Composite material crack propagation method, device and equipment and storage medium

Abstract

The invention discloses a composite material crack propagation method, device and equipment and a storage medium. Comprising the following steps: constructing a finite element model of a composite material test piece, positioning a crack tip node in the finite element model, establishing a local coordinate system according to the crack tip node, and calculating a crack jump length and a unit vector; node force and opening displacement under the global coordinate system are extracted based on a finite element model, and the node force and the opening displacement are converted into local coordinate system components based on unit vectors; and calculating each energy release rate component according to the local coordinate system component and the crack jump length, and substituting each energy release rate component into a preset fracture criterion formula to generate a crack propagation result of the composite material test piece. Through finite element modeling, the structure and crack position of the composite material can be accurately represented, a basic model is provided for subsequent expansion analysis, the accuracy of energy release rate calculation is improved, the fracture criterion application condition is optimized in combination with the crack jump characteristic, and the crack expansion simulation result is closer to the actual working condition.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of numerical simulation, and in particular to a composite material crack propagation method, device, equipment and storage medium. BACKGROUND

[0002] In modern high-end manufacturing, composite materials occupy a key position in the fields of aerospace, new energy equipment and high-end mechanical manufacturing due to their excellent mechanical properties and lightweight characteristics. However, the complex multi-phase structure inside the composite material makes it prone to crack under the action of load and environmental factors. The propagation of the crack will cause structural failure, threatening the safety and stability of the equipment. Therefore, in-depth research and accurate prediction of the crack propagation behavior of the composite material have become a core issue to ensure engineering safety.

[0003] Currently, for composite material crack propagation analysis, the industry generally adopts a method combining finite element simulation and testing. By establishing a finite element model of the composite material structure, setting initial crack parameters based on classical fracture mechanics theory, and calibrating model parameters using test data, the crack propagation process is simulated.

[0004] Traditional finite element simulation relies on a large amount of test data for calibration, and the modeling and calculation process is lengthy, making it difficult to meet the rapid iterative design requirements. Moreover, the anisotropy and complex stress state of the composite material are ignored, resulting in a large deviation between the predicted results and the actual working conditions, which limits the accurate assessment of the reliability of the composite material structure. SUMMARY

[0005] The present application provides a composite material crack propagation method, device, equipment and storage medium, based on a composite material crack propagation algorithm of virtual crack closure technology, to accurately calculate the strain energy release rate and predict the crack propagation behavior by combining the fracture criterion, solving the problems of cumbersome local coordinate system establishment, easy accumulation of mechanical quantity conversion error and insufficient consideration of multi-mode coupling effect of the fracture criterion in the prior art.

[0006] According to an aspect of the present application, a composite material crack propagation method is provided, the method comprising:

[0007] Constructing a finite element model of a composite material specimen, positioning a crack tip node in the finite element model, establishing a local coordinate system according to the crack tip node, and calculating a crack jump length and a unit vector;

[0008] Extracting node forces and opening displacements in a global coordinate system based on the finite element model, and converting the node forces and opening displacements into local coordinate system components based on the unit vector;

[0009] Calculating energy release rate components according to the local coordinate system components and the crack jump length, and substituting the energy release rate components into a preset fracture criterion formula to generate a crack propagation result of the composite material specimen.

[0010] Optionally, the finite element model of the composite specimen is constructed, including: obtaining the geometric size of the composite specimen, and determining the crack position to establish an initial geometric model; obtaining material parameters, and setting material attributes of the initial geometric model based on the material parameters, wherein the material parameters include elastic modulus, Poisson's ratio and fracture toughness parameters; performing mesh division on the set initial geometric model based on a preset configuration, and applying boundary conditions to construct the finite element model.

[0011] Optionally, the crack tip node is positioned in the finite element model, a local coordinate system is established according to the crack tip node, and the crack jump length and unit vectors are calculated, including: positioning the crack tip node in the mesh of the finite element model based on the crack position, and selecting two nodes adjacent to the crack tip node in the mesh as a first auxiliary node and a second auxiliary node; calculating the Euclidean distance of the spatial coordinate difference between the first auxiliary node and the crack tip node as the crack jump length; calculating the coordinate difference between the first auxiliary node and the crack tip node as a two-type crack direction vector; calculating the coordinate difference between the second auxiliary node and the crack tip node as a tangential auxiliary vector; performing cross multiplication on the two-type crack direction vector and the tangential auxiliary vector to obtain a three-type crack direction vector; performing cross multiplication on the three-type crack direction vector and the two-type crack direction vector to obtain a one-type crack direction vector; performing normalization processing on the two-type crack direction vector, the three-type crack direction vector and the one-type crack direction vector respectively to obtain unit vectors of the local coordinate system.

[0012] Optionally, the node force and the opening displacement are converted into local coordinate system components based on the unit vectors, including: performing vector dot product operation on the unit vectors and the node force and the opening displacement respectively to obtain node force components and opening displacement components; taking the node force components and the opening displacement components as the local coordinate system components.

[0013] Optionally, each energy release rate component is calculated according to the local coordinate system components and the crack jump length, including: calculating a first product value of each node force component and a corresponding opening displacement component respectively; obtaining the structural thickness of the composite specimen, and calculating a product of the structural thickness and twice the crack jump length as a second product value; taking a ratio of each first product value and the second product value as each energy release rate component.

[0014] Optionally, each energy release rate component is substituted into a preset fracture criterion formula to generate a crack propagation result of the composite specimen, including: substituting each energy release rate component and the fracture toughness parameter into the preset fracture criterion formula to determine an energy calculation value; performing crack propagation calculation according to the energy calculation value, and generating a crack propagation evolution diagram and a load displacement curve as the crack propagation result when an analysis termination condition is met.

[0015] Optionally, the crack propagation calculation is performed according to the energy calculation value, including: judging whether the energy calculation value is greater than a preset fracture threshold, if yes, determining that the crack propagates, releasing the crack tip node constraint, and performing the crack propagation calculation based on a preset crack path to position a next crack tip node in the finite element model; otherwise, determining that the crack does not propagate.

[0016] According to another aspect of the present application, there is provided a composite material crack propagation device, comprising:

[0017] a model construction and crack calculation module, configured to construct a finite element model of a composite material specimen, position a crack tip node in the finite element model, establish a local coordinate system according to the crack tip node, and calculate a crack jump length and a unit vector;

[0018] a local coordinate system component conversion module, configured to extract node force and opening displacement in a global coordinate system based on the finite element model, and convert the node force and opening displacement into local coordinate system components based on the unit vector;

[0019] a crack propagation result generation module, configured to calculate energy release rate components according to the local coordinate system components and the crack jump length, and substitute the energy release rate components into a preset fracture criterion formula to generate a crack propagation result of the composite material specimen.

[0020] According to another aspect of the present application, there is provided an electronic device, comprising:

[0021] at least one processor;

[0022] and a memory connected in communication with the at least one processor;

[0023] wherein the memory stores a computer program capable of being executed by the at least one processor, and the computer program is executed by the at least one processor to enable the at least one processor to perform a composite material crack propagation method according to any one of the embodiments of the present application.

[0024] According to another aspect of the present application, there is provided a computer readable storage medium, which stores computer instructions for enabling a processor to perform a composite material crack propagation method according to any one of the embodiments of the present application when executed.

[0025] The technical solution of the embodiment of the present invention can accurately characterize the composite material structure and crack position by constructing a finite element model and locating the crack tip node; establish a local coordinate system and calculate the crack jump length and unit vector, adapt the crack tip stress field, and quantify the expansion parameters; extract global physical quantities and convert them into local coordinate system components to ensure that the mechanical parameters are true and fit the actual working conditions; calculate the energy release rate based on local parameters and substitute it into the fracture criterion to achieve quantitative prediction of crack expansion, significantly improving simulation accuracy and engineering applicability.

[0026] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 This is a flow chart of a composite material crack propagation method provided according to the first embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of crack tip positioning according to the first embodiment of the present invention;

[0030] Figure 3 1 is a schematic diagram of a definition of a local coordinate system of a crack tip according to the first embodiment of the present invention;

[0031] Figure 4 This is a flow chart of another composite material crack propagation method provided according to the second embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of crack propagation results provided according to the second embodiment of the present invention;

[0033] Figure 6 2 is a schematic diagram of a Y-axis load-displacement relationship curve provided according to the second embodiment of the present invention;

[0034] Figure 7 This is a schematic structural diagram of a composite material crack propagation device provided according to the third embodiment of the present invention;

[0035] Figure 8 It is a structural schematic diagram of an electronic device for implementing a composite material crack propagation method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0037] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0038] Example 1

[0039] Figure 1 A flowchart of a composite material crack propagation method is provided for the first embodiment of the present invention. This embodiment is applicable to composite material fracture simulation analysis scenarios. The method can be performed by a composite material crack propagation device, which can be implemented in the form of hardware and / or software. The composite material crack propagation device can be configured in a computer controller. Figure 1 As shown, the method includes:

[0040] S110. Construct a finite element model of the composite material specimen, locate a crack tip node in the finite element model, establish a local coordinate system based on the crack tip node, and calculate a crack jump length and a unit vector.

[0041] The composite specimen refers to a specimen made of two or more materials with different properties to obtain new properties. For example, the composite specimen can be a cantilever beam double opening specimen. The finite element model refers to a model that simulates the mechanical behavior of the entire specimen by discretizing the composite specimen into a finite number of elements, such as a collection of shell elements QUAD75, establishing mechanical equations for each element, and assembling and solving them. When constructing, the grid needs to be divided, and the corresponding displacement boundary conditions need to be applied. By establishing a finite element model for discretization, a complex continuum problem can be converted into a numerical model that can be calculated, facilitating the analysis of crack propagation and other physical processes. The crack tip node refers to the node in the finite element model that represents the most forward position of the crack, which is the starting position and key control point of crack propagation. The local coordinate system refers to the coordinate system established with the crack tip node as the origin, which is usually associated with the crack propagation direction and the stress direction, and is used to describe the local mechanical state of the crack tip. The crack jump length refers to the unit length of crack propagation. The unit vector refers to the vector obtained by normalizing the components of the local coordinate system in each direction, which is used for coordinate transformation and subsequent calculation. The unit vector is used to convert the mechanical quantity in the global coordinate system into the component in the local coordinate system, so as to analyze the local stress state of the crack tip.

[0042] Optionally, the finite element model of the composite specimen is constructed, including: obtaining the geometric size of the composite specimen, and determining the crack position to establish an initial geometric model; obtaining material parameters, and setting material properties of the initial geometric model based on the material parameters, wherein the material parameters include elastic modulus, Poisson's ratio and fracture toughness parameters; performing grid division on the set initial geometric model based on a preset configuration, and applying boundary conditions to construct the finite element model.

[0043] Specifically, when constructing the finite element model of the composite specimen, taking the cantilever beam double opening specimen as an example, the geometric size needs to be determined, including total length L = 100 mm, width B = 20 mm and thickness h = 1.5 mm, the distance from the loading point to the crack tip a = 30 mm, based on the above size parameters, the geometric model containing the initial crack can be drawn in the modeling software. It should be noted that B represents the width of the model in the finite element model, and represents the thickness of the structure where the crack is located during crack propagation calculation. Then, the controller obtains the material parameters and sets the material properties of the initial geometric model. The controller refers to the computer controller for crack propagation calculation. The material parameters include longitudinal elastic modulus E 11 = 135.3 GPa, which is used to describe the elastic deformation ability of the material along the fiber direction, transverse elastic modulus E 22 = E 33 = 9.0 GPa, which is used to describe the elastic properties perpendicular to the fiber direction, in-plane shear modulus G 12= 5.2 GPa, reflecting the deformation capacity of the material under in-plane shear forces, the main Poisson's ratio v 12 = v 13 = 0.24, the transverse Poisson's ratio v 23 = 0.46, used to describe the ratio of transverse strain to longitudinal strain of the material when under stress. Mode I fracture toughness GIC= 0.28 N / mm (= 280 J / m 2 ), mode II fracture toughness GIIC= 1000000 N / mm (= 1000000000 J / m 2 ), mode III fracture toughness GIIIC= 1000000 N / mm (= 1000000000 J / m 2 ).

[0044] Further, the model is meshed and boundary conditions are applied based on the preset configuration. The meshing can adopt shell element type QUAD75. When meshing, the mesh density needs to be reasonably set according to the specimen size and crack location, and the mesh near the crack tip may need to be encrypted to capture the stress concentration phenomenon. The application of boundary conditions can adopt the following settings: a displacement load of 0.4 mm in the Y direction is applied to the upper end point on the left side to simulate external loading, all end points on the right side are constrained, the displacements in the X and Z directions are fixed X = Z = 0, and all angles MX = MY = MZ = 0 are constrained, which is equivalent to fixing the right side to form the support condition of the cantilever beam. Through meshing and application of boundary conditions, a finite element model for calculation and analysis is finally constructed, which can reflect the mechanical behavior of the specimen under actual load and provide a calculation basis for subsequent crack propagation analysis.

[0045] Optionally, the crack tip node is located in the finite element model, a local coordinate system is established according to the crack tip node, and the crack jump length and unit vectors are calculated, including: locating the crack tip node in the mesh of the finite element model based on the crack location, and selecting two nodes adjacent to the crack tip node in the mesh as a first auxiliary node and a second auxiliary node; calculating the Euclidean distance of the spatial coordinate difference between the first auxiliary node and the crack tip node as the crack jump length; calculating the coordinate difference between the first auxiliary node and the crack tip node as the biaxial crack direction vector; calculating the coordinate difference between the second auxiliary node and the crack tip node as the tangential auxiliary vector; cross-multiplying the biaxial crack direction vector and the tangential auxiliary vector to obtain the triaxial crack direction vector; cross-multiplying the triaxial crack direction vector and the biaxial crack direction vector to obtain the uniaxial crack direction vector; and normalizing the biaxial crack direction vector, the triaxial crack direction vector and the uniaxial crack direction vector respectively to obtain the unit vectors of the local coordinate system.

[0046] Specifically, when positioning the crack tip node in the finite element model and establishing the local coordinate system, the operation needs to be performed according to the principles of fracture mechanics and the rules of vector operation. First, the tip node is determined based on the crack position in the grid, and the crack tip node is determined based on the crack position in the grid, Figure 2 A crack tip positioning schematic diagram is provided for the first embodiment of the present application, Figure 2 The finite element grid after discretization of the above cantilever beam double-opening specimen is shown in the figure, each origin represents a node, and the X-Y coordinate system in the lower left corner is the global coordinate system, used to calibrate the overall spatial position of the model. The node marked as 30th node is the 30th node numbered in order, representing that the 31st node from the left edge of the finite element model is defined as the crack tip node, which is 30 mm away from the left boundary. Then, two nodes adjacent to the tip node are selected as the first auxiliary node and the second auxiliary node.

[0047] The first auxiliary node and the second auxiliary node are selected as the first auxiliary node and the second auxiliary node. Figure 3 A definition schematic diagram of the local coordinate system of the crack tip is provided for the first embodiment of the present application, and the X, u, Y, v, and Z, w in the lower left corner of the figure are the global coordinate system, used to describe the overall spatial position of the finite element model. The crack tip node, i.e. Figure 3 The node marked as 3 in the figure is the core, and the local coordinate system related vectors are constructed to serve the crack mechanics analysis. Figure 3 The node 3 in the figure is the positioning point of the crack tip in the finite element model grid, and is the core position for analyzing the initiation of crack propagation. The nodes 5 and 7 are auxiliary nodes adjacent to the crack tip node, used to construct the direction vectors of the local coordinate system. The nodes 1, 2, 4 and 6 can assist in extracting the node force, opening displacement and other data in the global coordinate system. II is a two-type crack direction vector, composed of the coordinate difference from node 3 to node 5, along the shear direction in the crack surface. T is a tangential auxiliary vector, composed of the coordinate difference from node 3 to node 7, which assists in determining the out-of-plane direction of the local coordinate system and participates in the subsequent vector cross multiplication to construct other directions. I is a one-type crack direction vector, whose direction is perpendicular to the crack surface and points to the positive direction of crack propagation, corresponding to the opening-type crack mode. III is a three-type crack direction vector, whose direction is perpendicular to the crack surface, corresponding to the anti-plane shear mode.

[0048] Specifically, the crack jump length calculation adopts the following formula (1):

[0049]

[0050] where Δa represents the crack jump length, x5, y5 and z5 represent the coordinates of the first auxiliary node, i.e. Figure 3Coordinates of the middle node 5, x3, y3 and z3 represent the coordinates of the crack tip node, that is Figure 3 Coordinates of the middle node 3. The crack jump length represents the unit step length of crack propagation, which is used for subsequent energy release rate calculation. Then, the bimodal crack direction vector is composed of the coordinate difference from the first auxiliary node to the tip node, which is calculated by the following formula (2):

[0051] N II =(x5-x3)i+(y5-y3)j+(z5-z3)k (2)

[0052] Wherein, N II is the bimodal crack direction vector, x5, y5 and z5 represent the coordinates of the first auxiliary node, that is Figure 3 Coordinates of the middle node 5, x3, y3 and z3 represent the coordinates of the crack tip node, that is Figure 3 Coordinates of the middle node 3. i, j and k represent the unit vectors of the global coordinate system X, Y and Z axes. The bimodal crack direction vector points to the shear direction in the crack surface. The coordinate difference from the second auxiliary node to the tip node constitutes the tangential auxiliary vector, which is calculated by the following formula (3):

[0053] N T =(x7-x3)i+(y7-y3)j+(z7-z3)k (3)

[0054] Wherein, N T is the tangential auxiliary vector, x3, y3 and z3 represent the coordinates of the crack tip node, that is Figure 3 Coordinates of the middle node 3, x7, y7 and z7 represent the coordinates of the second auxiliary node, that is Figure 3 Coordinates of the middle node 7. i, j and k represent the unit vectors of the global coordinate system X, Y and Z axes. The tangential auxiliary vector is used to assist in determining the out-of-plane direction. N I and N III are obtained by the cross product of N II and N T , that is respectively correspond to the opening type and anti-plane shear type crack analysis direction, which is the basis for dividing the energy release rate of different fracture modes. Finally, N I , N II and N III are normalized, and the unit vectors are obtained by normalizing the lengths of the vectors.

[0055] S120, based on the finite element model, extract the node force and opening displacement in the global coordinate system, and convert the node force and opening displacement into local coordinate system components based on the unit vector.

[0056] The global coordinate system refers to the unified coordinate system used for the entire finite element model, describing the overall geometry and stress state of the model. Nodal forces refer to the forces acting on the nodes of the finite element model. Opening displacements refer to the displacement difference between pairs of nodes behind the crack tip. Local coordinate system components are the components of nodal forces and opening displacements in the global coordinate system converted to the local coordinate system via the dot product with a unit vector.

[0057] Specifically, the node force calculation is expressed by the following formula (4):

[0058] F=K x (u3-u4)i+K y (v3-v4)j+K z (w3-w4)k (4)

[0059] Where F represents the crack tip node force, K x , K y and K z They are the node stiffness coefficients in the global coordinate system, in N / m or N / mm, u3 and u4 represent Figure 3 The displacement components of nodes 3 and 4 in the X-axis are expressed in units of length. v3 and v4 represent the displacement components of nodes 3 and 4 in the Y-axis direction. w3 and w4 represent the displacement components of nodes 3 and 4 in the Z-axis direction. i, j, and k represent the unit vectors of the global coordinate system X, Y, and Z axes, which are used to represent the direction of the force components in the directions of the respective coordinate axes. The opening displacement is calculated using the following formula (5):

[0060] Δ=(u1-u2)i+(v1-v2)j+(w1-w2)k (5)

[0061] Where Δ represents the opening displacement vector of the node pair behind the crack tip, in units of length, and u1 and u2 represent Figure 3 The displacement components of nodes 1 and 2 in the X-axis direction, v1 and v2 represent Figure 3 The displacement components of midpoint 1 and midpoint 2 in the Y-axis direction, w1 and w2 represent Figure 4 Displacement components of nodes 1 and 2 in the Z-axis direction, where nodes 1 and 2 are the node pair behind the crack. i, j, and k are the unit vectors of the global coordinate system X, Y, and Z axes.

[0062] Optionally, the nodal force and the opening displacement are converted into local coordinate system components based on the unit vector, including: performing vector dot product operations on the unit vector and the nodal force and the opening displacement respectively to obtain each nodal force component and each opening displacement component; and using each nodal force component and each opening displacement component as the local coordinate system component.

[0063] It should be noted that the geometric meaning of the vector dot product is to project one vector onto the direction of another vector. When the unit vector is dot multiplied with the nodal force vector or the opening displacement vector, the result is the component of the vector in the direction of the unit vector.

[0064] S130, calculate each energy release rate component according to the local coordinate system component and the crack jump length, and substitute each energy release rate component into a preset fracture criterion formula to generate a crack propagation result of the composite specimen.

[0065] The energy release rate component is used to measure the energy released per unit area when the crack propagates, and is calculated according to the local coordinate system component and the crack jump length. The fracture toughness parameter refers to the parameter of the material's resistance to crack propagation, and corresponds to the fracture toughness under the I-type, II-type and III-type fracture modes. The fracture criterion formula refers to a formula for judging whether the crack propagates or not. When the calculated value of the preset fracture criterion formula is greater than or equal to 1, it indicates that the crack propagates, and at this time the spring constraint between the node pairs at the crack tip is removed.

[0066] Optionally, each energy release rate component is calculated according to the local coordinate system component and the crack jump length, including: respectively calculating a first product value of each nodal force component and a corresponding opening displacement component; obtaining the structure thickness of the composite specimen, and calculating the product of the structure thickness and twice the crack jump length as a second product value; and taking the ratio of each first product value and the second product value as each energy release rate component.

[0067] Specifically, taking the I-type crack direction as an example, the I-type crack direction energy release rate component is calculated using the following formula (6):

[0068]

[0069] wherein G I represents the I-type crack direction energy release rate component, F I represents the I-type crack direction nodal force component, Δ I represents the I-type crack direction opening displacement component, Δa represents the crack jump length, and B represents the structure thickness. The energy release rate component calculation process of the II-type crack direction and the III-type crack direction is similar.

[0070] The technical scheme of the embodiment of the application can accurately characterize the composite material structure and the crack position by constructing a finite element model and positioning the crack tip node; the local coordinate system is established, the crack jump length and the unit vector are calculated, the stress field at the crack tip is adapted, and the expansion parameters are quantified; the global physical quantity is extracted and converted into the local coordinate system component, ensuring that the mechanical parameters are real and consistent with the actual working conditions; the energy release rate is calculated according to the local parameters and substituted into the fracture criterion to realize quantitative prediction of crack propagation, significantly improving the simulation accuracy and engineering applicability.

[0071] Embodiment Two

[0072] Figure 4 A flow chart of a composite material crack propagation method provided for Embodiment Two of the present application, which adds the process of substituting each energy release rate component into a preset fracture criterion formula to generate the crack propagation result of the composite material specimen based on Embodiment One described above. The specific content of steps S210-S220 is substantially the same as steps S110-S120 in Embodiment One, and therefore will not be described again in this embodiment. As shown in FIG. 2B, the method comprises the following steps. Figure 5

[0073] S210, constructing a finite element model of the composite material specimen, positioning a crack tip node in the finite element model, establishing a local coordinate system according to the crack tip node, and calculating a crack jump length and a unit vector.

[0074] Optionally, constructing the finite element model of the composite material specimen comprises: obtaining the geometric size of the composite material specimen and clearly defining the crack position to establish an initial geometric model; obtaining material parameters, and setting material properties of the initial geometric model based on the material parameters, wherein the material parameters include elastic modulus, Poisson's ratio, and fracture toughness parameters; performing meshing on the set initial geometric model based on a preset configuration, and applying boundary conditions to construct the finite element model.

[0075] Optionally, positioning the crack tip node in the finite element model, establishing the local coordinate system according to the crack tip node, and calculating the crack jump length and the unit vector comprise: positioning the crack tip node in the mesh of the finite element model based on the crack position, and selecting two nodes adjacent to the crack tip node in the mesh as a first auxiliary node and a second auxiliary node; calculating the Euclidean distance of the spatial coordinate difference between the first auxiliary node and the crack tip node as the crack jump length; calculating the coordinate difference from the first auxiliary node to the crack tip node as a two-type crack direction vector; calculating the coordinate difference from the second auxiliary node to the crack tip node as a tangential auxiliary vector; performing cross multiplication on the two-type crack direction vector and the tangential auxiliary vector to obtain a three-type crack direction vector; performing cross multiplication on the three-type crack direction vector and the two-type crack direction vector to obtain a one-type crack direction vector; and performing normalization processing on the two-type crack direction vector, the three-type crack direction vector, and the one-type crack direction vector respectively to obtain each unit vector of the local coordinate system.

[0076] S220, extracting node force and opening displacement in a global coordinate system based on the finite element model, and converting the node force and opening displacement into local coordinate system components based on the unit vector.

[0077] ​Optionally, the node force and the opening displacement are converted into the local coordinate system components based on a unit vector, including: performing vector dot product operation on the unit vector and the node force and the opening displacement respectively to obtain node force components and opening displacement components; and taking the node force components and the opening displacement components as the local coordinate system components.

[0078] S230, calculating each energy release rate component according to the local coordinate system components and the crack jump length.

[0079] Optionally, the energy release rate components are calculated according to the local coordinate system components and the crack jump length, including: calculating a first product value of each node force component and a corresponding opening displacement component respectively; obtaining a structure thickness of the composite specimen, and calculating a product of the structure thickness and twice the crack jump length as a second product value; and taking a ratio of each first product value and the second product value as each energy release rate component.

[0080] S240, substituting each energy release rate component and a fracture toughness parameter into a preset fracture criterion formula to determine an energy calculation value.

[0081] Specifically, the energy calculation value is shown in the following formula (7):

[0082]

[0083] wherein, G I represents a one-type crack direction energy release rate component, G II represents a two-type crack direction energy release rate component, G III represents a three-type crack direction energy release rate component, G IC , G IIC and G IIIC respectively represent fracture toughness parameters corresponding to each energy release rate component. G0 represents the energy calculation value, reflecting the relative relationship between the crack propagation driving force and the material resistance.

[0084] S250, performing crack propagation calculation according to the energy calculation value, and generating a crack propagation evolution diagram and a load displacement curve as a crack propagation result when an analysis termination condition is met.

[0085] Specifically, the analysis termination condition refers to that the crack propagation reaches the boundary of the test piece or the load-displacement curve shows a significant mutation, such as a sudden drop in stiffness, or the preset propagation step or time step reaches the upper limit. When the analysis termination condition is met, a crack propagation evolution diagram and a load-displacement curve are generated as the crack propagation result. In generating the crack propagation evolution diagram, the position of crack propagation at each step is recorded through finite element post-processing technology, and the evolution process of the crack from the initial position to the final state is presented in a visual manner. The crack propagation evolution diagram can directly show the dynamic process of crack propagation, thereby verifying the rationality of the preset path, and the load-displacement curve provides experimental data support for fracture toughness evaluation, and the area under the curve corresponds to the energy consumed by material fracture.

[0086] Exemplarily, Figure 5 A crack propagation result schematic diagram is provided for the second embodiment of the present application, Figure 6 The upper half is the basic load-bearing section of the test piece, corresponding to the complete structure before crack propagation, the grid is fine and regular, and is used for simulating the stress distribution in the initial elastic deformation stage, providing boundary constraint and load transmission for the crack tip. The lower half presents the crack propagation path and deformation form, simulates the crack tip at the bifurcation, and the grid is stretched and deformed along the crack direction, embodying the stress concentration and strain energy release process during crack propagation.

[0087] In a specific embodiment, Figure 6 A Y-direction load-displacement relationship curve schematic diagram is provided for the second embodiment of the present application, and the load-displacement curve is drawn by collecting the data of Y-direction load and displacement during loading, with displacement as the horizontal axis and load as the vertical axis. Figure 7 In the Y-direction load-displacement relationship curve, displacement 0-2.5mm or so is the initial rising section, the load increases linearly with displacement, corresponding to the elastic stage of the material. At this time, the crack has not propagated, the overall stiffness of the test piece is high, and the external force does work mainly as elastic strain energy. Displacement 2.5-17.5mm or so is the peak and falling section, the peak point indicates that the energy release rate component reaches the material fracture toughness, triggering crack initiation, corresponding to the critical state of the preset fracture criterion. In the falling section, the crack continues to propagate, the effective load-bearing area of the test piece decreases, the stiffness decreases, and the external force needs to overcome the energy consumption of crack propagation, which is manifested as the load decreases with the increase of displacement. Displacement 17.5-25mm or so is the late gentle rising section, the load slowly rises with the displacement, and the remaining structure of the test piece may redistribute the stress, and the external force does work for continuous deformation, but the overall stiffness is still lower than that in the initial elastic stage.

[0088] Optionally, the crack propagation calculation is performed according to the energy calculation value, including: judging whether the energy calculation value is greater than a preset fracture threshold value, if yes, determining that the crack propagates, releasing the crack tip node constraint, and performing crack propagation calculation based on a preset crack path to position a next crack tip node in the finite element model; otherwise, determining that the crack does not propagate.

[0089] The preset crack path refers to a crack propagation trend according to the geometry of the test piece, material properties and actual engineering, for example, in a composite laminated plate, the crack may propagate along the interlaminar interface and the fiber direction. When the finite element model is established, it is planned in advance that the crack will propagate in which direction and along which nodes.

[0090] Specifically, the preset fracture threshold value can be 1, that is, when the sum of the ratio of each mode energy release rate to the corresponding fracture toughness reaches or exceeds 1, it indicates that the driving force of crack propagation has exceeded the resistance of the material, and the crack will propagate. At this time, the controller will find a group of nodes corresponding to the subsequent crack tip node along the preset crack path, determine the group of nodes as the new crack tip node, and take the newly determined crack tip node as the analysis object to recalculate the energy release rate at this position. Then, the energy calculation value and the fracture threshold value are compared again to determine the propagation, and the iteration is continued until the crack propagates through the entire test piece or the preset analysis termination condition is met. When the energy calculation value is less than the preset fracture threshold value, it is determined that the crack does not propagate. At this time, the constraint of the crack tip node in the finite element model remains unchanged, and the analysis process continues to load and continuously monitor the change of the energy calculation value until the energy calculation value reaches or exceeds the fracture threshold value in the subsequent loading process, and the crack propagation determination and related operations are triggered again.

[0091] In addition, in the finite element model, the nodes at the crack tip are constrained to simulate the continuity of the material when the crack has not propagated in the initial state. When the crack propagates, it is equivalent to the material being disconnected, so the constraints are released. Therefore, when it is determined that the crack propagates, the controller will delete the constraint settings between the crack tip nodes, for example, remove the corresponding contact element definition from the constraint list of the model, or modify the stiffness matrix so that the nodes are no longer constrained, to simulate the physical process of crack face separation and release the strain energy accumulated before.

[0092] The technical solution of the embodiment of the present invention determines the energy calculation value by substituting each energy release rate component and fracture toughness parameter into the preset fracture criterion formula, and then performs crack extension calculation based on the energy calculation value. When the analysis termination condition is met, a crack extension evolution diagram and a load-displacement curve are generated. This process establishes a direct correlation between mechanical parameters and crack extension behavior through quantitative energy calculation, and can intuitively present the dynamic process of crack extension and changes in structural bearing performance in a visual chart. When judging whether the crack has extended based on the energy calculation value, the crack extension process is accurately controlled by comparing it with the preset fracture threshold. When the energy calculation value is greater than the threshold, the crack tip constraint is promptly released and the new node is located to simulate the dynamic extension of the crack. When it is less than the threshold, the crack is accurately determined to be stable. This effectively makes up for the shortcomings of existing methods in capturing the dynamic changes of the crack tip, and realizes a refined simulation of the entire process of crack extension behavior of composite materials from initiation, development to termination, significantly improving the accuracy and reliability of crack extension prediction.

[0093] Example 3

[0094] Figure 7 This is a schematic diagram of the structure of a composite material crack extension device provided in Example 3 of the present invention. Figure 8 As shown, the apparatus includes: a model building and crack calculation module 310, which is used to build a finite element model of the composite material specimen, locate the crack tip node in the finite element model, establish a local coordinate system based on the crack tip node, and calculate the crack jump length and unit vector;

[0095] A local coordinate system component conversion module 320 is used to extract the nodal forces and opening displacements in the global coordinate system based on the finite element model, and convert the nodal forces and opening displacements into local coordinate system components based on unit vectors;

[0096] The crack growth result generating module 330 is used to calculate each energy release rate component according to the local coordinate system component and the crack jump length, and substitute each energy release rate component into a preset fracture criterion formula to generate the crack growth result of the composite material specimen.

[0097] Optionally, the model construction and crack calculation module 310 specifically includes: a finite element model construction unit, which is used to: obtain the geometric dimensions of the composite material specimen and determine the crack location to establish an initial geometric model; obtain material parameters, and set the material properties of the initial geometric model based on the material parameters, wherein the material parameters include elastic modulus, Poisson's ratio and fracture toughness parameters; mesh the set initial geometric model based on a preset configuration, and apply boundary conditions to construct a finite element model.

[0098] Optionally, the model construction and crack calculation module 310 specifically comprises a crack tip positioning unit configured to: position a crack tip node based on a crack position in a mesh of a finite element model, and select two nodes adjacent to the crack tip node in the mesh as a first auxiliary node and a second auxiliary node; calculate a Euclidean distance of a spatial coordinate difference between the first auxiliary node and the crack tip node as a crack jump length; calculate a coordinate difference from the first auxiliary node to the crack tip node as a second-type crack direction vector; calculate a coordinate difference from the second auxiliary node to the crack tip node as a tangential auxiliary vector; perform cross multiplication on the second-type crack direction vector and the tangential auxiliary vector to obtain a third-type crack direction vector; perform cross multiplication on the third-type crack direction vector and the second-type crack direction vector to obtain a first-type crack direction vector; and perform normalization processing on the second-type crack direction vector, the third-type crack direction vector and the first-type crack direction vector respectively to obtain unit vectors of a local coordinate system.

[0099] Optionally, the local coordinate system component conversion module 320 is specifically configured to: perform vector dot product operation on the unit vectors respectively and node forces and opening displacements to obtain node force components and opening displacement components; and take the node force components and the opening displacement components as local coordinate system components.

[0100] Optionally, the crack propagation result generation module 330 specifically comprises an energy release rate component calculation unit configured to: calculate first product values of the node force components and corresponding opening displacement components respectively; obtain a structure thickness of the composite specimen, and calculate a product of the structure thickness and twice the crack jump length as a second product value; and take ratios of the first product values and the second product value as energy release rate components.

[0101] Optionally, the crack propagation result generation module 330 specifically comprises a propagation result generation unit configured to: substitute the energy release rate components and a fracture toughness parameter into a preset fracture criterion formula to determine an energy calculation value; and perform crack propagation calculation according to the energy calculation value, and generate a crack propagation evolution diagram and a load displacement curve as crack propagation results when an analysis termination condition is met.

[0102] Optionally, the propagation result generation unit specifically comprises a crack propagation calculation subunit configured to: determine whether the energy calculation value is greater than a preset fracture threshold value, if yes, determine that the crack propagates, release a crack tip node constraint, and perform crack propagation calculation based on a preset crack path to position a next crack tip node in the finite element model; and otherwise, determine that the crack does not propagate.

[0103] The technical scheme of the embodiment of the present application can accurately characterize the composite material structure and the crack position by constructing a finite element model and positioning the crack tip node; the local coordinate system is established, and the crack jump length and unit vector are calculated, the crack tip stress field is adapted, and the expansion parameter is quantified; the global physical quantity is extracted and converted into the local coordinate system component, so that the mechanical parameters are real and consistent with the actual working condition; the energy release rate is calculated according to the local parameters and substituted into the fracture criterion, the quantitative prediction of crack propagation is realized, and the simulation accuracy and engineering applicability are significantly improved.

[0104] The composite material crack propagation device provided in the embodiment of the present application can execute the composite material crack propagation method provided in any embodiment of the present application, and has the corresponding function modules and beneficial effects of the execution method.

[0105] Embodiment four

[0106] Figure 8 A structural schematic diagram of an electronic device 10 that can be used to implement embodiments of the present application is shown. The electronic device is intended to represent various forms of digital computers, such as laptops, desktops, tablets, personal digital assistants, servers, blade servers, mainframes, and other appropriate computers. The electronic device can also represent various forms of mobile devices, such as personal digital assistants, cellular telephones, smartphones, wearable devices (e.g., headsets, glasses, watches, etc.), and other similar computing devices. The components shown here, their connections and relationships, and their functions, are meant to be examples only, and are not intended to limit the implementations of the present application described and / or claimed in this document.

[0107] As shown in ​ The electronic device 10 includes at least one processor 11, and a memory, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., which is communicatively connected to the at least one processor 11, wherein the memory stores a computer program that can be executed by the at least one processor. The processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 into the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other through a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0108] A plurality of components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a magnetic disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices through a computer network, such as the Internet, and / or various telecommunication networks.

[0109] The processor 11 can be various general and / or special purpose processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various specialized artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 performs various methods and processes described above, such as a composite material crack propagation method.

[0110] In some embodiments, a composite material crack propagation method can be implemented as a computer program tangibly embodied in a computer readable storage medium, such as the storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed onto the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded onto the RAM 13 and executed by the processor 11, one or more steps of a composite material crack propagation method described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to perform a composite material crack propagation method by any other appropriate means, such as by means of firmware.

[0111] Various implementations of the systems and techniques described above can be realized in digital electronic circuitry, integrated circuitry, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a system on a chip (SOC), a programmable logic device (PLD), a computer hardware, firmware, software, and / or combinations thereof. These various implementations can include implementation in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which can be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.

[0112] Computer programs for implementing the methods of the present application can be written in any combination of one or more programming languages. These computer programs can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the computer program, when executed, can cause instructions defined in the flow charts and / or block diagrams to be implemented. The computer program can be executed entirely on a machine, partially on a machine, partially on a machine as a stand-alone software package, and partially on a remote machine or entirely on a remote machine or server.

[0113] In the context of the present application, a computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by or in connection with an instruction execution system, apparatus, or device. A computer-readable storage medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium can be a machine-readable signal medium. More specific examples of a machine-readable storage medium will include one or more lines of a program of instructions in a transitory signal, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0114] To provide for interaction with a user, the systems and techniques described here can be implemented on an electronic device having a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the electronic device. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form, including acoustic, speech, or tactile input.

[0115] The systems and techniques described herein can be implemented in a computing system that includes a back end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front end component, e.g., a user computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the systems and techniques described herein, or any combination of such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0116] The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. A server can be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system, and solves the defects of large management difficulty and weak business scalability in traditional physical host and VPS service.

[0117] It should be understood that the various forms of flow shown above can be re-ordered, added to, or deleted from without departing from the scope of the present disclosure. For example, the steps recited in the present disclosure can be executed in parallel, executed in series, or executed in different orders, as long as the desired results of the technical solutions of the present disclosure can be achieved, and the present disclosure is not limited herein.

[0118] The above detailed description does not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A composite material crack propagation method, characterized in that: include: Constructing a finite element model of the composite material specimen, locating a crack tip node in the finite element model, establishing a local coordinate system based on the crack tip node, and calculating a crack jump length and a unit vector; Extracting nodal forces and opening displacements in a global coordinate system based on the finite element model, and converting the nodal forces and opening displacements into components in a local coordinate system based on the unit vectors; Each energy release rate component is calculated according to the local coordinate system component and the crack jump length, and each energy release rate component is substituted into a preset fracture criterion formula to generate a crack growth result of the composite material specimen.

2. The method according to claim 1, characterized in that The finite element model of the composite material specimen is constructed, comprising: Obtain the geometric dimensions of the composite specimen and identify the crack location to establish an initial geometric model; Acquiring material parameters, and setting material properties for the initial geometric model based on the material parameters, wherein the material parameters include elastic modulus, Poisson's ratio, and fracture toughness parameter; The set initial geometry model is meshed based on a preset configuration and boundary conditions are applied to construct a finite element model.

3. The method according to claim 2, characterized in that Positioning the crack tip node in the finite element model, establishing a local coordinate system according to the crack tip node, and calculating the crack jump length and unit vector include: Locating a crack tip node in the mesh of the finite element model based on the crack position, and selecting two nodes in the mesh adjacent to the crack tip node as a first auxiliary node and a second auxiliary node; Calculating the Euclidean distance of the spatial coordinate difference between the first auxiliary node and the crack tip node as the crack jump length; Calculating a coordinate difference between the first auxiliary node and the crack tip node as a mode II crack direction vector; calculating a coordinate difference between the second auxiliary node and the crack tip node as a tangential auxiliary vector; Cross-product the mode II crack direction vector and the tangential auxiliary vector to obtain a mode III crack direction vector; Cross-product the three-mode crack direction vector and the two-mode crack direction vector to obtain a one-mode crack direction vector; The mode II crack direction vector, the mode III crack direction vector, and the mode I crack direction vector are respectively normalized to obtain unit vectors of a local coordinate system.

4. The method according to claim 1, wherein The converting the nodal force and the opening displacement into local coordinate system components based on the unit vector comprises: Performing vector dot product operations on the unit vector, the nodal force, and the opening displacement to obtain each nodal force component and each opening displacement component; Each of the nodal force components and each of the opening displacement components is used as a local coordinate system component.

5. The method according to claim 4, characterized in that Calculating each energy release rate component according to the local coordinate system component and the crack jump length includes: Calculating first product values ​​of each of the node force components and the corresponding opening displacement components respectively; Obtaining a structural thickness of the composite material specimen, and calculating a product of the structural thickness and twice the crack jump length as a second product value; The ratio of each of the first product values ​​to the second product value is used as each energy release rate component.

6. The method according to claim 2, characterized in that Substituting each of the energy release rate components into a preset fracture criterion formula to generate a crack growth result of the composite material specimen includes: Substituting each of the energy release rate components and the fracture toughness parameter into a preset fracture criterion formula to determine an energy calculation value; Crack propagation calculation is performed based on the energy calculation value, and when the analysis termination condition is met, a crack propagation evolution diagram and a load-displacement curve are generated as crack propagation results.

7. The method according to claim 6, characterized in that The performing crack extension calculation according to the energy calculation value includes: Determining whether the calculated energy value is greater than a preset fracture threshold, and if so, determining crack propagation, releasing the crack tip node constraint, and locating the next crack tip node in the finite element model based on the preset crack path to perform crack propagation calculation; Otherwise, it is determined that the crack does not extend.

8. A composite material crack propagation device, characterized in that: include: A model construction and crack calculation module is used to construct a finite element model of the composite material specimen, locate the crack tip node in the finite element model, establish a local coordinate system based on the crack tip node, and calculate the crack jump length and unit vector; A local coordinate system component conversion module is used to extract the nodal force and opening displacement in the global coordinate system based on the finite element model, and convert the nodal force and opening displacement into local coordinate system components based on the unit vector; The crack growth result generating module is used to calculate each energy release rate component according to the local coordinate system component and the crack jump length, and substitute each energy release rate component into a preset fracture criterion formula to generate a crack growth result of the composite material specimen.

9. An electronic device, characterized in that: The electronic device comprises: at least one processor; and a memory communicatively coupled to the at least one processor; The memory stores a computer program that can be executed by the at least one processor, and the computer program is executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 7.

10. A computer storage medium, characterized in that The computer storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the method according to any one of claims 1 to 7 when executed.

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