Method for simplifying head and neck of human body finite element model

Abstract

The invention relates to the technical field of human body modeling, in particular to a head and neck simplification method of a human body finite element model, which comprises the following steps: S1, acquiring medical image data, and establishing a detailed human body finite element model; s2, head and neck simplified treatment parts are determined through head and neck motion response analysis; s3, simplifying the head model; s4, performing stiffening treatment on the head skeleton and the cervical vertebra, and converting the 3D entity grid of the cervical vertebra into 2D grid units; s5, performing 1D treatment on the neck 3D muscle, and performing tetrahedron filling on the inner layer of the neck subcutaneous soft tissue; s6, performing reconstruction and grid common node amplification transition processing on the head and neck skin grid; s7, checking, optimizing and simplifying the grid quality of the head and neck of the model; and S8, carrying out part-level verification on the head and neck part of the simplified model. According to the method, the structural similarity and the biological fidelity of the simplified head and neck model and the real head are ensured while the model calculation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of human body modeling, and specifically to a method for simplifying the head and neck of a human finite element model. Background Art

[0002] At present, human body models have been widely used in various digital collision simulation scenarios. However, due to the grid complexity and structural diversity of human body models, the simulation calculation time of the models is long; and in most simulation occasions, the analysis requirements for the calculation results of model parts are local or single. For example, in some special cases, only the response of the human lower limbs needs to be analyzed. Therefore, there is an urgent need for a method for simplifying the segment model of the human body model to improve the calculation time efficiency of the model. Summary of the Invention

[0003] The present invention provides a method for simplifying the head and neck of a human finite element model, which can ensure the structural similarity and biological fidelity between the simplified head and neck model and the real head while realizing the simplification of the head and neck of the human body model, and improve the model calculation efficiency.

[0004] The present application provides the following technical solutions:

[0005] A method for simplifying the head and neck of a human finite element model includes the following steps:

[0006] S1. Collect medical image data and establish a detailed human finite element model;

[0007] S2. Analyze the structure of the head and neck of the detailed human body model through head and neck movement response to determine the parts for head and neck simplification processing;

[0008] S3. Simplify the head model;

[0009] S4. Rigidify the head bones and each cervical vertebra, and convert the 3D solid mesh of the cervical vertebra into a 2D mesh element;

[0010] S5. Perform 1D processing on the 3D muscles of the neck and tetrahedron filling on the inner layer of the subcutaneous soft tissue of the neck;

[0011] S6. Reconstruct the head and neck skin mesh and perform mesh co-node magnification and transition processing;

[0012] S7. Check and optimize the mesh quality of the head and neck of the simplified model;

[0013] S8. Perform component-level verification on the head and neck of the simplified model and adjust the material parameters according to the verification results.

[0014] Technical principle: Determine the target simplified parts according to the analysis of the head and neck movement response, simplify the head, head bones, cervical vertebrae, and neck muscle units one by one, and check and optimize the skin mesh quality of the head and neck connection parts. Finally, perform component-level verification and optimization on the simplified head and neck.

[0015] Beneficial effects: By gradually simplifying the model, the total number of meshes in the human finite element model is significantly reduced, and the computational complexity and calculation time are significantly reduced; high-quality meshes and optimized material parameters can improve the stability of the simulation and the credibility of the results. Through targeted analysis and optimization after the simplification process, the accuracy of key structures and functions is ensured, and the authenticity and reliability of the model are improved.

[0016] Further, in S2, set the head and neck movement scenarios, use finite element analysis tools for dynamic simulation, record the movement response data of each structure in the head and neck under different movement scenarios, and determine the simplified parts of the head and neck according to the movement response data. The head and neck movement scenarios include nodding, shaking the head, lateral deviation, and rotation.

[0017] Beneficial effects: Through the detailed analysis of the head and neck movement response, identify the structures and parts with less influence or redundancy in actual applications, and thus simplify them targeted, reducing the computational complexity without losing key information. The subsequent modeling and simulation processes are more efficient, saving computational resources and time.

[0018] Further, the simplified parts of the head and neck include the brain tissue, head bones, cervical vertebrae, and muscle units.

[0019] Beneficial effects: Through the simplification of the brain tissue, head bones, cervical vertebrae, and muscle units, the computational complexity and calculation time are significantly reduced, making large-scale simulation possible, especially suitable for real-time dynamic analysis and long-term simulation;

[0020] Despite the simplification, through targeted processing methods (such as rigidification, 1D conversion, and homogenization), the key mechanical properties and functions of each part can still be retained, ensuring the accuracy when analyzing the head and neck movement response.

[0021] Further, S3 includes:

[0022] S31. Delete the brain tissue and retain the skull;

[0023] S32. Adjust the weight of the head after deleting the brain tissue.

[0024] Further, S32 includes:

[0025] S321. Select the mesh elements of the brain tissue in the finite element analysis software, obtain the total mass of the brain tissue using the built-in mass calculation function of the software, and obtain the coordinate position of the centroid of the brain tissue using the centroid calculation function.

[0026] S322. Create a mass point at the centroid position to replace the brain tissue.

[0027] S323. Verify the effectiveness of the simplified model through dynamic simulation analysis.

[0028] Further, the S4 includes:

[0029] S41. Mark the target area and perform stiffening treatment.

[0030] S42. Extract the geometric information of the cervical vertebra surface.

[0031] S43. Convert the extracted geometric information of the cervical vertebra surface into 2D mesh elements.

[0032] S44. Set the material properties of the 2D mesh elements.

[0033] S45. Weigh each cervical vertebra one by one.

[0034] Beneficial effects: Simplify the complex 3D solid model into a rigid body or a model with fewer degrees of freedom, significantly reduce the variables in the calculation, and can greatly improve the simulation speed; the simplified 2D mesh elements are easier to adjust the material parameters and boundary conditions, can be flexibly set according to actual needs, and provide the adaptability of the model; weighing the cervical vertebra can ensure that the mechanical responses of the simplified model and the detailed model are consistent.

[0035] Further, the S5 includes:

[0036] S51. Refine the 3D solid muscle units of the head and neck.

[0037] S52. Perform tetrahedron filling on the inner layer of the subcutaneous soft tissue of the neck.

[0038] Beneficial effects: The tetrahedron elements have good geometric adaptability, can accurately describe complex three-dimensional shapes and irregular boundaries. At the same time, tetrahedron filling can form a uniform stress distribution inside the soft tissue, avoid stress concentration phenomena, ensure that abnormal displacements or deformations do not occur during the simulation, can comprehensively describe the behavior of soft tissue from micro to macro, support complex dynamic simulation and multi-scale analysis, and are applicable to a variety of application scenarios.

[0039] Further, the S7 includes:

[0040] S71. Define the mesh quality standard according to the specific requirements of the simplified model and optimize the low-quality meshes.

[0041] S72. Check the connection relationship of the head and neck connection area;

[0042] S73. Select an appropriate time step for simplifying the model.

[0043] Furthermore, the low-quality mesh is determined according to mesh quality indicators, and the mesh quality indicators include element shape factor, Jacobian ratio, distortion, orthogonality, and volume change rate. The optimization includes refining the mesh, smoothing, remeshing, and adjusting mesh generation parameters.

[0044] Furthermore, the S8 includes:

[0045] S81. Build a simulation platform for simulating the motion response of the head and neck;

[0046] S82. Rigidify all components below the head and neck;

[0047] S83. Compare the simulation results of the simplified model and the detailed model, and gradually adjust the components modified or simplified in the simplified model according to the comparison results to conduct debugging of material parameters;

[0048] S84. Independently verify each component of the simplified model.

[0049] Beneficial effects: The motion response simulation platform can flexibly configure different parameters and boundary conditions, support various types of simulation tasks. Rigidifying the components below the head and neck can accurately reflect the mechanical responses of these components in the simulation and significantly improve the calculation speed; independent verification of each component helps to capture subtle mechanical behaviors and deformation modes, can improve the credibility of the simulation accuracy, and enhance the practicality of the model. Brief Description of the Drawings

[0050] Figure 1 It is a flowchart of a method for simplifying the head and neck of a human finite element model;

[0051] Figure 2 It is a schematic diagram of replacing the brain tissue with mass points;

[0052] Figure 3 It is a simplified schematic diagram of the neck finite element model;

[0053] Figure 4 It is a schematic diagram of 1D modeling of muscles;

[0054] Figure 5 It is a schematic diagram of filling tetrahedrons in the inner layer of the neck subcutaneous soft tissue;

[0055] Figure 6 It is a schematic diagram of the reconstruction and connection of the head and neck skin mesh. Detailed Implementation Modes

[0056] The modeling and analysis of the human finite element model are usually carried out with the help of pre-processing tools and solvers. Among them, the pre-processing tools can complete functions such as mesh creation and model setting, including multiple functional modules such as geometric modeling, mesh generation, material and property definition, load and boundary conditions, and post-processing integration. And through the solver interface, multiple finite element solvers are accessed to solve complex non-linear dynamic problem calculations, so as to support the entire process from geometric modeling, mesh generation to solution analysis and post-processing. In the finite element pre-processing tool of the present invention, Hypermesh software is selected, and LS-DYNA is selected as the solver. It should be noted that the software selection is only for illustrative purposes, and the method described in the present invention can also be completed using other finite element processing software and solvers.

[0057] The following is a further detailed description through specific embodiments:

[0058] Embodiment 1

[0059] This embodiment provides a method for simplifying the head and neck of a human finite element model, as Figure 1 shown, including the following steps:

[0060] S1. Collect medical image data and establish a detailed human finite element model. Specifically as follows:

[0061] High-quality medical image data, including CT, MRI, etc., is used as the basis for constructing the human finite element model.

[0062] The collected image data is pre-processed, including denoising and contrast enhancement, etc. The pre-processed image data is imported into Hypermesh, different tissues and structures are segmented and labeled, and a three-dimensional geometric model of each tissue and structure is generated according to the labeling results. Check that the topological structure of the three-dimensional geometric model should not have holes or overlapping errors.

[0063] Select the mesh generation tool of Hypermesh to discretize the three-dimensional geometric model into finite element meshes.

[0064] Assign appropriate material properties and set boundary conditions for different tissues.

[0065] Configure various parameters of the finite element analysis, including solver selection, analysis type, setting loads and constraints, etc.

[0066] Submit the configured model to the solver for finite element analysis to obtain results such as stress distribution, displacement, and deformation. Compare the analysis results with experimental data to verify the accuracy of the model and make corresponding optimizations.

[0067] S2. Analyze the structure of the head and neck of the detailed human model through the head and neck motion response analysis to determine the parts for simplifying the head and neck;

[0068] This step analyzes the motion response to understand the impact of different structures on the overall motion of the head and neck, thereby determining which structures can be simplified or omitted.

[0069] First, typical head and neck motion scenarios need to be set to ensure that these scenarios can cover the main motion patterns in daily activities, usually including nodding, shaking the head, lateral deviation, rotation, etc. Define boundary conditions that conform to the actual situation for each motion scenario, such as fixing certain joints or applying quantitative external forces.

[0070] Use the solver LS-DYNA for dynamic simulation, record data such as stress distribution, displacement, and deformation of each structure under different motion scenarios, compare the impact of different structures on the overall motion response, and focus on areas and structures with less deformation or more uniform stress distribution during the motion.

[0071] According to the analysis results of the motion response, in the special injury analysis of a certain part other than head injury, the role of the brain tissue is extremely minimal. In addition, the animation display of the simulation results of the detailed human body model using Hypermesh shows that the kinematic response of the head and neck is mainly affected by ligaments, muscles, and intervertebral disc tissues, and there is no obvious deformation in relatively hard parts such as the head bones and cervical vertebrae. Finally, due to the complexity of the 3D muscle structure of the human body model neck and the instability of the calculation, in this embodiment, the target parts for simplifying the head and neck of the human finite element model are determined to be the brain tissue, head bones, cervical vertebrae, and muscle units, etc.

[0072] S3. Simplify the head model, including the following steps:

[0073] S31. Delete the brain tissue and retain the skull.

[0074] This step can significantly reduce the model complexity and improve the later simulation efficiency.

[0075] Specifically, after loading the detailed model containing the brain tissue and the skull, check the model structure to determine that there is a clearly distinguishable boundary between the brain tissue and the skull;

[0076] Separate and delete the brain tissue from the detailed model in Hypermesh, and check and correct the separation process to improve the accuracy.

[0077] Conduct a detailed analysis of the separated skull model, clarify the specific areas of each layer structure in the skull, smooth the mesh of the skull area, and reduce unnecessary details.

[0078] S32. Adjust the weight of the head after deleting the brain tissue.

[0079] After removing the brain tissue, the mass of the head model changes, which will affect the simulation calculation. Therefore, in order to ensure that the total head weight remains consistent before and after the simplification process, it is necessary to adjust the head mass and compensate the head weight according to the mass of the original brain tissue.

[0080] In this embodiment, the overall mass of the brain tissue is calculated, the centroid of the whole brain is found through the mass replacement technology, and a mass point is created at the centroid position to replace the total mass of the brain tissue, effectively reducing the complexity of the original model and maintaining its mechanical response characteristics, such as Figure 2 shown. Specifically, it includes:

[0081] S321. First, select the mesh elements of the brain tissue in the finite element analysis software, and calculate the total mass and centroid of the brain tissue.

[0082] Use the mass calculation function mass calc of Hypermesh to obtain the total mass of the brain tissue, and use the centroid calculation function summary of Hypermesh to obtain the coordinate position of the centroid of the brain tissue.

[0083] S322. Create a mass point at the centroid position to replace the brain tissue.

[0084] Define the keyword "ELEMENT_MASS" at the calculated centroid position of the brain, create a virtual mass point. The mass point has no geometric shape and only represents a concentrated mass. Assign a value equal to the overall mass of the brain to the mass point.

[0085] S323. Verify the effectiveness of the simplified model through dynamic simulation analysis.

[0086] Conduct dynamic simulation tests in the solver, mainly to verify whether the motion behavior of the simplified model is consistent with that of the detailed model, and particularly pay attention to the inertial characteristics (such as acceleration, angular velocity, etc.) of the simplified model under different mechanical conditions to ensure that its performance meets expectations.

[0087] S4. Rigidify the head bones and each cervical vertebra, and convert the 3D solid mesh of the cervical vertebra into 2D mesh elements.

[0088] In Hypermesh, convert the 3D solid mesh into 2D, which can effectively reduce the total number of mesh elements of the model, such as Figure 3 shown, including the following steps:

[0089] S41. Determine the target area and conduct rigidification processing;

[0090] Mark the areas of the head bones and each cervical vertebra, set the marked areas as rigid bodies, ignore the internal elastic deformation, and only retain the geometric shape and overall motion characteristics of the rigidified areas.

[0091] S42. Extract the geometric information of the cervical spine surface;

[0092] First, separate the cervical spine part from the detailed model, and avoid damaging other structures during the separation process;

[0093] Use geometric modeling tools (such as ANSYS, Abaqus, etc.) to extract the outer surface geometric information of the cervical spine part;

[0094] Clean the extracted surface, remove unnecessary details and noise, and check for topological errors or holes to ensure the surface is intact.

[0095] S43. Convert the extracted geometric information of the cervical spine surface into 2D mesh elements;

[0096] This step can effectively reduce the complexity and computational amount of the model.

[0097] Use Hypermesh to convert the extracted geometric information of the cervical spine surface into 2D mesh elements. During the conversion process, comprehensively consider the calculation accuracy and efficiency, and adjust the mesh density according to requirements. For some complex regions, the mesh density can be appropriately increased.

[0098] The converted 2D mesh elements need to be checked and verified to ensure there is no distortion or over-dense / under-dense situation, and the cervical spine structure characteristics reflected by the simplified model need to be consistent with the detailed model.

[0099] S44. Set the material properties of the 2D mesh elements;

[0100] Use the material property setting function of Hypermesh to set appropriate material properties for the 2D mesh elements to ensure that they can accurately simulate the rigid characteristics of the cervical spine. The set material properties include setting rigid body materials, material density, material thickness and other parameters for the 2D mesh elements, and adjusting the material parameters according to actual biomechanical data to make the mass distribution, structural characteristics and mechanical response of the simplified model consistent with the detailed model.

[0101] S45. Weigh each cervical vertebra one by one.

[0102] In Hypermesh, ignore the distributed mass of soft tissues for the stiffened cervical spine, and use concentrated mass points to simplify the calculation. The soft tissues include muscles, blood vessels, etc.

[0103] Among them, the first cervical vertebra (atlas) has a structural feature of a ring-shaped bone ring, no vertebral body, and supports the head. Its mass distribution is about 0.05 - 0.08 kg (accounting for 10% - 12% of the total cervical spine mass), and the centroid position is set as the midpoint of the line connecting the foramen magnum and the dens.

[0104] The structural feature of the second cervical vertebra (axis) is that it contains the dens, forming a pivot joint with the first cervical vertebra. Its mass distribution is about 0.06 - 0.09 kg (accounting for 12% - 14% of the total mass of the cervical vertebrae), and the centroid position is set at the midpoint of the line connecting the base of the dens and the posterior edge of the vertebral body.

[0105] The structural features of the third to seventh cervical vertebrae are that the vertebral bodies gradually increase in size and the thickness of the intervertebral discs increases. The mass distribution is as follows: the third cervical vertebra is 0.10 - 0.12 kg, the fourth cervical vertebra is 0.12 - 0.14 kg, the fifth cervical vertebra is 0.14 - 0.16 kg, the sixth cervical vertebra is 0.16 - 0.18 kg, and the seventh cervical vertebra is 0.18 - 0.20 kg. Each intervertebral disc is about 0.02 - 0.03 kg (added between adjacent vertebral bodies). The centroid position of each vertebral body is set at the geometric center of the vertebral body (i.e., the midpoint of the sagittal plane and 1 / 3 behind the coronal plane).

[0106] Referring to the masses of each cervical vertebra in the original detailed model, the material density of the simplified 2D rigid body cervical vertebra is calculated using the mass calc function of Hypermesh.

[0107] S5. Perform 1D processing on the 3D neck muscles and tetrahedral filling on the inner layer of the neck subcutaneous soft tissue.

[0108] The human neck contains numerous muscle units, which are numerous and have a very complex structure. Using too many meshes to describe these muscles will lead to waste of computing resources and reduced computing efficiency. To simplify the model and reduce the number of meshes, some muscle units that have less impact on the overall movement can be simplified. As Figure 4 shown, it includes the following steps:

[0109] S51. Refine the 3D solid muscle units of the head and neck;

[0110] Check the loaded three-dimensional model containing the head and neck muscles in Hypermesh and mark the muscle parts that need to be converted. For example, according to the analysis results, the key muscle units that have a greater impact on the overall movement include the trapezius muscle, sternocleidomastoid muscle, longus capitis muscle, etc.; the secondary muscle units that have less impact on the overall movement include the platysma muscle, digastric muscle, etc. Therefore, the secondary muscle units can be determined as the simplification targets and marked.

[0111] Use geometric modeling tools to extract the key geometric information of the muscle units, including the origin and insertion points of the muscles;

[0112] Convert the 3D muscle units into 1D units according to the extracted key geometric information:

[0113] Select appropriate beam element types (such as BEAM188, B21, etc.) in the solver software LS-DYNA; use the extracted key points and paths to define the paths of beam elements in the modeling tool, and connect two key points to create beam elements (BeamElements); adjust the cross-sectional properties of the beam elements according to actual needs to ensure that the beam elements can simulate the functional characteristics of the original muscles. The interface properties of the beam elements include area, moment of inertia, etc.

[0114] Subsequently, use card edit to edit the beam element and check the SuppressN3 option to effectively reduce the computational complexity without affecting the overall performance of the model. After editing, it is necessary to verify whether the behavior of the Beam element meets the expectations.

[0115] S52. Perform tetrahedral filling on the inner layer of the subcutaneous soft tissue of the neck;

[0116] After converting 3D muscles to 1D muscles, a large area of vacancy appears inside the neck skin, resulting in skin relaxation and collapse. Therefore, it is necessary to fill the tetrahedral elements to ensure the fullness inside the neck skin, as Figure 5 shown.

[0117] First, use the 3D visualization tool of Hypermesh to check the simplified model, identify the vacant areas generated due to muscle removal, and mark these vacant areas in the modeling software;

[0118] Use the mesh generation tool of Hypermesh to automatically generate tetrahedral elements, and fill the marked vacant areas according to the optimized mesh density to ensure that the filling effect is natural and does not affect the overall computational efficiency of the model;

[0119] Check and optimize the quality of the generated tetrahedral elements;

[0120] Assign appropriate filling materials to the filled tetrahedral elements and set the corresponding material properties through the material property setting tool of Hypermesh. Commonly used filling materials include soft tissue simulation materials, and the soft tissue simulation materials include adipose tissue, etc. The material properties usually include elastic modulus, Poisson's ratio, density, etc.;

[0121] Perform simulation verification and static mechanical analysis on the filled simplified model in the solver to check whether its motion behavior is consistent with the detailed model.

[0122] S6. Reconstruct the head and neck skin mesh and perform mesh co-node magnification and transition processing.

[0123] To appropriately reduce the number of elements in the tetrahedral elements filling the neck, it is necessary to increase the mesh size of the neck skin. However, the geometry of the human model's head is relatively round. To maintain the smoothness of its contour representation, it is recommended to retain the original refined mesh. Therefore, there is a difference in the mesh size between the head and the neck skin. At this time, the following Figure 6 co - node mesh transition processing of the head and neck skin as shown is required:

[0124] First, use the 3D visualization tool of Hypermesh to determine the transition area between the head and neck skin, that is, the junction between the two;

[0125] Adjust the nodes in the transition layer to coincide with the nodes of the head and neck meshes to form a co - node structure. This step can be completed by manual adjustment or the automatic optimization function of the mesh generation tool;

[0126] Check the quality of the generated transition layer mesh through the mesh inspection tool of Hypermesh to ensure that there is no distortion or uneven density. For the quality problems found, smoothing and refinement operations can be taken for optimization.

[0127] S7. Check and optimize the mesh quality of the head and neck of the simplified model.

[0128] The purpose of this step is to define and optimize the mesh quality of the model according to the actual needs of the simplified model, ensure the correct connection relationship of each region of the model, and select an appropriate time step to ensure the stability of the simulation degree and calculation efficiency. Specifically, it includes:

[0129] S71. Define the mesh quality standard according to the specific needs of the simplified model and optimize the low - quality mesh.

[0130] For damage analysis under different working conditions, there may be different analysis accuracy requirements and calculation resource limitations. Therefore, define the mesh quality according to the actual needs. Define multiple quality indicators for the mesh in Hypermesh, including:

[0131] Element shape factor (Aspect Ratio): The ratio of the maximum side length to the minimum side length of the element, and the ideal value is close to 1;

[0132] Jacobian Ratio: Measures the degree of element deformation, and the ideal value is close to 1;

[0133] Skewness: The degree to which the element deviates from the ideal shape, and the ideal value is close to 0;

[0134] Orthogonal Quality: The angle between the normal of the element face and the normals of other faces, and the ideal value is close to 1;

[0135] Volume Change Rate: The change rate of the unit volume, with the ideal value approaching 1;

[0136] Use post - processing tools to check the mesh quality and identify low - quality elements based on mesh quality metrics.

[0137] For low - quality elements, the following measures can be taken for optimization:

[0138] Mesh refinement: Increase the mesh density in key areas, especially in areas with complex geometry or stress concentration;

[0139] Smoothing: Use mesh smoothing algorithms (such as Laplacian smoothing, Winslow smoothing, etc.) to improve element shapes;

[0140] Mesh re - generation: For severely distorted elements, they can be deleted and locally remeshed;

[0141] Adjust mesh generation parameters: Modify the settings in the mesh generation tool (such as maximum edge length, minimum angle, etc.) and re - generate the mesh.

[0142] S72. Check the connection relationship in the head - neck connection area.

[0143] Since the rigidification process has been carried out on some parts of the head and neck during the simplification process, the connection method needs to be readjusted and checked, including:

[0144] Check whether the nodes are shared in the head - neck connection area through the mesh generation tool to ensure that there are no overlapping or disconnected situations;

[0145] Check whether there are contact surfaces in the model and whether the contact conditions are correctly set;

[0146] Confirm whether all boundary conditions are correctly applied to avoid over - constraint or under - constraint;

[0147] Conduct a static analysis or pre - load analysis through the solver to check the overall response of the model and observe whether there are abnormal deformations or stress concentrations.

[0148] S73. Select an appropriate time step for the model.

[0149] An overly large time step may lead to simulation instability or divergence, while an overly small time step can improve simulation accuracy but significantly increase the calculation time. Therefore, an appropriate calculation time step needs to be selected.

[0150] First, based on the physical characteristics of the model and the expected motion speed, and considering material properties and mesh size, preliminarily determine an initial time step in the solver;

[0151] Perform a stability analysis and calculate the maximum allowable time step;

[0152] Adjust the initial time step according to the maximum allowable time step;

[0153] Set the convergence criterion and perform a dynamic simulation, and further adjust the time step according to the stability performance during the simulation process;

[0154] Save the time step results that meet the requirements of stability and accuracy.

[0155] S8. Conduct component-level verification on the head and neck of the simplified model, and adjust the material parameters according to the verification results. It includes the following steps:

[0156] S81. Build a simulation platform for simulating the motion response of the head and neck.

[0157] Use professional finite element analysis software (such as ANSYS, Abaqus, LS-DYNA, Hypermesh, etc.) to build the simulation platform. Import the simplified model after mesh optimization and co-node transition processing into the simulation software, and set the boundary conditions according to the actual application scenario (such as fixing certain joints or applying external forces). Apply the corresponding loads according to the defined typical head and neck motion scenarios, select a suitable solver according to the actual analysis requirements, and set parameters such as the analysis time step and convergence criterion. In this embodiment, the LS-DYNA solver is selected.

[0158] S82. Rigidify all components below the head and neck.

[0159] Components below the head and neck, such as the chest and shoulders, have no impact on the typical head and neck motion scenarios. Therefore, these components are rigidified to achieve the verification of the motion response of only the head and neck.

[0160] Mark all the components that need to be rigidified in Hypermesh, and set the rigid body property (DEFORMABLE_TO_RIGID) for these components in the simulation software to ensure that these components only retain the geometric shape and overall motion characteristics and ignore the elastic deformation.

[0161] Conduct a preliminary simulation to check whether the rigidification process is correctly applied, and ensure that there is no unnecessary deformation in the rigidified components during the motion.

[0162] Perform the same kinematic simulation using the detailed model, obtain the reference results, and record the key indicators (such as stress distribution, displacement, deformation, etc.).

[0163] S83. Compare the simulation results of the simplified model with those of the detailed model. Gradually adjust the modified or simplified components in the simplified model according to the comparison results, and conduct debugging of the material parameters, where the material parameters include elastic modulus, Poisson's ratio, density, etc.

[0164] Re-run the simulation according to the adjusted material parameters, and make further adjustments based on the comparison of the new simulation results.

[0165] Through multiple iterations and optimizations of the above steps, ensure that the final result is as close as possible to the detailed model.

[0166] S84. Independently verify each component of the simplified model.

[0167] Select key components that have a greater impact on the overall movement in the simulation software for independent verification. The key components include the trapezius muscle, sternocleidomastoid muscle, etc.; define local movement scenarios for each key component, such as the contraction or extension movement of a certain muscle, and use the simulation platform to verify the local simulation results of each key component to ensure that the kinematic responses of each component are real and reasonable. If necessary, further adjust the material parameters or mesh quality.

[0168] The above are only embodiments of the present invention. The invention is not limited to the fields involved in this embodiment. Common general knowledge such as specific structures and characteristics in the solution is not described in detail here. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A method for simplifying the head and neck of a human finite element model, characterized in that: It includes the following steps: S1. Collect medical image data and establish a detailed human finite element model; S2. Analyze the structure of the head and neck of the detailed human model through head and neck motion response, and determine the simplified treatment parts of the head and neck; S3. Simplify the head model; S4. Rigidify the head bones and each cervical vertebra, and convert the 3D solid mesh of the cervical vertebra into 2D mesh elements; S5. Perform 1D treatment on the 3D neck muscles and perform tetrahedron filling on the inner layer of the neck subcutaneous soft tissue; S6. Reconstruct the head and neck skin mesh and perform co - node magnification transition processing on the mesh; S7. Check and optimize the mesh quality of the head and neck of the simplified model; S8. Perform component - level verification on the head and neck of the simplified model, and adjust the material parameters according to the verification results.

2. The head and neck simplification method of a human finite element model according to claim 1, characterized in that: In S2, set the head and neck motion scenarios, use finite element analysis tools for dynamic simulation, record the motion response data of each structure in the head and neck under different motion scenarios, and determine the simplified treatment parts of the head and neck according to the motion response data. The head and neck motion scenarios include nodding, shaking the head, lateral deviation, and rotation.

3. A method for simplifying the head and neck of a human finite element model according to claim 1, characterized in that: The simplified treatment parts of the head and neck include brain tissue, head bones, cervical vertebrae, and muscle units.

4. A method for simplifying the head and neck of a human finite element model according to claim 1, characterized in that: S3 includes: S31. Delete the brain tissue and retain the skull; S32. Adjust the head weight after deleting the brain tissue.

5. A method for simplifying the head and neck of a human finite element model according to claim 4, characterized in that: S32 includes: S321. Select the mesh elements of the brain tissue in the finite element analysis software, use the built - in quality calculation function of the software to obtain the total mass of the brain tissue, and use the centroid calculation function to obtain the coordinate position of the centroid of the brain tissue; S322. Create a mass point at the centroid position to replace the brain tissue; S323. Verify the effectiveness of the simplified model through dynamic simulation analysis.

6. A method for simplifying the head and neck of a human finite element model according to claim 1, characterized in that: S4 includes: S41. Mark the target area and perform rigidification treatment; S42. Extract the geometric information of the cervical vertebra surface; S43. Convert the extracted geometric information of the cervical vertebra surface into 2D mesh elements; S44. Set the material properties of the 2D mesh elements; S45. Perform weight adjustment on each cervical vertebra one by one.

7. A method for simplifying the head and neck of a human finite element model according to claim 1, characterized in that: S5 includes: S51. Refine the 3D solid muscle units of the head and neck; S52. Perform tetrahedron filling on the inner layer of the neck subcutaneous soft tissue.

8. A method for simplifying the head and neck of a human finite element model according to claim 7, characterized in that: S7 includes: S71. Define the mesh quality standard according to the specific requirements of the simplified model, and optimize the low - quality meshes; S72. Check the connection relationship of the connection area between the head and the neck; S73. Select a suitable time step for the simplified model.

9. A method for simplifying the head and neck of a human finite element model according to claim 8, characterized in that: The low - quality meshes are determined according to the mesh quality indicators, and the mesh quality indicators include element shape factor, Jacobian ratio, distortion, orthogonality, and volume change rate. The optimization includes mesh refinement, smoothing, re - meshing, and adjustment of mesh generation parameters.

10. A method for simplifying the head and neck of a human finite element model according to claim 1, characterized in that: S8 includes: S81. Build a simulation platform for simulating the head and neck motion response; S82. Rigidify all components below the head and neck; S83. Compare the simulation results of the simplified model and the detailed model, and gradually adjust the components modified or simplified in the simplified model according to the comparison results for material parameter debugging; S84. Independently verify each component of the simplified model.

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