A simulation method for shear fracture of a deformable object and a material simulation method

Abstract

The present disclosure relates to a simulation method for shear fracture of a deformable object, which is convenient for medical applications such as virtual surgery training and interactive surgery planning. The shape of the deformable object is simulated by using a composite finite element model, and when and how to generate a new cut is determined based on Griffith energy minimization to achieve interactive virtual cutting simulation; further, a material simulation method is designed to ensure that the indentation is consistent with the tool blade, and the visually plausible indentation-induced deformation is avoided to avoid a lot of calculations.

Description

Technical Field

[0001] The present disclosure relates to surgical simulation, and in particular to a shear fracture simulation method and a material simulation method for a deformable object. Background Art

[0002] As the core module of virtual surgical training system, deformable object cutting simulation has always been an important research topic. Existing methods focus on solving the three major tasks of virtual cutting simulation, namely, simulation of deformable bodies, detection and processing of collisions, and incorporation into computational models.

[0003] According to the fundamental situation, deformation models, cutting simulation methods can be divided into three categories: grid-based methods, mesh-free methods and adaptive / multi-resolution methods. Among them, the grid-based method can effectively reconstruct the cutting unit, the most common one is the finite element method (FEM). In recent years, the extended finite element method has been applied to the cutting simulation of deformation models to ensure that the deformation behavior near the cutting surface is physically correct; the mesh-free technology reduces the dependence on the simulation grid. The model used in this method is represented by a set of mobile nodes that interact according to the elastic control equation. Since the visual quality of the simulated object is closely related to the accuracy of the geometric representation, the improvement of the visual effect will be accompanied by a steady linear growth of the simulation unit; and the adaptive multi-resolution method, in which the composite finite element method (CFEM) embeds the high-resolution visual grid into the fine hexahedral grid and can perform branch analysis.

[0004] Regardless of the shear simulation method used, most existing shear simulation methods follow the "intersection means fracture" model, that is, as long as the cutting edge intersects with the object, cutting fracture will occur. However, real soft objects generally have a certain degree of fracture resistance. When the tool presses on the soft tissue, it usually produces an indentation first. When the pressing energy accumulates to a certain level, the tissue fracture will occur. Therefore, the existing shear simulation results are very different from the real soft object shear phenomenon. Summary of the invention

[0005] In view of this, the main purpose of the present application is to provide a highly realistic virtual cutting fracture simulation method and / or device for simulating the highly realistic cutting phenomenon of the anti-fracture ability of deformed objects.

[0006] In one aspect, the present invention provides a method for simulating shear fracture of a deformable object, the method comprising the following steps:

[0007] S100, simulating the shape of the deformable object based on the composite finite element model to obtain a connected mesh, embedding the original object surface on the connected mesh, and obtaining a visualized mesh of the deformable object;

[0008] The method for establishing the composite finite element model is as follows: firstly, the model of the deformable object is imported into the world coordinate system, and after the center of gravity thereof coincides with the origin of the world coordinate system, the model is normalized; then, an axisymmetric cube of the model is constructed, and a cube surrounding the deformable object is divided into a plurality of first grids according to a first grid resolution, and information of each first grid is stored; then, each first grid is divided into a second grid according to a second grid resolution, and information of the second grid is stored; and the center points of adjacent second grids are connected to form a connected grid;

[0009] S200: If cutting occurs, update the storage information of the first mesh, the second mesh, and the connected mesh, combine and generate the surface after cutting, and reconstruct the visual mesh.

[0010] Preferably, in the method, the updating comprises the following steps:

[0011] S201, obtaining mesh nodes of a simulated tool, and obtaining mesh nodes of a second mesh;

[0012] S202, using wide phase collision detection to determine whether the grid nodes of the simulated tool and the grid nodes of the second grid overlap, if so, executing S203; otherwise, executing S204;

[0013] S203, obtaining each point on the connection intersecting with the simulated tool, and then obtaining the symbol field distance value of the point, and executing S204;

[0014] S204, obtaining each visualized grid node, using wide phase collision detection to determine the first grid penetrated by the simulated tool, and then using narrow phase collision detection to determine the point on the second grid penetrated, and obtaining the symbol field distance value of the point, and executing S205;

[0015] S205, using the signed distance field value of the point, establishing an energy function for connecting the grids, and determining the first grid, the second grid, and the connection on the connecting grid that need to update the storage information by minimizing the energy function, thereby updating the storage information.

[0016] Preferably, in the method, the calculation process of the energy function is as follows:

[0017]

[0018] Where: t * is a pseudo parameter of the time evolution; is the signed distance field value of the intersection point at the current time, where the intersection point is a point on the connection that intersects with the tool trajectory;

[0019]

[0020] Where: x is any position in the region of the initial undeformed state; Q is the energy density function of the deformable object on the deformed region at time t;

[0021]

[0022] Where: S is the symmetric tensor obtained by polar decomposition of Q; I is the unit matrix of the same size as S; μ and λ are the coefficients of calculation, and the calculation formula is as follows:

[0023]

[0024] Where: E is the Young's modulus set according to the material of the deformable object, V is the Poisson's ratio;

[0025] e g =∫ ΩH Ψdx+∫ ΩD kdx

[0026] Where: e g is the energy function, ΩH represents the connection between all the second grids in the connected state, Ψ is the energy density of each connection; ΩD represents the connection between all the second grids from the connection state changing from connected to disconnected, k is the energy release rate from the connection state between the second grids changing from connected to disconnected.

[0027] Preferably, in the method, the cut surface determines the mesh nodes whose displacements are to be changed due to the cutting operation by the following steps:

[0028] Find the point that needs to be projected through the intersection with the simulated tool;

[0029] Based on the visualized mesh, obtain the triangular meshes of these points, and then obtain the Jacobian matrix of these triangular meshes;

[0030] Uniformly sample the simulated blade to obtain sampling points;

[0031] For each point to be projected, after calculating the displacement of its projection to the simulated blade sampling point, the sum of the algebraic quality measures of all triangular meshes containing the point to be projected is calculated through the Jacobian matrix;

[0032] The positions of the points projected onto the simulated tool are determined by minimizing the sum of the algebraic quality measures.

[0033] Preferably, in the method, the cut surface is formed by using a B-spline to realize the generation of a profile indentation, comprising the following steps:

[0034] Based on the control point (x 0 ,y 0 ), (x 1 ,y1 ), (x 2 ,y 2 ), (x 3 ,y 3 ), (x 4 ,y 4 ), (x 5 ,y 5 ) Use B-spline to construct the indentation adjustment function, where:

[0035] x 0 =0,y 0 =-a i ;x 1 =0.2cosθ i ,y 1 =a i (0.2sinθ i -1);

[0036] y 2 =γ; y 3 =0, y 4 =0;

[0037] x 5 =1,y 5 =0;

[0038] Among them: a i is the grid node v i Displacement after projection, i is the grid node number to be projected, i=1, 2, ..., N, N is the number of nodes to be projected, and the nodes to be projected are the nodes whose displacement changes due to cutting or pressing; D is the maximum geodesic distance; γ is a material-related parameter that can be adjusted to adjust the displacement change of the control node caused by indentation;

[0039] Get the grid node v i Nodes within the maximum geodesic range of the potential adjustment nodes are selected as potential adjustment nodes, and nodes within the maximum geodesic range of the potential adjustment nodes are continuously obtained until the number of obtained nodes reaches the set number;

[0040] Substitute the horizontal coordinates of the nodes to be adjusted into the indentation adjustment function to obtain the vertical coordinates of these nodes after the indentation is generated, combined with the displacement a of the projection point i , you can get the new position of the adjusted nodes, update the node information of these meshes, and get the visual mesh after the indentation is generated.

[0041] Preferably, in the method, the γ is calculated by the following formula:

[0042]

[0043] Where: τ is a value set according to the material, and E is Young's modulus.

[0044] Preferably, in the method, the maximum geodesic distance is material-dependent and is calculated by the following formula:

[0045]

[0046] Where V is Poisson's ratio and E is Young's modulus.

[0047] In another aspect, a material simulation method is provided to ensure that the indentation is consistent with the tool blade and the indentation-induced deformation is visually plausible to avoid extensive calculations. The method uses B-splines to adjust the indentation generation, and comprises the following steps:

[0048] Visualization grids of construction materials;

[0049] Based on the control point (x 0 ,y 0 ), (x 1 ,y 1 ), (x 2 ,y 2 ), (x 3 ,y 3 ), (x 4 ,y 4 ), (x 5 ,y 5 ) Use B-spline to construct the indentation adjustment function, where:

[0050] x 0 =0,y 0 =-a i ;x 1 =0.2cosθ i ,y 1 =a i (0.2sinθ i -1);

[0051] y 2 =γ; y 3 =0, y 4 =0;

[0052] x 5 =1,y 5 =0;

[0053] Among them: a i is the grid node v iThe displacement caused by pressing, i is the grid node number, i = 1, 2, ..., N, N is the number of nodes affected by pressing; D is the maximum geodesic distance; γ is a material-related parameter that can be adjusted to adjust the displacement change of the control node caused by indentation;

[0054] Get the grid node v i Nodes within the maximum geodesic range of the potential adjustment nodes are selected as potential adjustment nodes, and nodes within the maximum geodesic range of the potential adjustment nodes are continuously obtained until the number of obtained nodes reaches the set number;

[0055] Substitute the horizontal coordinates of the nodes to be adjusted into the indentation adjustment function to obtain the vertical coordinates of these nodes after the indentation is generated, combined with the displacement a of the projection point i , you can get the new position of the adjusted nodes, update the node information of these meshes, and get the visual mesh after the indentation is generated.

[0056] Preferably, in the material simulation method, the γ is calculated by the following formula:

[0057]

[0058] Where: τ is a value set according to the material, and E is Young's modulus.

[0059] Finally, the present invention also relates to a terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any of the above-mentioned methods when executing the computer program.

[0060] Compared with the prior art, the present invention uses a co-rotating linear finite element model to design a framework that supports large deformation of soft objects, and uses a composite finite element method to balance simulation accuracy and algorithm efficiency; the cutting fracture evolution model of Griffith energy is used for interactive virtual cutting simulation, which can determine when and how new cutting is generated; a material simulation method is particularly proposed to ensure that the indentation is consistent with the tool blade, and the visually plausible indentation-induced deformation is avoided to avoid a large amount of calculation. Therefore, the present invention is very suitable for medical applications such as virtual surgery training and interactive surgery planning. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0062] Figure 1 , is a schematic diagram of simulation before cutting;

[0063] Figure 2 , is a schematic diagram of the simulation after cutting;

[0064] Figure 3 , schematic diagram of the indentation adjustment nodes involved before cutting with a tool;

[0065] Figure 4 ,Schematic diagram of the change of indentation adjustment nodes during cutting;

[0066] Figure 5 , Schematic diagram of the change of the indentation adjustment node after cutting occurs;

[0067] Figure 6 , is a schematic diagram of cutting without indentation treatment;

[0068] Figure 7 , construct a schematic diagram for the indentation adjustment area;

[0069] Figure 8 , is a schematic diagram of cutting after indentation treatment;

[0070] Fig. 9 , is a schematic diagram of simulation of cutting changes when cutting is performed using the method of the present invention and using a basic composite finite element model;

[0071] Fig.10 , is a schematic diagram of simulation comparison when cutting different materials;

[0072] Fig.11 , is a schematic diagram of the simulation of the process from deformation to fracture when cutting an object using a tool of another shape;

[0073] Fig.12 , is a simulation schematic diagram of the cutting change process when the liver is cut arbitrarily using the method of the present invention;

[0074] Fig.13 , is a simulation schematic diagram of the cutting change process when the method of the present invention is used to perform arbitrary cutting on a horse;

[0075] Fig.14 , is a simulation schematic diagram of the cutting change process when the armadillo is cut arbitrarily using the method of the present invention;

[0076] Fig.15 , is a simulation schematic diagram of the cutting change process when the method of the present invention is used to perform arbitrary cutting on a rabbit. DETAILED DESCRIPTION

[0077] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0078] The terms "including" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or devices is not necessarily limited to those steps or devices explicitly listed, but may include other steps or devices that are not explicitly listed or inherent to these processes, methods, products, or devices.

[0079] In the description of this application, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0080] In a liver cutting simulation embodiment, the following method is used to simulate the cutting experiment, and the cross-sectional view perpendicular to the incision direction is as follows: Figure 1 and Figure 2 As shown, Figure 1 This is a schematic diagram before cutting. Figure 2 In this embodiment, the simulation adopts the following steps:

[0081] S100, simulating the shape of the deformable object based on the composite finite element model to obtain a connected mesh, embedding the original object surface on the connected mesh, and obtaining a visualized mesh of the deformable object;

[0082] S200: If cutting occurs, update the storage information of the first mesh, the second mesh, and the connected mesh, combine and generate the surface after cutting, and reconstruct the visual mesh.

[0083] In the above steps, the method for establishing the composite finite element model is as follows: first, the model of the deformable object is imported into the world coordinate system, so that its center of gravity coincides with the origin of the world coordinate system, and then the model is normalized; then, an axisymmetric cube of the model is constructed, and a cube surrounding the deformable object is divided into a plurality of first grids according to a first grid resolution, and each first grid information is stored; then, each first grid is divided into a second grid according to a second grid resolution, and the second grid information is stored; and the center points of adjacent second grids are connected to form a connected grid. The stored grid information includes node information, and the connected grid needs to store the intersection points and normals that intersect with the original object surface.

[0084] The first grid is mainly used for deformation calculation, and the higher discreteness ensures the real-time performance of the method. The second grid is used to approximate the actual shape of the object and can represent the connection between the various parts of the object. By using the intersection of the lines between the original object surface and the second grid, a visualization grid is obtained, which can more finely represent the object itself. Therefore, the first grid spatially contains the second grid, the visualization grid. Preferably, the first grid is a hexahedron and the second grid is a hexahedron. The original object surface is composed of triangular grids.

[0085] In the cutting simulation process of variable objects, it is necessary to first determine the time when the cutting occurs and simulate the cutout disconnection of the visualized grid. In the process of cutout disconnection, there will be two types of collisions. One is the collision between the tool and the deformable object, and the other is the collision between the disconnected tissues of the deformable object. Therefore, the present invention uses a hash table during simulation, puts the object to be detected into the spatial hash table, and combines the wide phase detection method to determine whether they overlap in space, that is, whether the tool and the deformable object, the deformable object itself, and the disconnected tissue of the deformable object overlap at the relevant nodes. If there is a collision between the tool and the deformable object, the cutout disconnection is simulated, or if there is a collision between the disconnected tissues, the simulation penetrates which first grids to determine the specific location of the penetration. When the cutout is disconnected, the cutout simulation is performed by updating the node information where the deformation occurs. Therefore, the overlapping points in the collision may be the points where deformation occurs. Using the symbol field distance value of the point, an energy function connecting the connected grids is established. By making the energy function obtain the minimum value, the first grid, the second grid, and the connection on the connected grid that need to update the storage information are determined, thereby updating the storage information.

[0086] The calculation process of the energy function in the present invention is as follows:

[0087]

[0088] Where: t * is a pseudo parameter of the time evolution; is the signed distance field value of the intersection point at the current time, where the intersection point is a point on the connection that intersects with the tool trajectory;

[0089]

[0090] Where: x is any position in the region of the initial undeformed state; Q is the energy density function of the deformable object on the deformed region at time t;

[0091]

[0092] Where: S is the symmetric tensor obtained by polar decomposition of Q; I is the unit matrix of the same size as S; μ and λ are the coefficients of calculation, and the calculation formula is as follows:

[0093]

[0094] Where: E is the Young's modulus set according to the material of the deformable object, V is the Poisson's ratio;

[0095] e g =∫ ΩH Ψdx+∫ ΩD kdx

[0096] Where: e g is the energy function, ΩH represents the connection between all the second grids in the connected state, Ψ is the energy density of each connection; ΩD represents the connection between all the second grids from the connection state changing from connected to disconnected, k is the energy release rate from the connection state between the second grids changing from connected to disconnected.

[0097] The above process is to find the point that will be deformed due to cutting pressure, but the simulation of the incision also requires knowing the cutting depth. In one embodiment, the following method is used to simulate the cutting depth, namely: find the point that needs to be projected through the intersection with the simulated tool; based on the visualization grid, obtain the triangular mesh of these points, and then obtain the Jacobian matrix of these triangular meshes; uniformly sample the simulated blade to obtain sampling points; for each point to be projected, calculate its displacement projected to the simulated blade sampling point, and then calculate the sum of the algebraic mass measures of all triangular meshes containing the point to be projected through the Jacobian matrix; determine the position of the point projected onto the simulated tool by minimizing the sum of the algebraic mass measures. The processing process of this embodiment is as follows: Figure 3-5 shown. Figure 3-5In the figure, Blade curve is the tool sampling point, which is obtained by uniformly sampling the blade of the simulated tool. Contact region vertices are points that may need to be projected, found through the intersection with the tool. For the triangular mesh containing these points, a Jacobian matrix is ​​constructed. Further, for all points that may need to be projected, the distance from the point to the blade sampling point is calculated, which is the projection. The sum of the algebraic quality measures of all triangular meshes containing the point to be projected is calculated through the Jacobian matrix, and the point where the sum of the algebraic quality measures takes the minimum value is the final projection point. Local coordinate system is a coordinate system established according to the projection position. Local mesh that may need to adjust is a visualization mesh that needs to adjust the position as shown in the figure. Approximate indentation curve is an approximate concave blade.

[0098] If the knife edge is not processed, the simulated knife edge above will look like Figure 6 As shown in the figure, as long as the cutting blade intersects with the model, cutting fracture will occur, which is different from the actual cutting experience. For elastic surfaces, there will be no edges and corners after cutting, and there will be no significant discontinuity from the uncut part to the edge of the cut, such as Figure 7 In order to simulate the cutting edge more realistically and improve the simulation efficiency, the present invention proposes a material simulation method. The method uses the maximum geodesic distance related to the material parameters to find the vertex near the indentation that needs to be deformed, and simulates the deformation and / or cutting process of objects with different hardness through the deformation model related to the material parameters.

[0099] In this deformation model, a visual mesh of the material is first constructed. The construction method is preferably based on the composite finite element model method in the above-mentioned simulation method for shear fracture of deformable objects. 0 ,y 0 ), (x 1 ,y 1 ), (x 2 ,y 2 ), (x 3 ,y 3 ), (x 4 ,y 4 ), (x 5 ,y 5 ), use B-spline to construct the indentation adjustment function, where: x 0 =0,y 0 =-a i ;x 1 =0.2cosθ i ,y 1 =ai (0.2sinθ i -1); y 2 =γ; y 3 =0, y 4 =0;x 5 =1,y 5 =0. Among them: a i is the grid node v i The displacement caused by pressing, i is the grid node number, i=1, 2, ..., N, N is the number of nodes affected by pressing, that is, the number of nodes to be deformed; D is the maximum geodesic distance; γ is a material-related parameter, which can be adjusted to adjust the displacement change of the control node caused by indentation; Get the grid node v i The nodes within the maximum geodesic range of the potential adjustment nodes are selected as potential adjustment nodes, and the nodes within the maximum geodesic range of the potential adjustment nodes are continuously obtained until the number of obtained nodes reaches the set number; the horizontal coordinates of the nodes to be adjusted are substituted into the indentation adjustment function to obtain the vertical coordinates of these nodes after the indentation is generated, and the vertical coordinates of the nodes are obtained by combining the displacement a of the projection point. i , you can get the new position of the adjusted node, update the node information of these grids, and get the visual grid after the indentation. The deformation caused by the indentation is related to the material of the object. The softer the material, the more obvious the deformation will be. Therefore, the indentation adjustment is used to simulate the deformation of the material after being subjected to pressure. In order to be closer to the properties of the material, during the calculation, the maximum geodesic distance D can be calculated by the following formula:

[0100]

[0101] Where V is Poisson's ratio and E is Young's modulus.

[0102] Similarly, in order to facilitate the setting of material parameter values, γ is calculated by the following formula:

[0103]

[0104] Where: τ is a value set according to the material, and E is the Young's modulus of the material.

[0105] By applying the above deformation model, a smooth transition between the cut surface and the original object surface can be achieved, making the simulated cut look more natural and realistic, and the above calculation process can avoid a lot of calculations.

[0106] Figure 9-15 It is a comparison diagram of the simulation effects of cutting using the present invention.

[0107] Fig. 9It is a schematic diagram for comparing the results of the basic composite finite element cutting simulation. The first line shows the basic cutting effect of the composite finite element method, and the second line shows the intermediate results of crack evolution and indentation generation. The third line shows the simulation effect after further indentation adjustment based on the composite finite element model. Each row of images consists of a front view of the cutting effect and a corresponding enlarged view. It can be seen from the figure that the shear simulation in the method of the present invention is more realistic and natural.

[0108] Fig.10 Schematic diagram of the cutting effect of different materials. This set of comparison pictures shows the simulation effects of three different materials. Every two rows with similar colors represent the simulation effect of one material. The bottom row of these two rows shows the corresponding enlarged view. It can be seen from the figure that the shear simulation in the present invention is suitable for the simulation of different materials and has strong practicality.

[0109] Fig.11 This is a set of simulation results of the process from deformation to fracture when cutting an object using a tool of another shape. The first to third groups are deformation, and the last group is fracture. Each group of figures shows a side view of the cutting effect, a corresponding top view, and a partial magnified view to see the details. It can be seen from these four groups of comparison figures that the method of the present invention is not restrictive on the shape of the tool, and the shearing effect is still highly realistic.

[0110] Figure 12-15 The schematic diagrams are respectively the cutting process changes when the method of the present invention is used to perform arbitrary cutting on liver, horse, armadillo and rabbit.

[0111] It can be seen that the method of the present invention has wide applicability and practicality. It can perform realistic and natural simulation on objects of any material, any tool and any shape, and can simulate the real cutting phenomenon of the fracture resistance of deformed objects, which is convenient for medical applications such as virtual surgery training and interactive surgery planning, and has high practical and promotion value.

[0112] The above methods can all be implemented by a terminal device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, the steps of any of the above methods are implemented.

[0113] Through the description of the above implementation modes, those skilled in the art can clearly understand that the disclosed method can also be implemented by means of software plus necessary general hardware, and of course can also be implemented by dedicated hardware including dedicated integrated circuits, dedicated CPUs, dedicated memories, dedicated components, etc. In general, all functions performed by computer programs can be easily implemented by corresponding hardware, and the specific hardware structures used to implement the same function can also be various, such as analog circuits, digital circuits or dedicated circuits, etc. However, for the present disclosure, software program implementation is a better implementation mode in most cases.

[0114] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for simulating shear fracture of a deformable object, characterized in that: The method comprises the following steps: S100, simulating the shape of the deformable object based on the composite finite element model to obtain a connected mesh, embedding the original object surface on the connected mesh, and obtaining a visualized mesh of the deformable object; The method for establishing the composite finite element model is as follows: firstly, the model of the deformable object is imported into the world coordinate system, and after the center of gravity thereof coincides with the origin of the world coordinate system, the model is normalized; Then, an axisymmetric cube of the model is constructed, a cube surrounding the deformable object is divided into a plurality of first grids according to the first grid resolution, and information of each first grid is stored; Then, according to the second grid resolution, each first grid is divided into second grids according to the second grid resolution, and the second grid information is stored; Connect the center points of the adjacent second grids to form a connected grid; S200, if cutting occurs, update the storage information of the first grid, the second grid and the connected grid, combine and generate the surface after cutting, and reconstruct the visual grid; the updating includes the following steps: S201, obtaining mesh nodes of a simulated tool, and obtaining mesh nodes of a second mesh; S202, using wide phase collision detection to determine whether the grid nodes of the simulated tool and the grid nodes of the second grid overlap, if so, executing S203; otherwise, executing S204; S203, obtaining each point on the connection intersecting with the simulated tool, and then obtaining the symbol field distance value of the point, and executing S204; S204, obtaining each visualized grid node, using wide phase collision detection to determine the first grid penetrated by the simulated tool, and then using narrow phase collision detection to determine the point on the second grid penetrated, and obtaining the symbol field distance value of the point, and executing S205; S205, using the signed distance field value of the point, establishing an energy function for connecting the grids, and determining the first grid, the second grid, and the connection on the connecting grid that need to update the storage information by minimizing the energy function, thereby updating the storage information.

2. The method according to claim 1, characterized in that: The calculation process of the energy function is as follows: Where: is a pseudo parameter of the time evolution; is the signed distance field value of the intersection point at the current time, where the intersection point is a point on the connection that intersects with the tool trajectory; Where: x is any position of the region in the initial undeformed state; is the energy density function of the deformable object on the deformation area at time t; In the formula: S is The symmetric tensor obtained after polar decomposition; I and S are unit matrices of the same size; μ and λ are the coefficients of calculation, and the calculation formula is as follows: ， Where: E is the Young's modulus set according to the material of the deformable object, is Poisson's ratio; Where: is the energy function, Indicates that all second grids are connected. is the energy density for each connection; Indicates that the connection status between all second grids changes from connected to disconnected. is the energy release rate when the connection state between the second grids changes from connected to disconnected.

3. The method according to claim 1, characterized in that The cut surface is determined by the following steps to determine the mesh nodes whose displacements are to be changed due to the cutting operation: Find the point that needs to be projected through the intersection with the simulated tool; Based on the visualized mesh, obtain the triangular meshes of these points, and then obtain the Jacobian matrix of these triangular meshes; Uniformly sample the simulated blade to obtain sampling points; For each point to be projected, after calculating the displacement of its projection to the simulated blade sampling point, the sum of the algebraic quality measures of all triangular meshes containing the point to be projected is calculated through the Jacobian matrix; The positions of the points projected onto the simulated tool are determined by minimizing the sum of the algebraic quality measures.

4. The method according to claim 1, characterized in that: The cut surface is subjected to the generation of profile indentation by using B-spline, comprising the following steps: Based on control points , , , , , , use B-spline to construct the indentation adjustment function, where: ， ； ， ； , ； , ； , ； , ； in: is a grid node The displacement after projection, i is the grid node number to be projected, i=1, 2, ..., N; N is the number of nodes to be projected; , ; D is the maximum geodesic distance; It is a material-related parameter, and the displacement change of the control node caused by indentation can be adjusted by adjusting this parameter; Get grid nodes Nodes within the maximum geodesic range of the potential adjustment nodes are selected as potential adjustment nodes, and nodes within the maximum geodesic range of the potential adjustment nodes are continuously obtained until the number of obtained nodes reaches the set number; Substitute the horizontal coordinates of the nodes to be adjusted into the indentation adjustment function to obtain the vertical coordinates of these nodes after the indentation is generated, combined with the displacement of the projection point , you can get the new position of the adjusted nodes, update the node information of these meshes, and get the visual mesh after the indentation is generated.

5. The method according to claim 4, characterized in that Said Calculated by the following formula: Where: is a value set according to the material, and E is Young's modulus.

6. The method according to claim 4, characterized in that The maximum geodesic distance is material dependent and is calculated by the following formula: In the formula, is Poisson's ratio and E is Young's modulus.

7. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

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