Method, system and equipment for simulating shear nonlinear behavior of composite material

Abstract

The invention discloses a shear nonlinear behavior simulation method, system and equipment for a composite material, and relates to the technical field of analogue simulation computation.The method comprises the steps that shear plastic strain of the composite material is obtained; inputting the shear plastic strain into a shear yield criterion, and adopting a Ludwik model as a hardening function in the shear direction to construct a constitutive equation for describing the elastic-plastic behavior in the composite material layer; a maximum stress criterion is used as a damage generation criterion, and a damage model used for describing generation and evolution of intra-layer damage is constructed through a damage evolution criterion of a damage evolution equation in an index form; constructing a finite element model; obtaining the current stress of the composite material, simulating the stress behavior and the damage process of the composite material based on the constitutive equation and the damage model, determining the updated stress, and when the updated stress reaches the yield stress, obtaining the shear nonlinear behavior of the composite material through finite element model simulation. And determining a nonlinear shear stress-strain relationship.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of simulation and calculation, in particular to a composite material shear nonlinear behavior simulation method, system and device. BACKGROUND

[0002] With the wide application of composite materials in the fields of aerospace, transportation and other fields, especially under the background of the continuous improvement of structural design level, the application of composite materials gradually develops from non-load-bearing structure to load-bearing structure. Composite materials have high specific strength, large specific stiffness, corrosion resistance and other excellent characteristics, and show great potential in structural lightweighting and performance improvement.

[0003] The failure modes of composite materials are diverse, including matrix cracking, fiber fracture and delamination, which increases the complexity of predicting their mechanical properties. The failure modes of composite materials are diverse, mainly including matrix cracking, fiber fracture and delamination. Failure criteria are the basis for predicting the strength of composite materials. According to whether to distinguish the failure mode, the failure criteria can be divided into failure mode distinguishing criteria and failure mode non-distinguishing criteria.

[0004] At present, Hashin criterion is the most widely used failure criterion in engineering applications. Hashin criterion can distinguish four damage modes: fiber tensile failure, fiber compression failure, matrix tensile failure and matrix compression failure. Puck established Puck criterion based on the Mohr-Coulomb fracture surface assumption. Puck criterion can reasonably explain the inter-fiber failure mechanism, and the theoretical prediction results are in good agreement with the experimental results. However, the above failure criteria are typical interlaminar failure criteria, i.e. only considering the failure mode within the single direction of the composite material, and not considering the interlaminar failure.

[0005] Therefore, how to accurately simulate the mechanical properties of composite materials, especially the shear nonlinear behavior, has become a research hotspot. SUMMARY

[0006] The present application provides a composite material shear nonlinear behavior simulation method, system and device to solve the above-mentioned problems existing in the prior art, i.e. how to accurately simulate the shear nonlinear behavior of composite materials in the prior art. The present application provides a composite material shear nonlinear behavior simulation method, which comprises: Obtaining the shear plastic strain of the composite material; Inputting the shear plastic strain into the shear yield criterion, and using Ludwik model as the hardening function in the shear direction to construct the constitutive equation for describing the interlaminar elastic-plastic behavior of the composite material; Taking the maximum stress criterion as the damage initiation criterion, and constructing the damage model for describing the initiation and evolution of interlaminar damage through the damage evolution criterion of the exponential form damage evolution equation; Constructing a finite element model of the composite material based on a finite element method; Obtaining a current stress of the composite material, simulating stress behavior and damage process of the composite material based on a constitutive equation and a damage model, determining an updated stress, simulating a shear nonlinear behavior of the composite material by the finite element model when the updated stress reaches a yield stress, determining a finite element analysis result, and extracting a nonlinear shear stress-strain relationship from the finite element analysis result.

[0007] Optionally, the obtaining of the shear plastic strain specifically includes: The shear plastic strain is obtained by using the following formula: wherein, is the shear plastic strain, is an elastic strain component, is a plastic strain component.

[0008] Optionally, the inputting of the shear plastic strain into a shear yield criterion and the adoption of a Ludwik model as a hardening function in a shear direction specifically includes: According to the shear plastic strain, an effective stress is obtained by using the following formula to describe an elastic-plastic behavior in the shear direction: In an effective stress space, a shear yield criterion is obtained by using the following formula: wherein, K is a hardening function, and is used to describe a size of a plastic yield surface; The hardening function is obtained by using the following formula: wherein, A and n are both fitting coefficients, is an initial yield stress.

[0009] Optionally, the shear nonlinear behavior of the composite material specifically includes: Elastic deformation, plastic deformation and damage evolution process.

[0010] Optionally, the composite material specifically includes: carbon fiber woven composite material and glass fiber woven composite material.

[0011] The present application provides a shear nonlinear behavior simulation system of a composite material, comprising: An obtaining module is configured to obtain a shear plastic strain of the composite material. The constitutive equation construction module is configured to input the shear plastic strain into the shear yield criterion and adopt a Ludwik model as a hardening function in the shear direction to construct a constitutive equation for describing the elastic-plastic behavior of the composite material layer; The damage model construction module is configured to adopt a maximum stress criterion as a damage initiation criterion and adopt a damage evolution criterion of an exponential form damage evolution equation to construct a damage model for describing the initiation and evolution of the damage in the layer. The finite element model construction module is configured to construct a finite element model of the composite material based on a finite element method. The simulation module is configured to acquire a current stress of the composite material, simulate the stress behavior and damage process of the composite material based on the constitutive equation and the damage model, determine an updated stress, simulate the shear nonlinear behavior of the composite material by the finite element model when the updated stress reaches a yield stress, determine a finite element analysis result, and extract a nonlinear shear stress-strain relationship from the finite element analysis result.

[0012] The application provides a computer device, which comprises a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and the processor implements the above-mentioned simulation method for the shear nonlinear behavior of the composite material when executing the program.

[0013] Compared with the prior art, the application has the following beneficial effects: the application provides a simulation method for the shear nonlinear behavior of a composite material, which adopts a maximum stress criterion as a damage initiation criterion for the damage mode in the layer of the woven composite material. The damage evolution criterion adopts an exponential form to describe the evolution law of the damage in the material after the damage initiation. Meanwhile, the bilinear cohesive force model is adopted to describe the interlayer damage and failure behavior. In addition, the load displacement curve, damage distribution, and failure morphology of the composite material in the shear loading process are obtained through finite element simulation analysis. BRIEF DESCRIPTION OF DRAWINGS

[0014] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate an embodiment consistent with the application and, together with the description, serve to explain the principles of the application.

[0015] Figure 1 A flowchart of the simulation method for the shear nonlinear behavior of the composite material provided in the embodiment of the application is shown in the figure. Figure 2 A size diagram of the in-plane shear test piece provided in the embodiment of the application is shown in the figure. Figure 3 A load displacement curve and a shear stress-shear strain curve of the woven composite material provided in the embodiment of the application are shown in the figure. Wherein, Figure 3 (a) in the figure is the load displacement curve of the glass fiber test piece.Figure 3 (b) is a stress-strain curve of the glass fiber test piece of (a); Figure 3 (c) is a load-displacement curve of the carbon fiber test piece of (b); Figure 3 (d) is a stress-strain curve of the carbon fiber test piece of (c); Figure 4 A woven composite material layer material constitutive implementation flowchart provided by the embodiment of the application; Figure 5 An impact schematic diagram of the parameter α on the load-displacement curve provided by the embodiment of the application; Figure 5 (a) is a glass fiber composite material; Figure 5 (b) is a carbon fiber composite material; Figure 6 A comparison diagram of the impact of shear nonlinearity on the prediction result provided by the embodiment of the application; Figure 6 (a) is a glass fiber composite material; Figure 6 (b) is a carbon fiber composite material; Figure 7 A carbon fiber composite material damage and shear plastic strain cloud diagram provided by the embodiment of the application; Figure 8 A glass fiber composite material damage and shear plastic strain cloud diagram provided by the embodiment of the application; Figure 9 A computer device schematic diagram of the shear nonlinearity behavior simulation method of the composite material provided by the embodiment of the application. DETAILED DESCRIPTION

[0016] To make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0017] The technical solutions of the present application and how the technical solutions of the present application solve the above technical problems will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes can not be described again in some embodiments. The embodiments of the present application will be described below in combination with the drawings.

[0018] Figure 1 A flowchart of the shear nonlinearity behavior simulation method of the composite material provided by the embodiment of the present application, as shown in Figure 1 ​​As shown, the embodiment of the present application illustrates a composite material shear nonlinear behavior simulation method, which comprises: S1: obtaining the shear plastic strain of the composite material.

[0019] For example, the progressive damage analysis of the woven composite material needs to consider the intralaminar damage and interlaminar damage. Before the cohesive constitutive model is used to describe the interlaminar damage and failure behavior, the shear plastic strain needs to be obtained first. The shear plastic strain can be obtained by using the following formula: wherein, is the shear plastic strain, is the elastic strain component, is the plastic strain component.

[0020] For example, the in-plane shear response of the woven composite material can be tested by using the ± 45° laminated plate tensile test according to the ASTM D3518 standard. The materials of the in-plane shear test pieces include carbon fiber woven composite material and glass fiber woven composite material, and the models are CF3052 / 3238A and EW250F / 3238A respectively. The size of the test piece is as shown in the figure. Figure 2 The woven composite material is 10 layers, and the layer angle is ± 45°. The thickness of the single layer of the carbon fiber composite material is 0.36mm, and the total thickness t1=3.6mm, t2=6.6mm. The thickness of the single layer of the glass fiber composite material is 0.31mm, and the total thickness t1=3.1mm, t2=6.1mm. The in-plane tensile test of the woven composite material is carried out by using the MTS370.25, and the loading speed is 2mm / min. The strain data in the test process is collected by using the strain gauge.

[0021] S2: inputting the shear plastic strain into the shear yield criterion, and using the Ludwik model as the hardening function in the shear direction to construct the constitutive equation for describing the intralaminar elastic-plastic behavior of the composite material.

[0022] Optionally, the inputting of the shear plastic strain into the shear yield criterion and the using of the Ludwik model as the hardening function in the shear direction specifically comprises: According to the shear plastic strain, the effective stress is obtained by using the following formula to describe the elastic-plastic behavior in the shear direction: In the effective stress space, the shear yield criterion is obtained by using the following formula: wherein, K is the hardening function, which is used to describe the size of the plastic yield surface; The hardening function is obtained by using the following formula: wherein A and n are both fitting coefficients, is the initial yield stress.

[0023] The shear property data of the woven composite material is shown in Table 1.

[0024] Table 1 Shear property data of the woven composite material S3: Taking the maximum stress criterion as the damage initiation criterion, a damage evolution criterion is constructed by the damage evolution equation in the exponential form to construct a damage model for describing the initiation and evolution of the interlaminar damage.

[0025] S4: A finite element model of the composite material is constructed based on the finite element method.

[0026] Exemplarily, the finite element model of the woven composite material can be established based on the abaqus software, the SC8R continuous shell element is used to simulate the interlaminar single-layer composite material, the COH3D8 cohesive element is used to simulate the interlaminar adhesive layer, and the global grid size is 1mm. Reference points are established at both ends of the test piece, and the reference points and the end stiffeners are constrained together by coupling constraints. The displacement boundary condition is applied to the finite element model through the reference point.

[0027] S5: The current stress of the composite material is obtained, the stress behavior and damage process of the composite material are simulated based on the constitutive equation and the damage model, the updated stress is determined, when the updated stress reaches the yield stress, the shear nonlinear behavior of the composite material is simulated through the finite element model, the finite element analysis result is determined, and the nonlinear shear stress-strain relationship is extracted from the finite element analysis result.

[0028] Optionally, the shear nonlinear behavior of the composite material specifically includes: elastic deformation, plastic deformation and damage evolution process.

[0029] Optionally, the composite material specifically includes: carbon fiber woven composite material and glass fiber woven composite material.

[0030] Exemplarily, the progressive damage analysis of the woven composite material needs to consider the interlaminar damage and the interlaminar damage, and the interlaminar cohesive model is established by the present application, and the interlaminar damage and failure behavior are described by the cohesive constitutive relation.

[0031] Exemplarily, based on the method of continuous medium damage mechanics, the influence of damage on the interlaminar stress-strain relationship of the woven composite material is described by introducing a damage variable d: where d1 and d2 represent the fiber damage in the longitudinal and transverse directions, respectively, d 12 is the shear damage; σ 11 , σ 22 and τ 12 are the normal stresses and in-plane shear stress in directions 1 and 2, respectively; ε 11 , ε 22 and γ 12 are the normal strains and in-plane shear strain in directions 1 and 2, respectively; E1, E2 and G 12 are the Young's moduli and in-plane shear modulus in directions 1 and 2, respectively; v 12 and v 21 are the Poisson's ratios, satisfying v 12 / E1= v 21 / E2.

[0032] To distinguish the effects of tension and compression on damage, tension-compression damage variables d 1t , d 1c , d 2t and d 2c are introduced in both the longitudinal and transverse directions, where the subscript t represents tension and c represents compression. The total damage in the longitudinal and transverse directions is defined by

[0033] The Young's moduli in the longitudinal and transverse directions also consider the tension-compression anisotropy, such that when ε 11 + ε 22 > 0, E1= E 1t , E2= E 2t , In general, a plain weave laminate is relatively thin, so the in-plane damage only considers the mechanical properties in the warp and weft directions, and ignores the out-of-plane mechanical properties perpendicular to the panel direction. The in-plane damage modes of a woven laminate include the tensile and compressive failure of the warp fibers, the tensile and compressive failure of the weft fibers, and the fiber-matrix shear failure.

[0034] To predict the initiation and evolution of various in-plane damage modes, the following damage initiation criteria can be used as examples: f ( pha , rα ) = pha - rα ≤ 0 where α = 1t, 1c, 2t, 2c or 12, φ α is the failure criterion in different directions, and r α is the damage threshold, which has an initial value of 1.

[0035] For example, the damage evolution criterion defines the evolution law of the internal damage of the material after the effective stress reaches the damage surface. After the damage initiation, the effective stress state of the material remains on the damage surface, and according to the damage consistency condition:

[0036] By integrating the above formula and considering r α The initial value is 1 and the damage is irreversible, and the damage threshold can be obtained; the damage evolution equation in the exponential form can be used to describe the damage evolution law in the meridian direction and the latitude direction: Wherein, A α is a model parameter, is the fracture energy of the material, L c is the characteristic length of the unit, is the elastic energy density; The specific calculation formula of the elastic energy density is as follows: The logarithmic linear correlation between the shear damage and the shear damage threshold is as follows: In the formula, and are material parameters.

[0037] For example, the interlaminar cohesion model in the embodiment, that is, the interlaminar constitutive relation of the plain weave composite material can be described by using the biaxial linear cohesive model. The relationship between the traction force and the opening displacement satisfies the following formula:

[0038] Wherein, t i is the traction force, K i is the interface stiffness, δ i is the opening displacement, i=n, s, t represents three different directions.

[0039] The quadratic stress criterion is used to judge the damage initiation of the interface, and when the traction force on the interface satisfies the following relationship, the damage begins to initiate: In the formula, t is the interface strength.

[0040] After the damage initiation, the damage parameter D is introduced to describe the material softening.

[0041] The final failure criterion of the interface is described by the BK criterion. Where, GS=Gs+G, GT=Gn+Gs, Gn, Gs, and Gt are the fracture energy release rates in three directions respectively.

[0042] The load-displacement curve and stress-strain curve were obtained through the experiment. Figure 3 As shown in Figure 2 (since the strain gauge failed at approximately 70,000 με, only the first portion of the stress-strain curve was collected). It can be seen that both specimens exhibited linear elasticity at the initial loading stage, but exhibited significant nonlinear behavior as the deformation gradually increased.

[0043] according to Figure 3 The obtained test data are calculated with reference to ASTM D3518 standard to obtain the shear elastic modulus G, failure stress S and yield strength of the two composite materials. Listed in Table 1.

[0044] Table 1 Shear performance data of woven composite materials The failure mode for both composite materials in the specimens was fiber fracture in the ±45° direction. The specimens exhibited significant irreversible deformation, and a necking phenomenon similar to metal plasticity occurred near the fracture surface. Comparison of the fractured glass fiber specimens with the original specimens revealed extensive diffuse damage within the specimens, primarily consisting of fiber debonding and matrix damage. Observation of the fracture surfaces also revealed fiber breakage and significant fiber angle deflection.

[0045] For example, Abaqus software is used to simulate the progressive failure process of plain woven composite materials, and the Vumat subroutine is used to realize the initiation and evolution of intra-laminar damage and shear nonlinearity.

[0046] The incremental method is used to update the stress, strain and damage state of the material in the warp and weft directions. The plasticity in the shear direction is completely decoupled from the other two directions. The fully implicit backward Euler algorithm can be used to obtain: The process of numerical algorithm implementation is as follows Figure 4 As shown in Figure 3, the entire calculation process consists of two parts. Linear elastic constitutive models are used in the warp and weft directions, damage evolution is performed after damage initiation, and a step of updating plastic stress and strain is added in the shear direction.

[0047] The constitutive equation, damage initiation criterion, failure criterion and shear nonlinear behavior of the in-plane plain weave composite material are realized through the VUMAT subprogram, the interlaminar cohesive force model is realized through the built-in material attribute of Abaqus, and the material attributes of the in-plane and interlaminar are listed in Tables 2 and 3. Among them, the shear nonlinear parameters A and n are obtained by fitting the test curve, and the shear α is obtained by parameter identification.

[0048] Table 2 In-plane material properties of woven composite material Table 3 Interlaminar cohesive force model parameters Firstly, the influence of shear damage parameter α on the simulation results is discussed, and the appropriate material parameters are determined by parameter identification. Figure compares the influence of damage parameter α on the load displacement curve. From Figure 5 It can be found that the damage parameter α mainly affects the ultimate load, and has little effect on the nonlinear segment. With the increase of α, the ultimate load and failure displacement of glass fiber and carbon fiber composite material are obviously reduced. According to the calculation results, for carbon fiber composite material and glass fiber composite material, when α is 0.5 and 0.8 respectively, the simulation curve is in good agreement with the test curve. Therefore, α is taken as 0.5 and 0.8 as the material parameters of glass fiber and carbon fiber composite material in this paper.

[0049] Figure 6 The influence of shear nonlinearity on load displacement curve and ultimate load is compared. It can be found that when the shear nonlinearity is not considered, the load displacement curve shows a linear growth and then a sudden drop. After considering the shear nonlinearity, the calculation result can accurately reflect the nonlinear characteristics of the load displacement obtained by the test.

[0050] In order to further verify the accuracy of the model in predicting the damage and failure of woven composite material, the difference between the linear model and the model of the application in damage prediction and the test results is analyzed. Table 4 compares the ultimate load and ultimate displacement calculated by the two models. It can be found that the model selection has little effect on the ultimate load, and the prediction error is less than 5%. However, the ultimate displacement predicted by the linear model has a large error with the test result, reaching about 80%. The ultimate displacement error calculated by the method of the application is less than 2%, which also proves the accuracy of the shear nonlinearity model.

[0051] Table 4 Comparison of linear model and nonlinear model prediction Figure 7The carbon fiber composite material damage and shear plastic strain distribution cloud diagram obtained by simulation can be found. The dominant factor of composite material failure is the shear damage near the fracture. Although the longitudinal and latitudinal damage appears near the fracture, the size and distribution range of the two kinds of damage are small. At the same time, it can be found that a large range of shear plastic strain appears in the test piece, which also leads to the obvious irreversible deformation of the composite material. Figure 8 The glass fiber composite material damage and shear plastic strain distribution cloud diagram obtained by simulation can be found. It can be found that the damage distribution of glass fiber is obviously different from that of carbon fiber composite material. The glass fiber composite material also appears slight longitudinal and latitudinal damage, but they are concentrated near the clamping end and do not cause time damage. The shear damage distribution of the two kinds of composite materials is obviously different. The shear damage of the carbon fiber composite material is concentrated near the fracture, and the glass fiber composite material appears diffuse damage and shear plastic strain throughout the test piece.

[0052] According to the post-fracture morphology of the test piece, it can be found that the necking phenomenon appears near the fracture of the carbon fiber test piece, which is consistent with the test obtained post-fracture morphology. Therefore, by considering the influence of shear plasticity, the irreversible deformation of the composite material test piece in the loading process can be accurately described. The calculation results of the linear elastic model are shown in the figure. By comparison, it can be found that the linear elastic model cannot simulate the irreversible deformation of the composite material in the shear loading process, and the simulation results are obviously different from the true results. It can be found from the test results of glass fiber that a large area of plastic damage appears in the test piece during loading, which also leads to the change of the color of the glass fiber. The plastic damage distribution calculated by the model of the application is basically consistent with the phenomenon observed by the test. In addition, according to the test results, it can be found that there is an obvious damage transition zone near the clamping end of the test piece, that is, due to the influence of the clamping end constraint, the end of the test piece does not produce obvious damage. The numerical simulation results of the application also capture similar phenomena, that is, there is an obvious damage transition zone near the clamping end, and the transition zone morphology is consistent with the test results. The model used in the application can accurately reflect the failure morphology of the shear loading of the composite material, thereby proving the accuracy of the model of the application.

[0053] The application carries out test and numerical simulation analysis on the shear nonlinear behavior of woven composite material, accurately describes the shear nonlinear behavior of woven composite material by using a nonlinear constitutive model considering shear plasticity, and obtains the shear nonlinear parameters of woven composite material through parameter identification. The application can draw the following conclusions:

[0054] (1) The shear behavior of woven composite material is similar to the plasticity of metal, and obvious irreversible deformation and "necking phenomenon" appear in the tensile process, so the relevant theory of metal plasticity can be used to describe the macroscopic response of shear nonlinearity.

[0055] (2) The nonlinear constitutive equation considering shear plasticity adopted in the present application can accurately describe the shear nonlinear behavior of the woven composite material, the load displacement curve and damage distribution obtained by numerical simulation are similar to the test, and the fracture morphology and plastic distribution obtained by simulation are consistent with the test results, verifying the accuracy of the model of the present application.

[0056] (3) There is a significant difference in shear damage distribution between carbon fiber composite material and glass fiber composite material, the damage of carbon fiber composite material is concentrated near the fracture, and the glass fiber composite material appears diffuse damage in the test piece.

[0057] The above is the simulation method of the shear nonlinear behavior of the composite material provided by one or more embodiments of the present application, based on the same idea, the present application also provides a corresponding simulation system of the shear nonlinear behavior of the composite material, comprising: The acquisition module is configured to acquire the shear plastic strain of the composite material. The constitutive equation construction module is configured to input the shear plastic strain into the shear yield criterion, and use the Ludwik model as the hardening function in the shear direction to construct the constitutive equation for describing the elastic-plastic behavior in the layer of the composite material. The damage model construction module is configured to use the maximum stress criterion as the damage initiation criterion, and construct a damage model for describing the initiation and evolution of the damage in the layer through the damage evolution criterion of the exponential form of the damage evolution equation. The finite element model construction module is configured to construct a finite element model of the composite material based on the finite element method. The simulation module is configured to acquire the current stress of the composite material, simulate the stress behavior and damage process of the composite material based on the constitutive equation and the damage model, determine the updated stress, simulate the shear nonlinear behavior of the composite material through the finite element model when the updated stress reaches the yield stress, determine the finite element analysis result, and extract the nonlinear shear stress-strain relationship from the finite element analysis result.

[0058] The specific limitations of the simulation system of the shear nonlinear behavior of the composite material can be referred to the limitations of the simulation method of the shear nonlinear behavior of the composite material in the above, which will not be repeated here. Each module in the simulation system of the shear nonlinear behavior of the composite material can be realized by software, hardware and their combination. The above modules can be embedded in or independent of the processor in the computer device in hardware form, or can be stored in the memory in the computer device in software form, so that the processor can call and execute the operations of the above modules.

[0059] The present application also provides Figure 9 The structure diagram of the computer device is shown in the figure, such as Figure 9As shown, at the hardware level, the computer device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory, and of course can also include other hardware required by the business. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs to implement the composite material shear nonlinear behavior simulation method provided by the above embodiments.

[0060] The technical features of the above embodiments can be combined in any manner. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope disclosed by the present application.

Claims

1. A method for simulating the shear nonlinear behavior of a composite material, characterized in that: include: Obtain shear plastic strain of composite materials; The shear plastic strain is input into the shear yield criterion, and the Ludwik model is used as the hardening function in the shear direction to construct the constitutive equation for describing the elastic-plastic behavior within the composite layer. Taking the maximum stress criterion as the damage initiation criterion and the damage evolution criterion of the exponential damage evolution equation, a damage model is constructed to describe the initiation and evolution of intralayer damage. Construct finite element models of composite materials based on the finite element method; Obtain the current stress of the composite material, simulate the stress behavior and damage process of the composite material based on the constitutive equation and damage model, determine the updated stress, and when the updated stress reaches the yield stress, simulate the shear nonlinear behavior of the composite material through the finite element model, determine the finite element analysis results, and extract the nonlinear shear stress-strain relationship from the finite element analysis results.

2. The method for simulating the shear nonlinear behavior of a composite material according to claim 1, wherein: The acquisition of the shear plastic strain specifically includes: The shear plastic strain is obtained using the following formula: in, is the shear plastic strain, is the elastic strain component, is the plastic strain component.

3. The method for simulating the shear nonlinear behavior of a composite material according to claim 2, wherein: The shear plastic strain is input into the shear yield criterion, and the Ludwik model is used as the hardening function in the shear direction, specifically including: Based on the shear plastic strain, the effective stress is obtained using the following formula to describe the elastic-plastic behavior in the shear direction: In the effective stress space, the shear yield criterion is obtained using the following formula: Where K is the hardening function, which is used to describe the size of the plastic yield surface; The hardening function is obtained using the following formula: Among them, A and n are fitting coefficients, is the initial yield stress.

4. The method for simulating the shear nonlinear behavior of a composite material according to claim 1, wherein: The shear nonlinear behavior of the composite material specifically includes: Elastic deformation, plastic deformation and damage evolution process.

5. The method for simulating the shear nonlinear behavior of a composite material according to claim 1, wherein: The composite materials specifically include: carbon fiber woven composite materials and glass fiber woven composite materials.

6. A shear nonlinear behavior simulation system for composite materials, characterized in that: include: Acquisition module, used to obtain shear plastic strain of composite materials; A constitutive equation building module is used to input shear plastic strain into the shear yield criterion and use the Ludwik model as the hardening function in the shear direction to construct the constitutive equation for describing the elastic-plastic behavior within the composite layer; A damage model construction module is used to construct a damage model for describing the initiation and evolution of intralayer damage using the maximum stress criterion as the damage initiation criterion and the damage evolution criterion of the exponential damage evolution equation; Finite element model building module, used to build finite element models of composite materials based on the finite element method; The simulation module is used to obtain the current stress of the composite material, simulate the stress behavior and damage process of the composite material based on the constitutive equation and damage model, determine the updated stress, and when the updated stress reaches the yield stress, obtain the shear nonlinear behavior of the composite material through finite element model simulation, determine the finite element analysis results, and extract the nonlinear shear stress-strain relationship from the finite element analysis results.

7. A computer device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor. When the processor executes the program, the method for simulating the shear nonlinear behavior of the composite material according to any one of claims 1 to 5 is realized.

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