Method for predicting tensile failure of perforated plate based on splitting of ply sets

Abstract

The application discloses a kind of based on the prediction method of split of layer group of open hole plate tensile failure, comprising: respectively establishing the corresponding geometric model of 90° layer group, 0° layer group in the fiber layer group of to-be-predicted open hole plate and 0° layer group in matrix layer group;Define material parameters for each geometric model;Define fracture parameters for each geometric model;The integration and assembly of each geometric model are carried out to finite element model, and the coupling of motion degree of freedom is carried out, obtains assembly finite element model, and carries out analysis.Through 0° layer and 90° layer in open hole layer plate are divided into two groups, all 90° layer is modeled using a plane stress unit, all 0° layer is artificially divided into fiber layer group and matrix layer group, and each is modeled using a plane stress unit, then, assembly and the coupling constraint of degree of freedom are carried out, to realize the condition of different layer deformation coordination, consistent in laminate theory, to realize the prediction of open hole plate tensile failure.

Description

Technical Field

[0001] This invention relates to the field of tensile failure prediction methods, and in particular to a method for predicting tensile failure of perforated plates based on ply stack splitting. Background Technology

[0002] SiC f SiC composite materials are lightweight and heat-resistant, and have been applied to hot-end components of aero-engines. These SiC composites are prepared using a prepreg melt-infiltration process and are obtained through layer-by-layer lamination. f / SiC composite laminate is one of the most promising ceramic matrix composite materials for engine hot-end components in terms of engineering applications.

[0003] Due to the need for cooling, SiC f / SiC composite hot-end components need to be machined with air film pores in different distribution states. In addition, sometimes some holes are also machined on the structure for structural assembly purposes. Since there is usually severe stress concentration at the edge of the hole, cracks always start from the edge of the hole and eventually lead to the failure of the structure.

[0004] The complex stress field around the circular hole caused by the tension of perforated composite plates and the resulting complex failure modes have attracted widespread attention from researchers both domestically and internationally. By tracking the current state of technology at home and abroad, researchers have proposed a large number of numerical prediction methods for simulating the tensile behavior and failure modes of porous resin-based composite structures.

[0005] According to the technical solutions adopted by relevant domestic and foreign patents, the geometry of the initial crack needs to be specified. The holes in the perforated plate are different from cracks. The perforated plate structure only shows geometric discontinuity at the edge of the hole. In essence, it is a structure without initial cracks.

[0006] Traditional finite element modeling methods for composite laminates based on two-dimensional plane stress elements extract the two-dimensional geometric model of the composite shell and use a single plane stress element to simulate the entire laminate in the thickness direction. Therefore, a single plane stress element contains information on all plies in the thickness direction of the laminate, and cannot differentiate the initiation and propagation of hole edge cracks in 0° and 90° plies. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to provide a method for predicting the tensile failure of perforated plates based on ply stack splitting, which can realize the prediction of tensile failure of perforated plates of ceramic matrix composites.

[0008] To achieve the above objectives, the present invention provides the following solution:

[0009] A method for predicting tensile failure of perforated plates based on ply stack splitting includes:

[0010] Step S1: Establish geometric models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group for the perforated plate to be predicted, respectively.

[0011] Step S2: Define the material parameters of each geometric model to establish the material models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group for the perforated plate to be predicted.

[0012] Step S3: Define the fracture parameters of each of the geometric models to establish fracture models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group for the perforated plate to be predicted.

[0013] Step S4: Integrate and assemble the geometric models, each of which has defined material parameters and fracture parameters, into finite element models, and couple the degrees of freedom of motion to obtain an assembled finite element model. Perform finite element analysis on the assembled finite element model to obtain the calculation and analysis results.

[0014] In one specific implementation scheme, step S2 specifically includes:

[0015] Define the material model for the 90° ply group, select the elastic model under the mechanical properties tab, and select isotropic material constitutive type. Input the parameter value E under the Young's modulus card. 90 Enter the parameter value ν under the Poisson's ratio card. 90 ;

[0016] Define the material model for the fiber layer group of the 0° layup group, select the elastic model under the mechanical properties tab, and select isotropic material constitutive type. Input the parameter value E under the Young's modulus card. 0f Enter the parameter value ν under the Poisson's ratio card. 0f ;

[0017] Define the material model for the matrix layer group of the 0° ply group, select the elastic model under the mechanical properties tab, and select isotropic material constitutive type. Input the parameter value E under the Young's modulus card. 0m Enter the parameter value ν under the Poisson's ratio card. 0m .

[0018] In another specific implementation plan, E 90 =E2,ν 90 =ν 21 ;

[0019] E 0m =E2,ν 0m =ν 21 ;

[0020] ν 0f =ν 12 ;

[0021] Among them, E2 and ν 21 The tensile Young's modulus and Poisson's ratio, E1 and ν, respectively, are measured tensile values ​​for a 90° ply one-way sheet. 12 These are the tensile Young's modulus and Poisson's ratio of a 0° ply one-way sheet, measured under tensile stress. f This represents the fiber volume fraction.

[0022] In another specific implementation, step S3 specifically includes:

[0023] Define the fracture model for the 90° ply group, select the damage tensile-opening displacement rule under the mechanical properties label, and select the maximum principal stress criterion as the damage initiation criterion. Input the critical value σ of the maximum principal stress under the label of the strength parameter corresponding to the maximum principal stress. 90 Simultaneously, crack propagation is controlled by defining fracture criteria. An energy-based fracture criterion type is selected, and the opening force softening type is set to linear. The fracture energy parameter value G is then entered under the fracture energy card. 90 ;

[0024] Define the fracture model for the fiber layer group of the 0° layup group, select the damage tensile force-opening displacement rule under the mechanical properties label, and select the maximum principal stress criterion as the damage initiation criterion. Input the normal tensile strength σ under the strength parameter label corresponding to the maximum principal stress. 0f and the shear strength S in both directions 12 S 13 Simultaneously, crack propagation is controlled by defining fracture criteria. An energy-based fracture criterion type is selected, and the opening force softening type is chosen as exponential. The fracture energy parameter value G is entered under the fracture energy card. 0f ;

[0025] Define the fracture model for the matrix layer group of the 0° ply group, select the damage tensile-opening displacement rule under the mechanical properties label, and select the maximum principal stress criterion as the damage initiation criterion. Input the critical value σ of the maximum principal stress under the label of the strength parameter corresponding to the maximum principal stress. 0m Simultaneously, crack propagation is controlled by defining fracture criteria. An energy-based fracture criterion type is selected, and the opening force softening type is set to linear. The fracture energy parameter value G is then entered under the fracture energy card. 0m .

[0026] In another specific implementation, the maximum principal stress critical value σ 90 The tensile proportional limit is taken as the tensile limit obtained from the tensile test of the orthogonal plywood, and the fracture energy parameter value G is taken as the tensile limit.90 The fracture toughness was measured by three-point bending of a one-sided notched beam with a 90° ply one-way slab.

[0027] The maximum principal stress critical value σ 0m The ultimate strength value obtained from the tensile test of the orthogonal plywood is taken as the fracture energy parameter value G. 0m Fracture toughness obtained by three-point bending test of a single-sided notched beam taken as an orthogonal plate;

[0028] The normal tensile strength σ 0f The tensile ultimate strength is taken as the tensile strength measured by tensile testing of a 0° ply unidirectional plate, and the shear strength S is... 12 S 13 The in-plane shear strength and interlaminar shear strength are measured in a double-notched beam test of a 0° ply one-way slab.

[0029] In another specific implementation, step S4 includes:

[0030] Step S41: Define the cross-sectional properties of the geometric models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group, respectively;

[0031] Step S42: Mesh the geometric models of the 90° ply group, the fiber layer group of the 0° ply group, and the combined model of the matrix layer group of the 0° ply group, and define the element type as plane stress element;

[0032] Step S43: Integrate the geometric models corresponding to the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group after definition and meshing to obtain the finite element models corresponding to the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group respectively.

[0033] Step S44: Assemble the finite element models of the 90° layup group, the fiber layer group of the 0° layup group, and the matrix layer group of the 0° layup group after definition and meshing to obtain the assembled finite element model.

[0034] Step S45: Set the constraints and loads of the assembly finite element model;

[0035] Step S46: Define the analysis step and incremental step;

[0036] Step S47: Submit the calculation and analyze the results.

[0037] In another specific implementation, step S41 specifically includes:

[0038] Define the cross-sectional properties of the 90° ply group, select the cross-sectional type as solid and homogeneous, link to the material model defined for the 90° ply group under the material type tab, and specify the cross-sectional thickness h. 90 , where h 90 The sum of the thicknesses of all 90° plies in the perforated plate to be predicted;

[0039] Define the cross-sectional properties of the fiber layer group of the 0° layup group. The cross-sectional type should also be selected as solid and homogeneous. Under the Material Type tab, link to the material model defined for the fiber layer group of the 0° layup group above. Simultaneously, specify the cross-sectional thickness h. 0f , where h 0f The sum of the thicknesses of all 0° layups in the perforated plate to be predicted, multiplied by the fiber volume fraction V. f ;

[0040] Define the cross-sectional properties of the matrix layer group for the 0° layup group. The cross-sectional type should also be selected as solid and homogeneous. Under the Material Type tab, link to the material model defined for the matrix layer group of the 0° layup group. Simultaneously, specify the cross-sectional thickness h. 0m , where h 0m Multiply the sum of the thicknesses of all 0° plies in the perforated plate to be predicted by V. m , where V m =1-V f V m This represents the volume fraction of the matrix.

[0041] In another specific implementation, step S42 specifically includes:

[0042] The geometric models of the 90° layup group, the fiber layer group of the 0° layup group, and the matrix layer group of the 0° layup group are respectively divided into cross sections. Each geometric model is divided into a cross-shaped region consisting of a first rectangular strip in the length direction and a second rectangular strip in the width direction, with the central hole on each geometric model as the center. The width of the first rectangular strip and the second rectangular strip is twice the diameter of the hole. The square region at the intersection and overlap of the first rectangular strip and the second rectangular strip is divided into four equal parts along the diagonal.

[0043] The number of grids is set along the circumferential edge of the central hole, and a radial grid pattern is adopted at the edge of the hole. A first preset number of grids is set in the areas of the first rectangular band and the second rectangular band respectively, and a second preset number of grids is set in other areas outside the areas of the first rectangular band and the second rectangular band, so as to obtain a grid that radiates along the edge of the hole and gradually densifies from both ends of the long rectangle towards the central hole.

[0044] The element type is defined using plane stress elements with reduced integrals, and the elements in the second rectangular strip region along the width direction are strengthened into enriched elements with extended finite element shape functions.

[0045] In another specific implementation, step S44 specifically includes:

[0046] In the assembly module of the simulation software, import the finite element models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group, which have been assigned cross-sectional properties and meshed, and make the three finite element models completely overlap in space.

[0047] A first reference point is defined at a first preset distance from one edge of each finite element model, and a second reference point is defined at a second preset distance from the other edge of each finite element model. Constraints are used to couple all displacement components of one edge of the three finite element models with the first reference point, so as to control the displacement of the three finite element models to one side by means of the displacement of the point. Constraints are also used to couple all displacement components of the other edge of the three finite element models with the second reference point, so as to control the displacement of the three finite element models to the other side by means of the displacement of the point.

[0048] In another specific implementation, step S45 specifically includes: applying a fully fixed constraint at the first reference point, and applying a displacement load in the X-axis direction at the first reference point;

[0049] And / or,

[0050] Step S47 specifically includes: submitting the assembly model for calculation, and performing numerical simulation of the tensile loading process and crack propagation behavior at the hole edge of the assembly model.

[0051] In another specific implementation, the method for predicting tensile failure of perforated plates based on ply stack splitting is applicable to SiC prepreg melt-infiltration processes. f / SiC ceramic matrix composites.

[0052] The various embodiments of the present invention can be combined arbitrarily as needed, and the resulting embodiments are also within the scope of the present invention and are part of the specific implementation of the present invention.

[0053] The present invention provides a method for predicting tensile failure of perforated plates. By dividing the 0° and 90° plies in the perforated plate into two groups, and artificially further dividing the 0° ply group into a fiber layer group and a matrix layer group based on the differences in material composition, different cracking and fracture criteria can be applied to the fiber layer group and the matrix layer group, thereby improving the prediction accuracy. Next, all 90° plies are modeled using a single plane stress element. Then, the 90° plies, the fiber layer group of the 0° plies, and the matrix layer group of the 0° plies are assembled using finite element methods and coupled with the degrees of freedom of motion to achieve the condition of coordinated and consistent deformation of different plies in laminate theory, thereby realizing the prediction of tensile failure of ceramic matrix composite perforated plates. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 This is a schematic diagram of the main view structure of the pre-predicted perforated plate after the installation of the reinforcing sheet, as provided by the present invention.

[0056] Figure 2 A top view of the structure of the perforated plate to be predicted after the reinforcing sheet is installed, as provided by the present invention.

[0057] Figure 3 A top view of the geometric model of the two-dimensional planar shell configuration of the perforated plate to be predicted provided by the present invention.

[0058] Figure 4 A top view of the cross-sectional structure of the geometric model provided by the present invention;

[0059] Figure 5 This is a top view diagram of the geometric model mesh provided by the present invention;

[0060] Figure 6 for Figure 5 A partially enlarged structural diagram;

[0061] Figure 7 A top view of the assembly model provided by the present invention;

[0062] Figure 8 A schematic diagram comparing the simulation results and experimental results of the load-displacement curve provided by this invention;

[0063] Figure 9A schematic diagram illustrating the initiation of cracks at the center hole edge of a 90° ply provided by the present invention;

[0064] Figure 10 A schematic diagram illustrating the initiation of cracks at the center hole edge of the 0° layup matrix layer group provided by the present invention;

[0065] Figure 11 A schematic diagram illustrating the initiation of cracks at the center hole edge of a 0° ply fiber layer assembly provided by the present invention;

[0066] Figure 12 A schematic diagram showing a 90° layup crack penetrating the entire width direction, provided for the present invention;

[0067] Figure 13 A schematic diagram illustrating the penetration of cracks through all layers, as provided by the present invention;

[0068] Figure 14 The flowchart shows the tensile failure prediction method for perforated plates provided by this invention.

[0069] in, Figures 1-13 middle:

[0070] 1. Predicted perforated plate; 2. Reinforcing sheet; 3. First rectangular strip; 4. First rectangular strip; 5. Square area; 6. First reference point; 7. Second reference point. Detailed Implementation

[0071] The following will refer to the appendices in the embodiments of the present invention. Figures 1-14 The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0072] In the description of this invention, it should be understood that the terms "upper," "lower," "top surface," "bottom surface," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the indicated position or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0073] Combination Figures 1-14 As shown, the present invention provides a method for predicting the tensile failure of perforated plates based on ply stack splitting, so as to realize the prediction of tensile failure of perforated plates of ceramic matrix composites.

[0074] Specifically, the configuration and geometry of the perforated plate 1 to be predicted are as follows: Figures 1-2 As shown, the length of the perforated plate 1 to be predicted is 100mm, the width is 10mm, and the thickness is 2.4mm. The layup sequence of the test piece is [0° layup / 90° layup / 0° layup / 90° layup / 90° layup / 0° layup / 90° layup / 0° layup], for a total of 8 layers. The thickness of each layer is 0.3mm. A circular hole with a diameter of 0.5mm is laser-processed in the center of the plate.

[0075] In order to conduct a tensile test, four reinforcing plates 2 with a thickness of 2 mm, a length of 30 mm, and a width equal to the width of the perforated plate 1 (10 mm) are attached to both ends of the perforated plate 1 to be predicted. Therefore, the working section length of the perforated plate 1 to be predicted is 40 mm.

[0076] The perforated plate 1 to be predicted is a SiC substrate produced using a prepreg melt infiltration process and arranged in an orthogonal layup configuration. f It is prepared from SiC composite materials. It should be noted that this process can also be extended to other prepreg melt-infiltration processes for SiC. f Prediction of strength and failure mode of open-pore structures in SiC composites.

[0077] In this embodiment, taking the perforated plate 1 to be predicted as being made of SiC fiber with a fiber volume fraction of 20% as an example, the Young's modulus E2 and Poisson's ratio ν of the composite material single layer were measured by tensile testing of a 90° layup unidirectional plate. 21 The Young's modulus E1 and Poisson's ratio ν of the composite material were measured under tensile stress using a 0° layup unidirectional plate at 204 GPa and 0.1, respectively. 12 The specific strengths and ultimate tensile strengths were 347 GPa and 0.19, respectively. Tensile testing of orthogonal plywood yielded a proportional limit of 120 MPa, an ultimate tensile strength of 200 MPa, and a fracture toughness of 40 MPa·m. 1 / 2 The fracture toughness of the ceramic matrix, tested using the three-point bending method with a single-sided notched beam, was 20 MPa·m. 1 / 2 .

[0078] like Figure 14 As shown, the prediction method for tensile failure of perforated plates based on ply stack splitting includes:

[0079] Step S1: Establish the geometric models of the 90° layup group, the fiber layer group of the 0° layup group, and the matrix layer group of the 0° layup group for the perforated plate 1 to be predicted.

[0080] Specifically, using the finite element software ABAQUS, a model of the perforated plate 1 (SiC) to be predicted was established. f The geometric model of the two-dimensional planar shell configuration of the middle working section (the area between the clamping areas at both ends of the perforated plate 1 to be predicted) of the SiC perforated plate is as follows: Figure 3As shown; then, the two-dimensional planar geometric model of the perforated plate 1 to be predicted is copied twice, resulting in a total of 3 geometric models, which are used to simulate the geometric model of the 90° ply group in the perforated plate 1 to be predicted, the geometric model of the fiber layer group in the 0° ply group, and the geometric model of the matrix layer group in the 0° ply group.

[0081] Step S2: Define the material parameters of each geometric model to establish the material models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group of the perforated plate 1 to be predicted.

[0082] SiC f The anisotropy of modulus parameters in different directions of SiC composite materials is not obvious. In the process of establishing the numerical analysis model of the perforated plate to be predicted, according to the mechanical behavior and fracture mechanism of the layup, all layups are divided into 90° layup group, 0° layup group fiber layer group and 0° layup group matrix layer group according to the form of characteristic groups. Isotropic material constitutive models are used to describe the stress-strain response of the above three layup characteristic groups before damage.

[0083] In the Material Property Definition module of ABAQUS software, define a material model for a 90° ply group, select the Elastic model under the Mechanical Properties tab, and choose Isotropic as the material constitutive type. Enter the parameter value E under the Young's Modulus card. 90 Enter the parameter value ν under the Poisson's Ratio card. 90 Among them, E 90 =E2,ν 90 =ν 21 E2 and ν 21 The tensile Young's modulus and Poisson's ratio are the actual measured values ​​for a 90° ply unidirectional sheet under tensile stress. In this embodiment, E is used as the tensile modulus. 90 =204MPa, ν 90 For example, =0.3.

[0084] Define the material model for the fiber layer group of the 0° layup group in the same way, select the elastic model under the mechanical properties tab, and select isotropic material constitutive type. Enter the parameter value E under the Young's modulus card. 0f Enter the parameter value ν under the Poisson's ratio card. 0f Among them, E 0m =E2,ν 0m =ν 21 In this embodiment, E 0m =204MPa, ν 0m For example, =0.3.

[0085] Define the material model for the matrix layer group of the 0° layup group in the same way, select the elastic model under the mechanical properties tab, and select isotropic material constitutive type. Enter the parameter value E under the Young's modulus card. 0m Enter the parameter value ν under the Poisson's ratio card. 0m .in, ν 0f =ν 12 E1 and ν 12 These are the tensile Young's modulus and Poisson's ratio of a 0° ply one-way sheet, measured under tensile stress. f This represents the fiber volume fraction. In this embodiment, E is used as... 0f =347MPa, ν 0f For example, 0.19.

[0086] Step S3: Establish fracture models for the 90° layup group, the fiber layer group of the 0° layup group, and the matrix layer group of the 0° layup group of the perforated plate 1 to be predicted.

[0087] Specifically, in the material property definition module of the ABAQUS software, under the material model in step S2 above, add a fracture model to define the 90° ply group. Select the Damage for Traction Separation laws under the Mechanical Properties tab, and select the Maxps Damage criterion as the damage initiation criterion. Enter the critical value σ of the Maxps Damage under the strength parameter label corresponding to the Maxps Damage. 90 Simultaneously, crack propagation is controlled by defining fracture criteria. An energy-based fracture criterion type is selected, and the opening force softening type is set to linear. The fracture energy parameter value G is input under the fracture energy card. 90 Specifically, the critical value of the maximum principal stress σ 90 The tensile proportional limit obtained from the tensile test of the orthogonal plywood is taken as the fracture energy parameter value G. 90 The fracture toughness of the ceramic matrix is ​​taken as σ. In this embodiment, σ is used as the fracture toughness of the ceramic matrix. 90 =120MPa, G 90 =0 MPa·m 1 / 2 For example.

[0088] The fracture model for the fiber layer group with 0° layup is defined in the same way. The damage for tension-displacement laws are selected under the mechanical properties label, and the maximum stress criterion is chosen as the damage initiation criterion. Appropriate parameter values, including the normal tensile strength σ, are entered under the strength parameter label corresponding to the maximum stress. 0fand the shear strength S in both directions 12 S 13 Simultaneously, crack propagation is controlled by defining fracture criteria. An energy-based fracture criterion type is selected, and the opening force softening type is chosen as exponential. The fracture energy parameter value G is entered under the fracture energy card. 0f Specifically, the normal tensile strength σ 0f The tensile ultimate strength and shear strength S are measured using a 0° ply unidirectional plate. 12 S 13 The in-plane shear strength and interlaminar shear strength are measured from double-notched beam specimens prepared from 0° ply unidirectional slabs. In this embodiment, σ is used as the in-plane shear strength and interlaminar shear strength. 0f =400MPa,

[0089] S 12 =120MPa, S 13 =90MPa, G 0f =0.5MPa·m 1 / 2 For example.

[0090] The fracture model for the matrix layer group with 0° ply group is defined in the same way. Damage for Traction Separation laws are selected under the Mechanical Properties label, and the Maxps Damage criterion is selected as the damage initiation criterion. The critical value of the Maxps Damage is entered under the label of the strength parameter corresponding to the Maxps Damage. 0m Simultaneously, crack propagation is controlled by defining fracture criteria. An energy-based fracture criterion type is selected, and the opening force softening type is set to linear. The fracture energy parameter value G is input under the fracture energy card. 0m Specifically, the critical value of the maximum principal stress σ 0m The ultimate strength value and fracture energy parameter value G are obtained from the tensile test of orthogonal plywood. 0m The fracture toughness is obtained by three-point bending test of a single-sided notched beam, which is an orthogonal plate. In this embodiment, σ is used as the fracture toughness. 0m =2000MPa, G 0m =40MPa·m 1 / 2 For example.

[0091] Step S4: Integrate and assemble the finite element models of the geometric models that have been defined with material parameters and fracture parameters, and couple the degrees of freedom of motion to obtain the assembled finite element model. Perform finite element analysis on the assembled finite element model to obtain the calculation and analysis results.

[0092] Specifically, the finite element model is assembled in commercial CAE software.

[0093] Step S4 specifically includes:

[0094] Step S41: Define the cross-sectional properties of the geometric models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group.

[0095] Specifically, define the cross-sectional properties of the 90° ply group, select the cross-sectional type as Solid and Homogenous, link to the material model defined for the 90° ply group under the Material Type tab, and specify the cross-sectional thickness h. 90 , where h 90 The sum of the thicknesses of all 90° plies in the perforated plate is numerically equal to the product of the single-layer thickness t and the number of 90° plies. This defined cross-sectional property is assigned to the geometric model of the aforementioned 90° ply group. In this embodiment, h is used as... 90 For example, =1.2mm.

[0096] Define the cross-sectional properties of the fiber layer group for the 0° layup group in the same way, selecting Solid and Homogenous as the cross-sectional type. Under the Material Type tab, link to the material model defined for the fiber layer group of the 0° layup group, and specify the cross-sectional thickness h. 0f , where h 0f The sum of the thicknesses of all 0° layups in the perforated plate multiplied by the fiber volume fraction V f The defined cross-sectional properties are then assigned to the geometric model of the fibers in the aforementioned 0° layup group. In this embodiment, h is used as... 0f For example, 0.24mm.

[0097] Define the cross-sectional properties of the matrix layer group for the 0° layup group in the same way, selecting Solid and Homogenous as the cross-sectional type. Under the Material Type tab, link to the material model defined for the matrix layer group of the 0° layup group, and specify the cross-sectional thickness h. 0m , where h 0m Multiply the sum of the thicknesses of all 0° plies in the perforated plate by V. m , where V m =1-V f V m The defined cross-sectional properties, representing the matrix volume fraction, are assigned to the geometric model of the matrix layer group in the aforementioned 0° layup group. In this embodiment, h is used as... 0m For example, 0.96mm.

[0098] Step S42: Mesh the geometric models of the 90° layup group, the fiber layer group of the 0° layup group, and the matrix layer group of the 0° layup group, and define the element type.

[0099] Specifically, in the finite element software ABAQUS, the geometric models of the three ply feature groups are sectioned. Each geometric model is divided into a cross-shaped region centered on the central hole, as shown below. Figure 4 As shown, the cross-shaped region includes a first rectangular band 43 along the length direction and a second rectangular band along the width direction. The width of both the first rectangular band 43 and the second rectangular band is twice the diameter of the central hole. The square region 5 at the intersection of the first rectangular band 43 and the second rectangular band is divided into four equal parts along the diagonal.

[0100] Based on the geometric model after the above cross-section division, the mesh size is set, such as... Figure 5 and Figure 6 As shown, the number of grids is set circumferentially along the edge of the central hole. In this embodiment, 20 grids are used as an example. A radial grid pattern is adopted around the hole, and a first preset number of grids is set in the areas of the first rectangular band 43 and the second rectangular band, respectively. In this embodiment, 5 grids are used as an example. A certain number of grids are also set in other areas besides the cross-shaped area, resulting in a grid that radiates along the hole edge and gradually densifies from both ends of the rectangular band towards the central hole. In this embodiment, 50 grids are set in the length direction and 20 grids are set in the width direction in other areas, for example. Figure 3 As shown. The element type is defined as a plane stress element (CPS4R) using reduced integral, and the elements in the second rectangular region are strengthened into enriched elements with XFEM shape functions to simulate the propagation of hole edge cracks in this region.

[0101] Step S43: Integrate the geometric models corresponding to the 90° ply group, the 0° ply group fiber layer group, and the 0° ply group matrix layer group after definition and meshing to obtain the finite element models corresponding to the 90° ply group, the 0° ply group fiber layer group, and the 0° ply group matrix layer group respectively.

[0102] The geometric models of the three ply feature groups are the geometric models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group, which are defined with material parameters and fracture parameters. Therefore, the finite element models of the 90° ply, the fiber layer group of the 0° ply, and the matrix layer group of the 0° ply are obtained respectively.

[0103] Step S44: Assemble the finite element model of the 90° layup group, the fracture finite element model of the fiber layer group of the 0° layup group, and the finite element model of the matrix layer group of the 0° layup group after definition and meshing, and couple the degrees of freedom of motion to obtain the assembled finite element model.

[0104] Specifically, in the assembly module of the ABAQUS software, import the finite element models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group, which have been assigned cross-sectional properties and divided into meshes, and make the three finite element models completely overlap in space.

[0105] like Figure 7 As shown, a first reference point 6 is defined at a first preset position on one edge of each finite element model, and a second reference point 7 is defined at the other edge of each finite element model. Figure 7 Taking the direction in the middle as an example, one edge refers to the left edge, and the other edge refers to the right edge.

[0106] Using the "coupling" constraint in ABAQUS software, the left edges of all three ply feature group models are coupled with all displacement components (U1, U2, UR3) of the first reference point 6, so as to control the displacement of the left edges of the three models by the displacement of the point.

[0107] Similarly, using the "coupling" constraint in ABAQUS software, the right edge of all three ply feature groups is coupled to all displacement components of the second reference point 7. This setting ensures that both ends of each ply feature group have the same displacement, satisfying the condition of coordinated and consistent deformation of different plies in the laminate.

[0108] Step S45: Set the constraints and loads for the assembly finite element model.

[0109] Specifically, based on the loading method for the tension of the perforated plate 1 to be predicted, a fully fixed constraint (U1=0, U2=0, UR3=0) is applied at the first reference point 6, and the left edge is also completely fixed. A displacement load in the X-axis direction is applied at the first reference point 6, and a suitable parameter value is set for U1 to represent the displacement along the X direction. In this embodiment, U1=4mm is taken as an example.

[0110] It should be noted that along the X-axis direction is... Figure 7 The direction set in the text is for ease of expression only and does not have any other specific meaning.

[0111] Step S46: Define the analysis step and the incremental step.

[0112] Specifically, in the analysis step setting module of the ABAQUS software, select the quasi-static loading step, set the time to 1, and set the incremental step parameters as follows: initial incremental step size is 0.001, minimum incremental step size is 1e-5, and maximum incremental step size is 0.1.

[0113] Step S47: Submit the calculation and analyze the results.

[0114] The assembly model was submitted for calculation, and numerical simulations were performed on the tensile loading process and crack propagation behavior at the hole edges of the assembly model.

[0115] Specifically, in the calculation module of the ABAQUS software, the assembly model is submitted for calculation, and the tensile loading process of the assembly model and the crack propagation behavior at the hole edge are numerically simulated.

[0116] Using the ABAQUS post-processing module, the load-displacement data at the second reference point 7 in the simulated loading process are output, resulting in the simulated load-displacement curve of the perforated plate 1 during the tensile process. The simulated load-displacement curve is then compared with the experimentally measured load-displacement curve. The comparison results are as follows: Figure 8 As shown.

[0117] Figures 9-13 This study demonstrates the propagation patterns of pore edge cracks within different plies at typical time points during the simulated loading process. It shows that pore edge cracks initiate earliest in the 90° ply. Figure 9 Subsequently, pore edge cracks appeared in the 0° layup matrix layer, as seen in... Figure 10 Finally, the fibers in the 0° layup begin to break along the edge of the hole, see... Figure 11 As the crack propagates, the crack at the hole edge in the 90° layup is the first to penetrate the width direction. At this time, the matrix layer cracks in the 0° layup have not yet penetrated the width direction due to the bridging effect of the fibers. Figure 12 As the crack continues to propagate, cracks in the matrix layers of the 0° layup also extend across the width. At this point, the fibers in the 0° layup also break, as shown in the diagram. Figure 13 .

[0118] The present invention has the following advantages:

[0119] (1) A quasi-three-dimensional finite element modeling method based on two-dimensional plane stress elements is proposed to distinguish and independently model 0° ply groups and 90° ply groups in laminate composite materials. By dividing the 0° ply and 90° ply in the perforated plate 1 to be predicted into two groups, the crack propagation of all 90° ply groups is controlled by a single plane stress element model. All 0° ply groups are artificially divided into fiber layer groups and matrix layer groups, and the fiber layer groups and matrix layer groups of 0° ply are modeled separately, and the same plane stress element simulation is used. Then, the geometric models of the 90° ply, the fiber layer group of 0° ply, and the matrix layer group of 0° ply are assembled by overlapping them in geometric space. Then, at both ends of the geometric model, the geometric models of all three groups of layers are coupled to a common reference point, so that the 0° ply, the fiber layer group of 0° ply, and the matrix layer group of 0° ply have the same displacement with the reference point, so as to realize the condition of coordinated and consistent deformation of different ply groups in laminate theory.

[0120] (2) For the orthogonal ply to be predicted open plate 1, a special crack initiation criterion and fracture criterion are proposed under the XFEM crack propagation simulation framework based on the cohesive force model. Based on the microscopic evolution mechanism of damage in the 0° ply in the open plate 1 to be predicted, the 0° ply is artificially divided into fiber layer group and matrix layer group in physical terms. Different crack initiation and fracture criteria are adopted for the fiber layer group and the matrix layer group. The fracture of the matrix layer group of 90° ply and 0° ply adopts the linear tensile force softening model, while the fracture of the fiber of 0° ply adopts the exponential tensile force softening model, so as to simulate the tough fracture behavior of ceramic matrix composites.

[0121] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0122] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and inventive features disclosed herein.

[0123] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0124] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for predicting tensile failure of perforated plates based on ply stack splitting, characterized in that, include: Step S1: Establish geometric models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group for the perforated plate to be predicted, respectively. Step S2: Define the material parameters of each of the geometric models to establish the material models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group of the perforated plate to be predicted. Step S3: Define the fracture parameters of each of the geometric models to establish fracture models for the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group of the perforated plate to be predicted; Step S3 specifically includes: Define the fracture model for the 90° ply group, select the damage tensile-opening displacement rule under the mechanical properties label, and select the maximum principal stress criterion as the damage initiation criterion. Input the critical value σ of the maximum principal stress under the label of the strength parameter corresponding to the maximum principal stress. 90 Simultaneously, crack propagation is controlled by defining fracture criteria. An energy-based fracture criterion type is selected, and the opening force softening type is set to linear. The fracture energy parameter value G is then entered under the fracture energy card. 90 ; Define the fracture model for the fiber layer group of the 0° layup group, select the damage tensile force-opening displacement rule under the mechanical properties label, and select the maximum principal stress criterion as the damage initiation criterion. Input the normal tensile strength σ under the strength parameter label corresponding to the maximum principal stress. 0f and the shear strength S in both directions 12 S 13 Simultaneously, crack propagation is controlled by defining fracture criteria. An energy-based fracture criterion type is selected, and the opening force softening type is chosen as exponential. The fracture energy parameter value G is entered under the fracture energy card. 0f ; Define the fracture model for the matrix layer group of the 0° ply group, select the damage tensile-opening displacement rule under the mechanical properties label, and select the maximum principal stress criterion as the damage initiation criterion. Input the critical value σ of the maximum principal stress under the label of the strength parameter corresponding to the maximum principal stress. 0m Simultaneously, crack propagation is controlled by defining fracture criteria. An energy-based fracture criterion type is selected, and the opening force softening type is set to linear. The fracture energy parameter value G is then entered under the fracture energy card. 0m ; The maximum principal stress critical value σ 90 The proportional limit is taken as obtained from the orthogonal ply test, and the fracture energy parameter value G is... 90 The fracture toughness was measured by three-point bending of a one-sided notched beam with a 90° ply one-way slab. The maximum principal stress critical value σ 0m The ultimate strength value obtained from the tensile test of the orthogonal plywood is taken as the fracture energy parameter value G. 0m Fracture toughness obtained by three-point bending test of a single-sided notched beam taken as an orthogonal plate; The normal tensile strength σ 0f The tensile ultimate strength is taken as the tensile strength measured by tensile testing of a 0° ply unidirectional plate, and the shear strength S is... 12 S 13 The in-plane shear strength and interlaminar shear strength are obtained from the shear test of a double-cut beam of a 0° ply one-way slab. Step S4: Integrate and assemble the geometric models, each of which has defined material parameters and fracture parameters, into finite element models, and couple the degrees of freedom of motion to obtain an assembled finite element model. Perform finite element analysis on the assembled finite element model to obtain the calculation and analysis results.

2. The method for predicting tensile failure of perforated plates based on ply group splitting according to claim 1, characterized in that, Step S2 specifically includes: Define the material model for the 90° ply group, select the elastic model under the mechanical properties tab, and select isotropic material constitutive type. Input the parameter value E under the Young's modulus card. 90 Enter the parameter value ν under the Poisson's ratio card. 90 ; Define the material model for the fiber layer group of the 0° layup group, select the elastic model under the mechanical properties tab, and select isotropic material constitutive type. Input the parameter value E under the Young's modulus card. 0f Enter the parameter value ν under the Poisson's ratio card. 0f ; Define the material model for the matrix layer group of the 0° ply group, select the elastic model under the mechanical properties tab, and select isotropic material constitutive type. Input the parameter value E under the Young's modulus card. 0m Enter the parameter value ν under the Poisson's ratio card. 0m .

3. The method for predicting tensile failure of perforated plates based on ply group splitting according to claim 2, characterized in that, E 90 =E2,ν 90 =n 21 ; E 0m =E2,ν 0m =n 21 ; ,n 0f =n 12 ; Among them, E2 and ν 21 The tensile Young's modulus and Poisson's ratio, E1 and ν, respectively, are measured tensile values ​​for a 90° ply one-way sheet. 12 These are the tensile Young's modulus and Poisson's ratio of a 0° ply one-way sheet, measured under tensile stress. f This represents the fiber volume fraction.

4. The method for predicting tensile failure of perforated plates based on ply group splitting according to claim 1, characterized in that, Step S4 includes: Step S41: Define the cross-sectional properties of the geometric models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group, respectively; Step S42: Mesh the geometric models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group, and define the element type as plane stress element; Step S43: Integrate the geometric models corresponding to the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group after definition and meshing to obtain the finite element models corresponding to the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group respectively. Step S44: Assemble the finite element models of the 90° layup group, the fiber layer group of the 0° layup group, and the matrix layer group of the 0° layup group after definition and meshing, and couple the degrees of freedom of motion to obtain the assembled finite element model. Step S45: Set the constraints and loads of the assembly finite element model; Step S46: Define the analysis step and incremental step; Step S47: Submit the calculation and analyze the results.

5. The method for predicting tensile failure of perforated plates based on ply group splitting according to claim 4, characterized in that, Step S41 specifically includes: Define the cross-sectional properties of the 90° ply group, select the cross-sectional type as solid and homogeneous, link to the material model defined by the 90° ply group under the material type tab, and specify the cross-sectional thickness h. 90 , where h 90 The sum of the thicknesses of all 90° plies in the perforated plate to be predicted; Define the cross-sectional properties of the fiber layer group of the 0° layup group. The cross-sectional type should also be selected as solid and homogeneous. Under the Material Type tab, link to the material model defined for the fiber layer group of the 0° layup group. Simultaneously, specify the cross-sectional thickness h. 0f , where h 0f The sum of the thicknesses of all 0° layups in the perforated plate to be predicted, multiplied by the fiber volume fraction V. f ; Define the cross-sectional properties of the matrix layer group of the 0° ply group. The cross-sectional type should also be selected as solid and homogeneous. Under the Material Type tab, link to the material model defined for the matrix layer group of the 0° ply group. Simultaneously, specify the cross-sectional thickness h. 0m , where h 0m Multiply the sum of the thicknesses of all 0° plies in the perforated plate to be predicted by V. m , where V m =1-V f V m This represents the volume fraction of the matrix.

6. The method for predicting tensile failure of perforated plates based on ply group splitting according to claim 5, characterized in that, Step S42 specifically includes: The geometric models of the 90° layup group, the fiber layer group of the 0° layup group, and the matrix layer group of the 0° layup group are respectively divided into cross sections. Each geometric model is divided into a cross-shaped region consisting of a first rectangular strip in the length direction and a second rectangular strip in the width direction, with the central hole on each geometric model as the center. The width of the first rectangular strip and the second rectangular strip is twice the diameter of the hole. The square region at the intersection and overlap of the first rectangular strip and the second rectangular strip is divided into four equal parts along the diagonal. The number of grids is set along the circumferential edge of the central hole, and a radial grid pattern is adopted at the edge of the hole. A first preset number of grids is set in the areas of the first rectangular band and the second rectangular band respectively, and a second preset number of grids is set in other areas outside the areas of the first rectangular band and the second rectangular band, so as to obtain a grid that radiates along the edge of the hole and gradually densifies from both ends of the long rectangle towards the central hole. The element type is defined using plane stress elements with reduced integrals, and the elements in the second rectangular strip region along the width direction are strengthened into enriched elements with extended finite element shape functions.

7. The method for predicting tensile failure of perforated plates based on ply group splitting according to claim 6, characterized in that, Step S44 specifically includes: In the assembly module of the simulation software, import the finite element models of the 90° ply group, the fiber layer group of the 0° ply group, and the matrix layer group of the 0° ply group, which have been assigned cross-sectional properties and meshed, and make the three finite element models completely overlap in space. A first reference point is defined at a first preset distance from one edge of each finite element model, and a second reference point is defined at a second preset distance from the other edge of each finite element model. Constraints are used to couple all displacement components of one edge of the three finite element models with the first reference point, so as to control the displacement of the three finite element models to one side by means of the displacement of the point. Constraints are also used to couple all displacement components of the other edge of the three finite element models with the second reference point, so as to control the displacement of the three finite element models to the other side by means of the displacement of the point.

8. The method for predicting tensile failure of perforated plates based on ply group splitting according to claim 7, characterized in that, Step S45 specifically includes: applying a fully fixed constraint at the first reference point, and applying a displacement load in the X-axis direction at the first reference point; And / or, Step S47 specifically includes: submitting the assembly model for calculation, and performing numerical simulation of the tensile loading process and crack propagation behavior at the hole edge of the assembly model.

9. The method for predicting tensile failure of perforated plates based on ply group splitting according to any one of claims 1-8, characterized in that, The method is applicable to SiC prepreg melt infiltration process. f / SiC ceramic matrix composites.

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