Analysis method and analysis apparatus

Abstract

Even with fiber sheets where fiber layers are linked together, the behavior of the fiber sheet can be analyzed with high accuracy. [Solution] An analysis method in which a finite element analysis is performed by an analysis device using an analysis model that simulates a laminated body, wherein a plurality of fiber sheets are stacked, each having at least two fiber layers connected by stitching, the analysis model includes a mesoscale analysis model which is a detailed analysis model of the fiber sheet and a spatial shell element, the mesoscale analysis model has fiber layer elements which simulate two adjacent fiber layers and stitch elements which simulate the stitching, and the spatial shell element is provided on each of the fiber layer elements and serves as an element that fixes the fiber layer element and the stitch element.

Description

Technical Field

[0001] The present disclosure relates to an analysis method and an analysis apparatus.

Background Art

[0002] Conventionally, a multiscale analysis method for prepreg that predicts the shaping of prepreg by simulation is known (see, for example, Patent Document 1). This analysis method uses a macroscale model of the prepreg and a mesoscale model including resin elements and reinforcing fiber bundle elements of the prepreg. In this analysis method, analysis is performed by applying displacement boundaries to the mesoscale model based on displacement information of each element in the macroscale model obtained by executing global analysis using the macroscale model.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, examples of the analysis target include multi-axial non-crimp fabric (NCF). NCF is a fiber sheet in which a plurality of fiber layers, each formed by arranging a plurality of fiber bundles aligned in one direction in the width direction, are laminated with different orientation directions, and the laminated fiber layers are stitched together. When a fiber sheet in which fiber layers are connected by stitches such as the above stitches is set as the analysis target, for example, with a homogenized macroscale model as in Patent Document 1, it is difficult to accurately analyze the behavior of the fiber sheet. In addition, the mesoscale model as in Patent Document 1 cannot reproduce the above-described NCF structure, and thus similarly makes it difficult to accurately analyze the behavior of the fiber sheet.

[0005] Therefore, the object of this disclosure is to provide an analysis method and an analysis apparatus that can accurately analyze the behavior of a fiber sheet, even if the fiber layers are linked together. [Means for solving the problem]

[0006] The analysis method of this disclosure is an analysis method in which a multiplier of fiber sheets, each having at least two fiber layers connected by stitching, is stacked, and an analysis device performs finite element analysis using an analysis model that simulates the stacked laminate, wherein the analysis model includes a mesoscale analysis model which is a detailed analysis model of the fiber sheet, and a spatial shell element, the mesoscale analysis model having fiber layer elements that simulate two adjacent fiber layers and stitch elements that simulate the stitching, and the spatial shell element is provided on each of the fiber layer elements and serves as an element that fixes the fiber layer element and the stitch element.

[0007] The analytical apparatus of the present disclosure comprises a control unit that performs finite element analysis using an analytical model that simulates a laminated body, wherein a plurality of fiber sheets, each having at least two fiber layers connected by stitching, are stacked, the analytical model includes a mesoscale analytical model which is a detailed analytical model of the fiber sheet, and a spatial shell element, the mesoscale analytical model having fiber layer elements that simulate two adjacent fiber layers and stitch elements that simulate the stitching, and the spatial shell element is provided on each of the fiber layer elements and serves as an element that fixes the fiber layer element and the stitch element. [Effects of the Invention]

[0008] According to this disclosure, even in the case of a fiber sheet in which fiber layers are linked together, the behavior of the fiber sheet can be analyzed with high accuracy. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic example of a fiber sheet. [Figure 2] Figure 2 is a diagram relating to the analysis apparatus according to this embodiment. [Figure 3] Figure 3 shows a diagram relating to the mesoscale analysis model. [Figure 4] Figure 4 shows the main components of the mesoscale analysis model. [Figure 5] Figure 5 is an example of a mesoscale analysis model. [Figure 6] Figure 6 is an example of a mesoscale analysis model. [Figure 7] Figure 7 is a flowchart of the analysis method according to this embodiment. [Modes for carrying out the invention]

[0010] Embodiments relating to this disclosure will be described in detail below with reference to the drawings. However, the present invention is not limited by these embodiments. Furthermore, some of the components in the embodiments described below are substituted or substantially identical to those easily substituted by those skilled in the art. Moreover, the components described below can be combined as appropriate, and if there are multiple embodiments, each embodiment can be combined.

[0011] [This Circumstance] The analysis method and analysis apparatus 10 according to this embodiment are for analyzing the behavior of a laminate formed by stacking fiber sheets S. Specifically, the analysis method and analysis apparatus 10 predict the occurrence of wrinkles in the laminate during the shaping process.

[0012] (Fiber sheet) Figure 1 is a schematic diagram of a fiber sheet. As shown in Figure 1, the fiber sheet S is made up of at least two fiber layers 21 connected by stitches 24. The fiber sheet S is, for example, a multiaxial non-crimp fabric (NCF). The NCF is a fiber sheet S made by stacking multiple fiber layers 21, each consisting of multiple fiber bundles 22 arranged in one direction and arranged in the width direction, with different orientations, and then stitching the stacked fiber layers 21 together with stitches 24. In this embodiment, the fiber sheet S to be analyzed is described using NCF, but it is not particularly limited to NCF, and may be, for example, a woven fabric formed by weaving fibers.

[0013] The fiber sheet S in Figure 1 has, for example, two stacked fiber layers 21 and stitches 24. Each fiber layer 21 contains a plurality of fiber bundles 22 extending in a predetermined orientation direction, which are arranged in a width direction perpendicular to the orientation direction. One of the two fiber layers 21 has an orientation direction of +45°, and the other has an orientation direction of -45°. The stitches 24 are seams formed by thread. The stitches 24 are made by passing thread between the fiber bundles 22 and also by passing thread through the two fiber layers 21. The fiber sheet S may have two or more layers. Also, the angle of the orientation direction is not limited to ±45°, but may be in the range up to ±90°. Furthermore, the stitches 24 may be chain stitches, tricot stitches, or a combination of both.

[0014] (Analysis device) Next, the analysis device 10 will be described with reference to Figure 2. Figure 2 is a diagram relating to the analysis device according to this embodiment. The analysis device 10 is a device for analyzing displacement, stress, etc., during the shaping of a laminate. The analysis device 10 comprises a control unit 15 and a storage unit 16.

[0015] The storage unit 16 stores programs and data. The storage unit 16 may also function as a work area for temporarily storing the processing results of the control unit 15. The storage unit 16 may include any storage device such as a semiconductor storage device and a magnetic storage device.

[0016] The storage unit 16 stores an analysis model M as data. The analysis model M is a model used for finite element analysis. Hereinafter, the analysis model M will be described with reference to FIGS. 3 to 6. FIG. 3 is a diagram related to a mesoscale analysis model. FIG. 4 is a diagram related to a main part of the mesoscale analysis model. FIGS. 5 and 6 are diagrams of examples related to the mesoscale analysis model.

[0017] The analysis model M includes a macroscale analysis model, a mesoscale analysis model M1, and spatial shell elements 33. The macroscale analysis model is an analysis model obtained by homogenizing the fiber sheet S. As shown in FIG. 3, the mesoscale analysis model M1 is a detailed analysis model of the fiber sheet S.

[0018] As shown in FIGS. 3 and 4, the mesoscale analysis model M1 includes fiber layer elements 31 that simulate the fiber layers 21, and stitch elements 32 that simulate the stitches 24. The fiber layer elements 31 include bundle elements 35 that simulate the fiber bundles 22, and the bundle elements 35 are arranged side by side in the width direction. A space that simulates a gap is provided between the bundle elements 35 adjacent in the width direction. Further, the fiber layer elements 31 are stacked in the thickness direction to simulate two fiber layers 21. Of the two fiber layer elements 31, one is the fiber layer element 31 with an orientation direction of +45°, and the other is the fiber layer element 31 with an orientation direction of -45°. A space that simulates a gap is provided between the fiber layer elements 31 adjacent in the thickness direction. Since the fiber layer elements 31 simulate the fiber sheet S, the fiber layer elements 31 may be a multilayer of two or more layers. Further, the angle of the orientation direction is not limited to ±45°, and may be any value within a range up to ±90°.

[0019] The spatial shell element 33 serves as an element that fixes the fiber layer element 31 and the stitch element 32. The spatial shell element 33 is provided on each of the fiber layer elements 31. The spatial shell element 33 is arranged in the gap between the bundle elements 35 where the stitch element 32 is provided. The spatial shell element 33 is defined as a dummy element having no rigidity. Therefore, the spatial shell element 33 becomes an element that does not contribute to the displacement of the fiber sheet S. In addition, the spatial shell element 33 shares the nodes included in the bundle element 35.

[0020] The stitch element 32 is provided at a position corresponding to the stitch 24, and is a bar element. In addition, the stitch element 32 is connected to the center of the spatial shell element 33 at the position where the stitch 24 penetrates the two fiber layers 21 (the position where the spatial shell element 33 is provided). Therefore, the stitch element 32 stays at the intermediate position of the gap between the adjacent bundle elements 35.

[0021] Further, as shown in FIG. 5 and FIG. 6, the fiber layer element 31 has different elements defined depending on the orientation direction of the fiber bundle 22. As shown in FIG. 5, in the fiber layer element 31, the material physical properties in the orientation direction are defined by the shell element 31a. On the other hand, in the fiber layer element 31, the material physical properties in the width direction (orthogonal direction) orthogonal to the orientation direction are defined by the solid element 31b.

[0022] Further, as shown in FIG. 6, the fiber layer element 31 defined by the shell element 31a includes a first shell element 31a1 related to the tensile component and a second shell element 31a2 related to the bending component. The first shell element 31a1 is a shell element that does not consider the bending component but considers the tensile component by setting the number of integration points in the thickness direction to one. The second shell element 31a2 is a shell element that considers the bending component by setting the number of integration points in the thickness direction to three.

[0023] The control unit 15 executes programs and exchanges data with the storage unit 16. The control unit 15 includes an integrated circuit such as a CPU (Central Processing Unit). Specifically, the control unit 15 analyzes the behavior of the stacked structure using the analysis model M stored in the storage unit 16.

[0024] (Analysis method) Next, with reference to Figure 7, an analysis method in which the analysis is performed using the analysis device 10 described above with respect to the analysis model M will be explained. Figure 7 is a flowchart of the analysis method according to this embodiment.

[0025] As shown in Figure 7, first, in the analysis method, the control unit 15 of the analysis device 10 creates an analysis model M of the laminate including the fiber sheet S to be analyzed (step S1). In step S1, the analysis model M creates a macro-scale analysis model of the fiber sheet S, a meso-scale analysis model M1 of the fiber sheet S, and a spatial shell element 33.

[0026] Next, the control unit 15 performs a finite element analysis using the created mesoscale analysis model M1 and spatial shell elements 33 (step S2). When performing step S2, the control unit 15 obtains the test results of a previously performed material property test (step S11). The material property test is the behavior of the fiber sheet S as it changes with the stress applied to it. The control unit 15 performs a finite element analysis using the mesoscale analysis model M1 and spatial shell elements 33 to reproduce the test results of the material property test. Then, the control unit 15 derives and obtains the material property values ​​of the fiber sheet S as the analysis result (step S3).

[0027] Next, the control unit 15 performs finite element analysis using the analysis model M based on the acquired material properties of the fiber sheet S (step S4). In step S4, the behavior of the fiber sheet S when it is shaped into a predetermined evaluation shape is analyzed. The predetermined evaluation shape is, for example, a hemispherical shape, which is a shape for evaluating material properties.

[0028] Then, based on the analysis results of step S4, the control unit 15 evaluates whether the material properties of the fiber sheet S are appropriate (step S5). When step S5 is performed, the control unit 15 obtains the test results of a previously performed evaluation test (step S12). The evaluation test is the behavior of the fiber sheet S when it is shaped into the evaluation shape. In step S5, the control unit 15 compares the analysis results of step S4 with the test results of the evaluation test, and if the displacement of the fiber sheet S is within a predetermined threshold for determining appropriateness, it evaluates that it is appropriate (step S5: Yes). On the other hand, in step S5, the control unit 15 compares the analysis results of step S4 with the test results of the evaluation test, and if the displacement of the fiber sheet S exceeds a predetermined threshold for determining appropriateness, it evaluates that it is not appropriate (step S5: No), and proceeds back to step S2, repeating steps S2 to S5 until it is determined that it is appropriate.

[0029] The control unit 15 performs finite element analysis using the analysis model M of the laminate to be analyzed, based on appropriate material properties that have been evaluated as valid (step S6). By performing step S6, the control unit 15 predicts and obtains the behavior of the laminate during shaping and terminates the processing related to the analysis method. Then, by designing the laminate based on the analysis results, it becomes possible to perform appropriate shaping that suppresses the occurrence of wrinkles and the like.

[0030] Furthermore, if appropriate material properties are known, the analysis method may involve performing step S1 to create an analysis model M, and then performing step S6 to perform finite element analysis on the object of analysis using the generated analysis model M.

[0031] As described above, the analysis method and analysis apparatus described in this embodiment can be understood, for example, as follows.

[0032] The analysis method according to the first embodiment is an analysis method in which a plurality of fiber sheets S, each having at least two fiber layers 21 connected by stitches 24, are stacked, and an analysis device 10 performs finite element analysis using an analysis model M that simulates the stacked laminate, wherein the analysis model M includes a mesoscale analysis model M1 which is a detailed analysis model of the fiber sheet S, and a spatial shell element 33, the mesoscale analysis model M1 has fiber layer elements 31 that simulate two adjacent fiber layers and stitch elements 32 that simulate the stitches, and the spatial shell element 33 is provided on each of the fiber layer elements 31 and serves as an element that fixes the fiber layer elements 31 and the stitch elements 32.

[0033] With this configuration, the fiber sheet S, in which the fiber layers 21 are linked, can be suitably reproduced using the mesoscale analysis model M1, thereby enabling accurate analysis of the behavior of the fiber sheet S.

[0034] In a second embodiment, in the analysis method according to the first embodiment, the fiber sheet S is a multiaxial non-crimp fabric (NCF) in which the fiber layer 21 is a layer in which fiber bundles 22 with their orientation direction aligned in one direction are arranged in the width direction, and the stitch is a stitch 24 that sews together at least two layers of the fiber layer 21.

[0035] This configuration allows for accurate analysis of NCF behavior.

[0036] In a third embodiment, in the analysis method according to the first or second embodiment, the analysis device 10 performs the following steps: step S2, which involves performing finite element analysis using the mesoscale analysis model M1 and the spatial shell elements 33 to reproduce the displacement of the fiber sheet S due to stress previously obtained by material property testing, thereby deriving material property values ​​of the fiber sheet S; step S4, which involves performing finite element analysis using the analysis model M based on the derived material property values ​​of the fiber sheet S so that it becomes an evaluation shape for evaluating the material property values; and step S6, which involves performing finite element analysis using the analysis model M of the laminate to be analyzed based on the material property values ​​that are deemed appropriate by comparing the evaluation shape of the fiber sheet previously formed by evaluation testing with the evaluation shape of the fiber sheet obtained by the finite element analysis.

[0037] This configuration allows for analysis of laminates based on appropriate material properties, thereby improving the accuracy of the analysis.

[0038] In a fourth aspect, in the analysis method relating to any one of the first to third aspects, the mesoscale analysis model M1 defines the material properties in the orientation direction of the fiber layer element 31 using the shell element 31a, and defines the material properties in the orthogonal direction perpendicular to the orientation direction of the fiber layer element 31 using the solid element 31b.

[0039] This configuration allows for a mesoscale analysis model M1 that takes into account the anisotropy of the fiber layer 21, thus enabling a favorable reproduction of the fiber sheet S's behavior in the analysis.

[0040] In a fifth aspect, in the analysis method according to the fourth aspect, the fiber layer element 31 defined by the shell element 31a includes a first shell element 31a1 relating to the tensile component and a second shell element 31a2 relating to the bending component.

[0041] This configuration allows for the appropriate reproduction of the behavior of the fiber sheet S in the tensile component and the behavior of the fiber sheet S in the bending component during analysis.

[0042] The analysis apparatus 10 according to the sixth embodiment comprises a control unit 15 that performs finite element analysis using an analysis model M that simulates a laminated body, wherein a plurality of fiber sheets S, each having at least two fiber layers 21 connected by stitching, are laminated, the analysis model M includes a mesoscale analysis model M1 which is a detailed analysis model of the fiber sheet S, and a spatial shell element 33, the mesoscale analysis model M1 has fiber layer elements 31 that simulate two adjacent fiber layers and stitch elements 32 that simulate the stitching, and the spatial shell element 33 is provided on each of the fiber layer elements 31 and serves as an element that fixes the fiber layer elements 31 and the stitch elements 32.

[0043] With this configuration, the fiber sheet S, in which the fiber layers 21 are linked, can be suitably reproduced using the mesoscale analysis model M1, thereby enabling accurate analysis of the behavior of the fiber sheet S. [Explanation of symbols]

[0044] 10 Analysis device 15 Control Unit 16 Memory section 21 Fiber layer 22 Fiber bundles 24 Stitch 31 Fiber layer elements 32 stitching elements 33 Spatial Shell Elements 35 bundle elements S Fiber Sheet M-analysis model M1 Mesoscale Analysis Model

Claims

1. An analytical method in which a finite element analysis is performed by an analytical device using an analytical model that simulates a laminated body, wherein multiple fiber sheets are stacked, each consisting of at least two fiber layers connected by stitching, and the analytical device performs finite element analysis. The aforementioned analysis model is, The aforementioned fiber sheet includes a mesoscale analysis model, which is a detailed analysis model of the fiber sheet, and a spatial shell element. The aforementioned mesoscale analysis model is, A fiber layer element that simulates two adjacent fiber layers, It has a stitch element that simulates the aforementioned stitch, The analysis method wherein the spatial shell element is provided on each of the fiber layer elements and serves as an element that fixes the fiber layer element and the stitch element.

2. The aforementioned fiber sheet is The aforementioned fiber layer is a layer in which fiber bundles, whose orientation direction is aligned in one direction, are arranged in the width direction. The analysis method according to claim 1, wherein the stitch is a stitch that sews together at least two layers of fiber, and the fabric is a multiaxial non-crimp fabric (NCF).

3. The aforementioned analysis device, The steps include: deriving material properties of the fiber sheet by performing finite element analysis using the mesoscale analysis model and the spatial shell elements to reproduce the displacement of the fiber sheet due to stress previously obtained by material property testing; The steps include: performing finite element analysis using the analysis model based on the derived material properties of the fiber sheet so that it becomes an evaluation shape for evaluating the material properties; The analysis method according to claim 1, which includes the step of performing a finite element analysis using the analysis model of the laminate to be analyzed, based on the material properties that are deemed appropriate by comparing the evaluation shape of the fiber sheet that has been preformed by evaluation testing with the evaluation shape of the fiber sheet obtained by finite element analysis.

4. The aforementioned mesoscale analysis model is, The material properties of the fiber layer element in the orientation direction are defined by the shell element, The analysis method according to claim 1, wherein the material properties in a direction perpendicular to the orientation direction of the fiber layer elements are defined by solid elements.

5. The analysis method according to claim 4, wherein the fiber layer element defined by the shell element includes a first shell element relating to the tensile component and a second shell element relating to the bending component.

6. An analysis apparatus comprising a control unit that performs finite element analysis using an analysis model that simulates a laminated body, wherein multiple fiber sheets are stacked, each consisting of at least two fiber layers connected by stitching, are stacked, The analysis model includes a mesoscale analysis model, which is a detailed analysis model of the fiber sheet, and a spatial shell element. The aforementioned mesoscale analysis model is, A fiber layer element that simulates two adjacent fiber layers, It has a stitch element that simulates the aforementioned stitch, The spatial shell element is provided on each of the fiber layer elements and serves as an element for fixing the fiber layer element and the stitch element in the analysis device.

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