JP2018139029A - Method and device of optimizing shape of reinforcing member for vehicle body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device of optimizing the shape of a reinforcing member for a vehicle body for finding an optimum shape of the reinforcing member which reinforces the vehicle body.SOLUTION: A method of optimizing the shape of a reinforcing member for a vehicle body according to the present invention finds an optimum shape of the structure body combined to a part of a structure body which is the vehicle body and the reinforcing member having different material property. The method has: a structure body model acquisition step for acquiring a structure body model which models the structure body by using planar elements and/or stereoscopic elements; a reinforcing member model generation step which generates a reinforcing member model different from the structure body consisting of the stereoscopic element and combined with the part of the structure body model; a material property setting step which sets the material property of the reinforcing member model; an optimization analysis model generation step which combines the reinforcing member model with the part of the structure body model to generate an optimization analysis model; and an optimization analysis step which performs an optimization analysis with the reinforcing member model as an analysis object to find the optimum shape of the reinforcing member model.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method and an apparatus for optimizing the shape of a reinforcing member for a vehicle body that seeks an optimal shape of a reinforcing member that reinforces a vehicle body structure, and more particularly, to reinforce a vehicle body that optimizes the shape of the reinforcing member by an optimization analysis method The present invention relates to a member shape optimization method and apparatus.
In the present invention, the shape optimization means that a predetermined shape, for example, a T-shape is assumed in advance, and that an optimal shape is not obtained on the basis of the predetermined shape, and an analysis is performed without assuming a predetermined shape. This means finding an optimal shape that satisfies the conditions.

In recent years, especially in the automobile industry, weight reduction of vehicle bodies due to environmental problems has been promoted, and analysis by computer-aided engineering (hereinafter referred to as “CAE analysis”) has become an indispensable technique for vehicle body design.
It is known that this CAE analysis can improve vehicle performance such as weight reduction and rigidity improvement by using optimization techniques such as mathematical optimization, plate thickness optimization, shape optimization, and topology optimization. These optimization techniques are often used to optimize the structure of castings such as engine blocks.

Among optimization techniques, topology optimization is particularly attracting attention.
Topology optimization means that a design space of a certain size is provided, a solid element is incorporated in the design space, a given condition is satisfied, and the minimum necessary solid element part is left, thereby satisfying the condition. This is a method for obtaining the optimum shape. Therefore, topology optimization uses a method in which a direct load is applied by directly constraining the three-dimensional elements forming the design space.

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

JP 2010-250818 A

Yumi, 1 other, "Optimum Design of Construction Machinery", Seikei University Engineering Research Report, Vol.41, No.1, 2004, p.1-5

  A structure such as a car body of an automobile is mainly configured by using a thin plate, and in the case of optimizing the shape of one part of the vehicle body constituted by such a thin plate by an optimization technique, conventionally, Non-Patent Document 1 As described, a part of the target vehicle body is taken out and optimized independently, and it is difficult to reflect the load and restraint state from the entire vehicle body on the design space. Therefore, there is a problem that it is difficult to apply the optimization technique to one part of the vehicle body. In addition, even if the optimized shape is obtained from optimization analysis of the whole body part, the optimized part may disappear, and how should it be reflected appropriately in the thin plate structure? There were also challenges.

  The technique disclosed in Patent Document 1 relates to a mathematical calculation method and a physical system related to optimization analysis by topology optimization, and does not deal with the problem of optimization of the thin plate structure as described above. It does not give a solution.

  Furthermore, in recent years, reinforcing members made of resin and FRP (Fiber-Reinforced Plastics), which have different material properties from the thin plate, have been applied to the thin plate that constitutes the body of an automobile to reinforce it. However, there is no conventional technique for optimizing the shape of the reinforcing member and the attachment position of the reinforcing member, and the optimum for obtaining the optimized shape of the reinforcing member that reinforces the vehicle body Development of a new technology has been desired.

  The present invention has been made to solve the above-described problems. When a reinforcing member having a material characteristic different from that of the structure is coupled to a part of the structure that is a vehicle body, the structure is reinforced. An object of the present invention is to provide a method and an apparatus for optimizing the shape of a reinforcing member of a vehicle body for obtaining the optimum shape of the reinforcing member.

(1) A method for optimizing the shape of a reinforcing member for a vehicle body according to the present invention is to obtain an optimal shape of a reinforcing member having a material characteristic different from that of the structural body coupled to a part of the structure that is a vehicle body. Performs the following steps: a structure model acquisition step of acquiring a structure model obtained by modeling the structure using a planar element and / or a three-dimensional element, and the structure model including a three-dimensional element A reinforcing member model generating step for generating a reinforcing member model different from the structural body coupled to a part of the structural member, a material characteristic setting step for setting material characteristics of the reinforcing member model, and the reinforcing member model as the structural body An optimization analysis model generation step for generating an optimization analysis model by combining with a part of the model, an analysis condition is given to the generated optimization analysis model, and the reinforcing member model is optimized Of optimizes the analysis as an analysis object, it is characterized in that it comprises a and optimization analyzing step of determining an optimum shape of the reinforcing member model.

(2) In the above (1), the material property setting step is characterized by setting Young's modulus, Poisson's ratio, and specific gravity as material properties of the reinforcing member model.

(3) In the above (1) or (2), the material property setting step gives a principal axis angle that gives in-plane anisotropy of the material property of the reinforcing member model, and corresponds to the principal axis angle. In the case where the material property value is set and a plurality of layers are formed, layers having respective principal axis angles are overlapped.

(4) In the device according to any one of the above (1) to (3), the optimization analysis step performs an analysis process by topology optimization.

(5) A shape optimization device for a reinforcing member of a vehicle body according to the present invention is for obtaining an optimal shape of a reinforcing member having a material characteristic different from that of the structure that is coupled to a part of the structure that is a vehicle body, A structure model acquisition unit that acquires a structure model obtained by modeling the structure using a planar element and / or a three-dimensional element, and the structure that includes a three-dimensional element and is coupled to a part of the structure model A reinforcing member model generating unit for generating a reinforcing member model, a material property setting unit for setting material properties of the reinforcing member model, and an optimization analysis model by combining the reinforcing member model with a part of the structure model An optimization analysis model generation unit for generating the optimization analysis model, an analysis condition is given to the generated optimization analysis model, the optimization analysis is performed with the reinforcement member model as an analysis target, and the optimal shape of the reinforcement member model is determined. Asking It is characterized in that and a optimization analysis unit.

(6) In the above (5), the material property setting unit sets Young's modulus, Poisson's ratio, and specific gravity as material properties of the reinforcing member model.

(7) In the above-described (5) or (6), the material property setting unit provides a principal axis angle that gives in-plane anisotropy of the material property of the reinforcing member model, and corresponds to the principal axis angle. In the case where the material property value is set and a plurality of layers are formed, layers having respective principal axis angles are overlapped.

(8) In the device according to any one of (5) to (7), the optimization analysis unit performs analysis processing by topology optimization.

  In the present invention, the optimal shape of the reinforcing member having a material characteristic different from that of the structural body that is coupled to a part of the structural body that is a vehicle body is obtained, and the computer performs the following steps. A structure model acquisition step for acquiring a structure model obtained by modeling the structure using an element and / or a three-dimensional element; and the structure that includes a three-dimensional element and is combined with a part of the structure model. A reinforcing member model generating step for generating a reinforcing member model, a material property setting step for setting material properties of the reinforcing member model, and an optimization analysis model by combining the reinforcing member model with a part of the structure model. An optimization analysis model generation step to be generated, an analysis condition is given to the generated optimization analysis model, and an optimization analysis is performed with the reinforcing member model as an analysis target of the optimization And an optimization analysis step for obtaining an optimum shape of the reinforcing member model, whereby the optimum shape of the reinforcing member that reinforces the structure can be obtained with high accuracy. By coupling to the structure, it is possible to improve the predetermined performance of the structure or contribute to weight reduction while maintaining the predetermined performance.

It is a block diagram of the shape optimization apparatus of the reinforcement member of the vehicle body which concerns on embodiment of this invention. It is a figure explaining the vehicle body model, reinforcement member model, and optimization analysis model which are made into analysis object in an embodiment. In embodiment, it is a figure explaining the connection state and method of the reinforcement member model produced | generated using the three-dimensional element, this reinforcement member model, and a vehicle body model. It is a figure which shows an example of the load constraint conditions given to an optimization analysis model in the optimization analysis which concerns on embodiment. It is a figure which shows an example of the optimal shape reinforcement member model shape-optimized by the optimization analysis which concerns on embodiment ((a): perspective view, (b): top view). It is a flowchart figure which shows the flow of a process of the shape optimization method of the reinforcement member of the vehicle body which concerns on embodiment. In an Example, it is a figure which shows the analysis result of a vehicle body displacement when a load restraint condition is given to the vehicle body model. In an Example, it is a figure explaining the shape of the thickness direction of the optimal shape reinforcement member model by which the shape was optimized ((a): AA cross section, (b): Upper surface, (c): BB cross section). . In an Example, it is a figure explaining the stress distribution which arises in the reinforcement member model when giving a load constraint condition to an optimization analysis model ((a): AA cross section, (b): Whole, (c): BB cross section). In an Example, it is a figure explaining the weight reduction analysis model which lightens a vehicle body model using an optimal shape reinforcement member model (a): Vehicle body model which has a roof reinforcement, (b): A roof reinforcement is removed (C): Optimal shape reinforcing member model). In an Example, it is a graph which shows the relationship (a) of the plate | board thickness of the roof part of a vehicle body model, and the weight of a roof part, and the relationship (b) of the plate | board thickness of a roof part, and the change weight of a vehicle body model. In an Example, it is a graph which shows the relationship between the plate | board thickness of the roof part of a weight reduction analysis model which combined the optimal shape reinforcement member model, and the rigidity improvement rate. In an Example, it is a figure explaining the deformation | transformation in the roof part when a load constraint condition is given to the vehicle body model and the weight reduction analysis model.

Prior to describing the method and apparatus for optimizing the shape of a reinforcing member for a vehicle body according to an embodiment of the present invention, a structure model targeted by the present invention will be described.
In the drawings attached to the present specification, shapes and dimensions may be shown, but the present invention is not limited to these shapes and dimensions.

<Structure model>
The structure model is obtained by modeling the structure using a planar element and / or a three-dimensional element when a reinforcing member having a material characteristic different from that of the structure is coupled to a part of the structure. In the embodiment, the vehicle body model 31 shown in FIG. 2A is targeted as the structure model.

  The vehicle body model 31 is composed of a plurality of parts such as a car body skeleton part and a chassis part, and each part of the car body model 31 is modeled by a plane element and / or a three-dimensional element. In addition, information on elements (planar elements and solid elements), material characteristics (materials), and the like of each part constituting the vehicle body model 31 is stored in the structure model file 23 (see FIG. 1).

  In the present embodiment, the reinforcement of the vehicle body roof (corresponding to the roof portion 33 of the vehicle body model 31 shown in FIG. 2) is reinforced by attaching a reinforcing member having a material characteristic different from that of the vehicle body, thereby increasing the snow accumulation strength. An example for the case of improvement will be shown.

<Shape optimization device for vehicle body reinforcement>
Next, the configuration of the shape optimization device 1 (hereinafter simply referred to as “shape optimization device 1”) for the reinforcing member of the vehicle body according to the present embodiment will be described with reference to FIGS.

The shape optimizing device 1 according to the present embodiment includes a reinforcing member having a material characteristic different from that of a part of the structural body to reinforce the structural body. As shown in FIG. 1, it 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 work data memory 9, and an arithmetic processing unit 11. Have.
The display device 3, the input device 5, the storage device 7, and the work 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.
Hereinafter, each structure of the shape optimization apparatus 1 which concerns on this Embodiment is demonstrated.

≪Display device≫
The display device 3 is used for displaying analysis results and the like, and includes a liquid crystal monitor or the like.

≪Input device≫
The input device 5 is used for a display instruction of the structure model file 23, an operator's condition input, and the like, and includes a keyboard, a mouse, and the like.

≪Storage device≫
The storage device 7 is used for storing various files such as the structure model file 23 and is configured by a hard disk or the like.

≪Work data memory≫
The work data memory 9 is used for temporary storage and calculation of data used in the arithmetic processing unit 11, and is composed of a RAM (Random Access Memory) or the like.

≪Operation processing part≫
As shown in FIG. 1, the arithmetic processing unit 11 includes a structure model acquisition unit 13, a reinforcing member model generation unit 15, a material property setting unit 17, an optimization analysis model generation unit 19, and an optimization analysis unit 21. And is constituted by a CPU (Central Processing Unit) such as a PC. Each of these units functions when the CPU executes a predetermined program.
The function of each unit in the arithmetic processing unit 11 will be described below.

(Structure model acquisition unit)
The structure model acquisition unit 13 acquires a vehicle body model 31 (FIG. 2A) obtained by modeling a vehicle body using plane elements and / or three-dimensional elements, and the structure stored in the storage device 7. It can be obtained by reading element information and material property information of the vehicle body model 31 from the body model file 23.

  However, the structure model acquisition unit 13 may be configured to newly generate the vehicle body model 31 by modeling the vehicle body using a planar element and / or a solid element based on the CAD data of the vehicle body.

(Reinforcement member model generator)
The reinforcing member model generation unit 15 generates a reinforcing member model 35 (FIG. 2 (b)) different from the vehicle body model 31 composed of a three-dimensional element and coupled to a part of the vehicle body model 31 (FIG. 2 (a)). It is. Hereinafter, the roof portion 33 will be described as an example of the target portion of the vehicle body to be reinforced.
For example, as shown in FIG. 3, the reinforcing member model 35 can be generated so that three-dimensional elements 35 a are stacked downward from the lower surface of the roof portion 33, which is a portion to be reinforced in the vehicle body model 31.

  The reinforcement member model 35 generated by the reinforcement member model generation unit 15 is a target of optimization analysis by the optimization analysis unit 21 to be described later, and is a three-dimensional object positioned in a portion unnecessary for reinforcement in the process of optimization analysis. The element is deleted, and the three-dimensional element located at the site necessary for reinforcement is left.

  The reinforcing member model generation unit 15 generates a reinforcing member model 35 by setting a predetermined design space below the lower surface of the roof portion 33 and dividing the design space into a plurality of three-dimensional elements. There may be.

(Material property setting section)
The material property setting unit 17 sets the material property of the reinforcing member model 35 generated by the reinforcing member model generating unit 15. Examples of material properties of the reinforcing member model 35 set by the material property setting unit 17 include Young's modulus, Poisson's ratio, and specific gravity.

  Further, when the reinforcing member model 35 is a material whose material characteristics (mechanical characteristics) have in-plane anisotropy, such as FRP (Fiber Reinforced Plastics), for example, the reinforcing member In-plane anisotropy is set in the material characteristics of the reinforcing member model 35 by giving a principal axis angle that gives in-plane anisotropy of the material characteristics of the model 35 and setting the value of the material characteristic corresponding to the principal axis angle can do. In the case where the reinforcing member is composed of a plurality of layers, it is possible to set the principal axis angle for each of the plurality of layers.

  The material property setting unit 17 generates an optimization analysis model 41 (FIG. 2C) by combining the reinforcing member model 35 with a part of the vehicle body model 31 by the optimization analysis model generation unit 19 described later. The material characteristic of the reinforcing member model 35 in the optimization analysis model 41 may be set.

(Optimization analysis model generator)
As shown in FIG. 2, the optimization analysis model generation unit 19 combines the reinforcement member model 35 generated by the reinforcement member model generation unit 15 with a part of the vehicle body model 31 to generate an optimization analysis model 41. is there.

  For example, as a method of connecting the roof portion 33 and the reinforcing member model 35, when the roof portion 33 is modeled by a planar element 33a, for example, as shown in FIG. Some nodes share a node and a node of the planar element 33 a of the roof portion 33.

However, the optimization analysis model generation unit 19 may connect, for example, a part of the vehicle body model 31 and the nodes of the reinforcing member model 35 via a rigid element. There is no particular limitation as long as a load can be transmitted between the reinforcing member model 35 and a beam element, a beam element, a rod element, a rigid coupling element, or the like may be used.
Further, in the case where the part coupled to the reinforcing member model 35 in the vehicle body model 31 is modeled by a three-dimensional element, the optimization analysis model generating unit 19 similarly to the above, the optimization analysis model generating unit 19 performs the three-dimensional element of the part and the reinforcing member model 35. Any solid element may be used as long as the three-dimensional elements are coupled by sharing nodes.

  When the optimization analysis model generation unit 19 generates the optimization analysis model 41, the reinforcing member model 35 is combined and integrated with a part of the vehicle body model 31 that is separated from the vehicle body model 31, and the integration is performed. A part of the vehicle body model 31 and the reinforcing member model 35 may be coupled to the vehicle body model 31.

(Optimization analysis section)
The optimization analysis unit 21 gives analysis conditions to the optimization analysis model 41 (FIG. 2C) generated by the optimization analysis model generation unit 19, and optimizes the reinforcing member model 35 as an object for performing the analysis processing for optimization. Analysis is performed to obtain the optimum shape of the reinforcing member model 35.

  For example, topology optimization can be applied to the optimization analysis performed by the optimization analysis unit 21. When the density method is used in the topology optimization, if there are many intermediate densities, the discretization is preferable and is expressed by the following equation.

K (ρ) ＝ ρ ^p K
However,
K : Stiffness matrix that penalizes the stiffness matrix of the element
K: element stiffness matrix ρ: normalized density
p: Penalty coefficient

  The penalty coefficient often used for discretization is 2 or more, and the value of the penalty coefficient can be set as appropriate.

  The optimization analysis unit 21 may perform a topology optimization process or may be an optimization process based on another calculation method. Therefore, as the optimization analysis unit 21, for example, commercially available analysis software using a finite element can be used.

  The analysis conditions for performing the optimization analysis include a load constraint condition for giving a load position and a constraint position to the optimization analysis model 41, a target condition set according to the purpose of the optimization analysis, and an optimization analysis. There are constraints imposed on the

  FIG. 4 shows an example of the load constraint condition. The load constraint condition shown in FIG. 4 assumes that the snow cover strength of the roof portion 33 is evaluated. The four jack-up installation portions at the lower part of the optimization analysis model 41 are completely constrained, and the roof portion 33 A downward distributed load in the vehicle body height direction is applied to the upper surface of the vehicle.

Examples of the target condition include minimization of the total strain energy in the optimization analysis model 41, minimization of displacement, and maximization of rigidity.
Further, the constraint condition includes a volume constraint rate of the reinforcing member model 35 to be optimized. A plurality of constraint conditions can be set.

FIG. 5 shows an example of the optimum shape reinforcing member model 43 obtained by applying the topology optimization to the optimization analysis unit 21. In FIG. 5, the roof portion 33 is not displayed in order to display the optimum shape reinforcing member model 43.
As shown in FIG. 5, the optimal shape reinforcing member model 43 is obtained by remaining and erasing three-dimensional elements so as to satisfy the above analysis conditions (load constraint conditions, objective conditions, constraint conditions).

<Method for optimizing the shape of the reinforcing member of the vehicle body>
Next, the shape optimization method (hereinafter simply referred to as “shape optimization method”) for the reinforcing member of the vehicle body according to the present embodiment will be described below.

In the shape optimization method according to the present embodiment, when a reinforcing member made of a material different from a part of the structure is coupled to a part of the structure that is a vehicle body, the structure is optimized. As shown in FIG. 6, the structure model acquisition step S1, the reinforcing member model generation step S3, the material property setting step S5, the optimization analysis model generation step S7, and the optimization are performed. Analysis step S9. Hereinafter, each step will be described.
In the shape optimization method according to the present embodiment, the above steps are executed using a shape optimization apparatus 1 (see FIG. 1) configured by a computer.

≪Structure model acquisition step≫
The structure model acquisition step S1 is a step of acquiring a vehicle body model 31 shown in FIG. 2A as a structure model obtained by modeling the structure using a planar element and / or a three-dimensional element. 1, the structure model acquisition unit 13 performs the processing.

≪Reinforcement member model generation step≫
The reinforcing member model generation step S3 is a step of generating a reinforcing member model 35 (see FIG. 2B) that is different from the vehicle body model 31 that is composed of the three-dimensional element 35a (see FIG. 3) and is coupled to a part of the vehicle body model 31. In the shape optimizing apparatus 1 shown in FIG.

≪Material property setting step≫
The material property setting step S5 is a step of setting the material property of the reinforcing member model 35 generated in the reinforcing member model generating step S3, and is performed by the material property setting unit 17 in the shape optimization device 1.
Examples of the material properties set in the reinforcing member model 35 in the material property setting step S5 include Young's modulus, Poisson's ratio, and specific gravity.

  Furthermore, when the reinforcing member has an in-plane anisotropy in material characteristics, such as FRP, for example, a principal axis angle giving in-plane anisotropy of the material characteristics of the reinforcing member model 35 is given, and the principal axis angle The in-plane anisotropy of the material characteristic of the reinforcing member model 35 is set by setting the corresponding value of the material characteristic. In the case where the reinforcing member is composed of a plurality of layers, it is possible to set the principal axis angle for each of the plurality of layers.

≪Optimization analysis model generation step≫
The optimization analysis model generation step S7 combines the reinforcement member model 35 generated in the reinforcement member model generation step S3 with a part of the vehicle body model 31 to generate the optimization analysis model 41. The shape shown in FIG. In the optimization apparatus 1, the optimization analysis model generation unit 19 performs this.

≪Optimization analysis step≫
In the optimization analysis step S9, an analysis condition is given to the optimization analysis model 41 generated in the optimization analysis model generation step S5, the optimization analysis is performed with the reinforcing member model 35 as an object to be analyzed, and the reinforcing member This is a step of obtaining the optimum shape of the model 35, and is performed by the optimization analysis unit 21 in the shape optimization device 1 shown in FIG.

  The analysis conditions given to the optimization analysis model 41 include a load constraint condition (see FIG. 4) that gives a position to which the load is applied to the optimization analysis model 41 and a constraint position (see FIG. 4), and a target condition set according to the purpose of the optimization analysis. There is.

Topology optimization can be applied to the optimization analysis in the optimization analysis step S9. Further, when applying the density method in topology optimization, it is preferable to set the penalty coefficient of the element to 2 or more to perform discretization.
However, for the optimization analysis in the optimization analysis step S9, optimization analysis processing can be applied by other calculation methods. Examples of the optimization analysis processing include commercially available finite elements. Analysis software using can be used.

  As mentioned above, according to the shape optimization method and apparatus of the reinforcement member of the vehicle body which concerns on this Embodiment, the optimal shape of the reinforcement member which reinforces the structure which is a vehicle body can be calculated | required accurately. Furthermore, it is possible to reduce the weight of the structure by using the optimally shaped reinforcing member. The weight reduction of the structure using the optimally shaped reinforcing member will be specifically described in the embodiments described later.

  In the above description, the shape optimization of the reinforcing member that reinforces the roof of the vehicle body has been described as an object.However, the portion that is the object of shape optimization in the present invention is not limited to this, for example, the door panel of the vehicle body, The shape of the reinforcing member that reinforces the trunk, the hood, the fender, and the like may be optimized. Furthermore, although the above description is directed to the body of an automobile as the structure, the present invention does not limit the type of structure. Further, as an application example of the present invention, a case where a resin, FRP (fiber reinforced resin, GFRP, CFRP, etc.), an aluminum plate, a magnesium plate, a titanium plate, or the like is attached to a structure made of a steel plate corresponds.

  In order to confirm the effect of the present invention, in Example 1, an experiment for determining the optimum shape of a reinforcing member that reinforces the roof of a car body of an automobile is performed by the method and apparatus for optimizing the shape of the reinforcing member of the car body according to the present invention. Therefore, this will be described below.

  In the experiment, first, a vehicle body model 31 shown in FIG. 2 was obtained. The vehicle body model 31 is obtained by modeling a vehicle body using plane elements and / or three-dimensional elements. The vehicle body model 31 is made of a steel plate, the reinforcing member model 35 is made of a resin, and the material characteristics thereof are expressed. 1 was set.

Next, the reinforcing member model 35 shown in FIG. 2B was generated, and the material characteristics of the reinforcing member model 35 were set.
As shown in FIG. 3, the reinforcing member model 35 is generated so that the three-dimensional elements 35 a are stacked from the lower surface of the roof portion 33 downward. Here, the thickness of the reinforcing member model 35 was set to 10 mm. The roof portion 33 of the vehicle body model 31 is a shell model (planar element).
Further, the material of the reinforcing member model 35 is resin, and the values of Young's modulus, Poisson's ratio and specific gravity shown in Table 1 are set as the material characteristics.

  Then, the reinforcing member model 35 in which the material characteristics are set is coupled to the lower surface of the roof portion 33 of the vehicle body model 31 as shown in FIG. 3 to generate an optimization analysis model 41 shown in FIG. The reinforcing member model 35 and the roof portion 33 are coupled by sharing the nodes (nodes) of the three-dimensional element 35 a of the reinforcing member model 35 and the planar element 33 a of the roof portion 33.

Finally, topology optimization was performed by giving analysis conditions to the generated optimization analysis model 41, and the optimum shape of the reinforcing member model 35 was obtained.
As the analysis conditions, the load constraint condition shown in FIG. 4 was given, the objective condition was minimized the total strain energy, and the constraint condition was 20% or less of the volume constraint rate. The load restraint condition shown in FIG. 4 is that the four jack-up installation portions (Δ mark in FIG. 4) of the vehicle body model 31 are completely restrained, and 500 N downward from the node on the upper surface of the roof portion 33 in the vehicle body height direction. The distributed load is given. Here, the number of nodes of the roof portion 33 to which the distributed load was applied was 24248.

  FIG. 5 shows the result of the optimum shape reinforcing member model 43 obtained by the optimization analysis, and FIG. 7 shows the analysis result of the vehicle body displacement in the vehicle body height direction when the load restraint condition shown in FIG. Show.

7 that the displacement at the front end portion 81 and the rear end portion 83 of the roof portion 33 is larger than the central portion of the roof portion 33 (the portion surrounded by the broken line ellipse in FIG. 7).
From the results of FIGS. 5 and 7, in the process of optimization analysis, the three-dimensional element 35a does not remain in the part where the vehicle body displacement is small, and the solid element 35a remains so as to support the part where the vehicle body displacement is large. The optimum shape reinforcing member model 43 has a bridge shape that extends in the vehicle body width direction at the front end portion and the rear end portion of the vehicle body and connects the left and right side rail portions 37 as shown by broken lines in FIG. And, it has an L-shape connecting the bridge shape and the side rail portion 37.

  FIG. 8 shows a cross-sectional shape at the front part (cross section AA in FIG. 8B) and the central part (BB cross section in FIG. 8B) of the optimum shape reinforcing member model 43. It is.

  The optimum shape reinforcing member model 43 has a shape in which the three-dimensional elements on the outdoor side remain in the thickness direction as shown in FIG. 8A in the front part, whereas in the center part (FIG. 8C). ), The three-dimensional elements on the outdoor side are eliminated in the thickness direction, and the three-dimensional elements on the indoor side remain.

  The reason why the shape in the thickness direction is different between the front portion and the center portion of the optimum shape reinforcing member model 43 is that the roof portion 33 is connected to the side rail portion 37 of the vehicle body model 31 and the roof portion 33 is restrained. Since this varies depending on the position of the pillar 39 (see FIG. 8B), it may be caused by a difference in stress distribution generated in the thickness direction of the reinforcing member model 35 in the optimization analysis.

  FIG. 9 shows an analysis result of the stress distribution of the reinforcing member model 35 when the load constraint condition shown in FIG. 4 is given to the optimization analysis model 41 before performing the optimization analysis.

  Since the central part of the reinforcing member model 35 is in the vicinity of the pillar 39 (see FIG. 8B), the stress distribution is close to the beam mode of the fixed end as shown in FIG. 9D-2. Since the front part of the reinforcing member model 35 is located away from the pillar 39, the stress distribution as shown in FIG. And it is thought that the difference generate | occur | produced in the site | part in which a solid element remains in optimization analysis by the difference in the stress distribution in the thickness direction.

  From the above, it has been shown that the optimum shape of the reinforcing member for reinforcing the vehicle body can be obtained with high accuracy by the method and apparatus for optimizing the shape of the reinforcing member for the vehicle body according to the present invention.

  In Example 2, an experiment was conducted to examine the weight reduction of the vehicle body using the reinforcing member optimized in shape according to the present invention. This will be described below.

  In the experiment, the roof reinforcement 55 connecting the left and right side rail portions 57 as shown in FIG. 10 is used by using the optimum shape reinforcing member model obtained by the method and apparatus for optimizing the shape of the reinforcing member of the vehicle body according to the present invention. The weight reduction of the vehicle body was examined for the vehicle body model 51 disposed on the lower surface of the roof portion 53.

First, an optimal shape reinforcing member model shown in FIG. 10 (c) is targeted for the vehicle body model 61 from which the roof reinforcement 55 is removed from the vehicle body model 51, using the shape optimization device 1 or the shape optimization method according to the present embodiment. 65, and the optimum shape reinforcing member model 65 is coupled to the roof portion 63 of the vehicle body model 61 to reduce the weight analysis model (corresponding to the optimization analysis model 41 after performing the optimization analysis shown in FIG. 5A). Generate.
Here, the optimum shape reinforcing member model 65 was obtained by giving the same analysis conditions as the optimization analysis used in Example 1 described above, and its weight was 5.3 kg.

  Next, the vehicle body model 51 having the roof reinforcement 55 (FIG. 10A) is subjected to the structural analysis by giving the load constraint condition shown in FIG. 4 to obtain the target value of the vehicle body characteristic that is the target of maintaining the performance. . In this embodiment, the maximum displacement in the vehicle body height direction at the roof 53 is used as the vehicle body characteristic.

  Similarly, with respect to the weight reduction analysis model combined with the optimum shape reinforcing member model 65, the structural analysis is performed by giving the load constraint condition shown in FIG. The maximum displacement in the vehicle body height direction at 63 (FIG. 10B) was acquired.

  Further, the maximum displacement (analytical value) in the roof portion 63 of the light weight analysis model is compared with the maximum displacement (target value) in the roof portion 53 of the vehicle body model 51, and the maximum displacement of the light weight optimization model is the vehicle body model 51. When the displacement is smaller than the maximum displacement, the structural analysis is performed by further reducing the plate thickness of the roof portion 63 of the weight reduction analysis model, and the maximum displacement of the roof portion 63 is obtained again as the analysis value of the vehicle body characteristics.

  In this way, until the maximum displacement of the light weight analysis model becomes equal to the maximum displacement of the vehicle body model 51 (equivalent rigidity), the plate thickness of the roof portion 63 of the light weight analysis model is reduced to reduce the maximum displacement of the roof portion 63. I got it.

  FIG. 11 shows the relationship between the plate thickness of the roof portion 63 and its weight, and the relationship between the plate thickness of the roof portion 63 and the weight change of the vehicle body.

  The changed weight of the vehicle body shown in FIG. 11B is based on the weight of the vehicle body model 51 in which the roof reinforcement 55 is provided and the plate thickness of the roof portion 53 is 1.2 mm. The weight change of the weight reduction analysis model is obtained by subtracting the weight of the roof reinforcement 55 from the weight of the optimum shape reinforcing member model 65 and the weight changed by the reduction in the plate thickness of the roof portion 63.

  For example, when the roof portion 63 has an initial plate thickness of 1.2 mm, the weight of the vehicle body that changes due to the reduction in the plate thickness of the roof portion 63 is 0 kg, so the weight of the optimum shape reinforcing member model 65 (= 5.3 kg) The value obtained by subtracting the weight of the roof reinforcement 55 (= 1.7 kg) (5.3 kg-1.7 kg = + 3.6 kg).

The roof part 63 of the weight reduction analysis model targeted in Example 2 has an initial plate thickness of 1.2 mm and a weight of 15.6 kg. As shown in FIG. Since the correlation coefficient R with the plate thickness is R ² = 1, it decreases linearly as the plate thickness decreases.

  As shown in FIG. 11B, the weight change of the vehicle body decreases as the plate thickness of the roof portion 63 decreases, and when the plate thickness of the roof portion 63 is 0.93 mm, the weight change of the vehicle body becomes 0 kg. . That is, it can be seen that the weight reduction analysis model can be lighter than the vehicle body model 51 by reducing the thickness of the roof portion 63 to 0.93 mm or less.

  FIG. 12 shows the rigidity improvement rate of the weight reduction analysis model when the thickness of the roof portion 63 is changed. Here, the rigidity improvement rate is a ratio between the rigidity of the vehicle body model 51 provided with the roof reinforcement 55 and the rigidity of the light weight analysis model combined with the optimum shape reinforcing member model 65. The rigidity of the chemical analysis model is a value obtained by dividing the total load applied to the roof portion 53 and the roof portion 63 by the maximum displacement.

  From FIG. 12, when the roof portion 63 has an initial plate thickness of 1.2 mm, the rigidity of the weight reduction analysis model is about 33% higher than that of the vehicle body model 51. When the plate thickness of the roof portion 63 is decreased, the rigidity improvement rate of the weight reduction analysis model decreases. When the plate thickness is 0.53 mm, the rigidity improvement rate is almost 0%, that is, the vehicle body model having the roof reinforcement 55. It becomes substantially equal to the rigidity of 51 (equivalent rigidity).

  FIG. 13 shows a vehicle body model 51 (without the optimum shape reinforcing member model 65 (FIG. 10C)) and a weight reduction analysis model 71 (the plate thickness of the roof portion 63) in which the optimum shape reinforcing member model 65 is coupled to the roof portion 63. The analysis results of body displacement at 1.2mm and 0.53mm) are shown.

  When the plate thickness of the roof portion 63 of the lightening analysis model 71 is 1.2 mm (FIG. 13B), the vehicle body displacement of the lightening analysis model 71 is generally smaller than the vehicle body displacement of the vehicle body model 51, and the roof The maximum displacement (−0.21 mm) in the portion 63 is a value smaller than the maximum displacement (−0.28 mm) in the roof portion 53 of the vehicle body model 51.

  On the other hand, when the plate thickness of the roof portion 63 of the weight reduction analysis model 71 is 0.53 mm (FIG. 13C), the portion showing the maximum displacement (−0.28 mm) in the roof portion 63 is the roof portion 53 of the vehicle body model 51. Although the maximum displacement (-0.28mm) is different from that of the part, the maximum displacement of both is the same value.

  Therefore, from the results of FIGS. 11 to 13, when the optimum shape reinforcing member model 65 is used instead of the roof reinforcement 55, the plate thickness of the roof portion 63 is reduced from 1.2 mm to 0.53 mm, so that FIG. From the dotted arrow in b), the plate thickness of 0.53 mm of the roof portion 63 corresponds to the change weight of the vehicle body of -5.2 kg, so that the rigidity equivalent to that of the vehicle body model 51 provided with the roof reinforcement 55 is maintained. It was shown that the weight of the vehicle body can be reduced by 5.2 kg by reducing the roof reinforcement 55 and reducing the thickness of the roof portion 63.

  As described above, the optimum shape of the reinforcing member for reinforcing the vehicle body is obtained by the method and apparatus for optimizing the shape of the reinforcing member for the vehicle body according to the present invention, and the performance of the vehicle body is improved by coupling the reinforcing member having the optimal shape to the vehicle body. It has been demonstrated that the vehicle body can be reduced in weight while being maintained.

DESCRIPTION OF SYMBOLS 1 Shape optimization apparatus 3 Display apparatus 5 Input apparatus 7 Memory | storage device 9 Work data memory 11 Arithmetic processing part 13 Structure model acquisition part 15 Reinforcement member model generation part 17 Material characteristic setting part 19 Optimization analysis model generation part 21 Optimization Analysis unit 23 Structure model file 31 Car body model 33 Roof part 33a Plane element 35 Reinforcement member model 35a Solid element 37 Side rail part 39 Pillar 41 Optimization analysis model 43 Optimal shape reinforcement member model 51 Car body model 53 Roof part 55 Roof reinforcement 57 Side rail part 61 Car body model 63 Roof part 65 Optimal shape reinforcement member model 71 Lightweight analysis model 81 Roof part front end part 83 Roof part rear end part

Claims (8)

This is a method for optimizing the shape of a reinforcing member of a vehicle body that obtains the optimal shape of the reinforcing member having different material characteristics from that of the structural body that is coupled to a part of the structure that is a vehicle body. The computer performs the following steps. And
A structure model acquisition step of acquiring a structure model obtained by modeling the structure using a planar element and / or a three-dimensional element;
A reinforcing member model generating step for generating a reinforcing member model different from the structure that is composed of a three-dimensional element and is coupled to a part of the structure model;
A material property setting step for setting material properties of the reinforcing member model;
An optimization analysis model generation step of generating an optimization analysis model by combining the reinforcing member model with a part of the structure model;
An optimization analysis step for giving an analysis condition to the generated optimization analysis model, performing an optimization analysis with the reinforcement member model as an analysis object, and obtaining an optimum shape of the reinforcement member model; A method for optimizing the shape of a reinforcing member for a vehicle body.   The method for optimizing the shape of a reinforcing member for a vehicle body according to claim 1, wherein the material property setting step sets Young's modulus, Poisson's ratio, and specific gravity as material properties of the reinforcing member model.   The material property setting step gives a principal axis angle that gives in-plane anisotropy of the material property of the reinforcing member model, sets a value of the material property corresponding to the principal axis angle, and consists of a plurality of layers. The method for optimizing the shape of a reinforcing member for a vehicle body according to claim 1 or 2, wherein layers having respective principal axis angles are overlapped.   The method for optimizing the shape of a reinforcing member of a vehicle body according to any one of claims 1 to 3, wherein the optimization analysis step performs an analysis process by topology optimization. A shape optimization device for a reinforcing member of a vehicle body for obtaining an optimal shape of a reinforcing member having a material characteristic different from that of the structure coupled to a part of the structure that is a vehicle body,
A structure model acquisition unit that acquires a structure model obtained by modeling the structure using a planar element and / or a three-dimensional element;
A reinforcing member model generating unit that generates a reinforcing member model different from the structure that is composed of a three-dimensional element and is coupled to a part of the structure model;
A material property setting unit for setting material properties of the reinforcing member model;
An optimization analysis model generation unit that generates an optimization analysis model by combining the reinforcing member model with a part of the structure model;
An optimization analysis unit that gives analysis conditions to the generated optimization analysis model, performs an optimization analysis using the reinforcing member model as an optimization analysis target, and obtains an optimal shape of the reinforcing member model; An apparatus for optimizing the shape of a reinforcing member for a vehicle body.   6. The shape optimization device for a reinforcing member of a vehicle body according to claim 5, wherein the material property setting unit sets Young's modulus, Poisson's ratio, and specific gravity as material properties of the reinforcing member model.   The material property setting unit provides a principal axis angle that gives in-plane anisotropy of the material property of the reinforcing member model, sets a value of the material property corresponding to the principal axis angle, and includes a plurality of layers. The shape optimization device for a reinforcing member of a vehicle body according to claim 5 or 6, wherein layers having respective principal axis angles are overlapped.   The shape optimization device for a reinforcing member of a vehicle body according to any one of claims 5 to 7, wherein the optimization analysis unit performs an analysis process by topology optimization.