achieved by using a laminated composite member with CFRP as the material for the outer layer portion.

[0116] Furthermore, in this embodiment, the rear side members constituting the vehicle body model 31 were also modeled using laminated composite members, and optimization analysis was performed to determine their optimal shapes. When performing optimization analysis on the rear side members, a design space was first set in the vehicle body model 31. In the case of the rear side members, the rear bumper portion 39 to which the rear side members originally included in the vehicle body model 31 were joined was deleted, and a design space was defined that was enclosed by a surface shaped along the floor panel 33, a surface shaped along the side sill 37 to which the leading end in the vehicle body length direction is connected, a surface shaped along the rear bumper portion 39 to which the rear end in the vehicle body length direction is connected, and a surface defined based on the original shape of the rear side members.

[0117] 19 to 21, a laminated block model 51 was generated in the set design space, in which an outer layer portion 51a and an inner layer portion 51b were layered. Similar to the laminated block model 43 for the rear cross member described above, the outer layer portion 51a and the inner layer portion 51b were each generated by stacking three layers of hexahedral three-dimensional elements, and the thickness of each of the outer layer portion 51a and the inner layer portion 51b was set to 5 mm. Furthermore, the outer layer portion 51a and the inner layer portion 51b were connected by sharing the nodes of the hexahedral three-dimensional elements that constitute each portion.

[0118] The material properties of the outer layer 51a and inner layer 51b in the laminated block model 51, the connection between the laminated block model 51 and the vehicle body model 31, and the analysis conditions (load conditions, optimization analysis conditions) in the optimization analysis of the laminated block model 51 in the vehicle body model 31 connected to the laminated block model 51 were the same as those in the case of the rear cross member described above.

[0119] However, with regard to the constraint conditions in the optimization analysis, the optimization analysis was performed in both cases where the volume constraint rate of the entire stacked block model 43 was set to 20% or less, and where the volume constraint rate of each of the outer layer 51a and inner layer 51b of the stacked block model 51 was set to 10% or less individually.

[0120] 22 to 27 show the analysis results of an optimal shape 53 obtained by performing optimization analysis on a rear side member by changing the combination of materials of the outer layer portion 51 a and the inner layer portion 51 b of the laminated block model 51.

[0121] 22 to 25 show cases in which the constraint conditions in the optimization analysis are set to a volume constraint rate of 20% or less for the entire laminated block model 51, and the combination of materials of the outer layer 51 a and the inner layer 51 b of the laminated block model 51 (hereinafter, expressed in the format of "(material of outer layer) - (material of inner layer)") is changed. The material combinations in each figure are "steel-steel" (Case 1) in FIG. 22, "Al alloy-steel" (Case 2) in FIG. 23, "CFRP-steel" (Case 4) in FIG. 24, and "steel-CFRP" (Case 5) in FIG. 25.

[0122] 26 and 27 show constraints in the optimization analysis, imposing a volume constraint rate of 10% or less on each of the outer layer portion 51a and the inner layer portion 51b of the laminated block model 51, and the combination of materials for the outer layer portion 51a and the inner layer portion 51b, "(material of the outer layer portion) - (material of the inner layer portion)", is "steel-steel" (Case 1) in Fig. 26 and "CFRP-steel" (Case 4) in Fig. 27. Also, in Figs. 22 to 27, (a) shows the remaining state of the combined optimal-shape outer layer portion 53a and optimal-shape inner layer portion 53b, (b) shows only the optimal-shape outer layer portion 53a, and (c) shows only the optimal-shape inner layer portion 53b.

[0123] When a constraint of a volume constraint rate of 20% or less was imposed on the entire laminated block model 51, similar to the results for the rear cross member (Figures 10 to 16), in Cases 1 and 4, where a material with the same or higher Young's modulus was used for the outer layer 51a, the optimal shape outer layer 53a mainly remained, while in Cases 2 and 5, where a material with a higher Young's modulus was used for the inner layer 51b, the material of the optimal shape inner layer 53b was more likely to remain.

[0124] Furthermore, when a constraint condition of a volume constraint rate of 10% or less was imposed on each of the outer layer portion 51a and the inner layer portion 51b of the laminated block model 51, the volume constraint rate constraint condition was satisfied regardless of the Young's modulus of the outer layer portion 51a, resulting in an increase in the material of the optimal shape inner layer portion 53b.

[0125] 28 and 29 show the rigidity improvement rate of the vehicle body model 31 to which a rear side member made of a laminated composite material having an optimal shape 53 obtained by optimization analysis under various conditions in which the material combinations and constraint conditions of the laminated block model 51 are changed.

[0126] 28 and 29, the horizontal axes representing "torsion," "lateral bending," "RH," and "LH," as well as the vertical axes representing "rigidity improvement rate" and "rigidity improvement rate per part weight," are all the same as those in FIGS. 17 and 18. The "rigidity improvement rate" is a value based on the rigidity of the vehicle body model 31 before the rear side member (steel plate thickness: 1.8 mm) that was the subject of the optimization analysis is removed. In the legends of FIGS. 28 and 29, "whole" indicates that the volume constraint rate is set for the entire laminated block model 51 as a constraint condition, and "individual layers" indicates that the volume constraint rate is set for each of the outer layer portion 51a and the inner layer portion 51b of the laminated block model 51 as a constraint condition.

[0127] The results shown in Figure 28 indicate that when the optimal shape 53 obtained by optimization analysis was integrated into the vehicle body model 31 instead of the rear side member, the rigidity improvement rate was higher in Case 4, where the material of the optimal shape outer layer 53a was CFRP. This is synonymous with the fact that a layout on the outermost periphery increases rigidity, and placing a material with a high Young's modulus on the outermost periphery improves performance. This also coincides with the fact that in order to place a material with a high Young's modulus on the outermost periphery, the shape of that material must be larger, resulting in increased rigidity. In contrast, Case 2, where the material of the optimal shape outer layer 53a was made of an Al alloy, showed the smallest rigidity improvement rate among the examples. This is likely due to the low Young's modulus of the Al alloy.

[0128] Furthermore, when Case 1 (outer layer: steel, inner layer: steel) is compared with Case 4 (outer layer: CFRP, inner layer: steel), a difference is observed in the rate of rigidity improvement when a torsional load is applied, but the values ​​of the rate of rigidity improvement when a lateral bending load is applied are relatively similar. This is because, in the car body model 31, the torsional load contributes to the entire circumference (entire surface) of the car body model 31 centered on the centroid, while the lateral bending load contributes only to the centroid and the upper and lower surfaces centered on the centroid, and therefore it is thought that a more significant difference in the rate of rigidity improvement is more likely to appear when the torsional load is applied.

[0129] Furthermore, from the perspective of volume constraints as a constraint condition, imposing a volume constraint rate on the entire laminated block model resulted in a higher stiffness improvement rate than imposing a volume constraint rate on the outer layer and inner layer individually. This is thought to be because applying a volume constraint rate to the entire laminated block model allows for the selection of a more efficient material layout, for example, allowing more material to remain in the outer layer.

[0130] Furthermore, when the rigidity improvement rate per part weight shown in Fig. 29 is viewed from the perspective of weight efficiency, similar to the results for the rear cross member described above (Fig. 18), the highest weight efficiency was obtained when the material for the optimal-shape outer layer portion 53a was lightweight, high-rigidity CFRP. In other words, similar to the case of the rear cross member described above, it was suggested that when a laminated composite member is applied to the rear side member of a vehicle body, the greatest weight reduction can be achieved when a laminated composite member with CFRP as the material for the outer layer portion is used.

[0131] As described above, it has been shown that the shape optimization analysis method and shape optimization analysis device for laminated composite members according to the present invention can obtain the optimal shape of a laminated composite member when stiffening a part of a vehicle body using the laminated composite member.

[0132] According to the present invention, when a laminated composite member is used in a part of a structure such as a vehicle body to improve rigidity, a shape optimization analysis method and a shape optimization analysis device for a laminated composite member can be provided to determine the optimal shape of the laminated composite member.

[0133] REFERENCE SIGNS LIST 1 Shape optimization analysis device 3 Display device 5 Input device 7 Storage device 9 Working data memory 11 Arithmetic processing unit 13 Design space setting unit 15 Laminated block model generation unit 17 Connection processing unit 19 Optimization analysis unit 21 Structural model file 31 Vehicle body model 33 Floor panel 35 Rear side member 37 Side sill 39 Rear bumper unit 41 Design space of rear cross member 43 Laminated block model 43a Outer layer part 43b Inner layer part 45 Optimal shape 45a Optimal shape outer layer part 45b Optimal shape inner layer part 51 Laminated block model 51a Outer layer part 51b Inner layer part 53 Optimal shape 53a Optimal shape outer layer part 53b Optimal shape inner layer part

Claims

DEPCT641. Method for Geometry Optimization of Layered Composite Components. This method involves the acquisition of a layered composite component model, a structural model of a vehicle body including two-dimensional or two-dimensional and three-dimensional components, and the performance of geometry optimization of the acquired layered composite component model. This method is performed using a computer and consists of: the design area definition step, as the target area for optimizing the structural model of the vehicle body; the layered block model creation step, in which layered blocks are created within the defined design area, and the layered block model includes various layers, each three-dimensional and having different material properties; the connection processing step, which connects the created layered block model to a structural model of the vehicle body; and the optimization analysis step, which involves analyzing the input conditions for analysis.The optimization analysis of layered block models is performed as the objective of the optimization analysis, and the determination of the optimal shape of the layered block model is performed.

2. The method of optimizing the shape of layered composite components involves obtaining a model of a part of the car body structure model, including two-dimensional or two-dimensional and three-dimensional components, and performing the optimization analysis of the shape of the obtained layered composite component model. The method is performed using a computer and includes: the design area definition step, as a multiple of the design areas superimposed in the lamination, as the objective of optimizing the car body structure model; the layered block modeling step, which applies different material properties to the defined design areas to create a layered block model, including three-dimensional components.and the connection of laminated block models created for each design area to create layered block models including three-dimensional components; the connection processing steps of the layered block models created with the structural body model of the vehicle; and the optimization analysis steps of the analysis input conditions, performing optimization analysis on the layered block model as the optimization analysis target, and determining the optimal shape of the layered block model.

3. The optimization method of layered composite component shapes according to claim 1, where layered block models are obtained by: layering, where each layer is a three-dimensional component with different material properties, by using rigid components, beam components,or two-dimensional components; or layering by sharing joint points of different layers.

4. Method of analysis for determining the geometry of layered composite components under claim 2, where layered block models are obtained by: layering laminated block models created for each design area, and each area includes three-dimensional components by using rigid components, beam components,or two-dimensional parts; or the joining of block models which are laminated by using joint points of laminated block models together.

5. One of the geometric optimization methods of layered composite parts under Reputations 1 to 4 where the layered block model includes a three-dimensional part which is one of five to eight facets with at least one pair of two parallel surfaces.

6. One of the geometric optimization methods of layered composite parts under Reputations 1 to 5 where the layered block model is constructed such that the surfaces parallel to the surfaces surrounding the design area defined at part of the structural body model of the vehicle body have the maximum area.

7. One of the geometric optimization methods of layered composite parts under Reputations 1 to 6 where the layered block model is constructed by placing joint points at the joints of two-dimensional or three-dimensional parts of part of the structural body model of the vehicle body.By using six-sided three-dimensional parts as three-dimensional parts of a layered block model, and stacking the three-dimensional parts along the planes including the joint points which are arranged at the connection points.

8. A method for optimizing the geometry of layered composite parts according to one of the claims 1 to 7 where the optimization procedure is performed by segmenting the data with optimization parameters in the optimization analysis.

9. A method for optimizing the geometry of layered composite parts according to one of the claims 1 to 8 where the optimization procedure is performed by optimizing the geometry by topological optimization.

10. A geometry optimization device for layered composite parts which is designed to obtain, with layered composite parts, a model of a part of the structural body model of the car body including two-dimensional parts or two-dimensional and three-dimensional parts,The system performs optimization analysis on the layered composite model. It comprises: a design area definition unit, configured to define, as the design area, the optimization target of the vehicle body structure model; a layered block modeling unit, configured to create layered block models in the defined design area, including various layers, each a three-dimensional component with different material properties; a connectivity processing unit, configured to connect the created layered block models to a portion of the vehicle body structure model; and an optimization analysis unit, configured to input the analysis conditions, and perform optimization analysis on the layered block model as the optimization target.

11. The equipment analyzes the optimization of the shape of layered composite components, which are structured to obtain, with layered composite components, a model of a part of the car body structure model including two-dimensional components or two-dimensional and three-dimensional components, and performs optimization analysis of the shape of the layered composite components of the obtained model. The equipment consists of: a design area definition unit which is structured to define, as a multiple of design areas which are stacked in lamination, the target part for optimizing the car body structure model; a layered block modeling unit which is structured to provide different material properties to the design areas which are defined according to each area to create a layered block model, each area including three-dimensional components.and which is configured to connect the laminated block models created for each design area to create layered block models including three-dimensional components; a connection processing unit which is configured to connect the layered block models created to a portion of the structural body model of the vehicle body; and an optimization analysis unit which is configured to input the analysis conditions, perform optimization analysis on the layered block models as the optimization analysis target, and determine the optimal shape of the layered block models.

12. The optimization analysis device for layered composite component shapes according to claim 10 where the layered block models are obtained by: layering, where each layer is a three-dimensional component and has different material properties, by using rigid components, beam components,or two-dimensional components; or layering by using joint points of different layers together.

13. Geometry analysis equipment for layered composite components under claim 11 where layered block models are obtained by: layering laminated block models created for each design area and each area including three-dimensional components by using rigid components, beam components,or two-dimensional parts; or the lamination of block models which are laminated by using joint points of laminated block models together.

14. A composite layer geometry optimization analyzer under one of the claims 10 to 13 where the layered block model includes a three-dimensional part which is one of five to eight facets with at least one pair of two parallel surfaces.

15. A composite layer geometry optimization analyzer under one of the claims 10 to 14 where the layered block model is constructed such that the surfaces parallel to the surfaces surrounding the design area defined at part of the structural body model of the vehicle body have a maximum area.

16. A composite layer geometry optimization analyzer under one of the claims 10 to 15 where the layered block model is constructed by placing joint points at the connection of two-dimensional or three-dimensional parts of part of the structural body model of the vehicle body,By using six-sided three-dimensional parts as three-dimensional parts of a layered block model, and stacking the three-dimensional parts along the planes including the joint points which are arranged at the connection points.

17. A composite layered part geometry optimization analyzer according to one of the claims 10 to 16 where the optimization unit performs data segmentation with optimization parameters in the optimization analysis.

18. A composite layered part geometry optimization analyzer according to one of the claims 10 to 17 where the optimization unit performs optimization analysis by topological optimization.