A method and device for calculating the impact damage evolution of a braided composite material structure

Abstract

The present invention discloses a method and device for calculating the impact damage evolution of a braided composite material structure, which belongs to the field of mechanical performance calculation and analysis of composite material structures, and includes: obtaining material parameters and fiber content of a braided composite material; constructing a first representative volume unit model; adding material parameters to the first representative volume unit model, applying a quasi-static load to the first representative volume unit model, and obtaining a damage parameter curve of the braided composite material; applying a velocity load to the first representative volume unit model, and obtaining a stress-strain curve of the braided composite material; obtaining the braiding path of the fiber bundle of the braided composite material, and constructing a second representative volume unit model at a mesoscopic level; substituting the stress-strain curve into the second representative volume unit model, and obtaining a fiber bundle material matrix; and obtaining a damage evolution curve based on the fiber bundle material matrix and a set damage criterion. The present invention takes into account the structural characteristics of the braided composite material and can obtain a dynamic stress-strain curve.

Description

Technical Field

[0001] The invention belongs to the field of mechanical performance calculation and analysis of composite material structures, and in particular relates to a calculation method and a device for impact damage evolution of a braided composite material structure. Background Art

[0002] Braided composite materials are widely used in aerospace, shipbuilding, automobile and impact protection fields due to their advantages such as light weight, high strength, excellent impact resistance and good fatigue performance. The damage evolution of braided composite structures under impact can be effectively obtained by means based on theoretical models and numerical simulations. However, due to the natural multi-scale characteristics of braided composite materials, it is difficult to easily obtain mechanical performance parameters, which limits their widespread use. The existing calculation methods for braided composite structures all use homogenization theory to calculate them as orthogonal anisotropic materials, but the shortcomings of this method are as follows:

[0003] 1) Dynamic material parameters are difficult to obtain. The existing hierarchical multi-scale can only obtain the material parameters of quasi-static loads, but cannot obtain dynamic stress-strain curves.

[0004] 2) The homogenization theory ignores the structural characteristics of braided composite materials. At the mesoscopic level, the fiber bundles of braided composite materials are spatially distributed and are under eccentric stress under external loads, and their stress transfer is along the braiding direction of the fiber bundles. After simplified processing, the predicted damage evolution behavior of braided composite materials is quite different. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a method for calculating the evolution of impact damage of a braided composite material structure to solve the problems existing in the above prior art.

[0006] To achieve the above object, the present invention provides a method for calculating the impact damage evolution of a braided composite material structure, comprising:

[0007] Obtain material parameters and fiber content of woven composites;

[0008] constructing a first representative volume unit model at a microscopic level based on the fiber content;

[0009] adding the material parameters to the first representative volume unit model, and applying a quasi-static load to the first representative volume unit model to obtain a damage parameter curve of the braided composite material;

[0010] Based on the damage parameter curve, applying a velocity load to the first representative volume unit model to obtain a stress-strain curve of the braided composite material;

[0011] Obtaining a fiber bundle braiding path of the braided composite material, and constructing a second representative volume unit model at a mesoscopic level based on the fiber bundle braiding path;

[0012] Substituting the stress-strain curve into the second representative volume unit model to obtain a fiber bundle material matrix;

[0013] Based on the fiber bundle material matrix and the set damage criterion, a damage evolution curve of the braided composite material structure is obtained.

[0014] Preferably, the material parameters include: elastic modulus, Poisson's ratio, energy release rate, and tensile and compressive strength.

[0015] Preferably, the method further comprises applying a dynamic periodic boundary condition to the first representative volume unit model, wherein the dynamic periodic boundary condition is:

[0016]

[0017] in, and Represents the two opposing faces in the RVE cell, is the distance between the two surfaces, is the strain rate, is the duration of the strain rate.

[0018] Preferably, the quasi-static load is a plurality of static loads in an orthogonal relationship.

[0019] Preferably, the fiber bundle material matrix is:

[0020]

[0021] in, , is the elastic modulus of the material in the 1 / 2 / 3 direction, is the Poisson's ratio in the kl direction (k, l = 1,2,3), is the damage factor of material i in the kl direction.

[0022] Preferably, the damage criterion is set as follows:

[0023]

[0024] in, is the equivalent stress in the kl direction, and are the tensile and compressive strengths in the fiber direction, and is the tensile and compressive strength in the resin direction, is the shear strength, is the shear enhancement factor.

[0025] In order to achieve the above technical objectives, the present invention also provides a computing device, which is used to execute the above-mentioned calculation method for the impact damage evolution of the woven composite material structure.

[0026] In order to achieve the above technical objectives, the present invention also provides a computer storage medium, on which computer program instructions are stored. When the computer program instructions are executed by a processor, the impact damage evolution calculation method of the woven composite material structure is implemented.

[0027] Compared with the prior art, the present invention has the following advantages and technical effects:

[0028] The present invention provides a method for calculating the impact damage evolution of a woven composite material structure, comprising: obtaining material parameters and fiber content of the woven composite material; constructing a first representative volume unit model at a microscopic level based on the fiber content; adding the material parameters to the first representative volume unit model, and applying a quasi-static load to the first representative volume unit model to obtain a damage parameter curve of the woven composite material; applying a velocity load to the first representative volume unit model based on the damage parameter curve to obtain a stress-strain curve of the woven composite material; obtaining a fiber bundle weaving path of the woven composite material, and constructing a second representative volume unit model at a mesoscopic level based on the fiber bundle weaving path; substituting the stress-strain curve into the second representative volume unit model to obtain a fiber bundle material matrix; and obtaining a damage evolution curve of the woven composite material structure based on the fiber bundle material matrix and a set damage criterion.

[0029] The present invention can obtain a dynamic stress-strain curve by applying a velocity load to the first representative volume unit model, while solving the technical problem of ignoring the structural characteristics of woven composite materials in the prior art. Compared with the prior art, the present invention predicts the tensile and compressive strength of three-dimensional woven composite materials more accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0031] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0032] Figure 2 1 are representative volume element (RVE) model diagrams of the microscopic and mesoscopic levels of an embodiment of the present invention, wherein (a) is an RVE model of a mesoscopic model, and (b) is an RVE model of a three-dimensional four-directional braided composite material;

[0033] Figure 3 The simulation results of the micro-level RVE model of the embodiment of the present invention at different strain rates, where (a) is the strain rate of 535.43 s -1 Stress-strain curve of (b) when the strain rate is 1328.76 s -1 The stress-strain curve of (c) is the strain rate of 2495.67 s -1 The stress-strain curve of

[0034] Figure 4 For the embodiment of the present invention, Figure 3 Simulation results of the RVE model at different strain rates after inputting the mesoscopic level, where (a) and (b) are at a strain rate of 1380.18 s -1 Stress-strain curves of the impact direction in the transverse and longitudinal directions, respectively. (c) and (d) are at a strain rate of 2535.56 s -1 The stress-strain curves for the transverse and longitudinal impact directions respectively. DETAILED DESCRIPTION

[0035] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0036] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0037] Embodiment 1

[0038] like Figure 1-2 As shown, this embodiment provides a method for calculating the impact damage evolution of a braided composite material structure, taking a three-dimensional four-directional carbon fiber braided composite material as an example, comprising:

[0039] S1: Obtaining material parameters of the fiber and the resin; the material parameters include: elastic modulus, Poisson's ratio, energy release rate, and tensile and compressive strength;

[0040] S2: Establish a micro-level representative volume element (RVE) model based on fiber content and apply dynamic PBC boundary conditions:

[0041] (1)

[0042] In the formula and Represents two opposing faces in the RVE cell, with a distance between them of , strain rate The duration is ;

[0043] S3: Add the material parameters of resin and fiber to the RVE model at the micro level, and apply quasi-static loads in six orthogonal directions to obtain its stress-strain curve. Figure 3 Quasi-static material parameters in ;

[0044] S4: Apply velocity load to the micro-level RVE model according to the target strain rate and calculate it in finite element software (including but not limited to Abaqus) Figure 3 Its stress-strain curve in;

[0045] S5: According to the braiding path and cross-sectional area of ​​the braided fiber bundle, the coordinates of the fiber bundle in space are determined, and modeling is performed in finite element software (including but not limited to Abaqus) through python to obtain the RVE model at the mesoscopic level;

[0046] S6: The strain rate-based stress-strain curves obtained by the micro-level RVE model ( Figure 3 ) is brought into the material properties of the fiber bundle at the mesoscopic level. The material matrix of the fiber bundle at the mesoscopic level is:

[0047] (2)

[0048] (3)

[0049] The damage criteria are as follows:

[0050] (4)

[0051] S7: The damage evolution curve of the material structure is obtained by simulating the RVE model at the mesoscopic level, such as Figure 4 shown.

[0052] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for calculating the impact damage evolution of braided composite structures. It is characterized in that The following steps are involved: Obtain material parameters and fiber content of woven composites; constructing a first representative volume unit model at a microscopic level based on the fiber content; adding the material parameters to the first representative volume unit model, and applying a quasi-static load to the first representative volume unit model to obtain a damage parameter curve of the braided composite material; Based on the damage parameter curve, applying a velocity load to the first representative volume unit model to obtain a stress-strain curve of the braided composite material; Obtaining a fiber bundle braiding path of the braided composite material, and constructing a second representative volume unit model at a mesoscopic level based on the fiber bundle braiding path; Substituting the stress-strain curve into the second representative volume unit model to obtain a fiber bundle material matrix; Based on the fiber bundle material matrix and the set damage criterion, a damage evolution curve of the braided composite material structure is obtained.

2. The method for calculating the impact damage evolution of a braided composite material structure according to claim 1, It is characterized in that The material parameters include: elastic modulus, Poisson's ratio, energy release rate, and tensile and compressive strength.

3. The method for calculating the impact damage evolution of a braided composite material structure according to claim 1, It is characterized in that The method further includes applying a dynamic periodic boundary condition to the first representative volume unit model, wherein the dynamic periodic boundary condition is: in, and Represents the two opposing faces in the RVE cell, is the distance between the two surfaces, is the strain rate, is the duration of the strain rate.

4. The method for calculating the impact damage evolution of a braided composite material structure according to claim 1, It is characterized in that The quasi-static load is a plurality of static loads in an orthogonal relationship.

5. The method for calculating the impact damage evolution of a braided composite material structure according to claim 1, It is characterized in that The fiber bundle material matrix is: in, , is the elastic modulus of the material in the 1 / 2 / 3 direction, for kl Poisson's ratio of direction ( k, l = 1,2,3), For materials i exist kl Directional damage factor.

6. The method for calculating the impact damage evolution of a braided composite material structure according to claim 1, It is characterized in that The damage criterion is set as follows: in, for kl Equivalent stress in the direction, and are the tensile and compressive strengths in the fiber direction, and is the tensile and compressive strength in the resin direction, is the shear strength, is the shear enhancement factor.

7. A computing device, It is characterized in that The computing device is used to execute the impact damage evolution calculation method of the braided composite material structure as described in any one of claims 1-6.

8. A computer storage medium, It is characterized in that The computer storage medium stores computer program instructions, and when the computer program instructions are executed by a processor, the method for calculating the impact damage evolution of a braided composite material structure as described in any one of claims 1 to 6 is implemented.

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