Analysis device, analysis method, and computer program

Abstract

To easily select a natural vibration mode not dependent on a coordinate system that corresponds to spring-back deformation and easily and reliably carry out analysis for reducing the deformation of a member caused by spring-back.SOLUTION: The present invention finds a physical quantity not dependent on a coordinate system that includes at least one of stress and strain at a plurality of evaluation points of finite element model data, on the basis of finite element model data, material property data and stress distribution data, so as to generate a first distribution vector that indicates the distribution of physical quantity of a member caused by spring-back, finds a physical quantity at the plurality of evaluation points of the finite element model data regarding each natural vibration mode, on the basis of the finite element model data and the material property data, so as to generate a second distribution vector that indicates the distribution of physical quantity of a member in each natural vibration mode, and calculates the inner product of the first distribution vector and a second distribution vector in each natural vibration mode and finds the degree of coincidence.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an analysis device, an analysis method, and a computer program. [Background technology]

[0002] Due to the demand for collision safety and weight reduction, the tensile strength of steel plates used in automobile bodies and the like exceeds 590 MPa and is approaching the GPa unit. High-strength steel plates can increase the energy absorption and strength during a collision without increasing the plate thickness. Compared to other lightweight materials, the processing and assembly of parts using high-strength steel plates does not necessarily require major changes in equipment and production technology. Therefore, the burden on production costs of processing and assembly of parts using high-strength steel plates is considered to be relatively small compared to other lightweight materials.

[0003] However, in the case of press forming, as the strength of the steel plate increases, springback and wrinkles increase, making it difficult to ensure the dimensional accuracy of the parts. In addition, the decrease in ductility that accompanies the increase in strength increases the risk of breakage during press forming. As such, achieving both performance and productivity with high-strength steel plate is not necessarily easier than with conventional mild steel plate, and combined with the need to shorten development periods and reduce manufacturing costs, the burden of developing processing technology for mass production is greatly increased.

[0004] Of the above-mentioned breakage, wrinkles, and springback, breakage and wrinkles are issues that can occur even when conventional mild steel sheets are used, depending on the part shape, forming conditions, etc., and a great deal of knowledge, countermeasures, etc. have been accumulated so far. On the other hand, springback is an issue specific to the use of high-strength steel sheets, and has not yet been fully studied. It cannot be said that widely used forming simulations have sufficient practical reliability in terms of predicting dimensional accuracy by springback analysis.

[0005] Springback is the elastic deformation that occurs in a part to achieve a new equilibrium, driven by residual stress, when the part is removed from the mold after molding, when unnecessary parts are trimmed, or when other tasks that relieve the constraints on the part are performed. Since high-strength steel sheets have a large springback, it is difficult to ensure the dimensional accuracy required for the final product.

[0006] Springback is classified into "angle change", "wall warpage", "twist", "ridge warpage" and "punch bottom springback" according to the phenomenon. In all cases, residual stress distribution in the part acts as a bending or twisting moment, and the part is deformed according to the rigidity determined by the elastic coefficient of the material, plate thickness, part shape, etc. For example, the most well-known examples of springback are bending angle change and wall warpage. These springbacks are driven by stress distribution in the plate thickness direction, and the rigidity is mainly determined by the plate thickness. Alternatively, when a hat-shaped beam curved in the longitudinal direction is draw-formed, wall warpage and twist occur, but if the curvature of the curve is small, the part rigidity increases and the wall warpage decreases.

[0007] Based on this mechanism, one of the countermeasures against poor dimensional accuracy is to change the plate thickness, part shape, etc., to increase the rigidity according to the elastic deformation mode of springback, and to increase the resistance to springback.

[0008] Increasing the resistance to springback definitely reduces dimensional change. Resistance to springback is the stiffness of a part against its elastic deformation mode. To increase the stiffness of a part, the shape of the part is an important factor. Since the shape of a part is restricted by the requirements of performance, layout, etc., small measures such as beads and embossing are effective.

[0009] Beads against wall warpage are the most typical example of stiffness reinforcement measures. On the other hand, it is not easy to find the optimal stiffness reinforcement position for three-dimensional springback in complex parts. As a new attempt, a method of combining natural vibration analysis and optimization has been proposed (see Non-Patent Document 1).

[0010] That is, focusing on the fact that the natural frequency is proportional to the square root of the stiffness and inversely proportional to the square root of the density (mass), the elastic deformation mode of springback is identified, the natural vibration mode corresponding to that elastic deformation mode of springback is selected, some of the elements are replaced with highly elastic material of the same density so that the natural frequency of that natural vibration mode increases, and the optimal arrangement of the elements is found using an optimization tool, etc. This makes it easy to find the optimal position for stiffness reinforcement.

[0011] However, this method has the problem that the natural vibration mode must be selected manually, which is time-consuming. In addition, even if the natural vibration mode is selected automatically, the selection criteria are not clear, so it is not always possible to select a natural vibration mode that corresponds to the elastic deformation mode of springback, and the optimal arrangement of the high-elasticity material is not always obtained. Therefore, it is possible to select all natural vibration modes and find the optimal arrangement of the high-elasticity material for each of them, but this has the problem of being too costly. For this reason, it is not easy to perform an analysis to reduce the deformation of the member caused by springback.

[0012] Therefore, when selecting which natural vibration mode the shape after springback corresponds to, a method can be considered in which the springback displacement is compared with the eigenvectors of each natural vibration mode. In this case, the orientation (coordinate system) of the component before springback must match the orientation of the component in the natural vibration mode analysis. Also, if the orientation after springback changes significantly depending on the springback restraint position, it may not be possible to select the correct mode even if the orientation before springback is matched. [Prior art documents] [Non-patent literature]

[0013] [Non-Patent Document 1] Shunji Hiwatari and 1 other, "Comprehensive Approach to Forming Issues of High Strength Steel Plates," Special Lecture at the Plate Forming Forum of the Forming Engineering Division of the Iron and Steel Institute of Japan, The Iron and Steel Institute of Japan, January 14, 2005 Summary of the Invention [Problem to be solved by the invention]

[0014] The present invention has been made to solve these conventional problems, and aims to easily select a natural vibration mode that is independent of the coordinate system by calculating the inner product of a vector generated by arranging physical quantities that are independent of the posture (coordinate system) of a component and each natural vibration mode after springback, and evaluating the degree of agreement, thereby making it possible to easily and reliably perform analysis to reduce the deformation of the component caused by springback. [Means for solving the problem]

[0015] The analysis device of the present invention has a press forming analysis unit that acquires finite element model data indicating a shape of a member, material property data indicating material properties of the member, and stress distribution data indicating a stress distribution generated in the member; a springback analysis unit that generates a first distribution vector indicating a distribution of the physical quantity of the member generated by springback by determining a coordinate system-independent physical quantity including at least one of stress and strain at a plurality of evaluation points of the finite element model data based on the finite element model data, the material property data, and the stress distribution data; a natural vibration analysis unit that generates a second distribution vector indicating a distribution of the physical quantity of the member in each of the natural vibration modes by determining the physical quantity at a plurality of evaluation points of the finite element model data for each natural vibration mode based on the finite element model data and the material property data; a mode decomposition unit that calculates an inner product of the first distribution vector and each of the second distribution vectors in each of the natural vibration modes to determine a degree of agreement; and a mode selection unit that selects one or more natural vibration modes based on the degree of agreement.

[0016] In the analysis device of the present invention, the physical quantity is at least one of stress, strain, and strain energy density.

[0017] In the analysis device of the present invention, the physical quantity is at least one of the following invariants J1, J2, J3, I1, I2, and I3, where σ is stress, ε is strain, δ is Kronecker delta, and det is a determinant.

[0018]

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[0019] The analysis method of the present invention includes: The computer system A press molding analysis process for acquiring finite element model data indicating a shape of a member, material property data indicating a material property of the member, and stress distribution data indicating a stress distribution generated in the member; The computer system A springback analysis process for generating a first distribution vector indicating a distribution of the physical quantity of the member caused by springback by determining a physical quantity independent of a coordinate system including at least one of stress and strain at a plurality of evaluation points of the finite element model data based on the finite element model data, the material property data, and the stress distribution data; The computer system a natural vibration analysis process for generating a second distribution vector indicating a distribution of the physical quantity of the component in each natural vibration mode by determining the physical quantity at a plurality of evaluation points of the finite element model data for each natural vibration mode based on the finite element model data and the material property data; The computer system a mode decomposition process for calculating an inner product of the first distribution vector and each of the second distribution vectors in the natural vibration modes to obtain a degree of agreement; The computer system At least a mode selection step is performed in which one or more natural vibration modes are selected based on the degree of coincidence.

[0020] In the analysis method of the present invention, the physical quantity is at least one of stress, strain, and strain energy density.

[0021] In the analysis method of the present invention, the analysis device according to claim 1, wherein the physical quantity is at least one of the following invariants J1, J2, J3, I1, I2, and I3, where σ is stress, ε is strain, δ is Kronecker delta, and det is a determinant.

[0022]

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[0023] The computer program of the present invention causes a computer to execute the following steps: a press forming analysis step of acquiring finite element model data indicating a shape of a member, material property data indicating a material property of the member, and stress distribution data indicating a stress distribution generated in the member; a springback analysis step of generating a first distribution vector indicating a distribution of the physical quantity of the member generated by springback by determining a coordinate system-independent physical quantity including at least one of stress and strain at a plurality of evaluation points of the finite element model data based on the finite element model data, the material property data, and the stress distribution data; an inherent vibration analysis step of generating a second distribution vector indicating a distribution of the physical quantity of the member in each of the inherent vibration modes by determining the physical quantity at a plurality of evaluation points of the finite element model data for each inherent vibration mode based on the finite element model data and the material property data; a mode decomposition step of calculating an inner product of the first distribution vector and each of the second distribution vectors in each of the inherent vibration modes to determine a degree of agreement; and a mode selection step of selecting one or more inherent vibration modes based on the degree of agreement.

[0024] In the computer program of the present invention, the physical quantity is at least one of stress, strain, and strain energy density.

[0025] In the computer program of the present invention, the physical quantities are expressed by the following invariants J1, J2, J 3,At least one of I1, I2, and I3. σ is stress, ε is strain, δ is Kronecker delta, and det is a determinant.

[0026]

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[0027] According to the present invention, it is possible to easily select a natural vibration mode that corresponds to springback deformation and is independent of a coordinate system, and therefore it is possible to easily and reliably perform an analysis for reducing deformation of a member caused by springback. [Brief description of the drawings]

[0028] [Figure 1] 4 is a flowchart illustrating an example of an operation of the analysis device according to the present embodiment. [Diagram 2] 1A and 1B are schematic diagrams showing an example of a member before and after division into elements. [Diagram 3] FIG. 2 is a block diagram showing an example of a functional configuration of an analysis device according to the present embodiment. [Figure 4] FIG. 11 is a characteristic diagram showing the degree of agreement between stress distribution data in a springback analysis result and stress distribution data for each natural vibration mode in a natural vibration analysis result. [Diagram 5] FIG. 2 is a schematic diagram showing the internal configuration of a personal user terminal device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Various embodiments of the present invention will be described below with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to these embodiments, but extends to the inventions described in the claims and their equivalents.

[0030] Fig. 1 is a flowchart for explaining an example of the operation of the analysis device 1. The processing flow shown in Fig. 1 is executed mainly by the processing unit 13 of the analysis device 1 in cooperation with each element of the analysis device 1, based on a program previously stored in the storage unit 12 of the analysis device 1 shown in Fig. 11. The configuration of the analysis device 1 will be described later.

[0031] First, the processing unit 13 generates finite element model data by dividing the shape of a component into a plurality of elements of specific shapes and sizes based on the "CAD model data and generation condition data" stored in the storage unit 12 (step S101). The processing unit 13 also stores the generated finite element model data in the storage unit 12. Note that HyperMesh, a commercially available application program, is used for the generation process of the finite element model. However, it is also possible to use other application programs (e.g., ANSA).

[0032] Fig. 2(a) is a schematic diagram (perspective view) showing the posture of the target part incorporated in the structure, and Fig. 2(b) is a schematic diagram (perspective view) showing the posture of the target part at the time of completion of forming in forming analysis.

[0033] Next, the processing unit 13 generates stress distribution data of the member by determining the stress generated in each element of the member by the finite element method based on the finite element model data, material property data, and press molding condition data stored in the storage unit 12 (step S102). In this way, the stress distribution data of the member includes information indicating the stress generated in each element of the member. The processing unit 13 also stores the generated stress distribution data in the storage unit 12. Note that HyperForm, which is a commercially available application program, is used for the analysis processing of press molding. However, it is also possible to use other application programs (LS-DYNA, PAM-STAMP, ABAQUS, etc.).

[0034] Next, the processing unit 13 uses the finite element method to obtain physical quantities that are independent of the orientation (coordinate system) of the component at multiple evaluation points of the finite element model data based on the finite element model data, stress distribution data, material property data, and boundary condition data stored in the storage unit 12, and arranges them in the order of evaluation points to generate a first distribution vector indicating the distribution of the physical quantities of the component caused by springback (step S103). As the physical quantities, stress (maximum principal stress, minimum principal stress), strain (maximum principal strain, minimum principal strain), strain energy density, various invariants, etc. can be used. As the evaluation points, any point such as an integration point or a node (or all nodes) in any element (or all elements) in the finite element model data may be used.

[0035] The first distribution vector when the physical quantity is the maximum principal strain is expressed by the following formula (8). In formula (8), ε 1,SB represents the maximum principal strain after springback, n is the number of evaluation points, and N is the number of candidate modes. Moreover, the first distribution vector when the physical quantity is the maximum principal strain and the minimum principal strain is shown in the following formula (9). In formula (9), ε1~ 2,SB represents the maximum principal strain and the minimum principal strain after springback, n is the number of evaluation points, and N is the number of candidate modes. In addition, when the physical quantities are the strain energy density U and the various invariants J1, J2, J3, I1, I2, and I3, they are shown in the following formulas (1) to (7). In these formulas, σ is stress, ε is strain, δ is Kronecker delta, and det is a determinant.

[0036] The processing unit 13 stores the generated first distribution vector in the storage unit 12. For the springback analysis process, LS-DYNA, which is a commercially available application program, is used. However, it is also possible to use other application programs (PAM-STAMP, etc.).

[0037]

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[0038]

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[0039]

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[0040] Next, the processing unit 13 obtains the physical quantities at multiple evaluation points of the finite element model data for each natural vibration mode by the finite element method based on the finite element model data (model shown in FIG. 2(b)), material property data, and boundary condition data stored in the storage unit 12, and arranges them in the order of evaluation points. As a result, a second distribution vector indicating the distribution of the physical quantities of the component in each natural vibration mode is generated (step S104).

[0041] The second distribution vector in each natural vibration mode when the physical quantity is the maximum principal strain is expressed by the following formula (10). In formula (10), ε 1,M represents the maximum principal strain in each natural vibration mode, n is the number of evaluation points, and N is the number of candidate modes. Moreover, the second distribution vector in each natural vibration mode when the physical quantity is the maximum principal strain and the minimum principal strain is expressed by the following formula (11). In formula (11), ε 1,M is the maximum principal strain in each natural vibration mode, ε 2,M represents the minimum principal strain in each natural vibration mode, n is the number of evaluation points, and N is the number of candidate modes.

[0042] The processing unit 13 stores each of the generated second distribution vectors in the storage unit 12. For the analysis processing of the natural vibration, OptiStruct, which is a commercially available application program, is used. However, it is also possible to use other application programs (such as Nastran).

[0043]

number

[0044]

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[0045] Next, the processing unit 13 calculates the inner product of the first distribution vector stored in the storage unit 12 and each of the second distribution vectors in each natural vibration mode to obtain the degree of agreement between the distribution vectors (step S105). That is, the processing unit 13 obtains the degree of agreement between the distribution vectors by obtaining, as an index, the absolute value of the inner product normalized by the magnitude of each distribution vector, which indicates the degree of correlation between the physical quantity in each natural vibration mode and the physical quantity after springback at each evaluation point.

[0046] Specifically, when the physical quantity is, for example, the maximum principal strain, the processing unit 13 calculates the degree of coincidence d between the distribution vectors as a vector by the following equation (12). i indicates the degree of agreement between the i-th natural vibration mode and the maximum principal strain after springback. d i The larger the magnitude of β, the higher the degree of match between the distribution vectors. The processing unit 13 stores the calculated degrees of match between the distribution vectors in the storage unit 12.

[0047] When the physical quantities are the maximum principal distortion and the minimum principal distortion, the processing unit 13 obtains the degree of coincidence d between the distribution vectors as a vector by the following formula (13). i indicates the degree of agreement between the i-th natural vibration mode and the maximum principal strain and minimum principal strain after springback. d i The larger the magnitude of β, the higher the degree of match between the distribution vectors. The processing unit 13 stores the calculated degrees of match between the distribution vectors in the storage unit 12.

[0048]

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[0049]

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[0050] Next, the processing unit 13 selects one or more (a small number), here two, natural vibration modes based on the degrees of agreement between the distribution vectors stored in the storage unit 12 (step S106). Unlike this embodiment, when the degree of agreement between the distribution vectors is evaluated using the shape (displacement) of the member, the relationship between the degree of agreement between the natural vibration mode and the distribution data cannot be obtained correctly unless the posture of the model is the same, and the natural vibration mode corresponding to the deformation of the member caused by springback cannot be selected. In contrast, in this embodiment, the degree of agreement between the distribution vectors is evaluated using physical quantities (stress (maximum principal stress, minimum principal stress), strain (maximum principal strain, minimum principal strain), strain energy density, various invariants, etc.) that do not depend on the posture (coordinate system) of the member. As a result, in this embodiment, as will be described later, the processing unit 13 can select, for example, the first mode and the sixth mode as the natural vibration modes corresponding to the deformation of the member caused by springback based on the degree of agreement between the distribution vectors.

[0051] Next, the processing unit 13 places beads in the finite element model data stored in the memory unit 12 based on the material property data, boundary condition data, and placement condition data stored in the memory unit 12 so as to increase the natural frequency of the generated natural vibration mode (step S107).

[0052] Here, arranging a bead in the finite element model data means providing irregularities on the surface of a member belonging to an element included in the finite element model data. In this way, the bead in the present invention means providing irregularities on the surface of a member, and is a concept that also includes embossing and the like.

[0053] Then, the processing unit 13 stores the finite element model data after the bead is placed in the storage unit 12. The bead placement process uses OptiStruct, a commercially available application program. In addition, when placing the bead, the ratio of the bead placement area to the component area can be specified. Here, the component area is the area of ​​the surface of the component on which the bead can be placed. The bead placement area is the area of ​​the surface of the component on which the bead is placed. If this ratio is made too large, the beads will be placed in most of the area of ​​the component. However, there are cases where restrictions are imposed on the area in which the beads are placed depending on the shape of the component, the attachment point of the component, and the relationship with other components. In addition, there are cases where it is desired to make it easier to design the component by placing the beads only in the area that contributes greatly to suppressing the deformation of the component caused by springback. From this perspective, the user operates the operation unit 14 to appropriately specify the ratio of the bead placement area to the component area.

[0054] Next, the processing unit 13 updates the stress distribution data of the component by determining the stress generated in each element of the component by the finite element method based on the "finite element model data, material property data, and press molding condition data after the bead is placed" stored in the storage unit 12 (step S108). The processing unit 13 also stores the "stress distribution data after the bead is placed" thus generated in the storage unit 12. Note that HyperForm, a commercially available application program, is used for the analysis processing of press molding. However, it is also possible to use other application programs (LS-DYNA, PAM-STAMP, etc.).

[0055] Next, the processing unit 13 maps the "updated stress distribution data" stored in the storage unit 12 to the finite element model data for each "finite element model data after the bead is placed" stored in the storage unit 12 (step S109). Then, the processing unit 13 obtains the physical quantities at a plurality of evaluation points of the finite element model data by the finite element method based on the finite element model data to which the updated stress distribution data is mapped and the "material property data and boundary condition data" stored in the storage unit 12, and arranges them in the order of evaluation points to generate a first distribution vector indicating the distribution of the physical quantities of the member caused by springback (step S109). The processing unit 13 also stores the "first distribution vector after the bead is placed" thus generated in the storage unit 12. In addition, LS-DYNA, which is a commercially available application program, is used for the analysis processing of springback. However, it is also possible to use other application programs (PAM-STAMP, etc.).

[0056] Next, the processing unit 13 judges whether or not the difference between the physical quantity of each node of the member determined based on the first distribution data after the bead is placed and the target physical quantity of the member is within a predetermined range (step S110). This judgment can be realized, for example, by judging whether or not all the differences between the physical quantity of each node of the member on which the bead is placed and the target physical quantity of each node are within a predetermined range.

[0057] If the result of this determination is that the difference between the physical quantity of the member determined based on the first distribution vector after the bead is placed and the target physical quantity of the member is not within a predetermined range, the process returns to step S104. Then, the process of steps S104 to S110 is repeated using "each (latest) finite element model data after the bead is placed" stored in the storage unit 12 until the difference between the physical quantity of the member determined based on the first distribution vector after the bead is placed and the target physical quantity of the member falls within a predetermined range. Then, when the difference between the physical quantity of the member determined based on the first distribution vector after the bead is placed and the target physical quantity of the member falls within a predetermined range, the processing unit 13 causes the display unit 15 to display information specifying the bead arrangement (the latest bead arrangement obtained in step S107) in which the difference between the physical quantity of the member after springback and the target physical quantity falls within a predetermined range. Then, the process according to the flowchart of FIG. 1 is terminated. The information specifying the bead arrangement can include, for example, information such as the position, shape, and height (depth) of the bead in addition to an image. In addition, information indicating the natural vibration mode selected when the physical quantity of the component after springback and the target physical quantity fall within a predetermined range (the latest natural vibration mode obtained in step S106) may be displayed on the display unit 15.

[0058] In the process of step S111, for example, information specifying the arrangement of the beads is displayed. However, the shape of the bead is complex. Therefore, it is not easy to arrange the beads on the component according to the information. Therefore, the user determines the actual arrangement of the beads with respect to the component (i.e., the shape of the component) based on the arrangement of the beads in the information, the shape and attachment position of the component, the relationship with other components, etc.

[0059] In this way, the processing unit 13 of the analysis device 1 performs press forming analysis, springback analysis, natural vibration analysis, etc. on the finite element model data. The processing unit 13 also selects one or more natural vibration modes based on the degree of agreement of the physical quantities, and arranges beads in the finite element model data so that the natural frequency of the natural vibration mode increases. Then, the processing unit 13 again performs press forming analysis and springback analysis on the finite element model data after the beads are arranged. Then, the arrangement of the beads, the press forming analysis, and the springback analysis are repeated until the difference between the physical quantities of the component after the springback analysis and the target physical quantities falls within a predetermined range. This allows the user to easily select the natural vibration mode corresponding to the springback deformation.

[0060] 1, the processes of steps S108 and S110 may not be performed. In this case, in step S109, the "stress distribution data of the member" generated in step S102 and stored in the storage unit 12 is mapped to the "finite element model data after the beads are placed" stored in the storage unit 12.

[0061] Next, an example of this embodiment will be described. In this example, a hat-shaped member having the shape shown in FIG. 2 was analyzed. The dimensions of the member were a length of 300 mm, a cross section of 58×36 to 46×26 mm, and a flange width of 26 mm. The plate thickness of the member was 1.2 mm. The material constituting the member was a steel plate. The physical properties of the steel plate were a Young's modulus of 206 GPa, a Poisson's ratio of 0.3, and a specific gravity of 7.8. The friction coefficient of the steel plate was 0.12.

[0062] Under the above conditions, press forming analysis, springback analysis, natural vibration analysis, and mode decomposition were performed, and a correspondence relationship was obtained between the stress distribution data in the springback analysis results and the stress distribution data for each natural vibration mode in the natural vibration analysis results, as shown in Figure 4. For comparison, Figure 4 also shows the correspondence obtained by the conventional technology between the displacement vector, which is the coordinate difference between the stress distribution data and the desired shape, and the eigenvector of the natural vibration mode obtained by the natural vibration analysis.

[0063] In this embodiment, the degree of agreement between the distribution vectors is evaluated using physical quantities (stress (maximum principal stress, minimum principal stress), strain (maximum principal strain, minimum principal strain), strain energy density, various invariants, etc.) that do not depend on the posture (coordinate system) of the member. For example, evaluation is performed at two points, the center of the plate thickness and the surface layer of the upper surface of the plate thickness, as multiple integration points, and two types of characteristic diagrams obtained corresponding to each integration point are created. The stress at the center of the plate thickness is a factor of torsional deformation, and the stress at the surface layer of the upper surface of the plate thickness is a factor of bending deformation, and it can be said that the mode of the order that shows a high degree of agreement in both is excellent in accuracy. From the two types of characteristic diagrams, only the first mode and the sixth mode have a high degree of agreement for both of the integration points. On the other hand, the degree of agreement between the displacement vector, which is the coordinate difference between the springback analysis result and the desired shape, and the eigenvector of the natural vibration mode obtained by the natural vibration analysis (the degree of agreement obtained by the conventional technology) is almost zero in all modes because there is a difference in the posture between the model of the eigenvalue analysis and the model of the forming analysis, and the natural mode cannot be extracted from the deformation due to springback.

[0064] Finally, a hardware configuration of the analysis device 1 in this embodiment will be described below.

[0065] The analysis device 1 executes programs that have already been installed, and executes various processes by referring to data stored in the storage unit 12 and / or data stored in other devices. The analysis device 1 also executes various processes according to instructions input by a user via the operation unit 14, and presents the results to the user via the display unit 15. To this end, the analysis device 1 has a communication unit 11, a storage unit 12, a processing unit 13, an operation unit 14, and a display unit 15.

[0066] The communication unit 11 has a communication interface circuit for connecting the analysis device 1 to a network (not shown). The communication unit 11 passes data received from other devices (not shown) via the network to the processing unit 13. The communication unit 11 also transmits data received from the processing unit 13 to other devices via the network.

[0067] The storage unit 12 has, for example, at least one of a semiconductor memory, a magnetic disk device, and an optical disk device. The storage unit 12 stores application programs, data, and the like used for processing in the processing unit 13. The storage unit 12 stores, for example, as application programs, a finite element model generation program, a press forming analysis program, a springback analysis program, a natural vibration analysis program, a mode decomposition program, a mode selection program, a bead placement program, and the like.

[0068] The storage unit 12 also stores the following data as preset initial setting data: As the first initial setting data, the storage unit 12 stores CAD (Computer Aided Design) model data indicating the position, size, and shape of the member. As the second initial setting data, the storage unit 12 stores material property data indicating the material properties of the member (dimensions, plate thickness, material, Young's modulus, Poisson's ratio, mass density, relationship between stress and strain, etc.). As the third initial setting data, the storage unit 12 stores generation condition data indicating the generation conditions of the finite element model (shape, size, etc. of elements). As the fourth initial setting data, the storage unit 12 stores press molding condition data indicating the press molding conditions (friction coefficient, member flange pressing force, etc.). As the fifth initial setting data, the storage unit 12 stores boundary condition data indicating boundary conditions (fixed points on the member, etc.). As the sixth initial setting data, the storage unit 12 stores arrangement condition data indicating the arrangement conditions of the bead (height, arrangement area, etc.).

[0069] Furthermore, the storage unit 12 stores the following data as intermediate data generated by the processing unit 13: That is, as the first intermediate data, the storage unit 12 stores finite element model data (position, shape, size, etc. of each element) corresponding to the CAD model data. As the second intermediate data, the storage unit 12 stores stress distribution data indicating the stress distribution of the member. As the third intermediate data, the storage unit 12 stores a first distribution vector indicating the distribution of the physical quantity of the member caused by springback. As the fourth intermediate data, the storage unit 12 stores second distribution data indicating the distribution of the physical quantity of the member in each natural vibration mode. As the fifth intermediate data, the storage unit 12 stores the degree of agreement between the distribution vectors. As the sixth intermediate data, the storage unit 12 stores the selected order of the natural vibration mode. As the seventh intermediate data, the storage unit 12 stores finite element model data after the bead is arranged. As the eighth intermediate data, the storage unit 12 stores distribution data indicating the distribution of the physical quantity after the bead is arranged. Furthermore, the storage unit 12 may temporarily store temporary data related to a predetermined process.

[0070] The processing unit 13 has one or more processors and their peripheral circuits. The processing unit 13 is a processing unit, such as a CPU (Central Processing Unit), that comprehensively controls the overall operation of the analysis device 1. That is, the processing unit 13 controls the operation of the communication unit 11, the display unit 15, etc. so that various processes of the analysis device 1 are executed in an appropriate order based on the operation of the operation unit 14, the programs stored in the storage unit 12, etc. The processing unit 13 executes processes based on the programs (operating system programs, application programs, etc.) stored in the storage unit 12. The processing unit 13 can also execute multiple programs (application programs, etc.) in parallel.

[0071] The processing unit 13 includes a finite element model generating unit 131 that executes the process of step S101 in FIG. 1, a press forming analysis unit 132 that executes the processes of steps S102 and S108, a springback analysis unit 133 that executes the processes of steps S103 and S109, a natural vibration analysis unit 134 that executes the process of step S104, a mode decomposition unit 135 that executes the process of step S105, a mode selection unit 136 that executes the process of step S106, a bead arrangement unit 137 that executes the process of step S107, an invariant determination unit 138 that executes the process of step S110, and a data drawing unit 139 that executes the process of step S111. Each of these units included in the processing unit 13 is a functional module implemented by a program executed on a processor included in the processing unit 13. Alternatively, each of these units included in the processing unit 13 may be implemented in the analysis device 1 as firmware.

[0072] The data drawing unit 139 executes a data drawing process. That is, the data provided from the finite element model generating unit 131, the press forming analysis unit 132, the springback analysis unit 133, the natural vibration analysis unit 134, the mode decomposition unit 135, the mode selection unit 136, and the bead arrangement unit 137 is analyzed, the data is rendered in a predetermined format (for example, a contour diagram), and the drawing data is generated. Then, the data drawing unit 139 outputs the generated drawing data to the display unit 15 or the like. In this case, the display unit 15 functions as an output unit. However, this is not necessarily required. For example, when the communication unit 11 transmits data provided from the finite element model generating unit 131, the press forming analysis unit 132, the springback analysis unit 133, the natural vibration analysis unit 134, the mode decomposition unit 135, the mode selection unit 136, and the bead arrangement unit 137 to an external device, the communication unit 11 functions as an output unit.

[0073] The operation unit 14 may be any device capable of operating the analysis device 1, such as a keyboard or a touch panel. A user can input instructions such as selection using this device. When operated by a user, the operation unit 14 generates a signal corresponding to the operation. The generated signal is then input to the processing unit 13 as an instruction from the user.

[0074] The display unit 15 may be any device capable of displaying a video, an image, etc., such as a liquid crystal display, an organic EL (Electro-Luminescence) display, etc. The display unit 15 displays a video, an image, etc. according to the drawing data supplied from the processing unit 13.

[0075] As described above, in this embodiment, it is possible to easily select a natural vibration mode corresponding to a physical quantity (stress (maximum principal stress, minimum principal stress), strain (maximum principal strain, minimum principal strain), strain energy density, various invariants, etc.) that is not dependent on the posture (coordinate system) of the component caused by springback, and to easily perform analysis to reduce the deformation of the component caused by springback.

[0076] In this embodiment, the physical quantity of a component in the springback analysis is one of stress (maximum principal stress, minimum principal stress), strain (maximum principal strain, minimum principal strain), strain energy density, various invariants, etc., but any two or all three of these may be used. By using multiple physical quantities, it is possible to more accurately select the natural vibration modes corresponding to these physical quantities and reliably reduce the deformation of the component caused by springback. In addition, the shape of the component (selecting the natural vibration deformation mode corresponding to the shape after springback) may be added to these physical quantities.

[0077] The present invention is not limited to this embodiment. For example, in this embodiment, the analysis device 1 has each unit shown in FIG. 3, but some of them may be included in a server device (not shown). The server device may have, for example, a storage unit corresponding to the storage unit 12 of the analysis device 1, and provide the analysis device 1 with the program, data, etc. stored in the storage unit, and cause the analysis device 1 to execute the analysis process. In this case, the processing unit 13 of the analysis device 1 acquires the program, data, etc. from the server device via the communication unit 11. On the other hand, when the program, data, etc. are stored in the storage unit 12 of the analysis device 1, the processing unit 13 acquires the program, data, etc. from the storage unit 12.

[0078] In addition, the server device may have a memory unit and a processing unit equivalent to the memory unit 12 and processing unit 13 of the analysis device 1, and perform analysis processing using programs, data, etc. stored in the memory unit, and provide only the results to the analysis device 1.

[0079] That is, the above-described embodiment can be realized by a computer executing a program. The functions of the components of the analysis device according to the embodiment (each unit 131-139 of the processing unit 13 in FIG. 3, etc.) can be realized by the operation of a program stored in a RAM (Random Access Memory), ROM, etc. of the computer. Similarly, each step of the analysis method according to the embodiment (steps S101-S111 of FIG. 1, etc.) can be realized by the operation of a program stored in a RAM, ROM, etc. of the computer. The functions may be realized by loading into a memory and executing a program for realizing the functions of each component of the analysis device according to the embodiment (each unit 131-139 of the processing unit 13 in FIG. 3, etc.) and each step of the analysis method according to the embodiment (steps S101-S111 of FIG. 1, etc.).

[0080] The memory unit 12 of the analysis device 1 shown in FIG. 3 may be composed of a hard disk device, a magneto-optical disk device, a non-volatile memory such as a flash memory, a read-only storage medium such as a CD-ROM, a volatile memory such as a RAM, or a combination of these.

[0081] In addition, a program for implementing the functions of each component of the analysis device according to this embodiment (such as each unit 131-139 of the processing unit 13 in FIG. 3) may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed to execute the processing of each component. Note that the term "computer system" here includes hardware such as an OS and peripheral devices.

[0082] Furthermore, if a WWW system is used, the "computer system" may also include the homepage providing environment (or display environment). In addition, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into computer systems. Furthermore, the term "computer-readable recording medium" may also include devices that dynamically hold a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, and devices that hold a program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or client in such cases. Furthermore, the above-mentioned program may be one that realizes part of the above-mentioned functions, or may be one that can realize the above-mentioned functions in combination with a program already recorded in the computer system.

[0083] As a specific example, the analysis device shown in this embodiment has a computer function 100 as shown in FIG. 5, and the operations in this embodiment are carried out by a CPU 101 thereof. 5, the computer function 100 includes a CPU 101, a ROM 102, and a RAM 103. It also includes a controller (CONSC) 105 for an operation unit (CONS) 109, and a display controller (DISPC) 106 for a display (DISP) 110 serving as a display unit such as a CRT or LCD. It also includes a controller (DCONT) 107 for a hard disk (HD) 111 and a storage device (STD) 112 such as a flexible disk, and a network interface card (NIC) 108. These functional units 101, 102, 103, 105, 106, 107, and 108 are connected to each other via a system bus 104 so as to be able to communicate with each other.

[0084] The CPU 101 executes software stored in the ROM 102 or the HD 111, or software supplied from the STD 112, thereby generally controlling each component connected to the system bus 104. That is, the CPU 101 performs control to realize the operation in this embodiment by reading out a processing program (analysis program) for performing the above-mentioned operation from the ROM 102, the HD 111, or the STD 112 and executing it. The RAM 103 functions as the main memory, work area, etc. of the CPU 101.

[0085] CONSC 105 controls instruction input from CONS 109. DISPC 105 controls the display of DISP 110. DCONT 107 controls access to HD 111 and STD 112 which store the boot program, various applications, user files, network management program, and the above-mentioned processing programs in this embodiment. NIC 108 exchanges data bidirectionally with other devices on network 113. Instead of using a personal user terminal device, a specific computer or the like specialized for the analysis device of this embodiment may be used. [Industrial Applicability]

[0086] The present invention can be used, for example, in molding components that are applied to automobile bodies and the like. [Explanation of symbols]

[0087] 11 Communications Department 12 Storage section 13 Processing section 14 Control section 15 Display section

Claims

1. a press molding analysis unit that acquires finite element model data indicating a shape of a member, material property data indicating a material property of the member, and stress distribution data indicating a stress distribution generated in the member; a springback analysis unit that generates a first distribution vector indicating a distribution of the physical quantity of the member caused by springback by determining a physical quantity that is independent of a coordinate system and includes at least one of stress and strain at a plurality of evaluation points of the finite element model data based on the finite element model data, the material property data, and the stress distribution data; a natural vibration analysis unit that generates a second distribution vector indicating a distribution of the physical quantity of the component in each natural vibration mode by determining the physical quantity at a plurality of evaluation points of the finite element model data for each natural vibration mode based on the finite element model data and the material property data; a mode decomposition unit that calculates an inner product of the first distribution vector and each of the second distribution vectors in the natural vibration modes to obtain a degree of coincidence; a mode selection unit that selects one or more natural vibration modes based on the degree of coincidence; An analysis device comprising:

2. 2. The analysis device according to claim 1, wherein the physical quantity is at least one of stress, strain, and strain energy density.

3. The physical quantity is expressed by the following invariant J 1 , J 2 , J 3 , I 1 , I 2 , I 3 2. The analysis device according to claim 1, wherein the analysis device is at least one of the following: σ denotes stress, ε denotes strain, δ denotes Kronecker delta, and det denotes a determinant. [0010]

4. A press molding analysis process in which a computer system acquires finite element model data indicating a shape of a member, material property data indicating a material property of the member, and stress distribution data indicating a stress distribution occurring in the member; A springback analysis process in which a computer system determines a physical quantity that is independent of a coordinate system and includes at least one of stress and strain at a plurality of evaluation points of the finite element model data based on the finite element model data, the material property data, and the stress distribution data, thereby generating a first distribution vector that indicates a distribution of the physical quantity of the member caused by springback; a natural vibration analysis process in which a computer system calculates the physical quantities at a plurality of evaluation points of the finite element model data for each natural vibration mode based on the finite element model data and the material property data, thereby generating a second distribution vector indicating a distribution of the physical quantities of the component in each natural vibration mode; a mode decomposition process in which the computer system calculates an inner product of the first distribution vector and each of the second distribution vectors in the natural vibration modes to obtain a degree of coincidence; a mode selection step of the computer system selecting one or more natural vibration modes based on the degree of agreement; An analysis method comprising at least the steps of:

5. 5. The analysis method according to claim 4, wherein the physical quantity is at least one of stress, strain, and strain energy density.

6. The physical quantity is expressed by the following invariant J 1 , J 2 , J 3 , I 1 , I 2 , I 3 5. The analysis method according to claim 4, wherein the analysis is performed in accordance with at least one of the following: σ denotes stress, ε denotes strain, δ denotes Kronecker delta, and det denotes a determinant. [0010]

7. A press molding analysis process for acquiring finite element model data indicating a shape of a member, material property data indicating a material property of the member, and stress distribution data indicating a stress distribution generated in the member; a springback analysis process for generating a first distribution vector indicating a distribution of the physical quantity of the member caused by springback by determining a physical quantity independent of a coordinate system including at least one of stress and strain at a plurality of evaluation points of the finite element model data based on the finite element model data, the material property data, and the stress distribution data; a natural vibration analysis process for generating a second distribution vector indicating a distribution of the physical quantity of the component in each natural vibration mode by determining the physical quantity at a plurality of evaluation points of the finite element model data for each natural vibration mode based on the finite element model data and the material property data; a mode decomposition process of calculating an inner product of the first distribution vector and each of the second distribution vectors in the natural vibration modes to obtain a degree of coincidence; a mode selection step of selecting one or more natural vibration modes based on the degree of agreement; A computer program characterized by causing a computer to execute the above.

8. 8. The computer program of claim 7, wherein the physical quantity is at least one of a stress, a strain, and a strain energy density.

9. The physical quantity is expressed by the following invariant J 1 , J 2 , J 3 , I 1 , I 2 , I 3 8. The computer program product according to claim 7, characterized in that the computer program product is at least one of the following: σ denotes stress, ε denotes strain, δ denotes Kronecker delta, and det denotes a determinant. [0010]

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