Cerebral dura mater cutting simulation method based on fracture mechanics, storage medium and computer

Abstract

The invention relates to the technical field of virtual reality, and provides a fracture mechanics-based dura mater cutting simulation method, a storage medium and a computer, according to position dynamics, a dura mater tissue model is obtained, nodes in the dura mater tissue model are used as vertexes of a tetrahedron to obtain cutting influence unit bodies, and mechanical analysis is performed on each cutting influence unit body to obtain a simulation result. The normal form equivalent stress of each cutting influence unit body is obtained; further, the state of each cutting influence unit body can be accurately judged according to normal form equivalent stress, the accuracy of judging whether a notch is formed or not is improved, and the simulation effect is improved; different analysis modes can be adopted for the cutting influence unit bodies in the elastic deformation state, the plastic damage state and the broken state, the requirement for the calculation force is reduced, and the simulation real-time performance is improved. According to the method, the cutting simulation effect of the dura mater tissue model can be effectively improved, and convenience is provided for application of dura mater cutting simulation.

Description

Technical Field

[0001] The invention relates to the field of virtual reality technology, and in particular to a dura mater cutting simulation method based on fracture mechanics, a storage medium and a computer. Background Art

[0002] The dura mater is a tough connective tissue membrane attached to the inner surface of the skull. It is composed of glial fibers and elastic fibers and is continuous with the dura mater at the foramen magnum. Dura mater cutting surgery is a key technical link in neurosurgery, skull base surgery and spinal surgery. Its purpose is to expose the soft tissue of the brain for further operations. The surgery requires high precision and the surgeon needs to be fully trained to ensure the safety of the surgery.

[0003] Traditional surgical training relies on cadaver dissection, animal experiments or real surgical operations under the supervision of a mentor, which involves ethical controversy, biosafety risks (such as infection) and patient safety pressure. With the development of technology, the application of virtual reality technology in neurosurgery simulation has gradually become an important supplement to traditional surgical training methods and can effectively improve training results.

[0004] In the existing technology, commonly used virtual cutting simulation technologies include finite element method (FEM), mass spring model (MSM), meshless method and position-based dynamics (PBD) method. Among them, the PBD method has high computing performance and good real-time performance compared with other methods, and is widely used in dura mater tissue models. However, it is based on geometric constraints to achieve model state updates in cutting simulations, and its simulation capabilities for actual physical rupture behaviors are insufficient, making its simulation authenticity insufficient and difficult to meet the accuracy requirements of neurosurgery, which is not conducive to the practical application of virtual cutting simulation technology. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide a dura mater cutting simulation method, storage medium and computer based on fracture mechanics, so as to solve the problem that the dura mater tissue model constructed based on position dynamics has insufficient simulation ability for the actual physical rupture behavior, resulting in insufficient simulation authenticity and difficulty in meeting the precision requirements of neurosurgery.

[0006] In one aspect, the present invention provides a dura mater cutting simulation method based on fracture mechanics, comprising: A dura mater tissue model is obtained according to the position dynamics, and collision detection is performed according to the dura mater tissue model and the instrument model to obtain a cutting influence area of ​​the dura mater tissue model, and a cutting influence node is obtained according to the cutting influence area; Obtaining a cutting influence unit body according to the cutting influence node, and performing mechanical analysis on each of the cutting influence unit bodies to obtain a paradigm equivalent stress of each of the cutting influence unit bodies; Determining the state of each cutting-affecting unit cell according to the paradigm equivalent stress, so as to update the dura mater tissue model according to the state of each cutting-affecting unit cell and the corresponding analysis method; The states of the cutting-affected unit body include an elastic deformation state, a plastic damage state and a crushing state, and the cutting-affected unit body is a tetrahedron.

[0007] Optionally, according to the state of each cutting-affecting unit cell and the corresponding analysis method, the step of updating the dura mater tissue model includes: Performing elastic deformation analysis based on position dynamics on the cutting-affecting unit body in an elastic deformation state to update the vertex position of the corresponding cutting-affecting unit body, thereby updating the dura mater tissue model; Performing stiffness analysis on the cutting-affected unit body in a plastic damage state, so as to update the dura mater tissue model according to stiffness change information corresponding to the cutting-affected unit body; Deleting the cutting-affected unit body in a broken state, defining the node whose connected unit bodies are all deleted as an invalid node, and defining the other nodes as valid nodes; Deleting the invalid node and allocating the mass of the invalid node to the adjacent valid node; The remaining valid nodes on the newly added incision surface are subjected to incision smoothing processing to update the model and update the dura mater tissue model.

[0008] Optionally, the step of performing cut smoothing processing on the remaining valid nodes on the newly added cut surface includes: obtaining a cutting plane and a maximum cutting width according to the moving characteristics of the tool model; The valid nodes constituting the cut are defined as cut nodes, a current distance from the cut node to the cut plane is obtained according to the cut plane, and an ideal distance from the cut node to the cut plane is obtained according to the maximum cut width; The normal deviation is obtained according to the difference between the ideal distance and the current distance, and the position of the cut node is updated in combination with the position change amount obtained according to the position dynamics elastic deformation analysis of the cut node.

[0009] Optionally, the step of performing position dynamics elastic deformation analysis to update the vertex position of the corresponding cutting-affecting unit body comprises: Update the location information of each node according to the node location update model; The updated position information is corrected according to the position constraint model, the distance constraint model and the volume preservation model so that the distance between each node is consistent with the expected distance and the volume of each unit body is kept constant.

[0010] Optionally, the method further includes: obtaining a cutting stiffness force according to a normal component of the Cauchy stress tensor in the dura mater tissue model, and obtaining a cutting force in combination with a friction force between the dura mater tissue model and the instrument model.

[0011] Optionally, collision detection is performed based on the dura mater tissue model and the instrument model to obtain a cutting influence area of ​​the dura mater tissue model, and the step of obtaining a cutting influence node based on the cutting influence area includes: Before performing collision detection, the simulation space is divided into cubes; and during collision detection, marking the cube where the contact point between the dura mater tissue model and the instrument model is located and the adjacent cubes as the cutting impact area; All nodes of the unit body associated with the cutting influence area in the dura mater tissue model are used as the cutting influence nodes.

[0012] Optionally, the step of performing mechanical analysis on each cutting-affecting unit body to obtain the paradigm equivalent stress of each cutting-affecting unit body comprises: Obtaining the first Piola-Kirchhoff stress tensor of the cutting-affected unit cell according to the strain energy density function; Obtaining the Cauchy stress tensor of the cutting-affected unit cell according to the first Piola-Kirchhoff stress tensor; The normal equivalent stress of the cutting-affected unit cell is obtained according to the Cauchy stress tensor.

[0013] Optionally, the step of judging the state of each cutting-affected unit body according to the paradigm equivalent stress includes: The state of the cutting-affected unit body with the paradigm equivalent stress less than the damage stress threshold is marked as the elastic deformation state; The state of the cutting-affected unit body whose paradigm equivalent stress is greater than the crushing stress threshold is marked as a crushing state; The state of the cutting-affected unit body whose normal equivalent stress is in the closed interval from the damage stress threshold to the crushing stress threshold is marked as a plastic damage state.

[0014] On the other hand, the present invention provides a storage medium, which is a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program is read and executed by a processor, the above-mentioned dura mater cutting simulation method based on fracture mechanics can be implemented.

[0015] The present invention also provides a computer, wherein a computer program is stored in the computer, and when the computer program is read and executed by a processor, the above-mentioned dura mater cutting simulation method based on fracture mechanics can be implemented.

[0016] The dura mater cutting simulation method based on fracture mechanics provided by the present invention obtains a dura mater tissue model according to position dynamics, and uses the nodes therein as tetrahedron vertices to obtain cutting influence units, and performs mechanical analysis on each cutting influence unit to obtain the paradigm equivalent stress of each cutting influence unit; then, the state of each cutting influence unit can be accurately judged according to the paradigm equivalent stress, and by distinguishing the state transition, the judgment accuracy of the rupture position and the crushing timing can be improved, the judgment accuracy of whether the incision is formed can be improved, and the simulation effect can be improved; and different analysis methods can be used for the cutting influence units in the elastic deformation state, the plastic damage state and the crushing state, so as to reduce the demand for computing power, improve the real-time performance of the dura mater tissue model state update, further improve the simulation effect, and provide convenience for the application of dura mater cutting simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the main process of the dura mater cutting simulation method based on fracture mechanics in an embodiment of the present invention.

[0018] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0020] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0022] In order to solve the problem that the dura tissue model constructed based on position dynamics has insufficient simulation ability for the actual physical rupture behavior, which makes its simulation authenticity insufficient and difficult to meet the precision requirements of neurosurgery. The present invention provides a dura cutting simulation method based on fracture mechanics, which is based on the dura tissue model obtained according to position dynamics, uses the nodes therein as the vertices of the tetrahedron to obtain the cutting influence unit body, and performs mechanical analysis on each cutting influence unit body to obtain the paradigm equivalent stress of each cutting influence unit body; then, the state of each cutting influence unit body can be accurately judged according to the paradigm equivalent stress, the judgment accuracy of whether the incision is formed is improved, and the simulation effect is improved; and different analysis methods can be used for the cutting influence unit bodies in the elastic deformation state, the plastic damage state and the broken state, so as to reduce the demand for computing power, improve the real-time update of the dura tissue model state, further improve the simulation effect, and provide convenience for the application of dura cutting simulation.

[0023] Specifically, Figure 1 FIG. 1 is a schematic diagram of the main process of the dura mater cutting simulation method based on fracture mechanics of this embodiment, including: Step S01: obtaining a dura mater tissue model according to position dynamics, and performing collision detection on the dura mater tissue model and the instrument model to obtain a cutting influence area of ​​the dura mater tissue model, and obtaining a cutting influence node according to the cutting influence area; Step S02: obtaining a cutting influence unit body according to the cutting influence node, and performing mechanical analysis on each cutting influence unit body to obtain a paradigm equivalent stress of each cutting influence unit body; Step S03: judging the state of each cutting-affecting unit cell according to the paradigm equivalent stress, so as to update the dura mater tissue model according to the state of each cutting-affecting unit cell and the corresponding analysis method; The states of the cutting-affected unit body include an elastic deformation state, a plastic damage state and a crushing state, and the cutting-affected unit body is a tetrahedron.

[0024] In step S01, the nodes of the dura tissue model are also used as vertices to divide multiple tetrahedral unit bodies. In order to reduce computing power, step S01 specifically includes: before performing collision detection, the simulation space is divided into cubes; and when collision detection occurs, the cube where the contact point of the dura tissue model and the instrument model is located and its adjacent cubes are marked as the cutting influence area; all nodes of the unit body associated with the cutting influence area in the dura tissue model are used as the cutting influence nodes.

[0025] The simulation space can completely accommodate the dura mater tissue model and the instrument model, and there is space for the instrument model to move. The size of the cube is calibrated according to the actual cutting impact area, and this application does not specifically limit its specific data. By dividing the cube, the cutting impact node can be quickly located to avoid global analysis, thereby reducing the amount of data processing and improving the simulation response speed.

[0026] The association between the unit body of the dura mater tissue model and the cutting influence area mainly includes two situations: the unit body is included in the cutting influence area, and the unit body intersects with the cutting influence area.

[0027] In step S02, the mechanical analysis includes: obtaining the first Piola-Kirchhoff stress tensor of the cutting-affected unit body according to the strain energy density function, obtaining the Cauchy stress tensor of the cutting-affected unit body according to the first Piola-Kirchhoff stress tensor, and obtaining the von Mises stress of the cutting-affected unit body according to the Cauchy stress tensor.

[0028] The designed calculation formula includes: ; ; ; ; ; Where W is the strain energy density, and The Young's modulus of the material and Poisson's ratio The Lamé parameters are determined respectively, F is the deformation gradient, X is the initial vertex position matrix, x is the current vertex position matrix, is the transpose of F, is the inverse matrix transpose of F, is the trace operator, J is the volume change ratio, P is the first Piola-Kirchhoff stress tensor, σ is the Cauchy stress tensor, is the paradigm equivalent stress (vm is its symbol subscript), are the components of the Cauchy stress tensor (i, j have values ​​in 1, 2, and 3).

[0029] Based on research data, the ultimate tensile strength of the dura mater of patients who need surgery is generally 7.01±0.77MPa, that is, when the paradigm equivalent stress is less than 7.01-0.77=6.24MPa, the dura mater will not be damaged and only elastic deformation will occur; when the paradigm equivalent stress is greater than 7.01+0.77=7.78MPa, the dura mater will be broken and can be cut; when the paradigm equivalent stress is in the closed interval of 6.24MPa to 7.78MPa, plastic damage will occur.

[0030] According to the ultimate tensile strength of the dura mater, the damage stress threshold and the crushing stress threshold can be confirmed, and then the state of the cutting-affected unit body with a paradigm equivalent stress less than the damage stress threshold can be marked as an elastic deformation state; the state of the cutting-affected unit body with a paradigm equivalent stress greater than the crushing stress threshold can be marked as a crushing state; the state of the cutting-affected unit body in the closed interval from the damage stress threshold to the crushing stress threshold can be marked as a plastic damage state. Among them, the specific value of the ultimate tensile strength of the dura mater generally varies according to the patient's age, tissue pathology, etc. According to its range of variation, the number of data samples in the database can be increased to improve the simulation coverage of various actual surgical situations.

[0031] For different states, different analysis methods can be selected to improve the analysis speed and the accuracy of simulation state changes. Specifically, in step S03, it includes: For the cutting influence unit body in the elastic deformation state, an elastic deformation analysis based on position dynamics is performed to update the vertex position of the corresponding cutting influence unit body, thereby updating the dura mater tissue model; For the cutting-affected unit body in the plastic damage state, a stiffness analysis is performed to update the dura mater tissue model according to the stiffness change information of the corresponding cutting-affected unit body; Delete the cutting-affected units in a broken state, define the nodes whose connected units are deleted as invalid nodes, and define the other nodes as valid nodes; delete the invalid nodes, and distribute the mass of the invalid nodes to the adjacent valid nodes; perform incision smoothing on the remaining valid nodes on the newly added incision surface to update the model and update the dura mater tissue model.

[0032] Specifically, the elastic deformation analysis based on position dynamics includes: updating the position information of each node according to the node position update model; correcting the updated position information according to the position constraint model, distance constraint model and volume preservation model, so that the distance between each node is consistent with the expected distance and the volume of each unit body is kept constant. The calculation formulas involved include: ; ; ; ; ; in, Representation Node At time step The position at Representation Node At time step The position at Represents node i at time step The speed of is the time step, For Node The position change of , s is the offset used to adjust the node position, is the weight of node i, is the mass of node i, C is the constraint function, ∇ is the gradient operator, is the gradient of the constraint, indicating the direction and magnitude that node i needs to move. is the distance constraint function between nodes i and j of the vector, and is the position of node i and node j, is the expected distance between node i and node j, is the current distance between node i and node j, is the vertex position of the tetrahedral element, is the volume constraint function of the tetrahedral element, and V is the maintained volume of the tetrahedral element.

[0033] The calculation formulas involved in stiffness analysis include: ; ; ; Where D is the damage variable, is the damage stress threshold, is the rupture stress threshold, is the paradigm equivalent stress, n is the stiffness loss rate control parameter, k is the stiffness coefficient, is the gradient of the constraint, max() is the maximum value operator, and min() is the minimum value operator.

[0034] The calculation formula for allocating the mass of an invalid node to adjacent valid nodes includes: ; in, represents the mass increment of the valid node j adjacent to the invalid node, m is the mass of the invalid node, and N is the number of valid nodes j adjacent to the invalid node.

[0035] The steps of smoothing the remaining valid nodes on the newly added cut surface include: obtaining the cutting plane and the maximum cutting width according to the moving characteristics of the tool model; defining the valid nodes constituting the cut as the cut nodes, obtaining the current distance from the cut nodes to the cutting plane according to the cutting plane, and obtaining the ideal distance from the cut nodes to the cutting plane according to the maximum cutting width; obtaining the normal deviation according to the difference between the ideal distance and the current distance, and updating the position of the cut nodes in combination with the position change obtained by the position dynamics elastic deformation analysis of the cut nodes. The calculation formulas involved include: ; ; ; ; ; in, is the adjustment amount of the cut node in the normal vector direction of the cutting plane, is the position adjustment of the cut node, is the ideal distance from the cut node to the cutting plane obtained according to the maximum cutting width, is the distance from the cut node to the cutting plane, is the normal vector of the cutting plane; is the reference point on the cutting plane, which means the position vector of a fixed reference point on the cutting plane; is the velocity direction of the tool model, is a unit vector pointing downward and perpendicular to the upper surface of the dura mater tissue model. is the time at which the incision node in the dura tissue model t The position vector represents the coordinates of the node in three-dimensional space. is the final position adjustment of the cut node i, × is the cross multiplication operator of the vector, is the maximum cutting width, and the variable R represents the smaller of the ratios of the distances from the projection point of the boundary node on the cutting surface to the cutting start point and the cutting end point.

[0036] Among them, in a specific example, when hour, ;when hour, ;when hour, .

[0037] To obtain the cutting force, in this embodiment, the method includes: obtaining the cutting stiffness force according to the normal component of the Cauchy stress tensor in the dura mater tissue model, and obtaining the cutting force in combination with the friction force between the dura mater tissue model and the instrument model. The calculation formula involved includes: ; ; ; in, is the cutting force, is the stiffness force, is the friction between the instrument model and the dura mater tissue model, is the contact area between the instrument model and the dura mater tissue model, is the normal component of the Cauchy stress tensor along the path of the tool model, reflecting the normal stress per unit area. is the friction coefficient, is the normal contact force on the contact surface between the instrument model and the dura mater tissue model.

[0038] The present invention also provides a storage medium, which is a computer-readable storage medium. A computer program is stored in the computer-readable storage medium. When the computer program is read and executed by a processor, the above-mentioned dura mater cutting simulation method based on fracture mechanics can be implemented.

[0039] Those skilled in the art will appreciate that the logic or steps represented in the flowchart or otherwise described herein, for example, may be considered as an ordered list of executable instructions for implementing logical functions, and may be specifically implemented in any computer-readable storage medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For purposes of this specification, a "computer-readable storage medium" may be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0040] More specific examples (a non-exhaustive list) of computer-readable storage media include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable storage medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0041] The present invention also provides a computer having a computer program stored therein. When the computer program is read and executed by a processor, the above-mentioned dura mater cutting simulation method based on fracture mechanics can be implemented.

[0042] The dura mater cutting simulation method based on fracture mechanics provided by the present invention obtains a dura mater tissue model according to position dynamics, and uses the nodes therein as tetrahedron vertices to obtain cutting influence units, and performs mechanical analysis on each cutting influence unit body to obtain the paradigm equivalent stress of each cutting influence unit body; then, the state of each cutting influence unit body can be accurately judged according to the paradigm equivalent stress, thereby improving the accuracy of judging whether an incision is formed and improving the simulation effect; and different analysis methods can be used for cutting influence units in an elastic deformation state, a plastic damage state and a broken state, thereby reducing the demand for computing power while ensuring the accuracy of incision judgment, improving the real-time performance of updating the state of the dura mater tissue model, further improving the simulation effect, and providing convenience for the application of dura mater cutting simulation.

[0043] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0044] The above-mentioned embodiments only express several specific implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A dura mater cutting simulation method based on fracture mechanics, characterized in that: include: A dura mater tissue model is obtained according to the position dynamics, and collision detection is performed according to the dura mater tissue model and the instrument model to obtain a cutting influence area of ​​the dura mater tissue model, and a cutting influence node is obtained according to the cutting influence area; Obtaining a cutting influence unit body according to the cutting influence node, and performing mechanical analysis on each of the cutting influence unit bodies to obtain a paradigm equivalent stress of each of the cutting influence unit bodies; Determining the state of each cutting-affecting unit cell according to the paradigm equivalent stress, so as to update the dura mater tissue model according to the state of each cutting-affecting unit cell and the corresponding analysis method; The states of the cutting-affected unit body include an elastic deformation state, a plastic damage state and a crushing state, and the cutting-affected unit body is a tetrahedron.

2. The dura mater cutting simulation method based on fracture mechanics according to claim 1, characterized in that: According to the state of each cutting-affecting unit body and the corresponding analysis method, the step of updating the dura mater tissue model comprises: Performing elastic deformation analysis based on position dynamics on the cutting-affecting unit body in an elastic deformation state to update the vertex position of the corresponding cutting-affecting unit body, thereby updating the dura mater tissue model; Performing stiffness analysis on the cutting-affected unit body in a plastic damage state, so as to update the dura mater tissue model according to stiffness change information corresponding to the cutting-affected unit body; Deleting the cutting-affected unit body in a broken state, defining the node whose connected unit bodies are all deleted as an invalid node, and defining the other nodes as valid nodes; Deleting the invalid node and allocating the mass of the invalid node to the adjacent valid node; The remaining valid nodes on the newly added incision surface are subjected to incision smoothing processing to update the model and update the dura mater tissue model.

3. The dura mater cutting simulation method based on fracture mechanics according to claim 2, characterized in that: The step of performing cut smoothing processing on the remaining valid nodes on the newly added cut surface includes: obtaining a cutting plane and a maximum cutting width according to the moving characteristics of the tool model; The valid nodes constituting the cut are defined as cut nodes, a current distance from the cut node to the cut plane is obtained according to the cut plane, and an ideal distance from the cut node to the cut plane is obtained according to the maximum cut width; The normal deviation is obtained according to the difference between the ideal distance and the current distance, and the position of the cut node is updated in combination with the position change amount obtained according to the position dynamics elastic deformation analysis of the cut node.

4. The dura mater cutting simulation method based on fracture mechanics according to claim 3, characterized in that: The step of performing position dynamics elastic deformation analysis to update the vertex position of the corresponding cutting-affecting unit body comprises: Update the location information of each node according to the node location update model; The updated position information is corrected according to the position constraint model, the distance constraint model and the volume preservation model so that the distance between each node is consistent with the expected distance and the volume of each unit body is kept constant.

5. The dura mater cutting simulation method based on fracture mechanics according to claim 1, characterized in that: Also includes: The cutting stiffness force is obtained according to the normal component of the Cauchy stress tensor in the dura mater tissue model, and the cutting force is obtained in combination with the friction force between the dura mater tissue model and the instrument model.

6. The dura mater cutting simulation method based on fracture mechanics according to claim 1, characterized in that: Performing collision detection based on the dura mater tissue model and the instrument model to obtain a cutting influence area of ​​the dura mater tissue model, and obtaining a cutting influence node based on the cutting influence area includes: Before performing collision detection, the simulation space is divided into cubes; When collision detection occurs, marking the cube where the contact point between the dura tissue model and the instrument model is located and the adjacent cubes as a cutting impact area; All nodes of the unit body associated with the cutting influence area in the dura mater tissue model are used as the cutting influence nodes.

7. The dura mater cutting simulation method based on fracture mechanics according to claim 6, characterized in that: The step of performing mechanical analysis on each cutting-affecting unit body to obtain the paradigm equivalent stress of each cutting-affecting unit body comprises: Obtaining the first Piola-Kirchhoff stress tensor of the cutting-affected unit cell according to the strain energy density function; Obtaining the Cauchy stress tensor of the cutting-affected unit cell according to the first Piola-Kirchhoff stress tensor; The normalized equivalent stress of the cutting-affected unit cell is obtained according to the Cauchy stress tensor.

8. The dura mater cutting simulation method based on fracture mechanics according to claim 7, characterized in that: The step of judging the state of each cutting-affected unit body according to the paradigm equivalent stress comprises: The state of the cutting-affected unit body with the paradigm equivalent stress less than the damage stress threshold is marked as the elastic deformation state; The state of the cutting-affected unit body whose paradigm equivalent stress is greater than the crushing stress threshold is marked as a crushing state; The state of the cutting-affected unit body whose normal equivalent stress is in the closed interval from the damage stress threshold to the crushing stress threshold is marked as a plastic damage state.

9. A storage medium, characterized in that: The storage medium is a computer-readable storage medium, in which a computer program is stored. When the computer program is read and executed by a processor, the dura mater cutting simulation method based on fracture mechanics according to any one of claims 1 to 8 can be implemented.

10. A computer, characterized in that: A computer program is stored in the computer. When the computer program is read and executed by the processor, the dura mater cutting simulation method based on fracture mechanics according to any one of claims 1 to 8 can be implemented.

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