Method for predicting multi-scale elastic property of 2.5 D woven porous composite material

Abstract

The invention discloses a method for predicting the multi-scale elastic property of a 2.5 D woven porous composite material. The method comprises the following steps: (1) establishing a carbon fiber tow micro-scale RVE model and a 2.5 D woven composite material micro-scale RVE model; (2) adding pore defects in the micro-scale RVE model and the meso-scale RVE model; (3) respectively inputting real material parameters into the micro-scale RVE model and the meso-scale RVE model; and (4) finite element analysis and verification. The method for predicting the elastic property of the 2.5 D woven composite material is established, the influence of pore defects on the mechanical properties of the carbon fiber tows and the 2.5 D woven fabric is explored in detail, and the calculation efficiency and prediction precision of the elastic property of the 2.5 D woven composite material are improved.

Description

Technical Field

[0001] The present invention relates to the field of predicting the mechanical properties of three-dimensional woven composites, and particularly to a method for predicting the elastic properties of three-dimensional woven composites. Background Art

[0002] Due to their excellent mechanical properties, high-temperature resistance, and impact resistance, 2.5D woven composites have been widely used in the fields of aerospace, automotive, etc. However, due to the inevitable generation of pores during the manufacturing process, the actual mechanical properties of the materials are often lower than the theoretical design values. Existing technologies for predicting the properties of porous composites mostly use empirical formulas or single-scale analysis methods, and fail to fully consider the distribution characteristics of multi-scale pores in the woven structure, resulting in a large deviation between the prediction results and the actual properties. Therefore, there is an urgent need for a prediction method that can accurately simulate the elastic properties of 2.5D woven composites in a multi-scale range. Summary of the Invention

[0003] In view of the above problems, the present invention provides a method for predicting the multi-scale elastic properties of 2.5D woven porous composites, which solves the problem of low prediction accuracy of traditional prediction methods under factors such as multi-scale pores in composites.

[0004] In order to achieve the above object, the technical solutions that the present invention can adopt are as follows:

[0005] A method for predicting the multi-scale elastic properties of 2.5D woven porous composites includes the following steps:

[0006] (1) Establish a microscopic-scale RVE model of carbon fiber tows and a mesoscopic-scale RVE model of 2.5D woven composites; wherein, the microscopic-scale RVE model of carbon fiber tows is a cuboid containing a fiber cross-section, and the fiber cross-section is circular; the mesoscopic-scale RVE model of 2.5D woven composites contains interwoven warp yarns and weft yarns, the cross-sectional shape of the warp yarns is rectangular, and the cross-sectional shape of the weft yarns is elliptical; both the warp yarns and the weft yarns are composed of carbon fiber tows;

[0007] (2) Add pore defects to the microscopic-scale RVE model of carbon fiber tows and the mesoscopic-scale RVE model of 2.5D woven composites by deleting grid cells;

[0008] (3) Input the material parameters of real carbon fiber tows into the microscopic-scale RVE model of carbon fiber tows and the mesoscopic-scale RVE model of 2.5D woven composites;

[0009] (4) For the microscopic-scale RVE model of carbon fiber tows, use the improved Halpin-Tsai semi-empirical formula to predict the elastic property constants of carbon fiber tows, including the tensile modulus of carbon fiber tows, the shear modulus of carbon fiber tows, and the Poisson's ratio of carbon fiber tows;

[0010] (5) Import the data of the tensile modulus, shear modulus, and Poisson's ratio of the obtained carbon fiber tow into the mesoscale RVE model of the 2.5D woven composite material to obtain the final mesoscale RVE model of the 2.5D woven composite material.

[0011] Furthermore, in step (2), the mesoscale RVE model of the carbon fiber tow and the mesoscale RVE model of the 2.5D woven composite material are meshed through finite element analysis software to form a number of grid cells, and then the grid cells are randomly selected and deleted. The positions of the deleted grid cells are used as the pore defects of the model; in each model, the ratio of the number of randomly selected grid cells to the total number of grid cells in the model is the simulated porosity.

[0012] Furthermore, in step (2), the grid cells of the mesoscale RVE model of the carbon fiber tow are pentahedral wedge-shaped cells; the grid cells of the mesoscale RVE model of the 2.5D woven composite material are hexahedral cells.

[0013] Furthermore, the simulated porosity of the mesoscale RVE model of the carbon fiber tow is selected to be consistent with the porosity of the real carbon fiber tow, and the simulated porosity of the mesoscale RVE model of the 2.5D woven composite material is selected to be consistent with the porosity of the real 2.5D woven composite material.

[0014] Furthermore, in step (3), the material parameters of the real carbon fiber tow include the elastic modulus E f1 in the 1 direction of the real carbon fiber, the elastic modulus E f2 in the 2 direction, the shear modulus G f12 in the 12 direction, the shear modulus G f23 in the 23 direction, the Poisson's ratio υ f12 in the 12 direction, the Poisson's ratio υ f23 in the 23 direction, and the elastic modulus E m of the matrix wrapping the carbon fiber tow, the shear modulus G m , and the Poisson's ratio υ m ; where the 1 direction is the axial direction of the carbon fiber tow, and the 2 direction and the 3 direction are the other two directions perpendicular to the 1 direction that form a three-dimensional coordinate.

[0015] Furthermore, in step (4), for the mesoscale RVE model of the carbon fiber tow, the total volume is set as V M , the volume of the pore defect is set as V v , and the volume fraction V Mv of the pore is:

[0016]

[0017] Furthermore, for the microscale RVE model of carbon fiber tows, the elastic modulus E1 in the 1-direction of the carbon fiber tow, the elastic modulus E2 in the 2-direction, and the Poisson's ratio υ in the 12-direction 12 , the Poisson's ratio υ in the 13-direction 13 :

[0018] E1 = V f E f1 +(1 - V f )E m (1 - V Mv ) 2

[0019] υ 12 = υ 13 = V f υ f12 +(1 - V f )υ m

[0020]

[0021] ξ represents the curve fitting parameter, E m , υ m represent the true matrix elastic modulus and Poisson's ratio respectively, E f1 , υ f12 represent the true elastic modulus in the 1-direction of the carbon fiber and the Poisson's ratio in the 12-direction respectively, E f2 represents the true elastic modulus in the 2-direction of the carbon fiber, V f represents the fiber volume fraction of the true carbon fiber yarn tow.

[0022] Furthermore, for the microscale RVE model of carbon fiber tows:

[0023] The mathematical expressions for the shear modulus G 12 in the 12-direction of the carbon fiber tow, the shear modulus G 13 in the 13-direction of the carbon fiber tow, and the shear modulus G 23 in the 23-direction of the carbon fiber tow:

[0024]

[0025] G f12 represents the true shear modulus in the 12-direction of the carbon fiber; G f23 represents the true shear modulus in the 23-direction of the carbon fiber;

[0026] According to the empirical formula, the mathematical expression for the Poisson's ratio υ 23 in the 23-direction of the carbon fiber tow:

[0027]

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: The multi-scale elastic property prediction method for the 2.5D woven porous composite material takes into account the influence of pores on the elastic properties of the composite material and solves the problem of predicting the elastic properties of the 2.5D woven porous composite material.

[0029] The design method provided by the present invention can be stored on a storage medium as a computer program, including the following technical solutions:

[0030] An electronic device includes: one or more processors; and a storage device for storing one or more programs, which, when executed by the one or more processors, cause the one or more processors to implement the above prediction method.

[0031] And:

[0032] A computer-readable medium has a computer program stored thereon, and when the program is executed by a processor, the above prediction method is implemented. Description of the Drawings

[0033] Figure 1 It is a microscopic scale RVE model diagram of the fiber bundle in the present invention;

[0034] Figure 2 It is a mesoscopic scale RVE model diagram of the 2.5D woven composite material in the present invention; Figure 2 In (a) is the overall view of the mesoscopic scale RVE model diagram of the 2.5D woven composite material, (b) is the cross-section of the weft yarn, and (c) is the cross-section of the warp yarn;

[0035] Figure 3 It is an analysis diagram of the fiber bundle of the real 2.5D woven composite material, Figure 3 In (a) is the cross-section of the warp yarn and (b) is the cross-section of the weft yarn;

[0036] Figure 4 It is the finite element analysis of the microscopic scale RVE model diagram of the fiber bundle in the present invention;

[0037] Figure 5 It is the finite element analysis of the mesoscopic scale RVE model diagram of the 2.5D woven composite material in the present invention;

[0038] Figure 6 It is the flowchart of the multi-scale elastic property prediction method for the 2.5D woven porous composite material in the present invention. Detailed Embodiments

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] As Figure 6 shown, the embodiment of the present invention provides a prediction scheme for the multi-scale elastic properties of 2.5D woven porous composites, including the following steps:

[0041] S1. Establish a multi-scale unit cell model, including a microscopic-scale RVE model of carbon fiber tows (as Figure 1 shown) and a mesoscopic-scale RVE model of 2.5D woven composites (as Figure 2 shown).

[0042] Among them, the carbon fiber tow is composed of thousands of randomly distributed carbon fibers. In order to more conveniently study and simulate the properties of this composite material, the present invention adopts a simplified microscopic-scale RVE model of carbon fiber tows, that is, a rectangular representative volume element (RVE) at the microscopic scale is set, and the fiber cross-section is circular. Figure 1 The parameters of the microscopic-scale RVE model of the carbon fiber tow in

[0043] are shown in Table 1.

[0044]

[0045] When constructing the mesoscopic-scale RVE model of 2.5D woven composites, the present invention makes the following settings:

[0046] (1) The cross-section shape of the warp yarn is rectangular, the cross-section shape of the weft yarn is elliptical, and the cross-section shape of the yarn remains unchanged during the weaving process.

[0047] (2) During the weaving process, it is assumed that the structure of the 2.5D woven composite is stable and uniform.

[0048] (3) In the study of the influence of pore defects on the mechanical properties of 2.5D woven composites, it is assumed that the matrix pores inside the carbon fiber tow and between the carbon fiber bundles are randomly distributed.

[0049] Figure 2 The parameters of the microscopic-scale RVE model of the carbon fiber tow in

[0050] are shown in Table 2.

[0051]

[0052]

[0053] S2. Add pore defects to the above microscopic-scale RVE model of carbon fiber tows and the mesoscopic-scale RVE model of 2.5D woven composites: In the present invention, the microscopic-scale RVE model of carbon fiber tows and the mesoscopic-scale RVE model of 2.5D woven composites are meshed by HyperMesh software. Among them, the C3D6 pentahedral wedge elements are used for the microscopic-scale RVE model of carbon fiber tows, and the C3D8R hexahedral elements are used for the mesoscopic-scale RVE model of 2.5D woven composites. The microscopic-scale RVE model of carbon fiber tows contains 27,976 mesh elements and 15,960 nodes, while the mesoscopic-scale RVE model of 2.5D woven composites contains 73,140 mesh elements and 82,390 nodes. To meet the requirement of transverse isotropy, two local coordinate systems are defined for the two types of fiber tows. At the same time, when applying the periodic boundary conditions, it is necessary to ensure that the number and position distribution of the mesh nodes on the master and slave surfaces are exactly the same, which can be achieved by the surface mesh replication of HyperMesh software. Then, the mesh model is imported into ABAQUS software for subsequent operations. The specific method of adding pores to the above two types of models is as follows: First, complete the meshing of the model. Then, add the random module to the Python script, and randomly select and delete mesh elements in the matrix of the microscopic-scale RVE model of carbon fiber tows and the mesoscopic-scale RVE model of 2.5D woven composites through ABAQUS software. The positions of the deleted mesh elements are used as the pore defects of the model. Finally, to ensure the unity of simulation and experiment, the simulated porosity of the microscopic-scale RVE model of carbon fiber tows is selected to be the same as the porosity of the real carbon fiber tows, and the simulated porosity of the mesoscopic-scale RVE model of 2.5D woven composites is selected to be the same as the porosity of the real 2.5D woven composites. The porosity of the real carbon fiber tows and the porosity of the real 2.5D woven composites can be obtained by CT slicing of the real carbon fiber tows and 2.5D woven composites. As Figure 3 shown, it is the CT slice diagram of the fiber bundle of the real 2.5D woven composite. In this example, the Micro-CT device uses the nanoVoxel 3000 model. For the carbon fiber tow sample, the scanning voltage is 60 kV, the current is 30 μA, and the resolution is 0.53 μm. For the composite sample, the scanning voltage is 35 kV, the current is 180 mA, and the resolution is 4.5 μm. After the scanning is completed, the Avizo 2019.1 software is used to perform image processing and three-dimensional reconstruction on the CT slices to obtain Figure 3The image shown, and the porosity of the carbon fiber tow is calculated to be 2.5%, and the porosity of the composite material is 2.7%. The analysis of the cross-sections of the warp and weft fiber tows of the composite material uses statistical methods. From Figure 3 it can be seen that the cross-section of the warp fiber tow is rectangular, while the cross-section of the weft fiber tow is elliptical. The results show that: the length of the warp is 2.542 mm, the width of the warp is 0.306 mm, the warp spacing is 2.742 mm, the length of the weft is 2.998 mm, the width of the weft is 0.499 mm, and the weft spacing is 4.233 mm.

[0054] S3. Respectively input the real carbon fiber material parameters into the microscopic scale RVE model of the carbon fiber tow and the mesoscopic scale RVE model of the 2.5D woven composite material: regard the fiber as a transversely isotropic material (E f2 =E f3 , G f13 =G f23 , υ f13 =υ f23 ), regard the epoxy resin matrix as an isotropic material, where the real carbon fiber material parameters are the real carbon fiber tow material parameters including the elastic modulus E f1 in the 1 direction of the real carbon fiber, the elastic modulus E f2 in the 2 direction, the shear modulus G f12 in the 12 direction, the shear modulus G f23 in the 23 direction, the Poisson's ratio υ f12 in the 12 direction, the Poisson's ratio υ f23 in the 23 direction, and the elastic modulus E m of the epoxy resin matrix wrapping the carbon fiber tow, the shear modulus G m , and the Poisson's ratio υ m nine parameters; where the 1 direction is the axial direction of the carbon fiber tow, and the 2 direction and the 3 direction are the other two directions perpendicular to the 1 direction forming a three-dimensional coordinate. In this embodiment, the provided material engineering constants are shown in Table 3.

[0055] Table 3 Real material engineering constants

[0056]

[0057] S4. Finite element analysis and verification: Based on the periodic structural characteristics of the 2.5D woven composite material itself, the overall mechanical properties of the composite material can be predicted by studying the properties of its representative volume element, that is, a mesoscopic scale RVE model of the 2.5D woven composite material provided in this embodiment can characterize the average mechanical properties of the 2.5D woven composite material as a periodic unit. The mathematical expression of the average stress σ ij in the mesoscopic scale RVE model of the 2.5D woven composite material is as follows:

[0058]

[0059] where V is the volume of the RVE.

[0060] To obtain the equivalent elastic modulus of the material, the mesoscale RVE model of the 2.5D woven composite material is assumed to be an orthotropic elastic material. The equivalent elastic constitutive equation of the periodic RVE is as follows:

[0061]

[0062] where [S] is the equivalent compliance matrix, and are the average strain and average stress, is in Equation (1)

[0063] In the microscale analysis, the fiber axial direction is defined as the 1-direction, and the other two directions perpendicular to the fiber axial direction are respectively labeled as the 2-direction and the 3-direction, as shown in the 123 three-dimensional coordinate system in Figure 1

[0064] Next, by establishing an analysis model of the microscale RVE model of the carbon fiber tow, the improved Halpin-Tsai semi-empirical formula is used to predict the elastic property constants of the carbon fiber tow in the microscale RVE model of the carbon fiber tow. The Halpin-Tsai semi-empirical formula is improved considering the pore defects in the matrix of the carbon fiber tow.

[0065] In the actual production process of the composite material, the volume V v of the pore defects is much smaller than the volume of the matrix. The volume V M includes the matrix volume and the pore volume. Therefore, relative to the volume V M , the volume fraction V Mv of the pores is:

[0066]

[0067] Assume that the pores in the epoxy resin matrix have no actual effect on the Poisson's ratio of the epoxy resin matrix (the epoxy resin is the matrix that wraps the carbon fiber tow in the carbon fiber resin composite material), then there is the following mathematical expression:

[0068]

[0069] E m , υ m respectively represent the elastic modulus and Poisson's ratio of the epoxy resin matrix, E f1 , υ f12 respectively represent the elastic modulus in the 1-direction of the carbon fiber and the Poisson's ratio in the 12-direction, V f ​Represents the fiber volume fraction of the actual carbon fiber yarn tow.

[0070] The improved Halpin-Tsai semi-empirical formula is as follows:

[0071]

[0072] ξ represents the curve fitting parameter, which is related to the fiber geometry, arrangement, and loading conditions, and is a measure of the fiber's reinforcement level for the matrix.

[0073] Substituting Equation (7) into Equation (6) gives the mathematical expression for the tensile modulus E2 of the carbon fiber tow:

[0074]

[0075] E f2 Represents the elastic modulus in the 2-direction of the actual carbon fiber.

[0076] Given that the microstructure of the carbon fiber tow can be regarded as transversely isotropic, we have: E2 = E3. Similarly, the shear modulus G of the carbon fiber tow in the 12-direction, 12 the shear modulus G of the carbon fiber tow in the 13-direction, 13 and the shear modulus G of the carbon fiber tow in the 23-direction 23 have the following mathematical expressions:

[0077]

[0078] G f12 Represents the shear modulus of the actual carbon fiber tow in the 12-direction.

[0079] According to the empirical formula, the mathematical expression for the Poisson's ratio υ of the carbon fiber tow 23 is as follows:

[0080]

[0081] Import the data of the tensile modulus, shear modulus, and Poisson's ratio of the obtained carbon fiber tow into the mesoscale RVE model of the 2.5D woven composite material to obtain the final mesoscale RVE model of the 2.5D woven composite material.

[0082] The finite element analysis of the mesoscale RVE model of the carbon fiber tow and the mesoscale RVE model of the 2.5D woven composite material is as Figure 4 , 5 shown. Through the finite element analysis using the above empirical formula, the analysis results of the mesoscale RVE model of the 2.5D woven composite material are compared with the test results of the actual composite material as a verification of this method. Among them, the finite element analysis result E of the mesoscale RVE model of the 2.5D woven composite material xx , Eyy (E xx is the longitudinal elastic modulus of the mesoscopic RVE model of the 2.5D woven composite material, and E yy is the transverse elastic modulus), which is in good agreement with the experimental test results of the longitudinal and transverse directions of the real composite material. Among them, for the longitudinal elastic modulus E xx , the relative error between the finite element analysis result and the longitudinal tensile test result is 5.98%. For the transverse elastic modulus E yy , the relative error between the finite element analysis result and the transverse tensile test result is 1.32%. It can be proved that the performance prediction conclusion of the composite material obtained by using the multi-scale elastic property prediction method of the 2.5D woven porous composite material of the present invention is basically consistent with the performance parameters of the real composite material, and the present invention can solve the problem of predicting the elastic properties of the 2.5D woven porous composite material.

[0083] In addition, there are many specific implementation methods and ways of the present invention, and the above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A prediction method for the multi-scale elastic properties of 2.5D woven porous composites, characterized in that It includes the following steps: (1) Establish a microscopic-scale RVE model of carbon fiber tows and a mesoscopic-scale RVE model of 2.5D woven composites; Among them, the microscopic-scale RVE model of carbon fiber tows is a cuboid containing fiber cross-sections, and the fiber cross-sections are circular; The mesoscopic-scale RVE model of 2.5D woven composites contains interwoven warp yarns and weft yarns. The cross-sectional shape of the warp yarns is rectangular, and the cross-sectional shape of the weft yarns is oval; both the warp yarns and the weft yarns are composed of carbon fiber tows; (2) Add pore defects to the microscopic-scale RVE model of carbon fiber tows and the mesoscopic-scale RVE model of 2.5D woven composites by deleting mesh elements; (3) Input the material parameters of real carbon fiber tows into the microscopic-scale RVE model of carbon fiber tows and the mesoscopic-scale RVE model of 2.5D woven composites; (4) For the microscopic-scale RVE model of carbon fiber tows, use the improved Halpin-Tsai semi-empirical formula to predict the elastic property constants of the carbon fiber tows, including the tensile modulus of the carbon fiber tows, the shear modulus of the carbon fiber tows, and the Poisson's ratio of the carbon fiber tows; (5) Import the data of the tensile modulus of the carbon fiber tows, the shear modulus of the carbon fiber tows, and the Poisson's ratio of the carbon fiber tows obtained into the mesoscopic-scale RVE model of 2.5D woven composites to obtain the final mesoscopic-scale RVE model of 2.5D woven composites.

2. The prediction method for multi-scale elastic properties of 2.5D woven porous composite materials according to claim 1, characterized in that: In step (2), the microscopic-scale RVE model of carbon fiber tows and the mesoscopic-scale RVE model of 2.5D woven composites are meshed by finite element analysis software to form a number of mesh elements, and then the mesh elements are randomly selected and deleted. The positions of the deleted mesh elements are used as the pore defects of the model; in each model, the ratio of the number of randomly selected mesh elements to the total number of mesh elements in the model is the simulated porosity.

3. The method for predicting the multi-scale elastic properties of the 2.5D woven porous composite material according to claim 1 or 2, characterized in that: In step (2), the mesh elements of the microscopic-scale RVE model of carbon fiber tows are pentahedral wedge elements; the mesh elements of the mesoscopic-scale RVE model of 2.5D woven composites are hexahedral elements.

4. The method for predicting the multi-scale elastic properties of the 2.5D woven porous composite material according to claim 2, wherein: Select the simulated porosity of the microscopic-scale RVE model of carbon fiber tows to be consistent with the porosity of the real carbon fiber tows, and select the simulated porosity of the mesoscopic-scale RVE model of 2.5D woven composites to be consistent with the porosity of the real 2.5D woven composites.

5. The prediction method for multi-scale elastic properties of 2.5D woven porous composite materials according to claim 1, characterized in that: In step (3), the true carbon fiber tow material parameters include the elastic modulus E of the true carbon fiber in the 1 direction f1 , the elastic modulus E of the 2 direction f2 , the shear modulus G of the 12 direction f12 , the shear modulus G of the 23 direction f23 , the Poisson's ratio υ of the 12 direction f12 , the Poisson's ratio υ of the 23 direction f23 , and the elastic modulus E of the matrix wrapping the carbon fiber tow m , the shear modulus G m , the Poisson's ratio υ m ; where the 1 direction is the axial direction of the carbon fiber tow, and the 2 direction and the 3 direction are the other two directions perpendicular to the 1 direction that form a three-dimensional coordinate with the 1 direction.

6. The method for predicting the multi-scale elastic properties of the 2.5D woven porous composite material according to claim 1, wherein: In step (4), the total volume of the microscopic-scale RVE model of the carbon fiber tow is set to V M , and the volume of the pore defect is set to V v . The volume fraction V Mv of the pores is as follows:

7. The multi-scale elastic property prediction method of the 2.5D woven porous composite material according to claim 6, characterized in that: For the micro-scale RVE model of carbon fiber tow, the elastic modulus E1 in the 1 direction of the carbon fiber tow, the elastic modulus E2 in the 2 direction, and the Poisson's ratio υ in the 12 direction 12 , and the Poisson's ratio υ in the 13 direction 13 : E1 = V f E f1 +(1 - V f )E m (1 - V Mv ) 2 v 12 = υ 13 = V f υ f12 +(1 - V f )υ m ξ represents the curve fitting parameter, E m , υ m respectively represent the true matrix elastic modulus and Poisson's ratio, E f1 , υ f12 respectively represent the elastic modulus in the 1 direction of the true carbon fiber and the Poisson's ratio in the 12 direction, E f2 represents the elastic modulus in the 2 direction of the true carbon fiber, V f represents the fiber volume fraction of the true carbon fiber yarn tow.

8. The prediction method for multi-scale elastic properties of 2.5D woven porous composite materials according to claim 7, characterized in that: For the microscopic-scale RVE model of carbon fiber tows: Shear modulus G in the 12 direction of the carbon fiber tow 12 、Shear modulus G in the 13 direction of the carbon fiber tow 13 and Shear modulus G in the 23 direction of the carbon fiber tow 23 Mathematical expressions for: G f12 represents the shear modulus in the 1-2 direction of the true carbon fiber; G f23 represents the shear modulus in the 2-3 direction of the true carbon fiber; According to the empirical formula, the mathematical expression of the Poisson's ratio υ of the carbon fiber tow 23 in the direction is: 23 ​ 9. An electronic device, comprising: One or more processors; And a storage device for storing one or more programs, which when executed by the one or more processors, cause the one or more processors to implement the design method described in any one of claims 1 to 8.

10. A computer-readable medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the design method described in any one of claims 1 to 8.

Images