A method for predicting impact damage of ceramic based on near-field dynamic bond damage model

Abstract

The application discloses a ceramic impact damage prediction method based on a near-field dynamic bond damage model, and belongs to the technical field of numerical simulation and failure evaluation of ceramic structures against impact. The method takes the bond level damage evolution driven by JH-2 equivalent plastic strain increment as the main body, describes the progressive damage and compression-shear crushing process of the ceramic material under the compression, shear and compression-shear coupling action, introduces the critical elongation as a supplementary criterion for tensile fracture, judges the bond fracture failure under the tensile dominant state, and thus realizes the unified representation of the compression-shear crushing and tensile cracking. The rate-dependent plastic flow is coupled with the bond level damage evolution, the damage degradation is fed back to the force state updating and yield judgment process, the stable prediction of crack initiation, expansion, crushing and residual bearing capacity of the ceramic material under quasi-static compression, normal impact and high strain rate load is realized, the problems of non-physical crack width, abnormal failure of material points and poor numerical convergence in the traditional point-level damage model can be effectively reduced, and the method can be used for the impact resistance analysis and safety evaluation of ceramic armors, engineering ceramic structures and brittle protective components.

Description

Technical Field

[0001] This invention belongs to the field of numerical simulation and failure assessment technology of ceramic structure impact resistance, and particularly relates to a method for predicting ceramic impact failure based on a near-field dynamic bond damage model. Background Technology

[0002] Ceramic materials possess advantages such as high hardness, high specific strength, high temperature resistance, and wear resistance, and are widely used in armor protection, aerospace, heat-resistant components, and engineering protective structures. Under impact, penetration, and other high strain rate loads, ceramic materials typically exhibit complex behaviors including pressure strengthening, strain rate sensitivity, brittle cracking, local crushing, and fragmentation failure. The crack initiation, propagation, penetration, and fragmentation processes directly affect the impact resistance and service safety of the structure. Therefore, accurately predicting the fracture failure process of ceramic materials under dynamic loads is a crucial foundation for the impact-resistant design and safety assessment of ceramic structures.

[0003] Currently, the dynamic fracture problem of ceramics is mainly studied through impact tests, empirical models, and traditional numerical methods for continuous media. Impact tests are costly and cannot fully reveal the crack propagation and fragmentation evolution process inside the material. Although traditional finite element method, element deletion method, and extended finite element method can be used for relevant analysis, they still have problems such as strong mesh sensitivity, crack path dependence pre-defined criteria, coarse handling of local failures, and insufficient computational stability when dealing with large deformation, strong nonlinear contact, crack bifurcation and penetration problems.

[0004] Peri-field dynamics methods use nonlocal integral equations to describe the interactions between material points, naturally characterizing crack initiation, propagation, and multi-crack interactions. Among these, conventional peri-field dynamics overcomes the Poisson's ratio limitation of bond-type peri-field dynamics, making it more suitable for constructing elastoplastic damage models for general materials. The JH-2 model can characterize the pressure strengthening, strain rate sensitivity, fracture softening, damage accumulation, and volumetric plastic response of ceramic materials under high pressure and high strain rate conditions. However, existing JH-2 numerical methods largely rely on a local continuous medium framework, making it difficult to directly describe complex crack evolution; existing peri-field dynamic ceramic models often employ point-level damage or single fracture criteria, easily leading to problems such as non-physical crack width, anomalous failure at material points, and insufficient damage degradation feedback.

[0005] Therefore, it is necessary to propose a method for predicting impact failure of ceramic materials based on a near-field dynamic bond-level damage model. Summary of the Invention

[0006] The purpose of this invention is to provide a method for predicting ceramic impact failure based on a near-field dynamic bond damage model, addressing the shortcomings of existing technologies in stably and accurately predicting the fracture failure process of ceramic materials under impact and high strain rate loads. This invention introduces the JH-2 pressure-rate related constitutive relation into a conventional near-field dynamic framework and constructs a progressive bond-level damage model, achieving a unified analysis of the entire process of impact damage, crack propagation, and fracture failure in ceramic materials.

[0007] To achieve the above objectives, this invention provides a method for predicting ceramic impact failure based on a near-field dynamic bond damage model, comprising the following steps: S1. Obtain the geometric parameters, material parameters, initial boundary conditions, and loading conditions of the ceramic material structure; S2. Establish an impact fracture failure analysis model based on the coupling of conventional peri-field dynamics and JH-2 constitutive relation. Embed the JH-2 pressure-rate related plastic constitutive relation into the volume response, bias response and force state update process of conventional peri-field dynamics, and construct a hybrid bond level damage model that combines plastic cumulative damage and critical elongation criterion. S3. Perform explicit time history calculation of the near-field dynamic analysis model, update the volume response, bias response, hydrostatic pressure, plastic state, bond damage state and material point damage state in each time step, and feed back the bond damage state to the force state update between material points, yield determination and material point bearing capacity degradation process. S4. When the calculation reaches the preset loading process or termination condition, the calculation will terminate and output the dynamic response, crack propagation morphology, damage distribution and failure mode of the ceramic material.

[0008] Preferably, the loading conditions in S1 include quasi-static compression, small ball normal impact, penetrating impact or other dynamic load conditions; The geometric parameters mentioned in S1 and S2 include the ceramic structure dimensions, loading region, and constraint region; the material parameters include at least the bulk modulus K, shear modulus G, JH-2 strength parameters A, B, C, M, N, Hugoniot elastic limit parameter, state equation parameters K1, K2, K3, reference strain rate, damage parameters D1, D2, and critical elongation s0 used for tensile fracture determination; the near-field dynamic analysis model discretizes the structure under analysis, dividing it into several near-field dynamic material points, and determines the spacing and near-field range of the material points; a neighborhood search table for the material points is established, and the parameters required for nonlocal integral calculation are initialized by combining the volume, mass, and density information of each material point.

[0009] Preferably, the specific content of the near-field dynamic impact fracture failure analysis model pre-constructed in S2 is as follows: S21. Discretize the ceramic structure into near-field dynamic material points containing material property information, and determine the spacing between material points, near-field range, calculation time step, and volume, mass and initial density of each material point. S22. Search for nearby material points based on the initial position of the material point and establish a neighborhood list; S23. Based on the conventional near-field dynamics framework, a pressure-rate-dependent plastic constitutive model of ceramic materials is constructed, and the JH-2 constitutive relation is introduced to characterize the pressure strengthening effect, strain rate sensitivity, fracture softening behavior and volumetric plastic response of the materials. S24. Construct a hybrid bond-level damage model based on the combination of bond damage accumulation and critical elongation s0. Drive the evolution of bond-level damage under compression, shear and compression-shear coupling with the JH-2 equivalent plastic strain increment. Use the critical elongation s0 as the tensile fracture criterion to judge the bond fracture failure under the tensile-dominant state. Describe the crack initiation, propagation and complete failure process of ceramic materials under impact load. S25. Configure the velocity boundary, displacement boundary, stress wave boundary or contact impact boundary of the loading area, as well as the boundary conditions of the constrained area.

[0010] Preferably, the specific content of the explicit time history calculation of the near-field dynamic impact fracture failure analysis model in S3 is as follows: S31. Calculate the interaction forces between material points at the current time step, and update the volume response, bias response, and hydrostatic pressure of the material points according to the normal state near-field dynamics framework. S32. Update the complete strength, fracture strength, yield state, plastic flow state, and damage variables based on the JH-2 constitutive relation; S33. Update the damage state of each bond based on a hybrid criterion combining bond damage accumulation and critical elongation s0; wherein, bond damage under compression and shear states is driven by JH-2 plastic damage evolution, and bond fracture under tension states is determined by comparing bond elongation with critical elongation s0; when any bond meets the complete failure condition, cut off the internal force transmission between the material points associated with that bond. S34. Update the displacement, velocity, and strain rate of the material point using an explicit time-integration scheme; S35. Determine whether the current calculation has reached the preset loading process or termination condition. If not, proceed to the next time step to continue the calculation; if it has, terminate the calculation and output the prediction result.

[0011] Preferably, the hydrostatic pressure response in S31 is updated using a combination of state equations and volumetric plasticity, satisfying the following expression during the compression loading stage: ; ; In the formula, It is the hydrostatic pressure; This refers to the relative volumetric compression. and These are the current density and the initial density, respectively. This refers to the additional pressure term for the damage; The distortion energy density; Additional pressure correction factor; During the unloading and reloading phases, the bulk modulus is used. The pressure is updated for the linear elastic path with slope, while preserving the volume expansion effect caused by damage accumulation; when the material is in a tensile volume state, the hydrostatic pressure is updated using tensile cutoff, and the tensile strength is limited by the maximum tensile hydrostatic pressure parameter.

[0012] Preferably, the constitutive relation of JH-2 in S32 is expressed in normalized strength form, and its intact strength, fragmentation strength, and current normalized equivalent strength satisfy the following expressions: ; ; ; In the formula, For complete strength; The breaking strength; This represents the current normalized equivalent strength. For material damage variables; Normalized hydrostatic pressure; The normalized maximum tensile hydrostatic stress; This represents the equivalent rate of change.

[0013] Preferably, in step S33, the yield function is constructed based on the deviatoric force state of the conventional peri-field dynamics, and the deviatoric extension, deviatoric force state, and equivalent plastic strain increment are updated using a pressure-rate related plastic correction algorithm, as expressed below: ; ; ; In the formula, To test the deviatoric force state; The radius of the near-field dynamic neighborhood; Dynamic fracture strength related to pressure and strain rate; For strain rate; For the plastic multiplier increment; for HEL stress; The material damage evolution coefficient; When the yield function is less than or equal to zero, the material point is in an elastic loading state; when the yield function is greater than zero, the material point enters a plastic loading state, and the yield function is adjusted according to the plastic multiplier increment. The equivalent plastic strain increment and plastic volumetric strain increment are updated to drive subsequent bond-level damage evolution.

[0014] Preferably, the bond-level damage evolution model constructed in S24 and the update relationship in S33 include the plastic cumulative damage criterion and the tensile fracture criterion; wherein, for bonds under compression, shear, or compression-shear coupled stress states, their damage state is driven by the cumulative accumulation of JH-2 equivalent plastic strain increments and satisfies the following expression: ; ; in, The total fracture plastic strain of the bond; This represents the equivalent plastic strain increment at the current time step. This represents the increment of key damage at the current time step. For key damage state variables.

[0015] For bonds under tensile-dominant stress, the critical elongation s0 is used as a supplementary criterion for tensile fracture. In this critical elongation criterion, a material point is defined. and Elongation of the bond between The expression is as follows: ; In the formula, This represents the relative position vector of two material points in the initial configuration; This represents the displacement of a point mass; This represents the relative displacement vector between two material points; This represents the distance between two material points under the current configuration; This represents the distance between two material points under the initial configuration; When the bond elongation s is greater than or equal to the critical elongation s0, the bond is determined to have undergone tensile fracture; when the bond damage state variable d reaches 1, the bond is determined to have undergone complete damage under compression, shear or compression-shear coupling; when the bond satisfies the tensile fracture condition or the plastic cumulative damage reaches the complete failure condition, the internal force transmission capacity of the bond between adjacent material points degrades to zero.

[0016] Preferably, the calculation of the interaction forces between matter points in S31 and the update of the motion state of matter points in S34 satisfy the conventional peri-field dynamics equations, as shown in the following expressions: ; In the formula, For matter points The near-field range; These are adjacent material points within the near-field range; The density of the substance at point depth; The acceleration of a point mass; Body density; and This refers to the state of interaction forces between material points.

[0017] Preferably, in S34, the explicit time integral uses the Verlet integral scheme to update displacement and velocity, as shown in the following expression: ; In the formula, That is, the displacement of the material point at step n; The velocity of the substance point at step n; Δt represents the acceleration of the material point at step n+1; Δt is the time step.

[0018] Therefore, the ceramic impact failure prediction method based on the near-field dynamic bond damage model described above has the following beneficial effects: (1) This invention combines the conventional near-field dynamics framework with the JH-2 constitutive relation, which can uniformly characterize the pressure strengthening effect, strain rate sensitivity, fracture softening and bulk plastic behavior of ceramic materials under dynamic load; (2) This invention adopts a hybrid bond-level damage model that combines plastic cumulative damage and critical elongation criterion to replace the traditional point-level damage model. The damage under compression, shear and compression-shear coupling action evolves progressively through plastic accumulation, which effectively reduces the non-physical crack width and material point abnormal failure problem. The brittle fracture under tension is determined by the critical elongation criterion, which can more reasonably describe the compression-shear breakage, tensile cracking and crack propagation process of ceramic materials. (3) This invention couples the bond damage evolution with rate-dependent plastic flow, so that the damage degradation can be fed back to the subsequent yield determination and force state update process, thereby improving the numerical stability, physical consistency and convergence reliability of dynamic fracture simulation. (4) This invention is applicable to the analysis of fracture behavior of ceramic materials under quasi-static compression, small ball normal impact, penetration impact, explosive impact and other complex load conditions, and can provide an effective tool for the impact resistance design and safety assessment of ceramic armor, engineering ceramic structures and brittle protective components.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1This is a flowchart of a ceramic impact damage prediction method based on a near-field dynamic bond damage model according to the present invention. Figure 2 A schematic diagram of the quasi-static compression model and damage morphology of a ceramic cylinder; Figure 3 A quasi-static compressive stress-strain diagram; Figure 4 A schematic diagram of the calculation model for the normal impact of a small ball on a ceramic target plate; Figure 5 The diagram shows the fracture mode and damage distribution of a ceramic target plate under normal impact, where (a) is the measured fracture mode diagram of the ceramic target plate in the impact test, and (b) is the damage distribution diagram obtained by near-field dynamic simulation of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not intended to limit the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0022] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as a process, method, system, product, or server that includes a series of steps or units, not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or device.

[0023] The following is combined with Figures 1-5 The following is a detailed description of a specific embodiment of the present invention. This embodiment is merely one of the preferred implementations of the present invention and is not intended to limit the scope of protection of the present invention.

[0024] Example 1 Prediction of quasi-static compression failure in ceramic specimens; In this embodiment, the ceramic specimen is a cylinder with a diameter of 10 mm and a height of 8 mm, with its axial direction taken as the z-direction. The upper and lower cover plates are also cylinders with a diameter of 12 mm and a thickness of 1 mm, respectively arranged at the upper and lower ends of the ceramic specimen. The ceramic specimen, the upper cover plate, and the lower cover plate are all discretized into near-field dynamic material points, with a spacing of 0.25 mm between the material points, and the near-field range is 3.01 times the spacing between the material points.

[0025] The ceramic specimens were subjected to a pressure-rate-dependent plastic damage model coupled with conventional near-field dynamics and the JH-2 model. The bulk modulus of the ceramic material was 250 GPa, and the shear modulus was 157 GPa. In the JH-2 model, the intact strength coefficient was 0.958, the fracture strength coefficient was 0.45, the pressure hardening exponent was 0.243, the strain rate sensitivity coefficient was 0.0076, the fracture strength exponent was 0.6, and the maximum fracture strength coefficient was 1.0. The equivalent stress at the Hugoniot elastic limit was 4.82 GPa, the Hugoniot elastic limit pressure was 3.785 GPa, and the maximum tensile hydrostatic pressure was 0.462 GPa. The coefficients of the first term in the equation of state were 250 GPa, the coefficients of the second term were -274 GPa, and the coefficients of the third term were 2934 GPa. In the damage model, the two damage constants were 0.1 and 0.7, respectively.

[0026] Establish a near-field dynamic quasi-static compression analysis model based on the following: (1) Discretization: The ceramic specimen, upper pressure plate, and lower pressure plate are discretized into near-field dynamic material points containing material property information. The discretization spacing of the material points is determined according to the calculation accuracy requirements, and the material points inside the specimen are uniformly distributed to reduce non-local integration error.

[0027] (2) Near field range setting: The near field range is determined according to the discrete spacing of the material points. The near field range can be a multiple of the spacing between the material points, and a neighborhood search list is established according to the initial position of the material points.

[0028] (3) Material model setup: The ceramic specimens adopted the JH-2 pressure-rate related plasticity model based on the conventional near-field dynamics framework, and a hybrid bond-level damage criterion combining bond damage accumulation and critical elongation s0 was introduced. Among them, the progressive damage under compression and shear is driven by the JH-2 plastic damage evolution relationship, and the brittle cracking under tension is determined by whether the bond elongation reaches the critical elongation s0; the pressure plate adopts a linear elastic material model.

[0029] (4) Boundary and loading condition settings: A fixed constraint is set at the bottom of the lower pressure plate, and a slow axial displacement boundary or velocity boundary is applied to the top of the upper pressure plate to put the ceramic specimen in an approximately quasi-static compression state. To reduce the inertial effect, a smaller loading speed can be used, and the ratio of kinetic energy to internal energy is monitored during the calculation process to keep the kinetic energy at a low level.

[0030] To begin the calculation, such as... Figure 1 As shown, the specific implementation steps are as follows: (1) Input the geometric parameters, material parameters, initial boundary conditions, and loading displacement or loading speed of the ceramic specimen, upper pressure plate, and lower pressure plate; (2) Initialize the position, velocity, acceleration, mass, volume and density information of all material points, and establish a near-field neighborhood list for each material point; (3) Start the time step loop, setting the initial time t=0; (4) Within the current time step, calculate the volumetric deformation, eccentric deformation and corresponding force state of each material point in the ceramic specimen, and update the volumetric response, eccentric response and hydrostatic pressure of the material point. (5) Based on the JH-2 constitutive relation, update the intact strength, fracture strength, normalized equivalent strength, yield state, plastic flow state and material point damage variables of ceramic materials; (6) When the material point satisfies the plastic loading condition, update the equivalent plastic strain increment, plastic volumetric strain increment, and partial extension and partial force state. (7) Update the damage status of each bond at the current time step based on the hybrid bond level damage criterion that combines bond damage accumulation and critical elongation s0. Specifically, for bond deformation dominated by compression and shear, update the bond damage variable based on the accumulation of equivalent plastic strain increment; for bond elongation caused by local tension or unloading back tension, when the bond elongation reaches the critical elongation s0, it is determined that the bond has completely failed due to tension. (8) Symmetric processing is performed on the bond damage state between two related material points, and the material point damage variables are statistically analyzed based on the damage state of each bond in the near field range; (9) Feedback the bond damage state to the inter-bond force transmission capacity and the material point bearing capacity, and update the evolution process of the compressive-shear damage zone, local cracks and fracture zone inside the ceramic specimen accordingly; (10) Based on the conventional near-field dynamics equations of motion, the acceleration, velocity and displacement of each material point are updated using an explicit time integration scheme; (11) Determine whether the current time t has reached the preset loading displacement, preset compressive strain, or termination condition. If not, set t=t+Δt and proceed to the next time step to continue the calculation; if it has, terminate the calculation and output the analysis results.

[0031] After the calculation, the axial stress-strain response, bond damage distribution, compressive-shear fracture zone morphology, and final failure mode of the ceramic specimen under quasi-static compression are output. The results show that, as Figure 2 and Figure 3 As shown, the present invention can describe the development process of ceramic materials under compressive load from elastic deformation and accumulation of plastic damage to local compressive shear failure, and can reflect the spatial distribution characteristics of crack and fracture areas through bond damage state.

[0032] Example 2 Prediction of fracture failure of ceramic target plate under normal impact of small ball; like Figure 4As shown, in this embodiment, the ceramic target plate adopts a square thin plate structure with dimensions of 70mm × 70mm × 9mm; the impact ball is located above the target plate, with the initial position of the ball's center at (0, 0, 17mm) and a radius of 3mm. Both the ceramic target plate and the ball are discretized into near-field dynamic material points, with a discretization interval of 1mm and a near-field range of 3.01 times the distance between the material points.

[0033] The ceramic target plate was subjected to a pressure-rate-dependent plastic damage model coupled with conventional near-field dynamics and the JH-2 model. The bulk modulus of the ceramic material was 130.95 GPa, and the shear modulus was 90.16 GPa. In the JH-2 model, the intact strength coefficient was 0.93, the fracture strength coefficient was 0.31, the pressure hardening exponent was 0.6, the fracture strength exponent was 0.6, and the maximum fracture strength coefficient was 0.2. The equivalent stress at the Hugoniot elastic limit was 2.0 GPa, the Hugoniot elastic limit pressure was 1.46 GPa, and the maximum tensile hydrostatic pressure was 0.2 GPa. The coefficient of the first term in the equation of state was 130.95 GPa, the coefficient of the second term was 0, and the coefficient of the third term was 0. In the damage model, the two damage constants were 0.005 and 1.0, respectively.

[0034] The impact sphere was modeled as a linear elastic material with an elastic modulus of 200 GPa and a Poisson's ratio of 0.3, and an initial velocity of 200 m / s was applied along the negative z-direction to simulate the normal impact process of the sphere on the ceramic target plate. During the calculation, the compressive-shear damage in the impact region of the ceramic target plate was controlled by the JH-2 plastic cumulative damage relation, while tensile cracking and radial cracking were determined by the critical elongation criterion. The material point damage variables and final failure morphology were statistically analyzed using the bond damage state.

[0035] Establish a normal impact analysis model for a small ball based on the following: (1) Discretization: The ceramic target plate and the impact ball are discretized into near-field dynamic material points. A smaller material point spacing can be used near the impact area of ​​the ceramic target plate to improve the calculation accuracy of local contact, crushing and crack propagation areas; a larger discretization spacing can be used in the part far from the impact area according to the calculation efficiency requirements.

[0036] (2) Near-field range setting: The near-field range is set according to the distance between the material points of the ceramic target plate and the impact ball, and a near-field neighborhood list of each material point is established. For the material points inside the ceramic target plate, the non-local interaction is calculated using the conventional near-field dynamic integral form; for the contact area between the ball and the ceramic target plate, the impact load is transferred using the contact interaction model.

[0037] (3) Material model settings: The ceramic target plate is described by the JH-2 constitutive relation to describe the pressure strengthening effect, strain rate sensitivity, fracture softening behavior and volumetric plastic response under impact conditions, and the mixed bond horizontal damage criterion is used to describe the compressive-shear damage and tensile fracture. Among them, the high pressure crushing and shear damage in the impact contact area are mainly controlled by the cumulative plastic damage of JH-2; the tensile reflection wave, radial crack and local opening crack on the back of the target plate are determined by the critical elongation s0.

[0038] (4) Boundary and loading condition settings: Set fixed, simply supported, or free boundary conditions for the edge or bottom of the ceramic target plate according to the actual working conditions. Apply an initial velocity to the impact ball along the normal direction of the ceramic target plate to make positive contact impact with the target plate. The normal force is transmitted between the ball and the ceramic target plate through the contact algorithm. If necessary, tangential contact parameters can be set to consider the effects of friction or slippage.

[0039] To begin the calculation, the specific steps are as follows: (1) Input the geometric parameters, material parameters, initial position, initial velocity, contact parameters and boundary conditions of the ceramic target plate and the impact ball; (2) Initialize the position, velocity, acceleration, mass, volume and density information of all material points in the ceramic target plate and impact ball, and establish a near-field neighborhood list for each material point; (3) Start the time step loop, setting the initial time t=0; (4) Determine the contact state based on the relative position between the ball and the ceramic target plate. When the two enter the contact range, calculate the contact normal force and transfer the impact load to the impact area of ​​the ceramic target plate. (5) Within the current time step, calculate the volume deformation, eccentric deformation, hydrostatic pressure and eccentric force state of each material point on the ceramic target plate. (6) Based on the JH-2 constitutive relation, update the intact strength, fracture strength, normalized equivalent strength, strain rate correction term, yield state, plastic flow state and material point damage variables of ceramic materials; (7) For the impact contact area and its adjacent area, update the bond damage variables under compression and shear based on the equivalent plastic strain increment to describe local crushing and shear failure; for the back of the target plate and the tensile area, determine whether the tensile bond is completely failed based on the comparison between the bond elongation and the critical elongation s0. (8) Symmetrically process the bond damage state and feed back the symmetric bond damage variables to the bond force transmission capacity, material point bearing capacity and subsequent yield determination process. (9) Update the acceleration, velocity and displacement of each material point in the ceramic target plate and the impact ball according to the normal state near-field dynamics equations; (10) Determine whether the current time t has reached the preset impact analysis duration, or whether the impact ball has rebounded, stopped penetrating, or the damage to the target plate has stabilized. If the termination condition is not met, proceed to the next time step to continue the calculation; if the termination condition is met, terminate the calculation and output the analysis results.

[0040] After the calculation is complete, a damage contour map of the ceramic plate is output. For example... Figure 5 As shown, where Figure 5 (a) is a diagram of the measured fracture mode of the ceramic target plate in the impact test. Figure 5 (b) is a schematic diagram of the damage distribution obtained from the near-field dynamics simulation of this invention. Comparing the actual damage photographs after the test, it can be seen that the near-field dynamics model established by this invention can reproduce the crushing zone, depression zone, and radial crack propagation characteristics formed at the center of the ceramic target plate after being impacted by a small ball. The cracks propagate outward from the impact center and exhibit a multi-directional fracture mode. Due to factors such as projectile deviation, material micro-defects, and imperfectly symmetrical sample boundary conditions that may exist in actual tests, the crack paths in the test results may have a certain degree of randomness and asymmetry. However, the calculation results of this invention can reproduce typical failure characteristics such as crushing at the center of the ceramic target plate and radial crack propagation under normal impact, indicating that this method can be used to predict the impact failure morphology and damage area of ​​ceramic target plates.

[0041] The above two embodiments illustrate the present invention under two typical working conditions: quasi-static compression and normal impact. The quasi-static compression example is mainly used to verify the present invention's ability to describe the pressure-related plasticity, compressive-shear damage accumulation, and macroscopic load-bearing degradation process of ceramic materials; the small-sphere normal impact example is mainly used to verify the present invention's ability to predict high local stress, high strain rate contact, tensile cracking, and fragmentation failure processes. As can be seen from the above embodiments, the conventional near-field dynamics and JH-2 coupling method proposed in this invention can describe the fracture failure behavior of ceramic materials under different loading rates and stress states within a unified framework, and can improve the stability and physical consistency of compressive-shear failure and tensile cracking predictions by utilizing a hybrid criterion combining bond damage accumulation and critical elongation s0.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for predicting ceramic impact failure based on a near-field dynamic bond damage model, characterized in that, Includes the following steps: S1. Obtain the geometric parameters, material parameters, initial boundary conditions, and loading conditions of the ceramic material structure; S2. Establish an impact fracture failure analysis model based on the coupling of conventional peri-field dynamics and JH-2 constitutive relation. Embed the JH-2 pressure-rate related plastic constitutive relation into the volume response, bias response and force state update process of conventional peri-field dynamics, and construct a hybrid bond level damage model that combines plastic cumulative damage and critical elongation criterion. S3. Perform explicit time history calculation of the near-field dynamic analysis model, update the volume response, bias response, hydrostatic pressure, plastic state, bond damage state and material point damage state in each time step, and feed back the bond damage state to the force state update between material points, yield determination and material point bearing capacity degradation process. S4. When the calculation reaches the preset loading process or termination condition, the calculation will terminate and output the dynamic response, crack propagation morphology, damage distribution and failure mode of the ceramic material.

2. The method for predicting ceramic impact failure based on a near-field dynamic bond damage model according to claim 1, characterized in that, The loading conditions in S1 include quasi-static compression, small ball normal impact, penetrating impact or other dynamic loading conditions; The geometric parameters mentioned in S1 and S2 include the ceramic structure dimensions, loading region, and constraint region; the material parameters include at least the bulk modulus K, shear modulus G, JH-2 strength parameters A, B, C, M, N, Hugoniot elastic limit parameter, state equation parameters K1, K2, K3, reference strain rate, damage parameters D1, D2, and critical elongation s0 used for tensile fracture determination; the near-field dynamic analysis model discretizes the structure under analysis, dividing it into several near-field dynamic material points, and determines the spacing and near-field range of the material points; a neighborhood search table for the material points is established, and the parameters required for nonlocal integral calculation are initialized by combining the volume, mass, and density information of each material point.

3. The method for predicting ceramic impact failure based on a near-field dynamic bond damage model according to claim 2, characterized in that, The specific details of the near-field dynamic impact fracture failure analysis model pre-built in S2 are as follows: S21. Discretize the ceramic structure into near-field dynamic material points containing material property information, and determine the spacing between material points, near-field range, calculation time step, and volume, mass and initial density of each material point. S22. Search for nearby material points based on the initial position of the material point and establish a neighborhood list; S23. Based on the conventional near-field dynamics framework, a pressure-rate-dependent plastic constitutive model of ceramic materials is constructed, and the JH-2 constitutive relation is introduced to characterize the pressure strengthening effect, strain rate sensitivity, fracture softening behavior and volumetric plastic response of the materials. S24. Construct a hybrid bond-level damage model based on the combination of bond damage accumulation and critical elongation s0. Drive the evolution of bond-level damage under compression, shear and compression-shear coupling with the JH-2 equivalent plastic strain increment. Use the critical elongation s0 as the tensile fracture criterion to judge the bond fracture failure under the tensile-dominant state. Describe the crack initiation, propagation and complete failure process of ceramic materials under impact load. S25. Configure the velocity boundary, displacement boundary, stress wave boundary or contact impact boundary of the loading area, as well as the boundary conditions of the constrained area.

4. The method for predicting ceramic impact failure based on a near-field dynamic bond damage model according to claim 3, characterized in that, The specific details of performing the explicit time history calculation of the near-field dynamic impact fracture failure analysis model in S3 are as follows: S31. Calculate the interaction forces between material points at the current time step, and update the volume response, bias response, and hydrostatic pressure of the material points according to the normal state near-field dynamics framework. S32. Update the complete strength, fracture strength, yield state, plastic flow state, and damage variables based on the JH-2 constitutive relation; S33. Update the damage state of each bond based on a hybrid criterion combining bond damage accumulation and critical elongation s0; wherein, bond damage under compression and shear states is driven by JH-2 plastic damage evolution, and bond fracture under tension states is determined by comparing bond elongation with critical elongation s0; when any bond meets the complete failure condition, cut off the internal force transmission between the material points associated with that bond. S34. Update the displacement, velocity, and strain rate of the material point using an explicit time-integration scheme; S35. Determine whether the current calculation has reached the preset loading process or termination condition. If not, proceed to the next time step to continue the calculation; if it has, terminate the calculation and output the prediction result.

5. The method for predicting ceramic impact failure based on a near-field dynamic bond damage model according to claim 4, characterized in that, The hydrostatic pressure response in S31 is updated using a combination of state equations and volumetric plasticity, and satisfies the following expression during the compression loading stage: ； ； In the formula, It is the hydrostatic pressure; This refers to the relative volumetric compression. and These are the current density and the initial density, respectively. This refers to the additional pressure term for the damage; The distortion energy density; Additional pressure correction factor; During the unloading and reloading phases, the bulk modulus is used. The pressure is updated for the linear elastic path with slope, while preserving the volume expansion effect caused by damage accumulation; when the material is in a tensile volume state, the hydrostatic pressure is updated using tensile cutoff, and the tensile strength is limited by the maximum tensile hydrostatic pressure parameter.

6. The method for predicting ceramic impact failure based on a near-field dynamic bond damage model according to claim 5, characterized in that, The constitutive relation of JH-2 described in S32 is expressed in normalized strength form, and its intact strength, fragmentation strength, and current normalized equivalent strength satisfy the following expressions: ； ； ； In the formula, For complete strength; The breaking strength; This represents the current normalized equivalent strength. For material damage variables; Normalized hydrostatic pressure; The normalized maximum tensile hydrostatic stress; This represents the equivalent rate of change.

7. The method for predicting ceramic impact failure based on a near-field dynamic bond damage model according to claim 6, characterized in that, S33. Based on the deviatoric force state of the conventional peri-field dynamics, the yield function is constructed, and the pressure-rate related plastic correction algorithm is used to update the deviatoric extension, deviatoric force state, and equivalent plastic strain increment. The expression is as follows: ； ； ； In the formula, To test the deviatoric force state; The radius of the near-field dynamic neighborhood; Dynamic fracture strength related to pressure and strain rate; For strain rate; For the plastic multiplier increment; for HEL stress; The material damage evolution coefficient; When the yield function is less than or equal to zero, the material point is in an elastic loading state; When the yield function is greater than zero, the material point enters the plastic loading state, and according to the plastic multiplier increment... The equivalent plastic strain increment and plastic volumetric strain increment are updated to drive subsequent bond-level damage evolution.

8. The method for predicting ceramic impact failure based on a near-field dynamic bond damage model according to claim 7, characterized in that, The bond-level damage evolution model constructed in S24 and the update relationship in S33 include the plastic cumulative damage criterion and the tensile fracture criterion; among them, for bonds under compression, shear, or compression-shear coupled stress states, their damage state is driven by the cumulative accumulation of JH-2 equivalent plastic strain increments and satisfies the following expression: ； ； in, The total fracture plastic strain of the bond; This represents the equivalent plastic strain increment at the current time step. This represents the increment of key damage at the current time step. For key damage state variables; For bonds under tensile-dominant stress, the critical elongation s0 is used as a supplementary criterion for tensile fracture. In this critical elongation criterion, a material point is defined. and Elongation of the bond between The expression is as follows: ； In the formula, This represents the relative position vector of two material points in the initial configuration; This represents the displacement of a point mass; This represents the relative displacement vector between two material points; This represents the distance between two material points under the current configuration; This represents the distance between two material points under the initial configuration; When the bond elongation s is greater than or equal to the critical elongation s0, the bond is determined to have undergone tensile fracture; when the bond damage state variable d reaches 1, the bond is determined to have undergone complete damage under compression, shear or compression-shear coupling; when the bond satisfies the tensile fracture condition or the plastic cumulative damage reaches the complete failure condition, the internal force transmission capacity of the bond between adjacent material points degrades to zero.

9. The method for predicting ceramic impact failure based on a near-field dynamic bond damage model according to claim 8, characterized in that, The calculation of the interaction forces between matter points in S31 and the update of the motion state of matter points in S34 satisfy the conventional peri-field dynamics equations, as expressed below: ； In the formula, For matter points The near-field range; These are adjacent material points within the near-field range; The density of the substance at point depth; The acceleration of a point mass; Body density; and This refers to the state of interaction forces between material points.

10. The method for predicting ceramic impact failure based on a near-field dynamic bond damage model according to claim 9, characterized in that, In S34, the explicit time integral uses the Verlet integral scheme to update displacement and velocity, as shown in the following expression: ； In the formula, That is, the displacement of the material point at step n; The velocity of the substance point at step n; Δt represents the acceleration of the material point at step n+1; Δt is the time step.

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