Composite material crack propagation method based on discrete cohesion zone model

Abstract

The invention discloses a composite material crack propagation method based on a discrete cohesion zone model. 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 the size of a cohesion region; carrying out crack tip separation amount calculation under the local coordinate system so as to determine each displacement component; calculating a critical parameter corresponding to each fracture mode according to the size of the cohesion zone, and calculating each energy release rate component according to each displacement component and each critical parameter; and substituting each energy release rate component into a preset fracture criterion inequality to generate a crack propagation result of the composite material test piece. Through finite element modeling, the structure and the crack position of the composite material can be accurately represented, a basis is provided for subsequent expansion analysis, and compatibility with finite elements is achieved by calculating the size of a cohesive region and quantifying a cohesive force acting region. And crack propagation is simulated through a fracture criterion inequality, artificial experience intervention is avoided, and the result accuracy is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of numerical simulation, in particular to a composite material crack propagation method based on a discrete cohesive zone model. 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 composite materials 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 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 structure. SUMMARY

[0005] The present application provides a composite material crack propagation method based on a discrete cohesive zone model. Through a composite material crack propagation algorithm based on a discrete cohesive zone model, a mixed mode cohesive constitutive model is constructed, a crack tip spring is set, and a separation amount is calculated to simulate the crack initiation, propagation and failure process, solving the problems of insufficient compatibility between the discrete model and the finite element method, unclear quantification of the cohesive zone size, and lack of automatic criterion for multi-mode fracture criterion in the prior art.

[0006] According to an aspect of the present application, a composite material crack propagation method based on a discrete cohesive zone model is provided, which comprises:

[0007] A finite element model of a composite material specimen is constructed, the crack tip nodes are positioned in the finite element model, a local coordinate system is established according to the crack tip nodes, and the size of the cohesive zone is calculated;

[0008] The crack tip separation amount is calculated in the local coordinate system to determine each displacement component;

[0009] The critical parameters corresponding to each fracture mode are calculated according to the size of the cohesive zone, and each energy release rate component is calculated according to each displacement component and each critical parameter;

[0010] The energy release rate components are substituted into the preset fracture criterion inequality to generate a crack propagation result of the composite specimen.

[0011] Optionally, the finite element model of the composite specimen is constructed, including: obtaining geometric dimensions of the composite specimen and determining a crack position to establish an initial geometric model; obtaining material parameters, and performing material attribute setting on the initial geometric model based on the material parameters, wherein the material parameters include an elastic modulus, a Poisson's ratio, a fracture toughness parameter, a cohesive strength, and a cohesive stiffness; performing meshing on the set initial geometric model based on a preset configuration, and applying a boundary condition to construct the finite element model.

[0012] Optionally, a local coordinate system is established according to a crack tip node, and a size of a cohesive zone is calculated, including: locating a crack tip node in a mesh of the finite element model based on a crack position, and selecting two nodes in the mesh having a specified spatial position as a first auxiliary node and a second auxiliary node; calculating an Euclidean distance of a spatial coordinate difference of the first auxiliary node and the second auxiliary node, and taking one-half of the Euclidean distance as the size of the cohesive zone.

[0013] Optionally, critical parameters corresponding to each fracture mode are calculated according to the size of the cohesive zone, including: obtaining a specimen thickness of the composite specimen, and calculating a product of the specimen thickness, the cohesive strength, and the size of the cohesive zone as a critical force; determining a value of twice the fracture toughness parameter, and taking a ratio of the value of twice the fracture toughness parameter and the cohesive strength as a maximum displacement; calculating a ratio of the critical force and the cohesive stiffness as a critical displacement; and taking each of the critical force, the maximum displacement, and the critical displacement as each of the critical parameters.

[0014] Optionally, each energy release rate component is calculated according to each displacement component and each critical parameter, including: taking each displacement component as a target displacement component, and determining a target maximum displacement, a target critical displacement, and a target fracture toughness parameter corresponding to the target displacement component; when the target displacement component is greater than the target critical displacement and less than the target maximum displacement, calculating a first difference value of the target displacement component and the target critical displacement, and calculating a second difference value of the maximum displacement and the target critical displacement, calculating a ratio of the first difference value and the second difference value, and taking a product of the ratio and the target fracture toughness parameter as the energy release rate component; and when the target displacement component is greater than the maximum displacement, taking the target fracture toughness parameter as the energy release rate component.

[0015] Optionally, the energy release rate components are substituted into a preset fracture criterion inequality to generate the crack propagation result of the composite specimen, including: substituting the energy release rate components and the fracture toughness parameters into the preset fracture criterion inequality, and performing crack propagation calculation according to the establishment of the inequality, wherein the preset fracture criterion inequality is a power law criterion or a Benzeggagh-Kenane criterion; when the analysis termination condition is met, a crack propagation evolution diagram and a load-displacement curve are generated as the crack propagation result.

[0016] Optionally, the crack propagation calculation is performed according to the establishment of the inequality, including: determining whether the establishment is established, if yes, determining that the crack propagates, releasing the crack tip node constraint, and positioning the next crack tip node based on the preset crack path in the finite element model to perform crack propagation calculation; otherwise, determining that the crack does not propagate.

[0017] According to another aspect of the present application, a composite material crack propagation device based on a discrete cohesive zone model is provided, which comprises:

[0018] A model construction and crack positioning module is configured to construct a finite element model of a composite 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 size of a cohesive zone.

[0019] A displacement component determination module is configured to perform crack tip separation calculation in the local coordinate system to determine displacement components.

[0020] An energy release rate component calculation module is configured to calculate critical parameters corresponding to each fracture mode according to the size of the cohesive zone, and calculate energy release rate components according to the displacement components and the critical parameters.

[0021] A crack propagation result generation module is configured to substitute the energy release rate components into a preset fracture criterion inequality to generate a crack propagation result of the composite specimen.

[0022] According to another aspect of the present application, an electronic device is provided, which comprises:

[0023] at least one processor;

[0024] and a memory connected in communication with the at least one processor;

[0025] 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 based on a discrete cohesive zone model according to any one of the embodiments of the present application.

[0026] According to another aspect of the present application, there is provided a computer readable storage medium storing computer instructions for causing a processor to implement a composite material crack propagation method based on a discrete cohesive zone model when executed.

[0027] The technical solution of the embodiment of the present application can accurately characterize the composite material structure and the crack position through finite element modeling, and provides a basis for subsequent expansion analysis. The crack initiation position is determined by positioning the crack tip node, which facilitates subsequent cohesive element arrangement. The cohesive force action area is quantified by calculating the size of the cohesive zone, which is compatible with the finite element. Each fracture mode displacement component is obtained by calculating the separation amount, which provides input for the cohesive constitutive model. The crack propagation is simulated by the inequality of the fracture criterion, which avoids artificial experience intervention and improves the accuracy of the results.

[0028] It should be understood that the content described in this part is not intended to identify key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0030] Figure 1 is a flow chart of a composite material crack propagation method based on a discrete cohesive zone model according to the first embodiment of the present application;

[0031] Figure 2 is a crack tip positioning schematic diagram according to the first embodiment of the present application;

[0032] Figure 3 is a definition schematic diagram of a local coordinate system of a crack tip according to the first embodiment of the present application;

[0033] Figure 4 is a flow chart of another composite material crack propagation method based on a discrete cohesive zone model according to the second embodiment of the present application;

[0034] Figure 5 is a crack propagation result schematic diagram according to the second embodiment of the present application;

[0035] Figure 6 is a Y-direction load-displacement relationship curve schematic diagram according to the second embodiment of the present application;

[0036] Figure 7 Figure 3 is a structural schematic diagram of a composite material crack propagation device based on a discrete cohesive zone model according to an embodiment of the present application;

[0037] Figure 8 Figure 4 is a structural schematic diagram of an electronic device for implementing a composite material crack propagation method based on a discrete cohesive zone model according to an embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to make the personnel in the technical field better understand the present application scheme, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person of ordinary skill in the art without making creative labor should belong to the protection scope of the present application.

[0039] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0040] Embodiment One

[0041] Figure 1 A flowchart of a composite material crack propagation method based on a discrete cohesive zone model is provided for the first embodiment of the present application. The present embodiment can be applicable to a composite material crack propagation simulation scenario. The method can be performed by a composite material crack propagation device based on a discrete cohesive zone model. The composite material crack propagation device based on a discrete cohesive zone model can be realized in the form of hardware and / or software. The composite material crack propagation device based on a discrete cohesive zone model can be configured in a computer controller. As shown in the figure, the method comprises the following steps. Figure 1

[0042] S110, 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 cohesive zone size.

[0043] ​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 discretizes the composite specimen into a finite number of elements, such as a collection of shell elements QUAD75, simulates the mechanical behavior of the entire specimen by 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 size of the cohesive zone refers to the length of the region near the crack tip that simulates material damage and fracture, which is calculated by the node coordinates.

[0044] 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, fracture toughness parameter, cohesive strength and cohesive stiffness; performing grid division on the set initial geometric model based on a preset configuration, and applying boundary conditions to construct the finite element model.

[0045] 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 in which 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, which reflects the deformation ability of the material under the action of in-plane shear force, main Poisson's ratio v 12 = v 13 = 0.24, transverse Poisson's ratio v 23= 0.46, for describing the ratio of lateral 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 ), and mode III fracture toughness GIIIC= 1000000 N / mm (= 1000000000 J / m 2 ). Cohesive strength is the maximum stress that the interface or interlayer of the material can withstand in the cohesive zone model, and cohesive stiffness relates to the slope of the force-displacement response of the cohesive zone.

[0046] In a specific embodiment, in the finite element software, the parameters such as elastic modulus and Poisson's ratio are filled into the constitutive model of the anisotropic material by finding the corresponding material property setting interface, and for the case with a crack, the parameters such as fracture toughness, cohesive strength, and cohesive stiffness are configured into the properties of the cohesive element by using the cohesive zone model, so that the model can simulate the initiation and evolution of damage at the crack.

[0047] Further, the model is meshed and boundary conditions are applied based on the preset configuration. The meshing can adopt the shell element type QUAD75. When meshing, the mesh density needs to be reasonably set according to the specimen size and crack position, and especially the mesh near the crack tip may need to be densified to capture the stress concentration phenomenon. The boundary conditions can be applied by 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 to fix the displacement in the X and Z directions X=Z=0, and all angles MX=MY=MZ=0 are also 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.

[0048] Optionally, a local coordinate system is established according to the crack tip node, and the size of the cohesive zone is calculated, including: locating the crack tip node in the mesh based on the crack position in the finite element model, and selecting two nodes in the mesh with specified spatial positions as the first auxiliary node and the second auxiliary node; calculating the Euclidean distance of the spatial coordinate difference of the first auxiliary node and the second auxiliary node, and taking one-half of the Euclidean distance as the size of the cohesive zone.

[0049] Specifically, when locating the crack tip node in the finite element model and establishing the local coordinate system, operations need to be performed according to the principles of fracture mechanics and vector operation rules. First, the tip node is determined in the mesh based on the crack position, for example, 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 cantilever beam double opening test piece is shown in the figure, each origin represents a node, 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 30th node is the 30th node numbered in order, representing that the 31st node from the left side edge is defined as the crack tip node, which is 30 mm away from the left boundary. Then select two nodes adjacent to the tip node as the first auxiliary node and the second auxiliary node.

[0050] Exemplary, Figure 3 A definition diagram of a crack tip local coordinate system is provided for embodiment one of the application, the X, u, Y, v, Z, w in the lower left corner of the figure is the global coordinate system, used to describe the overall spatial position of the finite element model. Figure 3 The black dots in the figure represent the crack tip nodes, corresponding to three fracture mechanics loading modes. The I mode is the opening type, that is, the direction of the 2, K1, Opening arrow in the figure, corresponding to the normal of the crack surface. The II mode is the sliding type, that is, the direction of the 1, K2, Sliding arrow in the figure, corresponding to the tangential direction in the crack surface, perpendicular to the crack front. The III mode is the tearing type, that is, the direction of the 3, K3, Twisting arrow in the figure, corresponding to the tangential direction in the crack surface, parallel to the crack front. Δa in the figure represents the size of the cohesive zone. The numbers 1-6 in the figure represent the nodes on both sides of the crack surface, and the cohesive zone model connects each node through the cohesive element to simulate the separation of the crack surface. When the separation displacement of the cohesive element reaches the critical value, the crack propagation is determined.

[0051] Specifically, the size of the cohesive zone is calculated by the following formula (1):

[0052]

[0053] Where Δa represents the size of the cohesive zone, x5, y5 and z5 represent the coordinates of the first auxiliary node, that is, Figure 3 the coordinates of node 5 in the figure, x1, y1 and z1 represent the coordinates of the second auxiliary node, that is, Figure 3 the coordinates of node 1 in the figure.

[0054] Further, a spring with very large rigidity can be set between the node pair (3, 4) at the crack tip, and the spring stiffness is defined in the local coordinate system, including: the rigidity K2 is applied in the local 1 direction, the rigidity K1 is applied in the local 2 direction, and the rigidity K3 is applied in the local 3 direction.

[0055] S120, calculate the crack tip separation in the local coordinate system to determine each displacement component.

[0056] The separation amount refers to the relative displacement of the nodes on both sides of the crack tip in the local coordinate system, and is divided into three displacement components. The relative displacement in the local first direction is the I-type opening displacement, the relative displacement in the local second direction is the II-type sliding displacement, and the relative displacement in the local third direction is the III-type tearing displacement.

[0057] Specifically, the displacement component calculation process adopts the formula (2) as shown below:

[0058] δ=δ2i+δ1j+δ3k=(u1-u2)i+(v1-v2)j+(w1-w2)k (2)

[0059] Wherein, δ represents the separation displacement, δ1 represents the displacement component in the I-type fracture mode, δ2 represents the displacement component in the II-type fracture mode, δ3 represents the displacement component in the III-type fracture mode, i, j and k represent the unit vectors of the global coordinate system X, Y and Z axes, v1 and v2 represent Figure 3 the displacement components of the middle nodes 1 and 2 in the Y-axis direction, and w1 and w2 represent Figure 3 the displacement components of the middle nodes 1 and 2 in the Z-axis direction, wherein nodes 1 and 2 are a pair of nodes behind the crack.

[0060] S130, according to the size of the cohesive zone, the critical parameters corresponding to each fracture mode are calculated, and each energy release rate component is calculated according to each displacement component and each critical parameter.

[0061] The critical parameter refers to the limit mechanical parameter of the material resisting fracture, including: critical stress, critical displacement and maximum displacement. The critical stress refers to the limit stress of I / II / III type fracture, the critical displacement refers to the displacement corresponding to the critical stress, and the maximum displacement refers to the displacement corresponding to the complete failure of the material. The energy release rate component refers to the energy released per unit crack propagation area, which characterizes the driving force of crack propagation.

[0062] Optionally, the critical parameters corresponding to each fracture mode are calculated according to the size of the cohesive zone, including: obtaining the specimen thickness of the composite material specimen, calculating the product of the specimen thickness, the cohesive strength and the size of the cohesive zone in each fracture mode as the critical force; determining the value of twice the fracture toughness parameter, and taking the ratio of twice the fracture toughness parameter value and the cohesive strength as the maximum displacement; calculating the ratio of the critical force and the cohesive stiffness as the critical displacement; taking each critical force, maximum displacement and critical displacement as each critical parameter.

[0063] Specifically, taking the I-type fracture mode as an example, the critical force is calculated by the following formula (3):

[0064] F 1c =σ 1c BΔα (3)

[0065] Wherein, F1c represents the critical force under the mode I fracture, Δa represents the size of the cohesive zone, B represents the thickness of the structure, and δ 1C represents the cohesive strength. The maximum displacement is calculated by using the following formula (3) :

[0066]

[0067] wherein δ 1m represents the maximum displacement under the mode I fracture, σ 1C represents the cohesive strength, and G IC represents the fracture toughness parameter corresponding to the mode I fracture. The critical displacement is calculated by using the following formula (3) :

[0068]

[0069] wherein δ 1c represents the critical displacement under the mode I fracture, F 1C represents the critical force under the mode I fracture, and K1 represents the local 2-direction applied stiffness. The energy release rate components in the mode II crack direction and the mode III crack direction are calculated by using the same method. The critical parameters under the mode II fracture and the mode III fracture are calculated by using the same method.

[0070] Optionally, each energy release rate component is calculated according to each displacement component and each critical parameter, including: taking each displacement component as a target displacement component respectively, and determining a target maximum displacement, a target critical displacement, and a target fracture toughness parameter corresponding to the target displacement component; when the target displacement component is greater than the target critical displacement and less than the target maximum displacement, calculating a first difference value of the target displacement component and the target critical displacement, and calculating a second difference value of the maximum displacement and the target critical displacement, calculating a ratio of the first difference value and the second difference value, and taking a product of the ratio and the target fracture toughness parameter as the energy release rate component; when the target displacement component is greater than the maximum displacement, taking the target fracture toughness parameter as the energy release rate component.

[0071] Specifically, taking the mode I fracture as an example, when δ 1C <δ1<δ 1m , the stiffness is calculated by using the following formula (6), and the energy release rate component is calculated by using the following formula (7) :

[0072]

[0073] wherein G I represents the energy release rate component under the mode I fracture, F 1C represents the critical force under the mode I fracture, δ 1m represents the maximum displacement under the mode I fracture, δ1 represents the displacement component under the mode I fracture, and K1' represents the updated local 2-direction stiffness.1c denotes the critical displacement under mode I fracture mode, G IC denotes the fracture toughness parameter corresponding to mode I fracture mode.

[0074] Further, when δ1> δ 1m , K1' is 0, G I is equal to the corresponding fracture toughness parameter, that is, G I is constantly increasing before the peak value, and G I is a fixed value of material properties after the peak value, at this time, the stiffness is also declared invalid. The energy release rate component calculation process under mode II fracture mode and mode III fracture mode is similar.

[0075] S140, substituting each energy release rate component into the preset fracture criterion inequality to generate the crack propagation result of the composite specimen.

[0076] Specifically, the calculated energy release rate components of different modes are put into the pre-set fracture criterion. If the calculated energy release rate component satisfies the inequality in the criterion, such as the energy release rate reaching or exceeding the energy threshold of the material resisting crack propagation, it indicates that the crack will propagate, at this time, the software can simulate the crack propagation path, the propagation length and other results.

[0077] The technical scheme of the embodiment of the application can accurately characterize the composite material structure and the crack position through finite element modeling, and provides a basis for subsequent expansion analysis. By positioning the crack tip node, the crack initiation position is determined, which facilitates subsequent cohesive element arrangement. By calculating the size of the cohesive zone, the cohesive force acting area is quantified, and compatibility with the finite element is achieved. By calculating the separation amount to obtain the displacement component of each fracture mode, the input of the cohesive constitutive is provided. The crack propagation is simulated through the fracture criterion inequality, avoiding artificial experience intervention, and improving the accuracy of the results.

[0078] Embodiment two

[0079] Figure 4 A flowchart of a composite material crack propagation method based on a discrete cohesive zone model is provided in the second embodiment of the application. The embodiment adds the specific process of substituting each energy release rate component into the preset fracture criterion inequality to generate the crack propagation result of the composite specimen based on the first embodiment. The specific content of steps S210-S230 is substantially the same as that of steps S110-S130 in the first embodiment, and therefore will not be described again in this embodiment. As shown in the figure, the method comprises the following steps. Figure 4

[0080] S210, constructing a finite element model of a composite specimen, positioning a crack tip node in the finite element model, establishing a local coordinate system according to the crack tip node, and calculating the size of the cohesive zone.​

[0081] Optionally, the finite element model of the composite specimen is constructed, including: obtaining geometric dimensions of the composite specimen and determining a crack position to establish an initial geometric model; obtaining material parameters, and performing material attribute setting on the initial geometric model based on the material parameters, wherein the material parameters include an elastic modulus, a Poisson's ratio, a fracture toughness parameter, a cohesive strength, and a cohesive stiffness; performing meshing on the initial geometric model after the setting based on a preset configuration, and applying a boundary condition to construct the finite element model.

[0082] Optionally, a local coordinate system is established according to a crack tip node, and a size of a cohesive zone is calculated, including: locating a crack tip node in a mesh of the finite element model based on a crack position, and selecting two nodes in the mesh having a specified spatial position as a first auxiliary node and a second auxiliary node; calculating an Euclidean distance of a spatial coordinate difference of the first auxiliary node and the second auxiliary node, and taking one-half of the Euclidean distance as the size of the cohesive zone.

[0083] S220, crack tip separation amount calculation is performed in the local coordinate system to determine each displacement component.

[0084] S230, critical parameters corresponding to each fracture mode are calculated according to the size of the cohesive zone, and each energy release rate component is calculated according to each displacement component and each critical parameter.

[0085] Optionally, the critical parameters corresponding to each fracture mode are calculated according to the size of the cohesive zone, including: obtaining a specimen thickness of the composite specimen, and calculating a product of the specimen thickness, the cohesive strength, and the size of the cohesive zone as a critical force; determining a value of twice the fracture toughness parameter, and taking a ratio of the value of twice the fracture toughness parameter and the cohesive strength as a maximum displacement; calculating a ratio of the critical force and the cohesive stiffness as a critical displacement; and taking each critical force, the maximum displacement, and the critical displacement as each critical parameter.

[0086] Optionally, each energy release rate component is calculated according to each displacement component and each critical parameter, including: taking each displacement component as a target displacement component, and determining a target maximum displacement, a target critical displacement, and a target fracture toughness parameter corresponding to the target displacement component; when the target displacement component is greater than the target critical displacement and less than the target maximum displacement, calculating a first difference value of the target displacement component and the target critical displacement, and calculating a second difference value of the maximum displacement and the target critical displacement, calculating a ratio of the first difference value and the second difference value, and taking a product of the ratio and the target fracture toughness parameter as an energy release rate component; and when the target displacement component is greater than the maximum displacement, taking the target fracture toughness parameter as the energy release rate component.

[0087] S240, substituting each energy release rate component and the fracture toughness parameter into a preset fracture criterion inequality, and performing crack propagation calculation according to the satisfaction of the inequality, wherein the preset fracture criterion inequality is a power law criterion or a Benzeggagh-Kenane criterion.

[0088] Specifically, the power law criterion adopts the formula (8) as shown below:

[0089]

[0090] wherein G I represents the energy release rate component in the I-type crack direction, G II represents the energy release rate component in the II-type crack direction, G III represents the energy release rate component in the III-type crack direction, G IC , G IIC and C IIIC respectively represent the fracture toughness parameters corresponding to each energy release rate component. α is the power index (material parameter), which can take a fractional value, and the typical value is 1. If the inequality is satisfied, all spring elements between the node pair (3, 4) where the crack tip is located will be released.

[0091] Specifically, the Benzeggagh-Kenane criterion (BK) adopts the formula (9) as shown below:

[0092]

[0093] wherein G I represents the energy release rate component in the I-type crack direction, G II represents the energy release rate component in the II-type crack direction, G III represents the energy release rate component in the III-type crack direction, G IC , G IIC and G IIIC respectively represent the fracture toughness parameters corresponding to each energy release rate component. η is a material parameter, which can take a fractional value, and the typical value is 1. If the inequality is satisfied, all spring elements between the node pair (3, 4) where the crack tip is located will be released. When the critical fracture energy in the in-plane shear and out-of-plane shear deformation processes of the material is the same, it is usually recommended to use the BK criterion.

[0094] S250, when the analysis termination condition is satisfied, generating a crack propagation evolution diagram and a load displacement curve as the crack propagation result.

[0095] 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.

[0096] Exemplarily, Figure 5 A crack propagation result schematic diagram is provided for the second embodiment of the present application, Figure 5 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, thereby providing boundary constraints 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, thereby embodying the stress concentration and strain energy release process during crack propagation.

[0097] 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, taking displacement as the horizontal axis and load as the vertical axis. Figure 6 In the Y-direction load-displacement relationship curve, displacement 0-2 mm 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 to store elastic strain energy. Displacement 2-4.755 mm 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, at this time the load reaches the maximum value, representing the ultimate load-bearing capacity of the material, and thereafter the curve falls, indicating that the material starts to be damaged and enters the damage propagation stage. In the falling section, the crack continues to propagate, the load gradually decreases with the increase of displacement, reflecting the accumulation of material damage and stiffness degradation, which may be accompanied by crack propagation, delamination and other failure modes, until the load tends to be stable.

[0098] Optionally, the crack propagation calculation is performed according to the establishment of the inequality, including: judging whether the establishment is established or not, if yes, determining that the crack propagates, releasing the node constraint of the crack tip, and positioning the next crack tip node based on the preset crack path in the finite element model to perform crack propagation calculation; otherwise, determining that the crack does not propagate.

[0099] The preset crack path refers to a crack possible expansion trend according to the geometric shape of the test piece, material properties and actual engineering, for example, in a composite laminated plate, the crack may expand along the interlaminar interface and fiber direction, and when the finite element model is established, the crack is planned to expand in which direction and along which nodes.

[0100] Specifically, when the inequality is established, it indicates that the driving force of crack expansion has exceeded the resistance of the material, and the crack will expand. At this time, the controller finds a group of nodes corresponding to the subsequent nodes of the current crack tip node along the preset crack path, determines the group of nodes as the new crack tip node, and re-calculates the energy release rate at the new crack tip node. Then, the energy calculation value is compared with the fracture threshold value again to determine whether the crack expands, and the iteration is continuously performed until the crack expands through the entire test piece or the preset analysis termination condition is met. When the inequality is not established, it is determined that the crack does not expand. 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 makes the inequality established in the subsequent loading process, and then the determination of crack expansion and related operations are triggered again.

[0101] In addition, in the finite element model, the nodes at the crack tip are constrained in the initial state to simulate the continuity of the material when the crack does not expand. When the crack expands, it is equivalent to the material being disconnected, so the constraints between the nodes at the crack tip are removed. For example, the corresponding contact element definition is removed from the constraint list of the model, or the stiffness matrix is modified so that the nodes are no longer constrained, to simulate the physical process of crack face separation and release the strain energy accumulated before.

[0102] The technical scheme of the embodiment of the present application determines the crack expansion critical condition through the fracture criterion inequality, provides a basis for crack expansion calculation, generates a crack expansion evolution diagram and a load displacement curve when the analysis termination condition is met, and directly associates the mechanical parameters with the crack expansion behavior through the quantitative energy calculation, so that the dynamic process of crack expansion and the change of structural bearing capacity can be intuitively presented in a visual chart. When determining whether the crack expands, the crack expansion process is controlled through the establishment of the inequality, the crack tip constraint is removed and the new node is positioned in time when the inequality is established, the dynamic extension of the crack is simulated, and the crack is determined to be stable when the inequality is not established. The present application effectively makes up for the deficiency of the existing method in capturing the dynamic changes of the crack tip, realizes the fine simulation of the whole process of the crack expansion behavior of the composite material from the beginning, development to termination, and significantly improves the accuracy and reliability of crack expansion prediction.

[0103] Embodiment three

[0104] Figure 7 A structure diagram of a composite material crack propagation device based on a discrete cohesive zone model is provided for Embodiment Three of the present application. As shown in the figure, the device comprises a model construction and crack positioning module 310 for 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 size of a cohesive zone; Figure 7

[0105] A displacement component determination module 320 for calculating a crack tip separation amount in the local coordinate system to determine each displacement component;

[0106] An energy release rate component calculation module 330 for calculating critical parameters corresponding to each fracture mode according to the size of the cohesive zone, and calculating each energy release rate component according to each displacement component and each critical parameter;

[0107] A crack propagation result generation module 340 for substituting each energy release rate component into a preset fracture criterion inequality to generate a crack propagation result of the composite material test piece.

[0108] Optionally, the model construction and crack positioning module 310 specifically comprises a finite element model construction unit for obtaining the geometric size of the composite material test piece and clearly positioning the crack 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, fracture toughness parameter, cohesive strength, and cohesive stiffness; and performing mesh division on the set initial geometric model based on a preset configuration and applying boundary conditions to construct the finite element model.

[0109] Optionally, the model construction and crack positioning module 310 specifically comprises a crack tip positioning unit for positioning a crack tip node in the mesh of the finite element model based on the crack position, and selecting two nodes in the mesh having a specified spatial position as a first auxiliary node and a second auxiliary node; calculating the Euclidean distance of the spatial coordinate difference of the first auxiliary node and the second auxiliary node, and taking one-half of the Euclidean distance as the size of the cohesive zone.

[0110] Optionally, the energy release rate component calculation module 330 specifically comprises a critical parameter calculation unit for obtaining the test piece thickness of the composite material test piece, calculating the product of the test piece thickness, the cohesive strength, and the size of the cohesive zone under each fracture mode as a critical force; determining a double fracture toughness parameter value, taking the ratio of the double fracture toughness parameter value and the cohesive strength as a maximum displacement; calculating the ratio of the critical force and the cohesive stiffness as a critical displacement; and taking each critical force, maximum displacement, and critical displacement as each critical parameter.

[0111] ​Optionally, the energy release rate component calculation module 330 specifically comprises an energy release rate component calculation unit, configured to: take each displacement component as a target displacement component respectively, and determine a target maximum displacement, a target critical displacement and a target fracture toughness parameter corresponding to the target displacement component; when the target displacement component is greater than the target critical displacement and less than the target maximum displacement, calculate a first difference value of the target displacement component and the target critical displacement, and calculate a second difference value of the maximum displacement and the target critical displacement, calculate a ratio of the first difference value and the second difference value, and take a product of the ratio and the target fracture toughness parameter as the energy release rate component; when the target displacement component is greater than the maximum displacement, take the target fracture toughness parameter as the energy release rate component.

[0112] Optionally, the crack propagation result generation module 340 is specifically configured to: substitute each energy release rate component and the fracture toughness parameter into a preset fracture criterion inequality, and perform crack propagation calculation according to a holding condition of the inequality, wherein the preset fracture criterion inequality is a power law criterion or a Barenblatt-Kanninen criterion; and when an analysis termination condition is met, generate a crack propagation evolution diagram and a load-displacement curve as the crack propagation result.

[0113] Optionally, the crack propagation result generation module 340 specifically comprises a crack propagation calculation unit, configured to: determine whether the holding condition is true, if yes, determine that the crack propagates, release the 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; or if not, determine that the crack does not propagate.

[0114] The technical scheme of the embodiment of the application can accurately characterize the composite material structure and the crack position through finite element modeling, and provides a basis for subsequent expansion analysis. By positioning the crack tip node, the crack starting position is determined, which facilitates subsequent cohesive element arrangement. By calculating the size of the cohesive zone, the cohesive force action area is quantified, which realizes compatibility with the finite element. By calculating the separation amount to obtain each fracture mode displacement component, input is provided for the cohesive constitutive relation. The crack propagation is simulated through the fracture criterion inequality, which avoids artificial experience intervention and improves the accuracy of the result.

[0115] The composite material crack propagation device based on the discrete cohesive zone model provided in the embodiment of the application can execute the composite material crack propagation method based on the discrete cohesive zone model provided in any embodiment of the application, and has the corresponding function modules and beneficial effects of the execution method.

[0116] Embodiment Four

[0117] Figure 8A structural 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.

[0118] As shown in Figure 8 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., communicatively connected to the at least one processor 11, where the memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes according to the computer programs stored in the read-only memory (ROM) 12 or loaded into the random access memory (RAM) 13 from the storage unit 18. 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.

[0119] Various 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.

[0120] 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 special-purpose 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 based on a discrete cohesive zone model.

[0121] In some embodiments, a composite material crack propagation method based on a discrete cohesive zone model can be implemented as a computer program tangibly embodied in a computer readable storage medium, e.g., storage unit 18. In some embodiments, parts or all of the computer program can be loaded and / or installed onto electronic device 10 via, e.g., ROM 12 and / or communication unit 19. When the computer program is loaded onto RAM 13 and executed by processor 11, one or more steps of a composite material crack propagation method based on a discrete cohesive zone model as described above can be performed. Alternatively, in other embodiments, processor 11 can be configured to perform a composite material crack propagation method based on a discrete cohesive zone model by way of other any suitable means, e.g., by way of firmware.

[0122] The various implementations of the system 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.

[0123] Computer programs used to implement the processes 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 to produce a machine, such that the computer program, when executed, implements the functions / acts specified in the flowcharts and / or block diagrams. The computer program can be executed entirely on a machine, partially on a machine and partially on a remote machine or entirely on a remote machine or server.

[0124] 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.

[0125] 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.

[0126] The systems and techniques described here 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 here), 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.

[0127] 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. The 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.

[0128] It should be understood that the various forms of flow shown above can be used to reorder, add or delete steps. For example, each step described in the present application can be executed in parallel, sequentially or in a different order, as long as the desired results of the technical solutions of the present application can be achieved, which is not limited herein.

[0129] 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 based on a discrete cohesive zone model, 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 the size of the cohesive zone; The crack tip separation is calculated in the local coordinate system to determine the displacement components; Calculating the critical parameters corresponding to each fracture mode according to the cohesive zone size, and calculating each energy release rate component according to each displacement component and each critical parameter; Each of the energy release rate components is substituted into a preset fracture criterion inequality 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, fracture toughness parameter, cohesive strength, and cohesive stiffness; 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 The establishing of a local coordinate system according to the crack tip node and calculating the size of the cohesive zone includes: 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 that have a specified spatial position with the crack tip node as a first auxiliary node and a second auxiliary node; The Euclidean distance of the spatial coordinate difference between the first auxiliary node and the second auxiliary node is calculated, and half of the Euclidean distance is used as the cohesive region size.

4. The method according to claim 2, characterized in that Calculating the critical parameters corresponding to each fracture mode according to the cohesive zone size includes: Obtaining the specimen thickness of the composite material specimen, and calculating the product of the specimen thickness, the cohesive strength, and the cohesive zone size under each fracture mode as the critical force; Determining twice the fracture toughness parameter value, and taking the ratio of the twice the fracture toughness parameter value to the cohesive strength as the maximum displacement; calculating a ratio of the critical force to the cohesive stiffness as a critical displacement; The critical force, the maximum displacement and the critical displacement are used as critical parameters.

5. The method according to claim 4, characterized in that Calculating each energy release rate component according to each displacement component and each critical parameter includes: Taking each displacement component as a target displacement component, the target maximum displacement, target critical displacement and target fracture toughness parameter corresponding to the target displacement component are determined; When the target displacement component is greater than the target critical displacement and less than the target maximum displacement, calculating a first difference between the target displacement component and the target critical displacement, calculating a second difference between the maximum displacement and the target critical displacement, calculating a ratio of the first difference to the second difference, and taking the product of the ratio and the target fracture toughness parameter as the energy release rate component; When the target displacement component is greater than the maximum displacement, the target fracture toughness parameter is used as the 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 inequality 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 inequality, and performing crack propagation calculation based on whether the inequality holds true, wherein the preset fracture criterion inequality is a power law criterion or a Benzheimer-Kanner criterion; When the analysis termination conditions are met, the crack growth evolution diagram and load-displacement curve are generated as the crack growth results.

7. The method according to claim 6, characterized in that The crack propagation calculation according to the establishment of the inequality includes: Determine whether the condition is established, and if so, determine crack propagation, release the crack tip node constraint, and locate 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 based on a discrete cohesive zone model, characterized in that: include: A model building and crack location module 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 cohesive zone size; A displacement component determination module is used to calculate the crack tip separation in a local coordinate system to determine each displacement component; an energy release rate component calculation module, configured to calculate the critical parameters corresponding to each fracture mode according to the cohesive zone size, and to calculate each energy release rate component according to each displacement component and each critical parameter; The crack growth result generating module is used to substitute each of the energy release rate components into a preset fracture criterion inequality 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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