Composite material finite element simulation method and modeling method based on flexible interface model

Abstract

The invention relates to the technical field of composite material simulation, in particular to a composite material finite element simulation method based on a flexible interface model and a modeling method.The composite material finite element simulation method based on the flexible interface model comprises the steps that a split scheme is formed according to the process of a composite material structure; dividing the composite material structure into a plurality of split substructures; establishing a finite element model of each split substructure; connecting the finite element models of the plurality of split substructures by adopting a flexible interface model to obtain a finite element model of the composite material structure; and performing finite element simulation analysis by adopting the finite element model of the composite material structure to obtain a rigidity analysis result and / or a strength analysis result of the composite material structure. The method is at least beneficial to improving the accuracy of finite element simulation analysis of the composite material structure.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material simulation, and in particular relates to a composite material finite element simulation method and a modeling method based on a flexible interface model. Background Art

[0002] Composite materials are widely used in aviation, aerospace, automobile and other fields due to their advantages of high specific strength, high specific stiffness and strong designability. With the increasing demand for lightweight structures and high load-bearing capacity, the traditional plate-shell structures and regular rotation structures suitable for the production and manufacturing of composite materials have gradually failed to meet the current product needs. Therefore, more complex types of composite materials, such as reinforced structures and 3D grid structures, have been widely used.

[0003] Generally, the finite element simulation analysis of composite structures needs to consider two basic requirements: on the one hand, the continuity of the laminated fibers, that is, the orientation and continuity of the laminated fibers in the composite structure should be as close as possible to the actual situation of the process implementation; on the other hand, the connection method. Complex types of composite structures are usually composed of multiple separate structures when they are formed. The connection method setting between the multiple separate structures will have a certain impact on the finite element simulation analysis results.

[0004] At present, the finite element modeling of composite structures is mostly based on the establishment of an integrated common node model based on plate and shell elements. This method has certain shortcomings, as follows: when modeling complex types of composite structures, the rigid connection of the common node of the integrated common node model makes the stiffness of the composite structure model too large, resulting in a certain error between the stiffness analysis results and the interlaminar stress state of the interface and the actual state. In addition, it is difficult to divide the interface positions of the separate structures in the complex composite structure and ensure the continuity of the plies. The correctness and accuracy of the finite element model are the basis for ensuring the accuracy of various simulation results. Therefore, it is necessary to establish a set of finite element modeling and simulation analysis methods that are suitable for complex composite structures and fit the actual process. Summary of the invention

[0005] In view of this, the present invention aims to provide a composite material finite element simulation method and modeling method based on a flexible interface model, which is at least beneficial to improving the accuracy of finite element simulation analysis of composite material structures.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0007] The present invention provides a composite material finite element simulation method based on a flexible interface model, comprising: dividing the composite material structure into a plurality of split substructures according to the process forming split scheme of the composite material structure; establishing a finite element model of each split substructure; using a flexible interface model to connect the finite element models of the plurality of split substructures to obtain a finite element model of the composite material structure; using the finite element model of the composite material structure to perform finite element simulation analysis to obtain a stiffness analysis result and / or a strength analysis result of the composite material structure, wherein the stiffness analysis result of the composite material structure includes a stiffness analysis result between interfaces and an overall stiffness analysis result, and the strength analysis result of the composite material structure includes a strength analysis result between interfaces and an overall strength analysis result.

[0008] Furthermore, after establishing the finite element model of each split substructure, it also includes: inputting the material parameters of the one-way plate of the split substructure into the finite element model of the corresponding split substructure, and inputting the material parameters of the resin matrix into the corresponding flexible interface model; setting the layup sequence and 0° direction of the finite element model of the corresponding split substructure according to the process layup plan of the split substructure.

[0009] Furthermore, the material parameters of the one-way plate include the longitudinal modulus of the one-way plate, the transverse modulus of the one-way plate, the Poisson's ratio of the one-way plate, the longitudinal and transverse shear moduli of the one-way plate, and the interlaminar shear modulus of the one-way plate.

[0010] Furthermore, the material parameters of the resin matrix include the elastic modulus of the resin matrix, the Poisson's ratio of the resin matrix, the normal tensile strength of the resin matrix, and the shear strength of the resin matrix.

[0011] Furthermore, the flexible interface model satisfies Formula 1, which is as follows:

[0012]

[0013] Among them, t is the interface force matrix of the split substructure, t n is the normal force between the interfaces of the split substructures, t s is the first orthogonal tangential force between the interfaces of the split substructures, t t is the tangential force in the second orthogonal direction between the interfaces of the split substructures, δ n is the relative normal displacement between the interfaces of the split substructures, δ s is the tangential displacement in the first orthogonal direction between the interfaces of the split substructures, δ t is the tangential displacement in the second orthogonal direction between the interfaces of the split substructures, K nn is the normal stiffness parameter, K ss is the tangential stiffness parameter in the first orthogonal direction, K tt is the tangential stiffness parameter in the second orthogonal direction, K ns , Knt and K st are all 0, K is the interface stiffness matrix, and δ is the interface relative displacement matrix.

[0014] Furthermore, the normal stiffness parameter K is calculated according to the flexible interface stiffness parameter formula: nn , the tangential stiffness parameter K in the first orthogonal direction ss And the tangential stiffness parameter K in the second orthogonal direction tt , the normal stiffness parameter K nn , the tangential stiffness parameter K in the first orthogonal direction ss And the tangential stiffness parameter K in the second orthogonal direction tt Applied to the flexible interface model to obtain the stiffness analysis results between interfaces;

[0015] The formula for the flexible interface stiffness parameter is as follows:

[0016]

[0017] Wherein, E is the elastic modulus of the resin matrix, μ is the Poisson's ratio of the resin matrix, and l is the thickness of the one-way plate.

[0018] Furthermore, the normal fracture energy P is calculated according to the flexible interface damage fracture energy formula. nn , the tangential fracture energy P in the first orthogonal direction ss and the tangential fracture energy P in the second orthogonal direction tt Applied to the flexible interface model to obtain the strength analysis results between interfaces;

[0019] The formula for the damage fracture energy of the flexible interface is as follows:

[0020]

[0021] Among them, σ s Represents the shear strength of the resin matrix in the first orthogonal direction, σ t Represents the shear strength of the resin matrix in the second orthogonal direction, σ n Represents the normal tensile strength of the resin matrix.

[0022] Furthermore, performing finite element simulation analysis using the finite element model of the composite material structure includes: applying corresponding constraints and loads to the finite element model of the composite material structure to obtain stiffness analysis results and / or strength analysis results of the composite material structure.

[0023] On the other hand, the present invention provides a finite element modeling method for composite materials based on a flexible interface model, comprising: dividing the composite material structure into a plurality of split substructures according to the process forming split scheme of the composite material structure; establishing a finite element model of each split substructure; and using a flexible interface model to connect the finite element models of the plurality of split substructures to obtain a finite element model of the composite material structure.

[0024] Compared with the prior art, the invention can achieve the following beneficial effects:

[0025] The composite material finite element simulation method based on the flexible interface model provided by the present invention is suitable for the finite element analysis of complex types of composite material structures. It can improve the consistency between the finite element model of the composite material structure and the actual formed structure of the composite material structure, thereby being beneficial to improving the accuracy of the stiffness analysis results and the strength analysis results of the composite material structure. It can obtain a more accurate interlaminar stress state of the interface of the split substructure, and can provide suggestions and references for the structural design and process design of composite material products. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0027] Figure 1 A schematic diagram of the structure of the T-shaped structure and its process forming split body described in an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of a finite element model of a split substructure of a T-shaped structure according to an embodiment of the present invention;

[0029] Figure 3 A schematic diagram of a finite element model of a split substructure of a T-shaped structure with a 0° direction as described in an embodiment of the present invention;

[0030] Figure 4 A schematic diagram of a support ring structure according to an embodiment of the present invention;

[0031] Figure 5 A partially enlarged schematic diagram of the support ring structure described in an embodiment of the present invention;

[0032] Figure 6 A schematic diagram of the structure of the process forming split body of the support ring structure described in the embodiment of the present invention;

[0033] Figure 7 A schematic diagram of a local finite element model of each split substructure of the support ring structure described in an embodiment of the present invention;

[0034] Figure 8 A data diagram of material parameters of the one-way plate constituting the support ring structure according to an embodiment of the present invention;

[0035] Fig. 9 A data graph of material parameters of the cyclic cyanate resin described in the embodiment of the present invention;

[0036] Fig.10 This is a data diagram of the plying sequence of each substructure of the support ring structure described in the embodiment of the present invention and the material 0° direction.

[0037] Explanation of the reference numerals: 10, inner box; 12, upper inner box interlayer; 13, first integral petal; 23, second integral petal; 20, lower inner box; 22, lower inner box interlayer; 14, first outer facade; 24, second outer facade. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0039] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0040] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0041] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0042] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0043] The invention provides a composite material finite element simulation method based on a flexible interface model, comprising: dividing the composite material structure into a plurality of split substructures according to the process forming split scheme of the composite material structure; establishing a finite element model of each split substructure; connecting the finite element models of the plurality of split substructures using a flexible interface model to obtain a finite element model of the composite material structure; performing finite element simulation analysis using the finite element model of the composite material structure to obtain a stiffness analysis result and / or a strength analysis result of the composite material structure, wherein the stiffness analysis result of the composite material structure includes a stiffness analysis result between interfaces and an overall stiffness analysis result, and the strength analysis result of the composite material structure includes a strength analysis result between interfaces and an overall strength analysis result. Wherein, the interfaces refer to the interfaces between the split substructures.

[0044] In the composite material finite element simulation method based on the flexible interface model provided in the embodiment of the present invention, a flexible interface model is used to connect the finite element models of multiple split substructures to obtain a finite element model of the composite material structure. Compared with the traditional common-node integrated composite material finite element model, in the finite element model of the composite material structure provided in the embodiment of the present invention, the combination of the connection of the split substructures and the flexible interface model is closer to the connection of the actual molding process of the actual composite material structure. Therefore, the results obtained by performing stiffness analysis and strength analysis on the finite element model of the composite material structure are closer to the stiffness state and strength state of the actual composite material structure, which is conducive to improving the accuracy of the simulation analysis.

[0045] It should be noted that, in some embodiments of the present invention, in the finite element simulation method of composite materials based on the flexible interface model, before dividing the composite material structure into a plurality of separate substructures, it may also include: establishing a separate process forming plan for the composite material structure based on the three-dimensional design model of the composite material structure.

[0046] The process forming split scheme of composite material structure refers to: complex composite material structure is usually composed of multiple split sub-structures during actual forming, for example, Figure 1 , Figure 1 The T-shaped structure shown in (a) is a relatively complex composite material structure. Such a T-shaped structure is usually split into 3 or 4 sub-structures during the actual process of forming. Each sub-structure is laid separately and then combined into one, and finally formed into one by curing. By establishing a finite element model of the sub-structure according to the sub-structure in the actual process, and then connecting each sub-structure with a flexible interface model, it is beneficial to ensure that the connection of the sub-structure in the finite element model of the composite material structure and the combination of the flexible interface model are closer to the connection of the actual forming process of the composite material structure.

[0047] The finite element models involved in the embodiments of the present invention are all finite element models established using finite element analysis software.

[0048] Figure 1 The T-shaped structure shown in (a) can be split into Figure 1 The four substructures shown in (b) are as follows: Figure 1 Taking the T-shaped structure and its process forming split scheme as an example, the finite element simulation method of composite materials based on the flexible interface model provided in an embodiment of the present invention is explained.

[0049] refer to Figure 1 and Figure 2 After obtaining the process forming split scheme of the composite material structure (T-shaped structure), the three-dimensional design model of the composite material is split into split substructures according to the process forming split scheme, and a finite element model of each split substructure is established. The finite element model of the split substructure is the finite element model of the plate and shell unit of the split substructure.

[0050] Furthermore, after establishing the finite element model of each substructure, the method further includes: inputting the material parameters of the one-way plate of the substructure into the finite element model of the corresponding substructure, and inputting the material parameters of the resin matrix into the corresponding flexible interface model. For details, refer to Figure 3 , set the ply order and 0° direction of the finite element model of the corresponding split substructure according to the process ply plan of the split substructure. The 0° direction is the extension direction of the fiber in the first layer of the unidirectional plate of the corresponding split substructure. After determining the 0° direction, the extension direction of the fiber in each unidirectional plate in the corresponding split substructure can be determined. The process ply plan of the split substructure is the actual process ply plan of the split substructure.

[0051] Furthermore, the material parameters of the one-way plate include the longitudinal modulus of the one-way plate, the transverse modulus of the one-way plate, the Poisson's ratio of the one-way plate, the longitudinal and transverse shear moduli of the one-way plate, and the interlaminar shear modulus of the one-way plate.

[0052] Furthermore, the material parameters of the resin matrix include the elastic modulus of the resin matrix, the Poisson's ratio of the resin matrix, the normal tensile strength of the resin matrix, and the shear strength of the resin matrix.

[0053] After obtaining the finite element model of the split substructure, the connection interface of the split substructure is connected through a flexible interface model, which is an interaction relationship model between two surfaces. Further, the flexible interface model satisfies formula 1, which is as follows:

[0054]

[0055] Among them, t is the interface force matrix of the split substructure, t n is the normal force between the interfaces of the split substructures, t s is the first orthogonal tangential force between the interfaces of the split substructures, t t is the tangential force in the second orthogonal direction between the interfaces of the split substructures, δ n is the relative normal displacement between the interfaces of the split substructures, δ s is the tangential displacement in the first orthogonal direction between the interfaces of the split substructures, δ t is the tangential displacement in the second orthogonal direction between the interfaces of the split substructures, K nn is the normal stiffness parameter, K ss is the tangential stiffness parameter in the first orthogonal direction, K tt is the tangential stiffness parameter in the second orthogonal direction, K ns , K nt and K st are all 0, K is the interface stiffness matrix, and δ is the interface relative displacement matrix.

[0056] Furthermore, the normal stiffness parameter K is calculated according to the flexible interface stiffness parameter formula: nn , the tangential stiffness parameter K in the first orthogonal direction ss And the tangential stiffness parameter K in the second orthogonal direction tt , the normal stiffness parameter K nn , the tangential stiffness parameter K in the first orthogonal direction ss And the tangential stiffness parameter K in the second orthogonal direction tt Applied to the flexible interface model to obtain the stiffness analysis results between interfaces;

[0057] The formula for the flexible interface stiffness parameter is as follows:

[0058]

[0059] Wherein, E is the elastic modulus of the resin matrix, μ is the Poisson's ratio of the resin matrix, and l is the thickness of the one-way plate.

[0060] Furthermore, the normal fracture energy P is calculated according to the flexible interface damage fracture energy formula. nn , the tangential fracture energy P in the first orthogonal direction ss and the tangential fracture energy P in the second orthogonal direction tt Applied to the flexible interface model to obtain the strength analysis results between interfaces;

[0061] The formula for the damage fracture energy of the flexible interface is as follows:

[0062]

[0063] Among them, σ s Represents the shear strength of the resin matrix in the first orthogonal direction, σ t Represents the shear strength of the resin matrix in the second orthogonal direction, σ n Represents the normal tensile strength of the resin matrix.

[0064] The connection interface of the split substructure is connected through a flexible interface model, that is, the normal stiffness parameter k of the split substructure interface obtained by calculation is nn , tangential stiffness parameter (K ss , k tt ), normal fracture energy P nn and tangential fracture energy (P ss and P tt ) is applied to the flexible interface model. Specifically, if a stiffness analysis is performed, the calculated stiffness parameter k nn , tangential stiffness parameter (K ss , K tt ) is applied to the flexible interface model; if the damage strength analysis and damage evolution analysis of the interface of the split substructure are to be performed, the calculated normal fracture energy P nn and tangential fracture energy (P ss and P tt ) is applied in the flexible interface model.

[0065] Furthermore, performing finite element simulation analysis using the finite element model of the composite material structure includes: applying corresponding constraints and loads to the finite element model of the composite material structure to obtain stiffness analysis results and / or strength analysis results of the composite material structure.

[0066] It should be noted that the strength analysis results between interfaces include the stress state of each split substructure and the interlayer stress state of the split substructure interface; the first orthogonal direction and the second orthogonal direction are perpendicular to each other, and the plane where the first orthogonal direction and the second orthogonal direction are located is the interface between the two split substructures.

[0067] A specific embodiment provided by the present invention is described in detail below.

[0068] refer to Figure 4 and Figure 5 The composite material structure provided in this embodiment is a support ring structure. In some examples, the outer diameter of the support ring structure may be 3500 mm, the inner diameter of the support ring structure may be 3370 mm, and the thickness of each part of the support ring structure may be 8 mm. The composite material finite element simulation method based on the flexible interface model includes the following steps:

[0069] Step 1: Based on the 3D design model of the support ring structure, establish a process forming split scheme for the support ring structure, such as Figure 6 As shown, the split substructure of the support ring structure may include eight parts: an inner box 10, an upper inner box interlayer 12, a first integral petal 13, a second integral petal 23, a lower inner box 20, a lower inner box interlayer 22, a first outer facade 14 and a second outer facade 24.

[0070] Step 2, according to the process forming split plan of the support ring structure, split the three-dimensional design model according to the process forming split plan, and establish finite element models of the upper inner box 10, the upper inner box interlayer 12, the first integral petal 13, the second integral petal 23, the lower inner box 20, the lower inner box interlayer 22, the first outer facade 14 and the second outer facade 24 respectively.

[0071] Step 3: Input the material parameters of the one-way plate of the split substructure into the finite element model of the corresponding split substructure, and input the material parameters of the resin matrix into the corresponding flexible interface model. The material parameters of the one-way plate include longitudinal modulus, transverse modulus, Poisson's ratio, longitudinal and transverse shear modulus and interlaminar shear modulus. The material parameters of the resin matrix include elastic modulus, Poisson's ratio, normal tensile strength and shear strength. When the fiber of the one-way plate is M55 carbon fiber, the material parameters of the one-way plate are as follows: Figure 8 As shown in the figure, when the resin matrix of the one-way board is cyclic cyanate resin, the material parameters of the resin matrix are as follows Fig. 9 shown.

[0072] Step 4: assign a plying sequence and a material 0° direction to each substructure according to the process plying scheme. Specifically, the plying sequence and material 0° direction of each substructure of the support ring structure can be as follows: Fig.10 As shown, the single layer thickness of the laminate (the thickness of the unidirectional board) can be 0.1 mm.

[0073] Step 5, reference Figure 7 , the combined interfaces of each substructure are connected through a flexible interface model, and the normal stiffness parameter K of the interface is calculated by the flexible interface stiffness parameter formula nn , tangential stiffness parameter (K ss and K tt) is applied to the flexible interface model. If the damage strength analysis and damage evolution analysis of the combined interface are performed, the normal fracture energy P needs to be calculated using the flexible interface damage fracture energy formula. nn and tangential fracture energy (P ss and P tt ) is applied in the flexible interface model.

[0074] The specific implementation steps of this step are as follows:

[0075] Select interfaces of each substructure that are in contact with each other during co-curing to be opposite, and apply a flexible interface model connection;

[0076] The parameter K nn , K ss and K tt Input into the flexible interface model;

[0077] If damage strength analysis and damage evolution analysis of the combined interface are to be performed, the parameter P nn , P ss and P tt Input into the flexible interface model;

[0078] The mold limit constraint force and temperature field load are applied to the established finite element model of the support ring structure, and the stress state of the support ring structure during the demolding temperature drop process is calculated. The simulation results of the interlayer delamination position and the fiber fracture position obtained by using the composite material finite element simulation method based on the flexible interface model provided in the embodiment of the present invention are highly consistent with the flaw detection results of the actual product, which verifies the correctness and accuracy of the composite material finite element simulation method based on the flexible interface model provided in the embodiment of the present invention.

[0079] The embodiment of the present invention provides a finite element simulation method for composite materials based on a flexible interface model. The method includes establishing a finite element model of a composite material structure using a flexible interface model. The flexible interface model can realize the interface connection of each substructure. Compared with the existing interface rigid connection methods of common node connection and binding connection, the flexible interface model can fully consider the stiffness of the resin matrix between the substructures, and the finite element modeling is performed in combination with the process partitioning of the actual substructure, which can basically reproduce the process molding process, improve the consistency between the finite element model of the composite material structure and the actual state of the product, and then use the finite element model of the composite material structure to calculate the true stress state of the ply of each substructure, and improve the stress simulation accuracy of the junction position of the substructure. At the same time, the flexible interface model can be used to obtain a high-precision interface interlayer stress state when calculating strength, and more accurate structural deformation and modal results can be obtained when calculating stiffness, which is conducive to providing effective suggestions and references for the structural design and process design of composite products.

[0080] On the other hand, the invention provides a finite element modeling method for composite materials based on a flexible interface model, including: dividing the composite material structure into a plurality of split substructures according to the process forming split scheme of the composite material structure; establishing a finite element model of each split substructure; and using a flexible interface model to connect the finite element models of the plurality of split substructures to obtain a finite element model of the composite material structure. It should be noted that the flexible interface model is the flexible interface model mentioned in the above embodiment. For the specific modeling method, please refer to the above embodiment, which will not be described in detail here.

[0081] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0082] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite material finite element simulation method based on a flexible interface model, characterized in that: include: According to the process forming splitting scheme of the composite material structure, the composite material structure is divided into a plurality of split substructures; Establishing a finite element model of each of the split substructures; Connecting the finite element models of the plurality of split substructures using a flexible interface model to obtain a finite element model of the composite material structure; A finite element simulation analysis is performed using a finite element model of the composite material structure to obtain a stiffness analysis result and / or a strength analysis result of the composite material structure. The stiffness analysis result of the composite material structure includes a stiffness analysis result between interfaces and an overall stiffness analysis result. The strength analysis result of the composite material structure includes a strength analysis result between interfaces and an overall strength analysis result.

2. The composite material finite element simulation method based on the flexible interface model according to claim 1 is characterized in that: After establishing the finite element model of each of the split substructures, the method further includes: Inputting material parameters of the one-way plate of the split substructure into the corresponding finite element model of the split substructure, and inputting material parameters of the resin matrix into the corresponding flexible interface model; The ply laying sequence and 0° direction of the finite element model of the split substructure are set according to the process ply laying scheme of the split substructure.

3. The composite material finite element simulation method based on the flexible interface model according to claim 2 is characterized in that: The material parameters of the one-way plate include the longitudinal modulus of the one-way plate, the transverse modulus of the one-way plate, the Poisson's ratio of the one-way plate, the longitudinal and transverse shear moduli of the one-way plate, and the interlaminar shear modulus of the one-way plate.

4. The composite material finite element simulation method based on the flexible interface model according to claim 2 is characterized in that: The material parameters of the resin matrix include the elastic modulus of the resin matrix, the Poisson's ratio of the resin matrix, the normal tensile strength of the resin matrix and the shear strength of the resin matrix.

5. The composite material finite element simulation method based on the flexible interface model according to claim 1 is characterized in that: The flexible interface model satisfies Formula 1, which is as follows: Among them, t is the interface force matrix of the split substructure, t n is the normal force between the interfaces of the split substructures, t s is the first orthogonal tangential force between the interfaces of the substructures, t t is the tangential force in the second orthogonal direction between the interfaces of the split substructures, δ n is the relative normal displacement between the interfaces of the split substructures, δ s is the tangential displacement in the first orthogonal direction between the interfaces of the split substructures, δ t is the tangential displacement in the second orthogonal direction between the interfaces of the split substructures, K nn is the normal stiffness parameter, K ss is the tangential stiffness parameter in the first orthogonal direction, K tt is the tangential stiffness parameter in the second orthogonal direction, K ns , K nt and K st are all 0, K is the interface stiffness matrix, and δ is the interface relative displacement matrix.

6. The composite material finite element simulation method based on the flexible interface model according to claim 5 is characterized in that: The normal stiffness parameter K is calculated according to the flexible interface stiffness parameter formula: nn , the first orthogonal direction tangential stiffness parameter K ss And the second orthogonal direction tangential stiffness parameter K tt , the normal stiffness parameter K nn , the first orthogonal direction tangential stiffness parameter K ss And the second orthogonal direction tangential stiffness parameter K tt Applying to the flexible interface model to obtain the stiffness analysis result between the interfaces; The flexible interface stiffness parameter formula is as follows: Wherein, E is the elastic modulus of the resin matrix, μ is the Poisson's ratio of the resin matrix, and l is the thickness of the one-way plate.

7. The composite material finite element simulation method based on the flexible interface model according to claim 6 is characterized in that: The normal fracture energy P is calculated based on the flexible interface damage fracture energy formula. nn , the tangential fracture energy P in the first orthogonal direction ss and the tangential fracture energy P in the second orthogonal direction tt Applying to the flexible interface model to obtain strength analysis results between the interfaces; The flexible interface damage fracture energy formula is as follows: Among them, σ s Represents the shear strength of the resin matrix in the first orthogonal direction, σ t Represents the shear strength of the resin matrix in the second orthogonal direction, σ n Represents the normal tensile strength of the resin matrix.

8. The composite material finite element simulation method based on the flexible interface model according to claim 1 is characterized in that: The adopting the finite element model of the composite material structure to perform finite element simulation analysis includes: applying corresponding constraints and loads to the finite element model of the composite material structure to obtain a stiffness analysis result and / or a strength analysis result of the composite material structure.

9. A composite material finite element modeling method based on a flexible interface model, characterized in that: include: According to the process forming splitting scheme of the composite material structure, the composite material structure is divided into a plurality of split substructures; Establishing a finite element model of each of the split substructures; A flexible interface model is used to connect the finite element models of a plurality of the split substructures to obtain a finite element model of the composite material structure.

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