Composite material microcosmic failure analysis method based on micromechanics failure theory

Abstract

The invention discloses a composite material microcosmic failure analysis method based on a micromechanical failure theory. The method comprises the following steps: obtaining performance parameters of each component of a composite material according to a composite material component performance test; establishing a finite element mesoscopic RVE model; the rigidity of the interface between the fiber and the matrix is reversely deduced through fitting of experimental data of a macroscopic experiment; applying a periodic boundary condition to the finite element mesoscopic RVE model; a load is applied to the finite element mesoscopic RVE model through ABAQUS finite element software, the failure behavior of the composite material in a complex stress state is simulated, and the stress-strain relation and the mesoscopic failure rule of the composite material in different loading modes are predicted. The method can be applied to composite material mesoscopic failure simulation analysis in axial, transverse and off-axis load, thermal load and composite load forms, can more accurately predict the mesoscopic failure rule of the composite material, and has important significance on research and application of the composite material.

Description

Technical Field

[0001] The invention relates to the technical field of progressive failure of metal matrix composite materials, in particular to a composite material microscopic failure analysis method based on microscopic mechanics failure theory. Background Art

[0002] Fiber-reinforced metal matrix composites have the following advantages: (1) high specific strength and large specific modulus; (2) designable material properties; (3) good corrosion resistance and durability; (4) small thermal expansion coefficient. Brittle fibers such as silicon carbide fibers, carbon fibers, and boron fibers have the advantages of high hardness and high specific modulus and are widely used as the reinforcement phase of composite materials.

[0003] As a new material in the aviation field, SiC / Ti composites have been applied to low-pressure turbine shafts, integral blade rings, and blades of aircraft engines. Due to the addition of reinforcement phases and the existence of interfaces, the damage evolution of SiC / Ti composites is complex and may involve multiple failure modes, such as fiber breakage, matrix yielding, matrix cracking, fiber-matrix interface debonding, etc. There is a strong interaction between them, which makes its failure analysis more difficult. In addition, in actual engineering applications, due to the diversity of composite structures (such as layer structures and open-pore structures) and the complexity of loads, composite structures are inevitably subject to complex loads. Therefore, considering the geometric inhomogeneity of the composite microstructure and the complex load state of actual working conditions, the fiber and matrix will play different roles under different conditions, and it becomes more difficult to analyze the failure behavior of composite materials under complex stress states.

[0004] The commonly used composite material failure analysis methods fail to take into account the interface model of the composite fiber surface and the failure model of the interface, and cannot accurately reflect the failure process of the composite material caused by damage to the microscopic component materials. It is necessary to propose a more accurate composite material microscopic failure analysis method based on the existing analysis method. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a composite material mesoscopic failure analysis method based on micromechanical failure theory that can accurately reflect the failure process of the composite material caused by damage to the mesoscopic component materials.

[0006] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0007] The present invention is a composite material microscopic failure analysis method based on micromechanical failure theory, comprising the following operations:

[0008] Obtain the performance parameters of each component of the composite material according to the composite material component performance test;

[0009] A finite element mesoscopic RVE model is established based on the performance parameters of each component of the composite material;

[0010] The stiffness of the interface between the fiber and the matrix in the composite material is inferred by fitting the experimental data of the macroscopic experiment; periodic boundary conditions are applied to the finite element mesoscopic RVE model to make the finite element mesoscopic RVE model compatible with load forms including axial load, shear load, thermal load and corresponding various load combination forms;

[0011] The load is applied to the finite element mesoscopic RVE model through ABAQUS finite element software, and the failure behavior of the composite material under complex stress state is simulated, and the stress-strain relationship and mesoscopic failure law of the composite material under different loading modes are predicted.

[0012] A further improvement of the present invention is that the composite material component performance test includes a composite material nano-indentation test and a fiber push-out test.

[0013] A further improvement of the present invention is that the composite material is a SiC / Ti metal-based composite material.

[0014] The further improvement of the present invention is that the composite material includes fibers, a matrix, an interface and a coating, and the established finite element RVE microscopic model includes a fiber failure model, a matrix failure model, an interface damage failure model and a coating; wherein the fiber failure model adopts a three-dimensional Hashin criterion, specifically including:

[0015] Fiber axial tensile failure, σ 11 ≥11:

[0016]

[0017] Fiber axial compression failure, σ 11 <11:

[0018]

[0019] Among them, X T is the fiber tensile strength, X C is the fiber compression strength, S 12 is the fiber shear strength, σ 11 is the axial stress on the fiber, σ 12 and σ 13 is the shear stress on the fiber;

[0020] The matrix failure model adopts the Mises criterion, and the Mises equivalent stress is expressed as:

[0021]

[0022] in, is the Mises equivalent stress on the matrix, σ x , σ y , σ z is the normal stress on the matrix in the three coordinate axis directions, τ xy , τ yz , τ zx is the shear stress on the matrix in the directions of the three coordinate axes;

[0023] Interface damage failure models include:

[0024] The secondary failure criterion is used to evaluate the interface damage:

[0025]

[0026] Among them, <σ n > indicates that pure compressive stress will not cause interface damage, N max , S max , and T max are the interfacial bonding strengths corresponding to the opening, sliding, and tearing cracks, respectively, and δ n ,δ s ,δ t is the opening displacement in the normal direction, the first shear direction, and the second shear direction;

[0027] When the cohesive element meets the secondary failure criterion, the Benzeggagh-Kenane criterion is used to define the damage evolution under the mixed stress mode.

[0028] A further improvement of the present invention is that a periodic boundary condition is applied to the finite element mesoscopic RVE model, specifically comprising: the finite element mesoscopic RVE model is any parallelepiped RVE model, and the periodic displacement field on a pair of opposite surfaces of any parallelepiped RVE model is expressed as:

[0029]

[0030] in, Indicates that along X j The displacement of the axis in the positive direction, Indicates that along X j The displacement of the axis in the negative direction, is the average strain of any parallelepiped RVE model, The parallelepiped RVE model boundary surface along X j The coordinates of any point in the positive direction of the axis, The parallelepiped RVE model boundary surface along X j The coordinates of any point in the negative direction of the axis, is the periodic displacement correction value;

[0031] Subtract the periodic displacement fields on a pair of relative surfaces to obtain the relationship between the displacements of the two points:

[0032]

[0033] in, It represents the coordinate difference between two corresponding points on a pair of parallel planes;

[0034] The unified periodic boundary conditions are:

[0035]

[0036] in, is the distance between a pair of parallel planes, and (x, y, z) is the coordinate of any point on the boundary surface of the parallelepiped RVE model.

[0037] The further improvement of the present invention is that: for the finite element mesoscopic RVE model in which the nodes of the coating and the substrate are overlapped at the boundary, the process of automatic identification of nodes and automatic application of periodic boundary conditions is as follows: a. Distinguish the overlapping nodes, divide all the nodes of the finite element mesoscopic RVE model into two groups, put the nodes located in the fiber and coating parts into the set Assembly_1, and put the nodes located in the substrate part into the set Assembly_2, the set Assembly_1 and the set Assembly_2 include all the nodes of the finite element mesoscopic RVE model, and there are no nodes with overlapping positions in each of them;

[0038] b. Take the set Assembly_1, select all nodes on the boundary surface based on the node position and classify them, put the eight corner nodes into the sets Node1 to Node8, put the nodes on the twelve edges into the sets Edge1 to Edge12, and put the nodes on the six surfaces into the sets Face1 to Face6; c. Reorder the nodes, and sort the corresponding points in different sets to the same order in their respective sets;

[0039] d. According to the expression Establish constraints on all nodes in the assembly_1;

[0040] e. Repeat operations b, c, and d to establish constraints for all nodes in the assembly Assembly_2.

[0041] The beneficial effects of the present invention are as follows: the composite material micro-progressive failure analysis method proposed in the present invention can be applied to the calculation and analysis of various tensile, torsion, eccentric loads, thermal loads and composite load forms, and can more accurately predict the micro-failure laws of composite materials, which is of great significance to the research and application of composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a flow chart of a method in an embodiment of the present invention;

[0043] Figure 2 is a schematic diagram of a finite element mesoscopic RVE model in an embodiment of the present invention;

[0044] Figure 3 is a constitutive relationship diagram of the Ti6Al4V matrix in an embodiment of the present invention;

[0045] Figure 4 is a schematic diagram of traction stress-separation displacement of a bilinear cohesive force model under tension in an embodiment of the present invention;

[0046] Figure 5 Schematic diagram of elastic modulus of SiC / Ti composite material at different off-axis angles in an embodiment of the present invention;

[0047] Figure 6 is a schematic diagram of a finite element mesoscopic RVE model with periodic boundary conditions applied in an embodiment of the present invention;

[0048] Figure 7 is a schematic diagram of a unified periodic boundary condition in an embodiment of the present invention;

[0049] Figure 8 Schematic diagram of axial residual thermal stress of the RVE model of SiC / Ti6Al4V composite material in an embodiment of the present invention;

[0050] Fig. 9 Schematic diagram of interface residual stress of RVE model of SiC / Ti6Al4V composite material in an embodiment of the present invention;

[0051] Fig.10 Schematic diagram of the axial stress-strain relationship of the SiC / Ti6Al4V composite material in an embodiment of the present invention;

[0052] Fig.11 Schematic diagram of the transverse stress-strain relationship of the SiC / Ti6Al4V composite material in an embodiment of the present invention;

[0053] Fig.12 It is a schematic diagram of the 45° eccentric stress-strain relationship of the SiC / Ti6Al4V composite material in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0055] The present invention proposes a composite material microscopic failure analysis method based on micromechanical failure theory. Combined with the micromechanical failure theory, the failure criteria of each component of the composite material are selected to evaluate the microscopic damage failure type of SiC / Ti6Al4V composite material, the influence of the interface cohesive unit on the overall performance of the composite material is considered, and the actual stiffness of the composite material interface is estimated by fitting. The Python language can be used to write a callable periodic boundary condition subroutine to apply boundary conditions to the RVE model. This method can be used to simulate the calculation and analysis of composite materials under various tensile, torsion, eccentric loads, thermal loads and composite loads.

[0056] In this embodiment, a microscopic failure analysis of SiC / Ti-6Al-4V composite material is performed. Figure 1 As shown, the following steps are included:

[0057] Step 1, obtain the performance parameters of each microscopic component of the SiC / Ti-6Al-4V composite material at different temperatures through nanoindentation test and fiber push-out test of the SiC / Ti-6Al-4V composite material or literature data.

[0058] The performance parameters of each microscopic component of SiC / Ti-6Al-4V composite material are shown in Tables 1 to 3:

[0059] Table 1 Performance parameters of SiC

[0060]

[0061] Table 2 Performance parameters of Ti-6Al-4V

[0062]

[0063]

[0064] Table 3 Performance parameters of coating

[0065]

[0066] Step 2: Establish a finite element microscopic RVE model using ABAQUS finite element software, such as Figure 2As shown. Reduced integration elements (C3D8R) are used for the fiber, matrix and coating, and eight-node cohesive elements (COH3D8) are used for the interface between the coating and the matrix. The fiber and matrix are considered to be isotropic materials in the global Cartesian coordinate system, and the coating and the interface are defined by engineering constants in the cylindrical coordinate system.

[0067] The fiber failure model uses the three-dimensional Hashin criterion, which includes:

[0068] Fiber axial tensile failure, σ 11 ≥11:

[0069]

[0070] Fiber axial compression failure, σ 11 <11:

[0071]

[0072] Among them, X T is the fiber tensile strength, X C is the fiber compression strength, S 12 is the fiber shear strength, σ 11 is the axial stress on the fiber, σ 12 and σ 13 is the shear stress on the fiber;

[0073] The matrix failure model adopts the Mises criterion, and the Mises equivalent stress is expressed as:

[0074]

[0075] in, is the Mises equivalent stress on the matrix, σ x , σ y , σ z is the normal stress on the matrix in the three coordinate axis directions, τ xy , τ yz , τ zx is the shear stress on the matrix in the three coordinate axis directions; the constitutive relationship of the Ti6Al4V matrix is ​​as follows Figure 3 shown.

[0076] The interface damage failure model adopts a bilinear cohesive force model. Figure 4 The figure is a schematic diagram of the traction stress-separation displacement of the bilinear cohesive model under tension. When the tensile load acts on the composite material, the opening displacement of the interface gradually increases, and the traction stress of the cohesive interface increases accordingly; when the traction stress of the interface exceeds the peak tensile strength, the interface begins to be damaged, and the corresponding opening displacement is recorded as δ 0; When the interface separation displacement gradually increases, the interface traction stress will gradually decrease to zero, and eventually the interface peeling will occur. At this time, the opening displacement corresponding to the complete damage of the interface unit is recorded as δ f The selection of interface damage failure model is explained as follows:

[0077] Before damage occurs at the composite interface, the relationship between cohesion and displacement is linear elastic, and the relationship between the traction stress and separation displacement of the interface can be expressed as:

[0078]

[0079] Among them, σ n is the stress value in the normal direction, σ s is the stress value in the first shear direction, σ t is the stress value in the second shear direction, δ n ,δ s ,δ t are the separation displacements in the normal direction, the first shear direction, and the second shear direction, respectively, and K nn , K ss , K tt They are the interface stiffness corresponding to the opening, sliding and tearing crack forms respectively.

[0080] Taking an opening crack as an example, when the interface begins to be damaged, the stress on the interface is expressed as:

[0081] σ=(1-D)N max

[0082] Where, σ is the stress value of the interface, N max is the maximum value of the traction stress of the interface cohesive force unit, and the damage variable D represents the degree of damage to the interface. The value of the damage variable D is between 0 and 1. In the stage where the interface is not damaged, the damage variable D is equal to 0. When the interface cohesive force unit is completely damaged, the damage variable D is equal to 1. In the process of the interface starting to be damaged, the damage variable D can be expressed as:

[0083]

[0084] Where δ is the separation displacement of the interface, δ 0 is the displacement when the interface begins to be damaged, δ f is the displacement when the interface is completely damaged.

[0085] The secondary failure criterion is used to evaluate the interface damage. The expression of the secondary failure criterion is:

[0086]

[0087] Among them, σ nis the stress value in the normal direction, σ s is the stress value in the first shear direction, σ t is the stress value in the second shear direction. <σ n > indicates that pure compressive stress will not cause interface damage. N max , S max , and T max are the interface bonding strengths corresponding to the opening, sliding, and tearing cracks, respectively. The interface normal bonding strength N of the composite material in the interface damage model max Take 120MPa, interface shear strength S max and T max Take 170MPa.

[0088] When the cohesive unit meets the secondary failure criterion, the Benzeggagh-Kenane criterion (BK criterion) is used to define the interface damage evolution under the mixed stress mode. The stress after the interface is damaged under the complex stress state can be expressed as:

[0089]

[0090] in, and are the stress values ​​when the interface begins to be damaged in the normal direction, the first shear direction, and the second shear direction, respectively. At this time, the damage variable D can be expressed as:

[0091]

[0092] in, is the equivalent displacement corresponding to the beginning of damage, is the equivalent displacement corresponding to the complete damage, is the maximum value of the equivalent displacement during the entire loading process, and the equivalent displacement δ m Defined as:

[0093]

[0094] Among them, <δ n > represents the normal separation displacement that will not cause interface damage.

[0095] Step 3, the actual stiffness of the SiC / Ti-6Al-4V composite interface is between the fully bonded interface (K→∞) and the debonded interface (K=0), and the interface stiffness is inferred by fitting the experimental data of the macro experiment. If a fully bonded interface is used, the predicted value of the overall elastic modulus of the composite material will be too high. On the contrary, if a completely debonded interface is used, the predicted value will be too low. By bringing different stiffness values ​​into the finite element microscopic RVE model, the eccentric elastic modulus of the composite material at different angles is calculated, such as Figure 5As shown in Figure 3, when the interface normal stiffness is 5850000 MPa / mm and the shear stiffness is 2950000 MPa / mm, the prediction results of the finite element mesoscopic RVE model are most consistent with the experimental data.

[0096] Step 4: Use Python to write a callable periodic boundary condition subroutine to apply boundary conditions to the finite element mesoscopic RVE model, so that the finite element mesoscopic RVE model is compatible with load forms including axial load, shear load, thermal load and corresponding various load combination forms, ensuring deformation coordination and correct stress transfer during loading. The finite element mesoscopic RVE model with periodic boundary conditions is shown in Figure 4. Figure 6 shown.

[0097] The theoretical and technical flow of Python subroutines is as follows:

[0098] For any parallelepiped RVE model, the periodic displacement field on a pair of opposing surfaces can be expressed as:

[0099]

[0100] in, Indicates that along X j The displacement of the axis in the positive direction, Indicates that along X j The displacement of the axis in the negative direction, is the average strain of the RVE model, x k are the coordinates of any point on the boundary surface of the parallelepiped RVE model, where The parallelepiped RVE model boundary surface along X j The coordinates of any point in the positive direction of the axis, The parallelepiped RVE model boundary surface along X j The coordinates of any point in the negative direction of the axis, is the periodic displacement correction value.

[0101] The difference between the two displacement fields of a pair of corresponding points on the above pair of opposite surfaces can be obtained to obtain the relationship between the displacements of the two points:

[0102]

[0103] in, It represents the coordinate difference between two corresponding points on a pair of parallel planes;

[0104] For the parallelepiped RVE model, The spacing between a pair of parallel surfaces is equal, which results in a uniform periodic boundary condition:

[0105]

[0106] Among them, the constant is the distance between a pair of parallel planes, and (x, y, z) is the coordinate of any point on the boundary surface of the parallelepiped RVE model.

[0107] A callable periodic boundary condition program is written in Python language to make the finite element mesoscopic RVE model compatible with axial load, shear load and thermal load at the same time, and a unified periodic boundary condition is applied to the finite element mesoscopic RVE model in the finite element.

[0108] For the parallelepiped RVE model, the eight corner nodes are A, B, C, D, E, F, G, H. The twelve edges are AB, BC, CD, DA, EF, FG, GH, HE, AE, BF, CG, DH. The six boundary surfaces are ABCD, EFGH, EABF, FBCG, GCDH, HDAE, as shown in Figure 7 As shown. For the control equations of the 8 vertices of the parallelepiped RVE model, you can select a vertex as a reference point to establish the equation. Take the control equations of reference points A and H, G, F as an example:

[0109]

[0110] The subscripts H, G, F, and A are the vertices of the parallelepiped RVE model, and u H 、u G 、u F 、u A is the displacement of vertices H, G, F and A in the x direction, v H 、v G 、v F 、v A is the displacement of vertices H, G, F and A in the y direction, w H 、w G 、w F 、w A is the displacement of vertices H, G, F and A in the z direction, D x , D y D z Respectively represent the lengths of the sides parallel to the x, y, and z axes, ε x 0 ε y 0 ε z 0 Represents the x, y, and z axes

[0111] ,,,Normal mechanical strain, ε x T , ε y T , ε z Trepresents the thermal strain in the x, y and z axes, γ xy 0 , γ xz 0 , γ yz 0 It represents the shear mechanical strain on the xy, xz, and yz planes.

[0112] The governing equations of the 12 edges of the parallelepiped RVE model can be divided into the following three categories: edges parallel to the X-axis; edges parallel to the Y-axis; edges parallel to the Z-axis. Take the four edges HD, GC, FB, and EA parallel to the Z-axis as an example:

[0113]

[0114] The subscripts EA, HD, GC, and FB are the edges of the parallelepiped RVE model, u EA 、u HD 、u GC 、u FB is the displacement of edges EA, HD, GC and FB in the x direction, v EA 、v HD 、v GC 、v FB is the displacement of edges EA, HD, GC and FB in the y direction, w EA 、w HD 、w GC 、w FB is the displacement of edges EA, HD, GC and FB in the z direction.

[0115] The control equations of the three pairs of boundary surfaces of the parallelepiped RVE model can be divided into the following three categories: opposite surfaces perpendicular to the X-axis, opposite surfaces perpendicular to the Y-axis, and opposite surfaces perpendicular to the X-axis. The control equations are as follows:

[0116]

[0117] The subscripts x+, x- represent a pair of surfaces perpendicular to the x-axis, y+, y- represent a pair of surfaces perpendicular to the y-axis, z+, z- represent a pair of surfaces perpendicular to the z-axis, and u x+ 、u x- represents the displacement of a pair of surfaces x+, x- perpendicular to the x-axis in the x-direction, v y+ 、v y- represents the displacement of a pair of surfaces marked y+ and y- perpendicular to the y axis in the y direction, w z+ 、w z- Represents the displacement in the z direction of a pair of surfaces marked z+ and z- perpendicular to the z axis.

[0118] In the finite element mesoscopic RVE model studied in this embodiment, the coating and substrate nodes are overlapped at the boundary. For the finite element mesoscopic RVE model with overlapping nodes, the process of automatic node identification and automatic application of boundary conditions is as follows:

[0119] Step (1) distinguish overlapping nodes. Divide all nodes of the finite element mesoscopic RVE model into two groups, put the nodes located in the fiber and coating part into the assembly Assembly_1, and put the nodes located in the substrate part into Assembly_2. These two sets include all nodes of the finite element mesoscopic RVE model, and there are no overlapping nodes in each set.

[0120] Step (2) Node classification. Take the Assembly_1 set in step (1), select all nodes on the boundary surface based on the node position and classify them. Put the eight corner nodes into the sets Node1 to Node8, put the nodes on the twelve edges into the sets Edge1 to Edge12, and put the nodes on the six surfaces into the sets Face1 to Face6.

[0121] Step (3) Reorder the nodes, and order the corresponding points in different sets to the same order in their respective sets. Take Face1 and Face2, which are opposite faces perpendicular to the X-axis, as an example. Select the first point in the node set Face1 to calculate the distance with all the nodes in the set Face2, and order the node with the shortest distance in the set Face2 to the order of the first point. And so on, order the nodes in all sets.

[0122] Step (4) According to the expression Create constraints for all nodes in the assembly Assembly_1.

[0123] Similarly, through steps (2) to (4), constraints are established for all nodes in the set Assembly_2.

[0124] Step 5: Use ABAQUS software to apply loads to the finite element microscopic RVE model, simulate the failure behavior of the composite material under complex stress states, and predict the stress-strain relationship and microscopic failure law of the composite material under different loading modes.

[0125] Set the material properties for the finite element microscopic RVE model, run the periodic boundary condition subroutine written in step 4, impose constraints on the model, divide the mesh, apply the temperature field, and predict the residual thermal stress of the composite material. Apply axial load, lateral load, and eccentric load respectively to predict the stress-strain relationship and microscopic failure law of the composite material under different loading modes.

[0126] Figures 8 to 12Taking SiC / Ti6Al4V composite material as an example, the residual thermal stress of the composite material was predicted, and the stress-strain relationship of the composite material was simulated when it was subjected to axial load, lateral load and 45° eccentric load at different temperatures.

[0127] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have the same meaning as in the context of the prior art, and will not be interpreted with an idealized or overly formal meaning unless defined similarly here.

[0128] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A composite material microscopic failure analysis method based on micromechanical failure theory, characterized by: The following operations are included: Obtain the performance parameters of each component of the composite material according to the composite material component performance test; A finite element mesoscopic RVE model is established based on the performance parameters of each component of the composite material; The stiffness of the interface between the fiber and the matrix in the composite material is inferred by fitting the experimental data of the macroscopic experiment; Periodic boundary conditions are applied to the finite element mesoscopic RVE model to make it compatible with load forms including axial load, shear load, thermal load and corresponding various load combination forms; loads are applied to the finite element mesoscopic RVE model through ABAQUS finite element software, and the failure behavior of composite materials under complex stress states is simulated, so as to predict the stress-strain relationship and mesoscopic failure law of composite materials under different loading modes.

2. The composite material microscopic failure analysis method based on micromechanical failure theory according to claim 1 is characterized in that: The composite material component performance test includes a composite material nanoindentation test and a fiber push-out test.

3. The composite material microscopic failure analysis method based on micromechanical failure theory according to claim 1 is characterized in that: The composite material is a SiC / Ti metal-based composite material.

4. The composite material microscopic failure analysis method based on micromechanical failure theory according to claim 1 is characterized in that: The composite material includes fibers, a matrix, an interface and a coating, and the established finite element RVE microscopic model includes a fiber failure model, a matrix failure model, an interface damage failure model and a coating; Among them, the fiber failure model adopts the three-dimensional Hashin criterion, which includes: Fiber axial tensile failure, σ 11 ≥11: Fiber axial compression failure, σ 11 <11: Among them, X T is the fiber tensile strength, X C is the fiber compression strength, S 12 is the fiber shear strength, σ 11 is the axial stress on the fiber, σ 12 and σ 13 is the shear stress on the fiber; The matrix failure model adopts the Mises criterion, and the Mises equivalent stress is expressed as: in, is the Mises equivalent stress on the matrix, σ x , σ y , σ z is the normal stress on the matrix in the three coordinate axis directions, τ xy , τ yz , τ zx is the shear stress on the matrix in the directions of the three coordinate axes; Interface damage failure models include: The secondary failure criterion is used to evaluate the interface damage: Among them, <σ n > indicates that pure compressive stress will not cause interface damage, N max , S max , and T max are the interfacial bonding strengths corresponding to the opening, sliding, and tearing cracks, δ n ,δ s , δ t is the opening displacement in the normal direction, the first shear direction, and the second shear direction; When the cohesive element meets the secondary failure criterion, the Benzeggagh-Kenane criterion is used to define the damage evolution under the mixed stress mode.

5. The composite material microscopic failure analysis method based on micromechanical failure theory according to claim 4 is characterized in that: The periodic boundary condition is applied to the finite element mesoscopic RVE model, specifically comprising: the finite element mesoscopic RVE model is any parallelepiped RVE model, and the periodic displacement field on a pair of opposite surfaces of any parallelepiped RVE model is expressed as: in, Indicates that along X j The displacement of the axis in the positive direction, Indicates that along X j The displacement of the axis in the negative direction, is the average strain of any parallelepiped RVE model, The parallelepiped RVE model boundary surface along X j The coordinates of any point in the positive direction of the axis, The parallelepiped RVE model boundary surface along X j The coordinates of any point in the negative direction of the axis, is the periodic displacement correction value; Subtract the periodic displacement fields on a pair of relative surfaces to obtain the relationship between the displacements of the two points: in, It represents the coordinate difference between two corresponding points on a pair of parallel planes; The unified periodic boundary conditions are: in, is the distance between a pair of parallel planes, and (x, y, z) is the coordinate of any point on the boundary surface of the parallelepiped RVE model.

6. The composite material microscopic failure analysis method based on micromechanical failure theory according to claim 5 is characterized in that: For the finite element mesoscopic RVE model where the nodes of the coating and substrate coincide at the boundary, the process of automatic node identification and automatic application of periodic boundary conditions is as follows: a. Distinguish the overlapping nodes, divide all the nodes of the finite element mesoscopic RVE model into two groups, put the nodes located in the fiber and coating part into the set Assembly_1, and put the nodes located in the matrix part into the set Assembly_2. The sets Assembly_1 and Assembly_2 include all the nodes of the finite element mesoscopic RVE model, and there are no overlapping nodes in each of them; b. Take the set Assembly_1, select all nodes on the boundary surface based on the node position and classify them, put the eight corner nodes into the sets Node1 to Node8, put the nodes on the twelve edges into the sets Edge1 to Edge12, and put the nodes on the six surfaces into the sets Face1 to Face6; c. Reorder the nodes, and sort the corresponding points in different sets to the same order in their respective sets; d. According to the expression Establish constraints on all nodes in the assembly_1; e. Repeat operations b, c, and d to establish constraints for all nodes in the assembly Assembly_2.

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