Meshless impact collision simulation method based on point-to-surface contact

Abstract

The invention relates to a meshless impact collision simulation method based on point-to-surface contact. The meshless impact collision simulation method comprises the following steps: (1) initializing meshless nodes and material points by utilizing a finite element grid; (2) determining master and slave contact nodes, reconstructing the nodes of the master contact surface, and obtaining an external normal vector of each node of the master contact surface; (3) establishing a contact pair and setting contact parameters; (4) judging whether the slave contact node enters a contact effective area or not, and obtaining a corresponding node contact acting force; (5) assembling node contact acting force, and obtaining physical information and dynamic data of the material points and the nodes in a time period from t0 to tn; and outputting a simulation result. According to the method, the main contact surface can be stably constructed without structural topology, the external normal direction is accurately obtained, the contact force is distributed, the numerical stability and the explicit time integral compatibility are kept, and the method is suitable for contact behavior simulation under the working conditions of large deformation of processing materials, impact collision, multi-body collision and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of mechanical simulation, and in particular relates to a meshless impact collision simulation method based on point-to-surface contact. BACKGROUND

[0002] Impact collision problems are hot issues in the field of aerospace and other fields, which usually involve complex characteristics such as large deformation of materials, crack initiation and propagation. The traditional finite element method (FEM) often faces problems such as severe grid distortion, high grid reconstruction cost, and complex topology change when simulating the above problems due to its inherent grid characteristics. In order to solve the above problems, meshless methods have developed rapidly. Meshless methods discretize the computational domain by discrete particles, do not rely on fixed element connection, and can adaptively handle large deformation, crack propagation, multi-substance separation and other phenomena, becoming an important research tool in the fields of impact dynamics, explosion mechanics and other fields.

[0003] However, unlike the finite element method, meshless methods have significant challenges in contact handling. The point-to-surface contact handling method widely used in traditional finite element methods relies on the explicit topology of the main surface element, and obtains the contact distance and normal force by projecting from the node to the main surface. However, in the meshless framework, due to the lack of explicit element surface structure and grid connection, there are technical difficulties such as missing or discontinuous main surface, difficulty in defining normal information, unstable or numerical oscillation of contact, large spatial search calculation, etc. in using the point-to-surface contact handling method. Recent studies have attempted to use penalty function method, distance function method or background grid assisted contact method to handle contact problems, but these methods usually have low processing efficiency, limited application scope or low contact precision.

[0004] The present application proposes a high-efficiency and stable point-to-surface contact handling method suitable for meshless methods to overcome the above problems. The method has good processing efficiency and high processing precision, is suitable for explicit dynamics simulation, and is particularly suitable for simulating contact behavior in problems such as large deformation of materials, impact collision, and multi-body contact. SUMMARY

[0005] To overcome the shortcomings of existing meshless methods in contact handling when simulating impact collision and other problems, the present application proposes a meshless impact collision simulation method based on point-to-surface contact. This method can stably construct the main contact surface under the structureless topology, accurately obtain the outer normal and distribute the contact force, maintain numerical stability and compatibility with explicit time integration, and is suitable for simulating contact behavior in conditions such as large deformation of materials, impact collision, and multi-body collision. The present application is suitable for simulation fields such as structural dynamics, large deformation problems, and impact dynamics, and is particularly suitable for core problems such as contact search, outer normal acquisition, and contact force application in the contact interface handling of meshless methods.

[0006] To achieve the above object, the present application adopts the following technical solutions: A meshless impact collision simulation method based on point-to-surface contact, comprising the following steps: (1) using finite element mesh to initialize spatial discretization in the meshless method, to obtain initialized nodes and material points; (2) determining master contact surface nodes and slave contact nodes according to the initialized nodes and material points after spatial discretization, reconstructing the master contact surface nodes to obtain the outward normal vector of each node of the master contact surface; (3) establishing contact pairs of the master contact surface nodes and the slave contact nodes, and determining contact parameters; (4) obtaining internal forces in each time step, and judging whether the slave contact nodes enter the contact effective area, obtaining contact forces after the slave contact nodes enter the contact effective area, and applying the contact forces on the master contact surface nodes and the slave contact nodes to obtain corresponding node contact forces; (5) assembling the node contact forces to obtain physical information and dynamic data of the material points and nodes from t0 to t n in the time period; and outputting simulation results.

[0007] As preferred, step (1) is specifically: initializing the model, dividing the problem domain by finite element mesh, and using the divided finite element mesh to initialize spatial discretization in the meshless method, to discretize the problem domain into nodes and material points, wherein the nodes are initialized by the nodes of the finite element mesh, and the material points are initialized by the center points of the finite element mesh.

[0008] As preferred, step (2) is specifically: (I) determining master contact surface nodes and slave contact nodes, marking in the input finite element mesh file to determine the master and slave two parties of the contact, the master contact party is the outer surface of an object, which is determined by grouping the nodes on the outer surface; the slave contact party is all or part of the nodes of another object, which is determined by the corresponding node grouping in the input file; after meshless discretization, the meshless nodes initialized by the finite element nodes on the master contact surface are the master contact surface nodes, and the meshless nodes initialized by the nodes in the slave contact node set are the slave contact nodes; (II) traversing all nodes on the master contact surface, searching for adjacent nodes within a given search radius to determine the adjacent nodes, constructing a neighborhood node set; taking the current node as the center point, traversing all nodes in the neighborhood node set, and constructing a covariance matrix; performing eigenvalue decomposition on the covariance matrix, and the eigenvector corresponding to the minimum eigenvalue is the local normal direction of the current node, thereby determining the outward normal direction of each node on the master contact surface.

[0009] As a preferred option, step (3) is to associate the main contact surface node and the slave contact node with each other, establish a contact pair between the main contact surface node and the slave contact node, and determine the contact parameters including the contact radius, contact stiffness, contact viscosity coefficient and contact power exponent.

[0010] As a preferred option, step (4) specifically involves: (i) Based on the determination of the neighborhood of a material point, the shape function of each material point and the derivative of the shape function of the material point are obtained; (ii) Update the node position and obtain the deformation gradient of the material point. Based on the obtained deformation gradient of each material point, obtain the strain of each material point and obtain the stress of each material point through the model. Determine whether each material point is damaged and cracks are generated. If it is not damaged, interpolate the stress of the material point to each node in its neighborhood to obtain the local nodal force of each node caused by material deformation. (iii) Using the contact node as the center and the contact radius as the search radius, search all nodes on the main contact surface to determine all main contact surface nodes within the contact radius and construct a set of effective contact nodes; traverse the set of effective contact nodes to obtain the intrusion distance of the contact node to each effective node set; after traversal, the maximum intrusion distance is the current intrusion distance of the contact node to the main contact surface; use a nonlinear model to obtain the contact force; (iv) Obtain other nodal forces to obtain the mass matrix, nodal forces, and accelerations; (v) Update the coordinates of the material point, update the neighborhood of the material point, update the shape function of the material point, and update the derivative of the shape function of the material point.

[0011] As a preferred option, step (5) specifically involves: Enter the next moment and determine the time step. ,like This indicates that the final step has been reached, and the final material points and nodes from t0 to t1 are obtained. n Physical information and dynamic data within a time period; like Then proceed to the next iteration. At the initial moment of each iteration step, the main contact surface is reconstructed using the method in step (II) to obtain the external normal vectors of each node on the main contact surface; then repeat steps (ii) to (v) until time step (v). So far, the final material points and nodes from t0 to t are obtained. n Physical information and dynamic data within a time period

[0012] Preferably, physical information and dynamic data include deformation, stress, density, displacement, velocity, acceleration, and temperature.

[0013] Preferably, in step (i), the local maximum entropy shape function is used as the shape function of the material point.

[0014] As a preferred method, the mass, velocity, and nodal force of each node are initialized using initial conditions, and the acceleration is obtained.

[0015] Preferably, in step (iv), other nodal forces include externally applied forces such as tension on the boundary.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1) This invention is a method for simulating contact behavior under conditions such as large material deformation, impact collision, and multi-body collision. It can overcome the technical difficulties of meshless methods in dealing with contact problems, such as missing or discontinuous principal surfaces, difficulty in defining normal information, unstable contact or numerical oscillation, and large spatial search computation. It has strong versatility and high accuracy. 2) This invention can stably construct the main contact surface, accurately estimate the outward normal of each node on the main contact surface, accurately obtain the contact force, and accurately distribute the contact force to the main contact surface, thereby maintaining numerical stability and robustness of explicit time integration. 3) This invention is used to simulate the contact behavior of materials under different conditions such as large deformation, impact collision, and multi-body contact using a meshless method, which greatly improves the computational efficiency and has high computational stability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the spatial discretization of the geometric model using a combination of material points and nodes according to the present invention. Figure 2 This is a schematic diagram illustrating the processing method of the main contact surface according to the present invention; Figure 3 This is a schematic diagram of the point-to-surface contact method in this invention; Figure 4 This is a schematic diagram of a simulated cylindrical nylon projectile with a diameter of 6 mm and a height of 6 mm impacting an aluminum target plate with a diameter of 80 mm and a thickness of 6 mm at a speed of 5.8 km / s in Embodiment 2 of the present invention, wherein the aluminum target plate is represented by material points. Figure 5 This is a simulation result diagram of the entire process of a nylon projectile impacting an aluminum target plate, penetrating the target plate, and forming a mushroom-shaped debris cloud in Embodiment 2 of the present invention. Detailed Implementation

[0018] The technical solution of the present invention will be further described in detail below through embodiments. These embodiments are for illustrative purposes only and are not intended to limit the present invention. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] Example 1 A meshless impact collision simulation method based on point-to-surface contact includes the following steps: (1) Initialize nodes and material points: Use finite element mesh for spatial discretization initialization, and initialize the problem domain as nodes and material points; specifically: The computational model is initialized by dividing the problem domain into a finite element mesh, and then using the meshed finite element mesh for spatial discretization initialization in the meshless method. This invention takes the Optimal Transport Meshless Method (OTM) as an example, performing spatial discretization of the OTM method, that is, discretizing the geometric model into a set of material points and a set of nodes. The nodes in the OTM method are initialized using the nodes of the finite element mesh, and the material points in the OTM method are initialized using the center points of each element in the finite element mesh. In the specific implementation, for two-dimensional problems, the geometric model is divided into first-order triangular element meshes or first-order quadrilateral element meshes; for three-dimensional problems, the geometric model is divided into first-order tetrahedral element meshes or first-order hexahedral element meshes. The material points and nodes in the OTM method are initialized using this mesh; that is, the nodes in the OTM method are initialized using the nodes of the finite element mesh, and the material points in the OTM method are initialized using the center points of each element in the finite element mesh. For example... Figure 1 As shown, the problem domain is meshed using finite element methods (FEM), and then the original nodes and material points of the FEM are converted into initialized nodes and material points. Hollow points represent nodes. ( Here, is the node index number in the discrete domain, representing which node it is. (This represents the nth time step; the time step size and number of steps are controlled by the user.) Solid triangles represent matter points. ( This is the index number of a material point in the discrete domain, representing which material point it is. (This represents the nth time step).

[0020] (2) Based on the nodes and material points after spatial discretization initialization, determine the main contact surface nodes (main contact surface) and slave contact nodes, reconstruct the main contact surface nodes, and obtain the external normal vector of each node of the main contact surface; specifically: (I) Determine the main contact surface and the slave contact nodes. In the input finite element mesh file, calibrate to determine the main and slave sides of the contact. The main contact surface is the outer surface of an object, which is determined by grouping the nodes on the surface. The slave contact surface is all or part of the nodes of another object, which is also determined by grouping the corresponding nodes in the input file. After meshless discretization, the meshless nodes formed by initializing the finite element nodes on the main contact surface are the main contact surface, and the meshless nodes formed by initializing the nodes in the slave contact node set are the slave contact nodes. (II) Reconstruct the main contact surface and calculate the external normal vector of each node: The processing method for the main contact surface is as follows: Figure 2 As shown, a neighborhood search is performed on each node on the main contact surface to determine the nearest nodes within a given search radius r, thus constructing a neighborhood node set. Within each node set, using the current node as the center point, all nodes within its neighborhood node set are traversed, and the outward normal direction of the current node is calculated by constructing a covariance matrix. Specifically, all nodes on the main contact surface are traversed, and a neighborhood search is performed on each node to determine the nearest nodes within a given search radius r, thus constructing a neighborhood node set. N ; with the current node As the central point, traverse all nodes within its neighborhood node set. ,definition And construct the covariance matrix T represents the transpose of a vector; the covariance matrix C is decomposed into eigenvalues, and the eigenvector corresponding to the smallest eigenvalue is the local normal direction of the current node, thereby determining the external normal direction of each node on the main contact surface; finally, the external normal direction of all nodes on the main contact surface is obtained, completing the construction of the main contact surface and the calculation of the external normal.

[0021] (3) Establish the contact pair between the main contact surface and the slave contact node, and determine the contact parameters; specifically: By associating the main contact surface and the slave contact node with each other, a contact pair between the main contact surface and the slave contact node is established, and contact parameters such as contact radius, contact stiffness, contact viscosity coefficient and contact power exponent are determined.

[0022] (4) Start the calculation, perform internal force calculations at each time step, and determine whether the slave node group has entered the contact effective region. After the slave node group enters the contact effective region, calculate the contact force (contact force) and apply the contact force to the main contact surface node and the slave node; specifically: (i) Perform calculation initialization, i.e., set Based on the determined neighborhood of each material point, the shape function of each material point is calculated. and the derivative of the point shape function of matter In this invention, a local maximum entropy shape function is used as the shape function of the material points. Simultaneously, the mass of each node is initialized using initial conditions. ,speed and node force And calculate acceleration ; (ii) Update node position And calculate the deformation gradient of the material point. ; Based on the obtained deformation gradients of each material point, the strain of each material point is calculated on each processor, and the stress of each material point is calculated using a material constitutive model. The J2 Power Law constitutive model is used for stress calculation, and the equivalent stress equation of this constitutive model is as follows:

[0023] In the formula, This is the equivalent yield stress; and For effective plastic strain and strain rate; Absolute temperature; The initial quasi-static yield stress; and For reference, effective plastic strain and strain rate; To strengthen the index; The strain rate index; For reference temperature; It is the melting temperature; The thermal softening index; After stress calculation, it is determined whether each material point has failed and developed cracks. Material failure and damage are calculated using the Eigenfracture model. At each material point, the equivalent energy release rate is calculated using the following formula:

[0024] in The size of the material point. Let V be the volume of a point mass. The elastic energy stored in a material point; when the calculated equivalent energy release rate of the material point is greater than the critical energy release rate that the material can withstand, i.e.

[0025] The material represented by this point breaks down and creates a free surface, which manifests as the initiation or propagation of cracks; the EigenFracture model theoretical proof converges to Griffith theory, regardless of the mesh. The above model is used to determine the state of the material. If the above formula holds true, the material represented by the material point is destroyed, a free surface is formed, the material point fails, and its stress is zero. If the material represented by the material point is not destroyed, the stress of the material point is interpolated to each node in its neighborhood to obtain the local nodal force of each node caused by material deformation. (iii) Calculate the contact force. Traverse each slave node in the slave node group. Using the slave node as the center and the contact radius as the search radius, search all nodes on the main contact surface to determine all main contact surface nodes within the contact radius, and construct the contact effective node set. If no corresponding node is found, it means that the slave node has not entered the contact effective area and the contact force does not need to be considered. Traverse the contact effective node set and calculate the intrusion distance of the slave node into each effective node set. Point-to-point contact method as follows Figure 3 As shown, during the impact collision, each node on the object is defined as a set of contact nodes, and a contact range is set. When the distance between nodes from two different contact node sets is less than the contact range, the contact pair between the two nodes takes effect, generating a contact force on these two nodes; (Figure) For contact objects that are subordinate to the contact node, For the contact object subordinate to the main contact surface, the red arrow represents the outward normal of each node on the main contact surface. Locate the node on the main contact surface that is within the effective contact area of ​​the secondary node. Calculate the distance between this node and the secondary node using the following formula, based on the node's outward normal and the distance between the secondary node and the primary node:

[0026] in For the search radius, The distance between the slave node and the master contact surface node. This represents the outward normal of the main contact surface node. After traversal, the maximum intrusion distance is the current intrusion distance of the slave node to the main contact surface; the contact force is calculated using a nonlinear model, as shown in the following formula:

[0027] in K, V These are contact stiffness and contact viscosity, respectively. c To access the power exponent, p i The intrusion distance from the node. For time step, N i The impact direction from the node (i.e., the outward normal of the main contact surface node in the contact pair); The direction of the contact force calculated by the above formula is the opposite direction of the impact direction of the slave node, that is, the same direction as the outward normal of the main contact surface, and is applied entirely to the slave node; if the contact force is in the opposite direction, it can be applied to the node corresponding to the main contact surface. (iv) Calculate other nodal forces, including tensile forces at the boundaries, to obtain the final mass matrix. Node forces and acceleration ; (v) Update the coordinates of the matter point Update the neighborhood of the matter point. Update the material point shape function Update the derivative of the point shape function of matter. ; (5) Assemble nodal forces to obtain material points and nodes from t0 to t n The simulation results include physical information and dynamic data within a given time period; specifically: Moving to the next moment Determine the time step ,like This indicates that the calculation has reached the final step. At this point, the calculation is exited, and the final material points and nodes from t0 to t1 are obtained. n Physical information and dynamic data over a time period, including deformation, stress, density, displacement, velocity, acceleration, and temperature, are used to complete the dynamic response analysis of the material. like Then proceed to the next iteration. At the initial moment of each iteration step, reconstruct the main contact surface using the method in step (II) and calculate the external normal vectors of each node on the main contact surface; then repeat steps (ii) to (v) until time step. So far, the final material points and nodes from t0 to t are obtained. n The physical information and dynamic data within a time period, including deformation, stress, density, displacement, velocity, acceleration, and temperature, are used to complete the dynamic response analysis of the material.

[0028] Example 2 Taking the high-speed impact of nylon projectiles on an aluminum plate as an example, this invention illustrates a highly efficient and stable point-to-surface contact treatment method for simulating impact collision processes. This embodiment simulates the impact of a cylindrical nylon projectile with a diameter of 6 mm and a height of 6 mm at a velocity of 5.8 km / s onto an aluminum target plate with a diameter of 80 mm. The aluminum plate is 5 mm thick. This case involves 4.77 million material points and 1.49 million degrees of freedom, such as... Figure 4 As shown. The orange cylinder represents the nylon projectile, and the target plate is displayed as blue dots. For the initialization method of the nylon projectile and target plate, please refer to [reference needed]. Figure 1The target plate was initialized using a finite element mesh, ultimately forming a group of nodes and a group of material points. The upper surface of the target plate was set as the primary contact surface, and all points in the nylon projectile were set as secondary contact points. The primary contact surface adopted... Figure 2 The reconstruction process is performed in a manner that calculates the outward normal direction of each node for subsequent contact calculations.

[0029] In the calculation process, an initial velocity of 5.8 km / s was first assigned to the nylon projectile, and it was determined whether the projectile would contact the target plate. If contact occurred, refer to... Figure 3 The penetration distance between the nodes on the nylon projectile (i.e., the contact point) and the nodes on the target plate (i.e., the main contact surface nodes) is calculated, and the contact force is calculated based on the penetration distance and applied to the projectile and the target plate, thus taking into account the physical process of contact between the two.

[0030] Figure 5 The simulation results for this embodiment are shown, where the aluminum target plate is displayed as blue material dots, and the cylindrical nylon projectile is displayed as black material dots. Figure 5 (a) in the diagram is the initial time frame. Figure 5 (b) Figure 5 (c) Figure 5 (d) Figure 5 (e) in the diagram represents the results at different moments during the impact, all represented as material points. From Figure 5 As can be seen, upon contact and collision with the aluminum plate, the nylon projectile rapidly shattered, forming a large cloud of fragments. As the nylon material continued to penetrate the aluminum plate, it created numerous dents, undergoing significant plastic deformation and generating considerable heat. The nylon also experienced significant plastic deformation during the impact, and under the thermal effect of this deformation, some of the nylon material vaporized. Subsequently, the aluminum target plate was penetrated, forming a mushroom-shaped fragment cloud along with the remaining nylon fragments.

[0031] This embodiment employs the point-to-surface contact processing method proposed in this invention, successfully predicting the fragmentation process of nylon projectiles and aluminum plates under ultra-high-speed (5.8 km / s) impact, accurately describing the shape of the debris cloud. Compared with actual experimental data, the maximum error is 5.36%. Compared with traditional point-to-point contact methods, the point-to-surface contact processing method proposed in this invention reduces the number of contact pairs in meshless methods by 80%, improving computational efficiency and demonstrating the accuracy and stability of the proposed method in numerical simulation of ultra-high-speed impact collision problems.

[0032] This invention provides a meshless impact collision simulation method based on point-to-surface contact, solving core challenges in meshless contact processing such as missing / discontinuous master surfaces, difficulty in defining normal information, numerical oscillations, and low computational efficiency. The method initializes meshless nodes and material points using a finite element mesh, determines the master-slave contact nodes, reconstructs the master contact surface, obtains the external normals of each node, establishes contact pairs, and sets contact parameters. Internal forces are calculated within a time step, the state of slave contact nodes is determined, and contact forces are applied. This process is iteratively updated until completion, outputting physical and dynamic data such as deformation, stress, and displacement. This invention can stably construct the master contact surface, accurately obtain normals and contact forces, maintain numerical stability and explicit integral robustness, and is applicable to conditions such as large material deformation, impact collisions, and multi-body collisions. It has advantages such as high processing efficiency, high accuracy, and computational stability, and can efficiently and accurately simulate complex scenarios such as ultra-high-speed impacts, providing a reliable numerical simulation tool for fields such as impact dynamics and explosion mechanics.

[0033] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A meshless impact collision simulation method based on point-to-surface contact, characterized by The method comprises the following steps: (1) using finite element grid to initialize spatial discretization in meshless method, obtaining initialized nodes and material points; (2) determining master contact surface nodes and slave contact nodes according to the initialized nodes and material points, reconstructing the master contact surface nodes to obtain the outer normal vector of each node of the master contact surface; (3) establishing contact pairs of the master contact surface nodes and the slave contact nodes, and determining contact parameters; (4) obtaining internal forces in each time step, and judging whether the slave contact nodes enter the contact effective area, obtaining contact forces after the slave contact nodes enter the contact effective area, and applying the contact forces on the master contact surface nodes and the slave contact nodes to obtain corresponding node contact forces. (5) Assemble nodal contact forces, obtain material point and nodal forces from t0 to t n physical information and dynamic data in the time period, and output simulation results.

2. The meshless impact collision simulation method based on point-to-surface contact according to claim 1, wherein, Step (1) is specifically: initializing the model, dividing the problem domain by finite element grid, and using the divided finite element grid to initialize spatial discretization in meshless method, and discretizing the problem domain into nodes and material points, wherein the nodes are initialized by the nodes of the finite element grid, and the material points are initialized by the center points of the finite element grid.

3. The meshless impact simulation method based on point-to-surface contact according to claim 2, wherein, Step (2) is specifically: (I) determining master contact surface nodes and slave contact nodes, marking in the input finite element grid file to determine the master and slave two parties of contact, the master contact party is the outer surface of an object, which is determined by grouping the nodes on the outer surface; the slave contact party is all or part of the nodes of another object, which is determined by grouping the corresponding nodes in the input file; after meshless discretization, the meshless nodes initialized by the finite element nodes on the master contact surface are the master contact surface nodes, and the meshless nodes initialized by the nodes in the slave contact node set are the slave contact nodes; (II) traversing all nodes on the master contact surface, searching for adjacent nodes within a given search radius to determine the adjacent nodes, constructing a neighborhood node set; taking the current node as the center point, traversing all nodes in the neighborhood node set, and constructing a covariance matrix; performing eigenvalue decomposition on the covariance matrix, and the eigenvector corresponding to the minimum eigenvalue is the local normal direction of the current node, thereby determining the outer normal direction of each node on the master contact surface.

4. The meshless impact crash simulation method based on point-to-surface contact according to claim 3, wherein, Step (3) is: correlating the master contact surface nodes and the slave contact nodes, establishing contact pairs of the master contact surface nodes and the slave contact nodes, and determining contact parameters including contact radius, contact stiffness, contact viscosity coefficient and contact power index.

5. The meshless impact crash simulation method based on point-to-surface contact according to claim 4, wherein, Step (4) is specifically: (i) obtaining the shape function and the derivative of the shape function of each material point on the basis of determining the neighborhood of the material point; (ii) updating the node position and obtaining the material point deformation gradient, obtaining the strain of each material point on the basis of the obtained material point deformation gradient, and obtaining the stress of each material point through the model, judging whether each material point is damaged and produces a crack, if not damaged, interpolating the stress of the material point to each node in the neighborhood to obtain the local node force caused by material deformation of each node; (iii) searching all nodes on the master contact surface with the contact node as the center and the contact radius as the search radius, determining all master contact surface nodes with a distance within the contact radius, and constructing a contact effective node set; traversing the contact effective node set to obtain the intrusion distance of the contact node to each effective node set; after the traversal is completed, the largest intrusion distance is the intrusion distance of the contact node to the master contact surface at present; using a nonlinear model to obtain the contact force; (iv) obtaining other node forces to obtain a mass matrix, node forces, and acceleration; (v) updating the material point coordinates, updating the material point neighborhood, updating the material point shape function, and updating the material point shape function derivative.

6. The meshless impact crash simulation method based on point-to-surface contact according to claim 5, wherein, Step (5) is specifically: Entering next time, determine time step , if , represent the last step has been reached, the final material points and nodes from t0 to t n period of time within the physical information and dynamic data; If , the next iteration is performed, at the initial time of each iteration step, the master contact surface is reconstructed using the method of step (II) to obtain the outward normal vector of each node on the master contact surface; then steps (ii) to (v) are repeated until the time step is reached, and finally the physical information and dynamic data of the material points and nodes from t0 to t n are obtained.

7. The meshless impact crash simulation method based on point-to-surface contact according to claim 1, wherein, Physical information and dynamic data include deformation, stress, density, displacement, velocity, acceleration, and temperature.

8. The meshless impact crash simulation method based on point-to-surface contact according to claim 5, wherein, In step (i), a local maximum entropy shape function is used as the shape function of the material point.

9. The meshless impact crash simulation method based on point-to-surface contact according to claim 8, wherein, The initial conditions are used to initialize the mass, velocity, and node force of each node, and the acceleration is obtained.

10. The meshless impact crash simulation method based on point-to-surface contact according to claim 5, wherein, In step (iv), the other node forces are external applied forces.

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