Simulation method for evaluating shock resistance of complex curved surface laying composite material structure

Abstract

The invention discloses a simulation method for evaluating the shock resistance of a complex curved surface laying composite material structure, and belongs to the technical field of numerical simulation and material engineering. The simulation method comprises the following steps: constructing a constitutive model of a complex curved surface layering composite material structure; obtaining test parameters of Young modulus, Poisson's ratio, yield strength, tensile strength and fracture tensile ratio of the matrix material and the fiber material; substituting the preset included angle of each fiber laying layer, the thickness of each fiber laying layer, the fiber volume fraction and the Young modulus and Poisson's ratio of the matrix material and the fiber material into the constitutive model to determine the three-direction elastic modulus, the three-direction shear modulus and the three-direction Poisson's ratio of the constitutive model; a CAE simulation model is constructed; and performing simulation evaluation. According to the method, the shock resistance of the composite material structure with the complex curved surface laying layer can be rapidly and accurately evaluated, the product design efficiency is high, the cost is low, the period is short, and the method is suitable for shock resistance simulation evaluation of the composite material structure with the complex curved surface laying layer.

Description

Technical Field

[0001] The present invention belongs to the technical fields of numerical simulation and materials engineering, and particularly relates to a simulation method for evaluating the impact resistance of a complex-curved laminated composite material structure. Background Art

[0002] As a protective equipment, a complex-curved laminated composite material structure (such as a helmet) is required to have a certain bulletproof performance. Among them, being able to resist the penetration of pistol bullets is a mandatory indicator in the national standard. Therefore, the structure and materials used in the complex-curved laminated composite material structure (such as a helmet) have been continuously improved and developed. Fiber materials are increasingly favored due to their light weight and high strength. Compared with traditional materials, the performance of composite materials is determined by factors such as the composition ratio, fiber laminate thickness, laminate direction, and basic performance of each matrix material of the fiber. It is necessary to continuously adjust the above factors to meet the design requirements, which greatly increases the development cycle of a helmet. In addition, the outer shape structure of a complex-curved laminated composite material structure (such as a helmet) is a complex surface, and the curvature changes at each position are irregular, which leads to the overall direction of the fiber layer changing irregularly during the fiber material laminating process, thereby increasing the uncertainty of the overall performance.

[0003] The existing composite material constitutive modeling adopts the laminate theory. The laminate theory is based on the plane stress assumption. Correspondingly, in finite element calculations, plate and shell elements need to be used to discretize the geometric model. However, it is difficult for two-dimensional plate and shell elements to achieve topological discretization of complex surfaces, resulting in large model errors. In addition, it is difficult to achieve dynamic explicit calculation using plate and shell elements, that is, it is not applicable to impact resistance simulation. Summary of the Invention

[0004] The purpose of the present invention is to provide a simulation method for evaluating the impact resistance of a complex-curved laminated composite material structure. The simulation method can quickly and accurately evaluate the impact resistance of a complex-curved laminated composite material structure, and has high design efficiency, low cost, and short cycle of the product, and is applicable to the impact simulation evaluation of a complex-curved laminated composite material structure.

[0005] In order to achieve the above purpose, the present invention is implemented by adopting the following technical solutions:

[0006] A simulation method for evaluating the impact resistance of a complex-curved laminated composite material structure, the simulation method comprising:

[0007] Step S1: Taking the Young's modulus, Poisson's ratio of the matrix material and fiber material in the complex-curved laminated composite material structure, as well as the fiber laminate angle, fiber laminate thickness, and fiber volume fraction as input variables, and taking the three-direction elastic modulus, three-direction shear modulus, and three-direction Poisson's ratio of the constitutive model as output variables to construct the constitutive model of the complex-curved laminated composite material structure;

[0008] Step S2: Obtain the Young's modulus, Poisson's ratio, yield strength, tensile strength, and fracture tensile ratio test parameters of the matrix material and fiber material in the complex curved surface laminated composite material structure;

[0009] Step S3: Substitute each preset fiber ply angle, each fiber ply thickness, fiber volume fraction, and the Young's modulus and Poisson's ratio of the matrix material and fiber material into the constitutive model to determine the three-direction elastic modulus, three-direction shear modulus, and three-direction Poisson's ratio of the constitutive model;

[0010] Step S4: Use the three-direction elastic modulus, three-direction shear modulus, and three-direction Poisson's ratio of the constitutive model to construct a CAE simulation model of the complex curved surface laminated composite material structure;

[0011] Step S5: Use the yield strength, tensile strength, and fracture tensile ratio test parameters of the matrix material and fiber material, and adopt the CAE simulation model to conduct simulation evaluation.

[0012] Further, in the step S1, the specific construction process of the constitutive model includes:

[0013] Step S11: Use the Young's modulus, Poisson's ratio, and fiber volume fraction of the matrix material and fiber material in the complex curved surface laminated composite material structure to determine the compliance coefficient matrix of the complex curved surface fiber laminated composite material structure;

[0014] Step S12: Use each fiber ply angle and each fiber ply thickness of the complex curved surface fiber laminated composite material structure to determine the stiffness coefficient matrix of the complex curved surface fiber laminated composite material structure;

[0015] Step S13: Invert the stiffness coefficient matrix of the complex curved surface fiber laminated composite material structure to determine the three-direction fiber Young's modulus, three-direction fiber shear modulus, and three-direction fiber Poisson's ratio of the complex curved surface fiber laminated composite material structure;

[0016] Step S14: Use the three-direction fiber Young's modulus, three-direction fiber shear modulus, and three-direction fiber Poisson's ratio of the complex curved surface fiber laminated composite material structure, and adopt the ABAQUS orthotropic material model to construct the constitutive model of the complex curved surface fiber laminated composite material structure.

[0017] Further, the specific implementation process of the step S11 includes:

[0018] Step S111: Use the Young's modulus and Poisson's ratio of the matrix material and fiber material to calculate the shear modulus and Lame coefficient of the base material and the shear modulus of the fiber material;

[0019] Step S112: Determine three volume-related variables of the fiber material by using the fiber volume fraction of the fiber material;

[0020] Step S113: Calculate a first intermediate process variable by using the shear modulus and Poisson's ratio of the base material and the shear modulus and Poisson's ratio of the fiber material;

[0021] Step S114: Calculate a second intermediate process variable by using the shear modulus of the base material, the shear modulus of the fiber material, the three volume-related variables of the fiber material, and the first intermediate process variable;

[0022] Step S115: Calculate the stiffness coefficients in the stress-strain relationship of the complex curved surface fiber-laid composite material structure by using the shear modulus and Lame coefficients of the base material, the shear modulus and fiber volume fraction of the fiber material, the three volume-related variables of the fiber material, the first intermediate process variable, and the second intermediate process variable, so as to determine the intermediate variables of the three-direction elastic modulus, the intermediate variables of the three-direction shear modulus, and the intermediate variables of the three-direction Poisson's ratio of the complex curved surface fiber-laid composite material structure;

[0023] Step S116: Determine the compliance coefficient matrix of the complex curved surface fiber-laid composite material structure by using the intermediate variables of the three-direction elastic modulus, the intermediate variables of the three-direction shear modulus, and the intermediate variables of the three-direction Poisson's ratio of the complex curved surface fiber-laid composite material structure.

[0024] Further, in the step S111, the shear modulus and Lame coefficients of the base material and the shear modulus of the fiber material are respectively:

[0025]

[0026] wherein, μ m and λ m are respectively the shear modulus and Lame coefficients of the base material; μ f is the shear modulus of the fiber material; E m and v m are respectively the Young's modulus and Poisson's ratio of the base material; E f and v f are respectively the Young's modulus and Poisson's ratio of the fiber material.

[0027] Further, in the step S112, the three volume-related variables of the fiber material are respectively:

[0028]

[0029] wherein, S3, S6, and S7 are the three volume-related variables of the fiber material; Vf is the fiber volume fraction of the fiber material;

[0030] In the step S113, the first intermediate process variable is:

[0031] a = μ f - μ m - 2μ f v m + 2μ m v f ;

[0032] b = - μ m v m + μ f v f – 2μ m v f - 2μ f v m v f ;

[0033]

[0034] g = 2 - 2v m ;

[0035] where a, b, c, and g are the first intermediate process variables; μ m and v m are the shear modulus and Poisson's ratio of the base material, respectively; μ f and v f are the shear modulus and Poisson's ratio of the fiber material, respectively.

[0036] Further, in the step S114, the second intermediate process variable is:

[0037]

[0038] where D is the second intermediate process variable; μ m and μ f are the shear moduli of the base material and the fiber material, respectively; S3, S6, and S7 are three volume-related variables of the fiber material; a, b, c, and g are the first intermediate process variables.

[0039] Further, in the step S115, the stiffness coefficients in the stress-strain relationship of the complex curved surface fiber ply composite structure are:

[0040]

[0041] where and are the stiffness coefficients in the stress-strain relationship of the complex curved surface fiber ply composite structure; μm and λ m are the shear modulus and Lame coefficient of the base material respectively; μ f and V f are the shear modulus and fiber volume fraction of the fiber material respectively; a, b, c, and g are the first intermediate process variables; S3, S6, and S7 are three volume-related variables of the fiber material; D is the second intermediate process variable;

[0042] In the step S115, the intermediate variables of the three-direction elastic modulus, the intermediate variables of the three-direction shear modulus, and the intermediate variables of the three-direction Poisson ratio of the complex curved surface fiber ply composite material structure are respectively:

[0043]

[0044] wherein, E1, E2, and E 23 are the intermediate variables of the three-direction elastic modulus of the complex curved surface fiber ply composite material structure; G 12 , G 13 and G 23 are the intermediate variables of the three-direction shear modulus of the complex curved surface fiber ply composite material structure; vx2, v 13 and v 23 are the intermediate variables of the three-direction Poisson ratio of the complex curved surface fiber ply composite material structure.

[0045] Furthermore, in the step S116, the compliance coefficient matrix of the complex curved surface fiber ply composite material structure is:

[0046]

[0047] wherein, [S]0 is the compliance coefficient matrix of the complex curved surface fiber ply composite material structure.

[0048] Furthermore, the specific implementation process of the step S12 includes:

[0049] Step S121: Use the included angle of each fiber ply of the complex curved surface fiber ply composite material structure to determine the positive rotation matrix and negative rotation matrix of each fiber ply of the complex curved surface fiber ply composite material structure;

[0050] Step S122: Multiply the transpose matrix of the positive rotation matrix of each fiber ply by the compliance coefficient matrix of the complex curved surface fiber ply composite material structure, then multiply by the positive rotation matrix of the corresponding fiber ply, and then take the inverse to obtain the positive rotation stiffness coefficient matrix of each fiber ply;

[0051] Step S123: Multiply the transpose matrix of the negative rotation angle matrix of each fiber ply by the flexibility coefficient matrix of the complex curved surface fiber ply composite structure, then multiply by the negative rotation angle matrix of the corresponding fiber ply, and then take the inverse to obtain the negative rotation angle stiffness coefficient matrix of each fiber ply;

[0052] Step S124: Calculate the thickness of the complex curved surface fiber ply composite structure using the thickness of each fiber ply, and calculate the thickness ratio of each fiber ply;

[0053] Step S125: Multiply the thickness ratio of each fiber ply by the positive rotation angle stiffness coefficient matrix and the negative rotation angle stiffness coefficient matrix of the corresponding fiber ply respectively, and then sum them to obtain the stiffness coefficient matrix of the complex curved surface fiber ply composite structure.

[0054] Further, in the step S4, the construction process of the CAE simulation model includes:

[0055] Step S41: Use the principal direction of the composite material in the constitutive model to determine the reference coordinates of the complex curved surface ply composite structure before forming in CAD, so as to determine the principal direction of the composite material in the CAD model of the complex curved surface ply composite structure;

[0056] Step S42: Discretize the CAD model according to the principal direction of the composite material in the CAD model to obtain each region on the CAD model;

[0057] Step S43: Determine whether the angle between the principal direction of the composite material on each region and the reference coordinates is greater than the threshold. If so, go to step S44; if not, go to step S45;

[0058] Step S44: Continue to discretize the region where the angle between the principal direction of the composite material and the reference coordinates is greater than the threshold according to the principal direction of the composite material in the CAD model to obtain each sub-region on the region, and take the each sub-region as a new region, and return to step S43;

[0059] Step S45: Establish equivalent local coordinates at the center points of the discretized regions to obtain the CAE simulation model of the complex curved surface ply composite structure.

[0060] In summary, the technical solution of the present invention has the following technical effects:

[0061] Through the constitutive model of the complex curved surface laminate composite material structure established by the present invention, the fiber laminate angle, fiber laminate thickness, fiber volume fraction, direction involved in the target equipment (such as a helmet), and the Young's modulus and Poisson's ratio of the matrix material and fiber material in the composite material are unified with the test basic data, ensuring the rationality, authenticity, and accuracy of the various material parameter values required for the CAE simulation model, improving the simulation accuracy, ensuring the accuracy of the evaluation results, and being applicable to the impact simulation evaluation of complex curved surface laminate composite material structures; the present invention can quickly and accurately evaluate the impact resistance performance of complex curved surface laminate composite material structures, and has high product design efficiency, low cost, and short cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0063] Figure 1 It is a flowchart of the simulation method for evaluating the impact resistance performance of a complex curved surface laminate composite material structure of the present invention. SPECIFIC EMBODIMENTS

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0065] This embodiment provides a simulation method for evaluating the impact resistance performance of a complex curved surface laminate composite material structure. Referring to Figure 1 , the simulation method includes:

[0066] Step S1: Take the Young's modulus, Poisson's ratio of the matrix material and fiber material in the complex curved surface laminate composite material structure, as well as the fiber laminate angle, fiber laminate thickness, and fiber volume fraction as input variables, and take the three-direction elastic modulus, three-direction shear modulus, and three-direction Poisson's ratio of the constitutive model as output variables to establish the constitutive model of the complex curved surface laminate composite material structure.

[0067] According to the constitutive principle of fiber materials, assuming a given ply sequence, thickness of each ply, Young's modulus of fibers, Poisson's ratio of fibers, Young's modulus of the base material, Poisson's ratio of the base material, and fiber volume fraction, the construction of the constitutive model (i.e., the mathematical model) is realized based on the LUCIANO algorithm. The specific construction process of the constitutive model includes:

[0068] Step S11: Determine the flexibility coefficient matrix of the complex curved surface fiber ply composite structure by using the Young's modulus, Poisson's ratio, and fiber volume fraction of the matrix material and fiber material in the complex curved surface fiber ply composite structure.

[0069] The specific implementation process of this step includes:

[0070] Step S111: Calculate the shear modulus and Lame coefficient of the base material and the shear modulus of the fiber material by using the Young's modulus and Poisson's ratio of the matrix material and fiber material.

[0071] The shear modulus and Lame coefficient of the base material and the shear modulus of the fiber material in this embodiment are respectively:

[0072]

[0073]

[0074] where μ m and λ m are respectively the shear modulus and Lame coefficient of the base material; μ f is the shear modulus of the fiber material; E m and v m are respectively the Young's modulus and Poisson's ratio of the base material; E f and v f are respectively the Young's modulus and Poisson's ratio of the fiber material.

[0075] Step S112: Determine three volume-related variables of the fiber material by using the fiber volume fraction of the fiber material.

[0076] In this embodiment, the three volume-related variables of the fiber material are respectively:

[0077]

[0078] where S3, S6, and S7 are the three volume-related variables of the fiber material; v f is the fiber volume fraction of the fiber material;

[0079] Step S113: Calculate the first intermediate process variable by using the shear modulus and Poisson's ratio of the base material and the shear modulus and Poisson's ratio of the fiber material.

[0080] The first intermediate process variable in this embodiment is:

[0081] a = μ f - μ m - 2μ f v m + 2μ m v f ;

[0082] b = - μ m v m + μ f v f – 2μ m v m – 2μ f v m v f ;

[0083]

[0084] g = 2 - 2v m ;

[0085] Among them, a, b, c, and g are the first intermediate process variables; μ m and v m are respectively the shear modulus and Poisson's ratio of the base material; μ f and v f are respectively the shear modulus and Poisson's ratio of the fiber material.

[0086] Step S114: Calculate the second intermediate process variable by using the shear modulus of the base material, the shear modulus of the fiber material, the three volume-related variables of the fiber material, and the first intermediate process variable.

[0087] The second intermediate process variable in this embodiment is:

[0088]

[0089] Among them, D is the second intermediate process variable; μ m and μ f are respectively the shear modulus of the base material and the fiber material; S3, S6, and S7 are the three volume-related variables of the fiber material; a, b, c, and g are the first intermediate process variables.

[0090] Step S115: Calculate the stiffness coefficients in the stress-strain relationship of the complex curved surface fiber laminated composite structure by using the shear modulus and Lame coefficients of the base material, the shear modulus and fiber volume fraction of the fiber material, as well as the three volume-related variables, the first intermediate process variable, and the second intermediate process variable of the fiber material, so as to determine the intermediate variables of the three-direction elastic modulus, the intermediate variables of the three-direction shear modulus, and the intermediate variables of the three-direction Poisson ratio of the complex curved surface fiber laminated composite structure.

[0091] In this embodiment, the stiffness coefficients in the stress-strain relationship of the complex curved surface fiber laminated composite structure are:

[0092]

[0093]

[0094] Among them, and are the stiffness coefficients in the stress-strain relationship of the complex curved surface fiber laminated composite structure; μ m and λ m are respectively the shear modulus and Lame coefficient of the base material; μ f and V f are respectively the shear modulus and fiber volume fraction of the fiber material; a, b, c, and g are the first intermediate process variables; S3, S6, and S7 are the three volume-related variables of the fiber material; D is the second intermediate process variable.

[0095] In this embodiment, the intermediate variables of the three-direction elastic modulus, the intermediate variables of the three-direction shear modulus, and the intermediate variables of the three-direction Poisson ratio of the complex curved surface fiber laminated composite structure are respectively:

[0096]

[0097] Among them, E1, E2, and E 23 are the intermediate variables of the three-direction elastic modulus of the complex curved surface fiber laminated composite structure; G 12 , G 13 , and G 23 are the intermediate variables of the three-direction shear modulus of the complex curved surface fiber laminated composite structure; v 12 , v 13 , and v 23 are the intermediate variables of the three-direction Poisson ratio of the complex curved surface fiber laminated composite structure.

[0098] Step S116: Determine the compliance coefficient matrix of the complex curved surface fiber laminated composite structure by using the intermediate variables of the three-direction elastic modulus, the intermediate variables of the three-direction shear modulus, and the intermediate variables of the three-direction Poisson ratio of the complex curved surface fiber laminated composite structure.

[0099] In this embodiment, the flexibility coefficient matrix of the complex curved surface fiber ply composite structure is as follows:

[0100]

[0101] where [S]0 is the flexibility coefficient matrix of the complex curved surface fiber ply composite structure.

[0102] Step S12: Determine the stiffness coefficient matrix of the complex curved surface fiber ply composite structure by using the included angle of each fiber ply and the thickness of each fiber ply of the complex curved surface fiber ply composite structure.

[0103] The specific implementation process of this step includes:

[0104] Step S121: Determine the positive rotation matrix and negative rotation matrix of each fiber ply of the complex curved surface fiber ply composite structure by using the included angle of each fiber ply of the complex curved surface fiber ply composite structure.

[0105] In this embodiment, the rotation matrix of each fiber ply is as follows:

[0106]

[0107] where θ k is the rotation angle of the k-th fiber ply, and the corresponding rotation matrix of θ k is the positive rotation matrix of the k-th fiber ply -θ k and the corresponding rotation matrix is the negative rotation matrix of the k-th fiber ply k = 1, 2,..., K, where K is the number of fiber plies.

[0108] Step S122: Multiply the transpose matrix of the positive rotation matrix of each fiber ply by the flexibility coefficient matrix of the complex curved surface fiber ply composite structure, then multiply by the positive rotation matrix of the corresponding fiber ply, and then take the inverse to obtain the positive rotation stiffness coefficient matrix of each fiber ply.

[0109] In this embodiment, the rotation stiffness coefficient matrix of each fiber ply is as follows:

[0110]

[0111] where is the positive rotation stiffness coefficient matrix of the k-th fiber ply; is the flexibility coefficient matrix of the k-th fiber ply; is the positive rotation matrix of the k-th fiber ply which is the transpose matrix.

[0112] Step S123: After multiplying the transpose matrix of the negative rotation angle matrix of each fiber ply by the flexibility coefficient matrix of the complex curved surface fiber ply composite structure, then multiplying by the negative rotation angle matrix of the corresponding fiber ply, and then taking the inverse, the negative rotation angle stiffness coefficient matrix of each fiber ply is obtained.

[0113] The negative rotation angle stiffness coefficient matrix of the k-th fiber ply in this embodiment is -θ k the corresponding rotation angle matrix.

[0114] Step S124: Using the thickness of each fiber ply, calculate the thickness of the complex curved surface fiber ply composite structure, and calculate the thickness ratio of each fiber ply.

[0115] The thickness of the complex curved surface fiber ply composite structure in this embodiment is t = 2(t1 + t2 + … + t k + … + t K ), where t k is the thickness of the k-th fiber ply.

[0116] Step S125: Multiply the thickness ratio of each fiber ply by the positive rotation angle stiffness coefficient matrix and the negative rotation angle stiffness coefficient matrix of the corresponding fiber ply respectively, and then sum them to obtain the stiffness coefficient matrix of the complex curved surface fiber ply composite structure.

[0117] For a composite material (with a reference direction) formed by laminating multiple fiber plies with different angles, the stiffness coefficient matrix of the complex curved surface fiber ply composite structure in this embodiment is:

[0118]

[0119] where, is the stiffness coefficient matrix of the complex curved surface fiber ply composite structure; t k is the thickness of the k-th fiber ply; θ k is the rotation angle (i.e., angle) of the k-th fiber ply.

[0120] Step S13: Take the inverse of the stiffness coefficient matrix of the complex curved surface fiber ply composite structure to determine the three-direction fiber Young's modulus, three-direction fiber shear modulus, and three-direction fiber Poisson's ratio of the complex curved surface fiber ply composite structure.

[0121] The three-direction fiber Young's modulus, three-direction fiber shear modulus, and three-direction fiber Poisson's ratio of the complex curved surface fiber ply composite structure in this embodiment are respectively:

[0122]

[0123] where, and is the Young's modulus of the three-directional fibers of the complex curved surface fiber-laminated composite material structure; and is the shear modulus of the three-directional fibers of the complex curved surface fiber-laminated composite material structure; and is the Poisson's ratio of the three-directional fibers of the complex curved surface fiber-laminated composite material structure.

[0124] Step S14: Using the Young's modulus of the three-directional fibers, the shear modulus of the three-directional fibers, and the Poisson's ratio of the three-directional fibers of the complex curved surface fiber-laminated composite material structure, and adopting the ABAQUS orthotropic material model, construct the constitutive model of the complex curved surface fiber-laminated composite material structure.

[0125] Through the linear range parameters (i.e., the Young's modulus of the three-directional fibers, the shear modulus of the three-directional fibers, and the Poisson's ratio of the three-directional fibers), it can be directly used in the ABAQUS orthotropic material model to complete the construction of the constitutive model of the fiber composite material.

[0126] Step S2: Obtain the experimental parameters of the Young's modulus, Poisson's ratio, yield strength, tensile strength, and fracture tensile ratio of the matrix material and the fiber material in the complex curved surface laminated composite material structure.

[0127] In this embodiment, the composite material of the complex curved surface laminated composite material structure is synthesized by the basic material fiber and the matrix material glue in a certain proportion. To obtain the composite material properties, it is necessary to conduct basic mechanical property tests on the single materials respectively, such as the conventional stress-strain tensile test, to obtain parameters such as the Young's modulus of the fiber material and the matrix material, and the Poisson's ratio of the fiber material and the matrix material, and provide them to the constitutive model of the complex curved surface laminated composite material structure to calculate the composite material performance parameters. Such as the ultimate failure test, to obtain the experimental parameters of the yield strength, tensile strength, and fracture tensile ratio of the fiber material and the matrix material, and construct a complete CAE calculation model (i.e., a CAE simulation model).

[0128] Step S3: Substitute each preset fiber lay-up angle, each fiber lay-up thickness, fiber volume fraction, and the Young's modulus and Poisson's ratio of the matrix material and the fiber material into the constitutive model to determine the three-directional elastic modulus, three-directional shear modulus, and three-directional Poisson's ratio of the constitutive model.

[0129] There are many factors affecting the performance of the composite material. The influence of the fiber lay-up angle on the performance of the composite material: As the fiber lay-up angle continuously increases, the three-directional performance parameters of the composite material do not show a unified trend, and each performance parameter shows a highly non-linear characteristic. In the range of 0° to 20°, the three-directional performance parameters of the composite material change violently, and after 20°, it shows a low-amplitude vibration characteristic.

[0130] The fiber volume fraction is the proportion of the base material (i.e., the colloidal material) in the composite material. Its effect on the properties of the composite material is as follows: as the fiber volume fraction increases, the three-direction performance parameters of the composite material show a unified change trend, and each performance parameter has an approximate linear characteristic, and the performance parameters in the first two directions coincide.

[0131] Therefore, in the design of the composite material, these parameters need to be continuously corrected. Based on these parameters, the constitutive model is used to predictively analyze the change law of the influence of each parameter adjustment on the properties of the composite material, so as to optimize the best scheme for the mechanical properties of the material.

[0132] Step S4: Using the three-direction elastic modulus, three-direction shear modulus, and three-direction Poisson's ratio of the constitutive model, construct a CAE simulation model of the complex curved surface laminated composite material structure.

[0133] CAD design and model construction: Different from the design of conventional metal material components, for the shape design of a complex curved surface laminated composite material structure (such as a helmet), it is necessary to consider the change in the laying direction of the composite material (the main direction of the material, X-axis) caused by the surface curvature at different positions during the compression molding process, as well as the influence of uneven thickness. In addition, there is also a problem of different bullet impact probabilities in each area during the use of a complex curved surface laminated composite material structure (such as a helmet). Generally, the front side is more likely to be impacted than other positions. The composite material is an anisotropic material with different mechanical properties in each direction. Among them, the mechanical properties in the main direction of the material (X-axis) are relatively the strongest. Therefore, in the process of optimizing the shape of a complex curved surface laminated composite material structure (such as a helmet), the above influences can be combined. First, it is necessary to define the reference coordinate in CAD for the complex curved surface laminated composite material structure (such as a helmet), that is, the X-axis (the main direction of the material) defined by the constitutive model. During model construction, while ensuring the overall thickness of the complex curved surface laminated composite material structure (such as a helmet) is consistent, adjust the material laying direction so that after molding, the material direction in the main bullet impact area of the complex curved surface laminated composite material structure (such as a helmet) is as consistent as possible with the reference coordinate direction, so as to ensure that the overall strength of the helmet does not decrease while improving the impact resistance of the main bullet impact area.

[0134] In the process of building CAE simulation models, the focus is on establishing local coordinates in each area of ​​the model as composite material laying coordinates. In order to ensure that the CAD design purpose is fully reflected in the construction of CAE simulation models, it is necessary to segment the complex curved surface layup composite material structure (such as a helmet). The segmentation principle is: when the angle (a or b or c) between the composite material laying direction (composite material laying coordinates) defined by the design of a certain area of ​​the surface and the composite material direction (reference coordinates) of the complex curved surface layup composite material structure (such as a helmet) before molding is greater than 5. (Recommended value), the CAD model needs to be segmented, the surface of each segmented area is equivalent to a plane, and the composite material laying direction of all units in this area is considered to be consistent, and the equivalent local coordinates consistent with the material laying direction here are established at the center point, and this coordinate is assigned to the composite material properties of this area.

[0135] In summary, the construction process of CAE simulation model includes:

[0136] Step S41, using the main direction of the composite material in the constitutive model, determining the reference coordinates of the complex curved surface laminated composite material structure in CAD before forming, so as to determine the main direction of the composite material in the CAD model of the complex curved surface laminated composite material structure;

[0137] Step S42, dividing the CAD model according to the main direction of the composite material in the CAD model to obtain various regions on the CAD model;

[0138] Step S43, judging whether the angle between the main direction of the composite material in each region and the reference coordinate is greater than a threshold value, if yes, proceeding to step S44; if no, proceeding to step S45;

[0139] Step S44, according to the main direction of the composite material in the CAD model, continue to divide the area where the angle between the main direction of the composite material and the reference coordinate is greater than the threshold value to obtain each sub-area on the area, and use each sub-area as a new area, and return to step S43;

[0140] Step S45, establishing equivalent local coordinates at the center points of each divided region to obtain a CAE simulation model of the complex curved surface laminated composite material structure.

[0141] The CAE simulation model introduces composite material laying methods and local coordinates during the construction process, eliminating the impact of local performance differences caused by geometric shapes (curvature, radian, etc.) and further improving the simulation accuracy.

[0142] Step S5: using the yield strength, tensile strength and breaking elongation ratio test parameters of the matrix material and the fiber material and adopting the CAE simulation model to perform simulation evaluation.

[0143] The purpose of the evaluation is to correct the mathematical model parameters of the fiber material (the interlayer angle and layer thickness of the fiber material will change with deformation during the force application process) and verify the feasibility of the overall method.

[0144] In this embodiment, through the constitutive model of the complex-curved surface laminated composite material structure constructed, the fiber laying angle, fiber laying thickness, fiber volume fraction, direction in the target equipment (such as a helmet), and the Young's modulus and Poisson's ratio of the matrix material and fiber material in the composite material are unified with the test basic data, ensuring the rationality, authenticity, and accuracy of the values of various material parameters required for the CAE simulation model, improving the simulation accuracy, ensuring the accuracy of the evaluation results, and being applicable to the impact resistance simulation evaluation of the complex-curved surface laminated composite material structure; this embodiment can quickly and accurately evaluate the impact resistance performance of the complex-curved surface laminated composite material structure, and has high product design efficiency, low cost, and short cycle.

[0145] The above embodiments only represent several implementation manners of the present application, and the description thereof is relatively specific and detailed, but should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A simulation method for evaluating the impact resistance of complex-curved surface laminated composite structures, characterized in that The simulation method includes: Step S1: Taking the Young's modulus, Poisson's ratio of the matrix material and fiber material in the complex curved surface laminated composite structure, as well as the fiber layer angle, fiber layer thickness and fiber volume fraction as input variables, and taking the three-direction elastic modulus, three-direction shear modulus and three-direction Poisson's ratio of the constitutive model as output variables, to construct the constitutive model of the complex curved surface laminated composite structure; Step S2: Obtaining the Young's modulus, Poisson's ratio, yield strength, tensile strength and fracture tensile ratio test parameters of the matrix material and fiber material in the complex curved surface laminated composite structure; Step S3: Substituting each preset fiber layer angle, each fiber layer thickness, fiber volume fraction, and the Young's modulus and Poisson's ratio of the matrix material and fiber material into the constitutive model to determine the three-direction elastic modulus, three-direction shear modulus and three-direction Poisson's ratio of the constitutive model; Step S4: Using the three-direction elastic modulus, three-direction shear modulus and three-direction Poisson's ratio of the constitutive model to construct the CAE simulation model of the complex curved surface laminated composite structure; Step S5: Using the yield strength, tensile strength and fracture tensile ratio test parameters of the matrix material and fiber material, and adopting the CAE simulation model to conduct simulation evaluation.

2. The simulation method according to claim 1, wherein In the step S1, the specific construction process of the constitutive model includes: Step S11: Using the Young's modulus, Poisson's ratio of the matrix material and fiber material in the complex curved surface laminated composite structure, and the fiber volume fraction to determine the compliance coefficient matrix of the complex curved surface fiber laminated composite structure; Step S12: Using each fiber layer angle and each fiber layer thickness of the complex curved surface fiber laminated composite structure to determine the stiffness coefficient matrix of the complex curved surface fiber laminated composite structure; Step S13: Inverting the stiffness coefficient matrix of the complex curved surface fiber laminated composite structure to determine the three-direction fiber Young's modulus, three-direction fiber shear modulus and three-direction fiber Poisson's ratio of the complex curved surface fiber laminated composite structure; Step S14: Using the three-direction fiber Young's modulus, three-direction fiber shear modulus and three-direction fiber Poisson's ratio of the complex curved surface fiber laminated composite structure, and adopting the ABAQUS orthotropic material model to construct the constitutive model of the complex curved surface fiber laminated composite structure.

3. The simulation method according to claim 2, wherein The specific implementation process of the step S11 includes: Step S111: Using the Young's modulus and Poisson's ratio of the matrix material and fiber material to calculate the shear modulus and Lame coefficient of the base material and the shear modulus of the fiber material; Step S112: Using the fiber volume fraction of the fiber material to determine three volume-related variables of the fiber material; Step S113: Using the shear modulus and Poisson's ratio of the base material and the shear modulus and Poisson's ratio of the fiber material to calculate the first intermediate process variable; Step S114: Calculate the second intermediate process variable by using the shear modulus of the base material, the shear modulus of the fiber material, three volume-related variables of the fiber material, and the first intermediate process variable; Step S115: Calculate the stiffness coefficients in the stress-strain relationship of the complex curved surface fiber-laid composite material structure by using the shear modulus and Lame coefficients of the base material, the shear modulus and fiber volume fraction of the fiber material, three volume-related variables of the fiber material, the first intermediate process variable, and the second intermediate process variable, so as to determine the intermediate variables of the three-direction elastic modulus, the intermediate variables of the three-direction shear modulus, and the intermediate variables of the three-direction Poisson ratio of the complex curved surface fiber-laid composite material structure; Step S116: Determine the compliance coefficient matrix of the complex curved surface fiber-laid composite material structure by using the intermediate variables of the three-direction elastic modulus, the intermediate variables of the three-direction shear modulus, and the intermediate variables of the three-direction Poisson ratio of the complex curved surface fiber-laid composite material structure.

4. The simulation method according to claim 3, wherein In the step S111, the shear modulus and Lame coefficients of the base material and the shear modulus of the fiber material are respectively: where μ m and λ m are the shear modulus and Lame coefficient of the base material, respectively; μ f is the shear modulus of the fiber material; E m and v m are the Young's modulus and Poisson's ratio of the base material, respectively; E f and v f are the Young's modulus and Poisson's ratio of the fiber material, respectively.

5. The simulation method according to claim 4, characterized in that In the step S112, the three volume-related variables of the fiber material are respectively: Among them, S3, S6, and S7 are three volume-related variables of the fiber material; V f is the fiber volume fraction of the fiber material; In the step S113, the first intermediate process variable is: a = μ f -μ m -2μ f v m +2μ m v f ; b = μ m -v m +μ f v f -2μ m v m v f +2μ f v m v f ; g = 2 - 2ν m ; Among them, a, b, c, and g are first intermediate process variables; μ m and v m are respectively the shear modulus and Poisson's ratio of the base material; μ f and v f are respectively the shear modulus and Poisson's ratio of the fiber material.

6. The simulation method according to claim 5, wherein In the step S114, the second intermediate process variable is: where D is the second intermediate process variable; μ m and μ f are the shear moduli of the base material and the fiber material, respectively; S3, S6, and S7 are three volume-related variables of the fiber material; a, b, c, and g are the first intermediate process variables.

7. The simulation method according to claim 6, wherein In the step S115, the stiffness coefficients in the stress-strain relationship of the complex curved surface fiber-laid composite material structure are: Among them, and are the stiffness coefficients in the stress-strain relationship of the complex curved surface fiber ply composite structure; μ m and λ m are the shear modulus and Lame coefficient of the base material, respectively; μ f and V f are the shear modulus and fiber volume fraction of the fiber material, respectively; a, b, c, and g are the first intermediate process variables; S3, S6, and S7 are three volume-related variables of the fiber material; D is the second intermediate process variable; In the step S115, the intermediate variables of the three-direction elastic modulus, the intermediate variables of the three-direction shear modulus, and the intermediate variables of the three-direction Poisson ratio of the complex curved surface fiber-laid composite material structure are respectively: Among them, E1, E2, and E 23 are intermediate variables of the three-direction elastic moduli of the complex curved surface fiber ply composite structure; G 12 , G 13 , and G 23 are intermediate variables of the three-direction shear moduli of the complex curved surface fiber ply composite structure; v 12 , v 13 , and v 23 are intermediate variables of the three-direction Poisson's ratios of the complex curved surface fiber ply composite structure.

8. The simulation method according to claim 7, characterized in that, In the step S116, the compliance coefficient matrix of the complex curved surface fiber-laid composite material structure is: Among them, [S]0 is the compliance coefficient matrix of the complex curved surface fiber-laid composite material structure.

9. The simulation method according to claim 8, wherein The specific implementation process of the step S12 includes: Step S121: Determine the positive rotation matrix and negative rotation matrix of each fiber layer of the complex curved surface fiber-laid composite material structure by using the included angle of each fiber layer of the complex curved surface fiber-laid composite material structure; Step S122: Multiply the transpose matrix of the positive rotation matrix of each fiber layer by the compliance coefficient matrix of the complex curved surface fiber-laid composite material structure, then multiply by the positive rotation matrix of the corresponding fiber layer, and then take the inverse to obtain the positive rotation stiffness coefficient matrix of each fiber layer; Step S123: Multiply the transpose matrix of the negative rotation matrix of each fiber layer by the compliance coefficient matrix of the complex curved surface fiber-laid composite material structure, then multiply by the negative rotation matrix of the corresponding fiber layer, and then take the inverse to obtain the negative rotation stiffness coefficient matrix of each fiber layer; Step S124: Calculate the thickness of the complex curved surface fiber-laid composite material structure by using the thickness of each fiber layer, and calculate the thickness ratio of each fiber layer; Step S125: Multiply each fiber ply thickness ratio by the corresponding positive rotation stiffness coefficient matrix and negative rotation stiffness coefficient matrix of the fiber ply respectively, and then sum them to obtain the stiffness coefficient matrix of the complex surface fiber ply composite material structure.

10. The simulation method according to claim 9, characterized in that In the said Step S4, the construction process of the CAE simulation model includes: Step S41: Use the main direction of the composite material in the constitutive model to determine the reference coordinates of the complex surface ply composite material structure before forming in CAD, so as to determine the main direction of the composite material in the CAD model of the complex surface ply composite material structure; Step S42: Dissect the CAD model according to the main direction of the composite material in the CAD model to obtain each area on the CAD model; Step S43: Judge whether the included angle between the main direction of the composite material on each area and the reference coordinates is greater than the threshold value. If so, go to Step S44; if not, go to Step S45; Step S44: Continue to dissect the area where the included angle between the main direction of the composite material and the reference coordinates is greater than the threshold value according to the main direction of the composite material in the CAD model to obtain each sub-area on the area, and take the each sub-area as a new area, and return to Step S43; Step S45: Establish equivalent local coordinates at the center points of each dissected area to obtain the CAE simulation model of the complex surface ply composite material structure.

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