Modeling method for finite element model of chest and abdomen of human body with fluid-solid coupling characteristic

Abstract

The invention belongs to the technical field of human body finite element model modeling, and particularly relates to a human body chest and abdomen finite element model modeling method with fluid-solid coupling characteristics, which comprises the following steps: firstly, acquiring human body medical image data to construct a human body chest finite element model with anatomical characteristics; then generating a boundary for defining a gap area by using shell units based on the outer surface of the organ in the thoracic cavity and the inner surface of the thoracic cavity, filling the defined gap area with entity units to obtain a defined area, deleting repeated shell units in the defined area, and retaining the shell units with structural grid characteristics; and finally, according to material attributes of fluid filling of the human chest, setting fluid-solid coupling characteristics between the structural grids and the fluid grids to obtain a finite element model of the human chest with the fluid-solid coupling characteristics. According to the method, the problem that the accuracy of a research result is influenced when the blunt chest trauma research is carried out by the chest and abdomen finite element model generated by modeling in the prior art can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of human finite element model modeling, and particularly relates to a method for modeling a human chest and abdomen finite element model with fluid-structure interaction characteristics. Background Art

[0002] In the clinical research of blunt abdominal and chest trauma (BABT) and the development of protective equipment, the human chest and abdomen finite element model is the core tool for evaluating the organ injury mechanism under impact loads. The chest and abdomen contain key organs such as the heart, lungs, and aorta. Its physiological structure has significant fluid-structure interaction characteristics. The tissue spaces are tightly filled with soft tissues (fat, muscle) and tissue fluid, without macroscopic voids, and there is blood fluid inside organs such as the heart and blood vessels. When stress waves propagate through the thoracic tissues under impact loads (such as traffic accidents, explosion shock waves), it is necessary to simultaneously consider the mechanical response of solid soft tissues and the pressure diffusion of fluids (blood, tissue fluid). The coupling effect between the two directly affects the evaluation accuracy of organ injuries (such as aortic tear, myocardial contusion).

[0003] Early human chest and abdomen finite element models were mainly oriented towards low-speed contact impact scenarios. Their modeling methods had the following characteristics: organ homogenization, ignoring the fluid characteristics of internal blood, and soft tissue idealization, without considering the void-free structure caused by tissue fluid filling.

[0004] Therefore, under the influence of the organ homogenization feature and soft tissue idealization feature in the existing human chest and abdomen finite element models, when conducting research on blunt chest trauma, on the one hand, due to the lack of fluid characteristics, the dynamic change distribution of fluid pressure will affect the injury degree of organs such as the aorta and the heart. On the other hand, due to the existence of voids in the thoracic cavity structure, the propagation of stress waves is discontinuous, resulting in the inability to accurately evaluate the organ injuries caused by shock waves and the shear tear injuries caused by relative displacement between organs, thereby affecting the accuracy of the results when using the human chest and abdomen finite element model for simulation. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for modeling a human chest and abdomen finite element model with fluid-structure interaction characteristics, so as to solve the problem that the accuracy of research results is affected when the existing chest and abdomen finite element model generated by modeling is used for research on blunt chest trauma.

[0006] The basic solution provided by the present invention: A method for modeling a human chest and abdomen finite element model with fluid-structure interaction characteristics, comprising:

[0007] S1: Obtain human medical image data and construct a human chest finite element model with anatomical characteristics;

[0008] S2: Generate the boundaries defining the void region using shell elements based on the outer surfaces of the intrathoracic organs and the inner surface of the chest cavity, fill the defined void region with solid elements to obtain a defined region, and delete the duplicate shell elements in the defined region, retaining the shell elements with structural mesh characteristics;

[0009] S3: Set the fluid-structure interaction characteristics between the structural mesh and the fluid mesh according to the material properties of the fluid filling in the human chest to obtain a finite element model of the human chest with fluid-structure interaction characteristics.

[0010] Furthermore, the S1 includes:

[0011] S1-1: Obtain the point cloud information of the human medical image file and reconstruct the geometric surfaces of the chest anatomical structures in sequence;

[0012] S1-2: Construct a finite element model of the human chest with anatomical characteristics including ribs, sternum, vertebrae, intercostal muscles, lungs, heart, aorta, and skin based on the geometric surfaces.

[0013] Furthermore, the S1-2 includes:

[0014] S1-2-1: Use quadrilateral shell elements to model the outer surface structures of the ribs, sternum, and intercostal muscles, as well as the full thickness of the skin; use hexahedral elements to model the internal structures of the ribs, sternum, and intercostal muscles;

[0015] S1-2-2: Use triangular shell elements to model the outer surface structures of the lungs and vertebrae, and use tetrahedral elements to model the internal structures of the lungs and vertebrae;

[0016] S1-2-3: Based on the injury characteristics of the heart and aorta in blunt chest trauma, use triangular shell elements to model the outer surface structures of the heart and aorta, use tetrahedral elements to model the inner surface structures of the heart and aorta, and establish the interconnections between the heart and aorta, as well as between their internal cavity structures and cavities according to the anatomical structures.

[0017] Furthermore, in the S1-2-3, establishing the interconnections between the heart and aorta, as well as between their internal cavity structures and cavities according to the anatomical structures specifically means:

[0018] Based on the cavity anatomical characteristics of the left atrium, left ventricle, right atrium, and right ventricle in the heart, model the cavity walls through triangular shell elements;

[0019] Based on the anatomical characteristics of the connection between the left ventricle of the heart and the aorta, use tetrahedral solid elements to model the connection between the aorta and the left ventricle;

[0020] Based on the anatomical characteristics of the ascending aorta, aortic arch, and descending aorta of the aorta, they are connected through co-nodes at the junctions of the ascending aorta, aortic arch, and descending aorta.

[0021] Furthermore, the S2 includes:

[0022] S2-1: Construct the diaphragm structure using shell elements. According to the positions of the thoracic and abdominal organs, the shell element-simulated diaphragm structure is used to close the lower end of the thoracic cavity, and the shell elements on the surfaces of the organs on both sides of the diaphragm structure are translated and combined to fill in to obtain the overall shell element structure of the diaphragm;

[0023] S2-2: Use shell elements at the position of the first rib to suture and generate a suture surface at the neck opening, and use triangular shell elements on the surface of the vertebrae translated to construct an envelope surface on the back of the thoracic vertebrae. The suture surface and the envelope surface are made of elastic materials;

[0024] S2-3: Construct a closed defined void region according to the overall shell element structure of the diaphragm in combination with the intercostal muscles and the inner surface of the ribs;

[0025] S2-4: Use tetrahedral elements to fill the voids in the defined void region to obtain a defined region. After the filling is completed, the duplicate shell elements on the closed surface of the defined region are deleted, and the shell elements of the upper suture surface of the thoracic cavity, the spinal envelope surface, and the diaphragm structure are retained.

[0026] Furthermore, the positions of the thoracic and abdominal organs in the S2-1 are specifically: According to the positions of the lungs and the liver, the periphery of the diaphragm structure is connected to the ends of the ribs and the lower boundaries of the costal cartilages; The diaphragm is made of fabric material.

[0027] Furthermore, the S3 includes:

[0028] S3-1: Select an empty material that defines the state equation of the hydraulic model to represent blood, and use it as the material property of the tetrahedral elements filled in the heart and the aorta;

[0029] S3-2: Use a rubber material that can define a load curve as the material property of the tetrahedral elements filled in the thoracic cavity, and represent it as the soft tissues in the thoracic cavity;

[0030] S3-3: Use the *ALE_MULTI-MATERIAL_GROUP to group ALE filling parts with the same characteristics. The ALE filling parts with the same characteristics include the filling of soft tissues in the thoracic cavity and the filling of blood in the heart and the aorta;

[0031] S3-4: Define the fluid-structure interaction effect between the two mesh structures between the Lagrangian structured mesh and the ALE fluid mesh using the *CONSTRAINED_LAGRANGE_IN_SOLID keyword; the ALE fluid mesh includes the fluid meshes filled in the soft tissues in the chest cavity and the blood in the heart and aorta; the Lagrangian structured mesh includes the organ wall mesh structure in contact with the ALE fluid mesh.

[0032] The principle and advantages of the present invention are as follows: The technical solution of this application takes anatomical accuracy and the reproduction of fluid-structure interaction (FSI) mechanical behavior as the core and is realized through a three-layer technical architecture:

[0033] 1. Hybrid mesh modeling: Based on the anatomical hierarchical structures of the ribs (quadrilateral shell + hexahedron solid), lungs (triangular shell + tetrahedron solid), and heart / aorta (shell-solid hybrid) reconstructed from human medical images, use shell elements to capture the bending stiffness of thin tissues (such as heart valves and blood vessel walls), and use solid elements to simulate three-dimensional deformations (such as myocardial compression and blood flow);

[0034] 2. Void area closure and fluid filling: Construct a closed chest cavity through diaphragm shell element suture and neck / spinal envelope surfaces, and combine ALE multi-material grouping (blood hydraulic model + soft tissue rubber material) to achieve zonal control of fluids (incompressible) and solids (nonlinear elastic);

[0035] 3. Bidirectional fluid-structure interaction: Use the *CONSTRAINED_LAGRANGE_IN_SOLID to constrain the interface between the Lagrangian structured mesh (organ wall) and the ALE fluid mesh (blood / soft tissue), and force the transfer of displacement-pressure feedback under impact loads (such as heart compression → sudden increase in blood hydrostatic pressure → stress concentration in the heart wall) to ensure the physiological authenticity of the mechanical response.

[0036] Therefore, the advantages of this application are as follows: Use the fluid-structure interaction method to calculate the mechanical response when soft tissues fill and contact the organs in the chest cavity, define the fluid properties for the internal filling in the internal cavities of the heart and aorta, and make the fluid pressure change with the change of the closed cavity volume by introducing the state equation; compared with the traditional surface-to-surface contact method, the fluid-structure interaction method can more reasonably reflect the chest injuries under blunt impact, and by introducing the internal filling with hydraulic characteristics in the organs, the impact of the fluid pressure change in the organ cavity during the impact on the injury can be reflected. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a flowchart of an embodiment of the present invention;

[0038] Figure 2 is a schematic diagram of the structure of the finite element model of the human chest in an embodiment of the present invention Figure 1 ;

[0039] Figure 3 Schematic diagram of the human chest finite element model structure according to an embodiment of the present invention Figure 2 ;

[0040] Figure 4 Schematic diagram of the human chest finite element model structure according to an embodiment of the present invention Figure 3 ;

[0041] Figure 5 It is a schematic diagram of the intrathoracic organ structure. Specific implementation manners

[0042] The following is a further detailed description through specific implementation manners:

[0043] The marks in the accompanying drawings of the specification include: suture surface 201, rib 202, intercostal muscle 203, sternum 204, costal cartilage 205, envelope surface 206, diaphragm structure 207, aorta 301, heart 302.

[0044] The human finite element model can be used to study the injury risk and injury mechanism of the human body under different impact load conditions, but the traditional human finite element model cannot accurately evaluate the chest injuries caused by blunt impacts. Based on the traditional human finite element model, this patent fills fluid property units between the inner wall of the thoracic cavity and the outer surface of the organs and inside the organs, and uses the fluid-structure interaction method to make the chest and abdomen finite element model closer to the injury response of the real human body under blunt trauma conditions.

[0045] The specific implementation technology is basically as shown in the attached Figure 1 figure: A modeling method for a human chest and abdomen finite element model with fluid-structure interaction characteristics, including:

[0046] S1: Obtain human medical image data to construct a human chest finite element model with anatomical features; among them, S1 includes:

[0047] S1-1: Obtain the point cloud information of the human medical image file, and reconstruct the geometric surface of the chest anatomical structure in sequence;

[0048] S1-2: Based on the geometric surface, construct a human chest finite element model with anatomical features including rib 202, sternum 204, vertebra, intercostal muscle 203, lung, heart 302, aorta 301, and skin.

[0049] In this embodiment, the point cloud information of the human medical image file is obtained by computer tomography (CT) and magnetic resonance imaging (MRT). Then, the geometric surface of the chest anatomical structure is reconstructed in sequence based on the point cloud information. Among them, the chest anatomical structure includes structures such as ribs 202, sternum 204, vertebrae, intercostal muscles 203, lungs, heart 302, aorta 301, and skin. Based on this geometric surface, a human chest finite element model with anatomical features is constructed. Specifically:

[0050] First, based on the structures of each part of the thoracic cavity above, a solid element structure covered with shell elements is used for modeling. Among them:

[0051] 1. The outer surface structures of the ribs 202, sternum 204, and intercostal muscles 203, as well as the entire skin layer, are modeled using quadrilateral shell elements; the internal structures of the ribs 202, sternum 204, and intercostal muscles 203 are modeled using hexahedron elements;

[0052] 2. The outer surface structures of the lungs and vertebrae are modeled using triangular shell elements, and the internal structures of the lungs and vertebrae are modeled using tetrahedron elements;

[0053] 3. Based on the injury characteristics of the heart 302 and aorta 301 in blunt chest trauma, the outer surface structures of the heart 302 and aorta 301 are modeled using triangular shell elements, the inner surface structures of the heart 302 and aorta 301 are modeled using tetrahedron elements, and the connections between the heart 302 and aorta 301, as well as between their internal cavity structures and cavities, are established according to the anatomical structure.

[0054] And for the connection between the heart 302 and aorta 301, as well as between their internal cavity structures and cavities established according to the anatomical structure in point 3, specifically:

[0055] Based on the cavity anatomical characteristics of the left atrium, left ventricle, right atrium, and right ventricle in the heart 302, the cavity walls are modeled using triangular shell elements;

[0056] Based on the anatomical characteristics of the connection between the left ventricle of the heart and the aorta, the connection between the aorta 301 and the left ventricle is modeled using tetrahedron solid elements;

[0057] Based on the anatomical characteristics of the ascending aorta 301, aortic arch 301, and descending aorta 301 of the aorta 301, they are connected by co - nodes at the junctions of the ascending aorta 301, aortic arch 301, and descending aorta 301.

[0058] For the structure generated above, material properties also need to be assigned. Specifically, for bone structures such as the rib 202, sternum 204, vertebrae, etc., cortical bone is an elastoplastic material that can characterize the strain rate, cancellous bone uses a viscoelastic-plastic material with continuous damage characteristics, the shell elements on the surface of the remaining organs are simulated with fabric materials, the lung solid uses an isotropic low-elasticity material, and the heart 302 and aorta 301 solids use a rubber material with a definable load curve.

[0059] S2: Based on the outer surface of the intrathoracic organs and the inner surface of the chest cavity, use shell elements to generate the boundaries defining the void area, fill the defined void area with solid elements to obtain the defined area, and delete the repeated shell elements in the defined area, retaining the shell elements with structural grid characteristics; where S2 includes:

[0060] S2-1: Use shell elements to construct the diaphragm structure 207, and according to the positions of the thoracic and abdominal organs, use the diaphragm structure 207 simulated by shell elements to close the lower end of the chest cavity, and combine and fill by translating the shell elements on the surfaces of the organs on both sides of the diaphragm to obtain the overall shell element structure of the diaphragm;

[0061] S2-2: Use shell elements at the position of the first rib 202 to suture the neck opening to generate the suture surface 201, and use the triangular shell elements on the surface of the vertebra to translate and construct the envelope surface 206 on the back of the thoracic vertebra. The suture surface 201 and the envelope surface 206 use elastic materials;

[0062] S2-3: According to the overall shell element structure of the diaphragm, combine the intercostal muscles 203 and the inner surface of the rib 202 to construct a closed defined void area;

[0063] S2-4: Use tetrahedral elements to fill the void in the defined void area to obtain the defined area. After filling, delete the repeated shell elements on the closed surface of the defined area, retaining the shell elements of the upper suture surface 201 of the chest cavity, the spinal envelope surface 206, and the diaphragm structure 207.

[0064] In this embodiment, use shell elements to construct the diaphragm structure 207; according to the positions of the thoracic and abdominal organs, use the diaphragm structure 207 simulated by shell elements to close the lower end of the chest cavity, and obtain the overall structure of the diaphragm by translating and combining the shell elements on the surfaces of the organs on both sides of the diaphragm. The main surfaces of the organs are the lungs and the liver. The periphery of the diaphragm structure 207 is connected to the end of the rib 202 and the lower boundary of the costal cartilage 205, as Figure 3 shown. The diaphragm uses fabric materials, the cortical bone of the costal cartilage 205 uses *MAT_9 empty material, and the cancellous bone uses viscoelastic-plastic material. As Figure 2 shown, the neck opening is sutured using shell elements at the position of the first rib 202, as Figure 3As shown, the envelope surface 206 is constructed using translational vertebral surface shell elements on the back, and the upper envelope surface 206 and the suture surface 201 are made of elastic materials.

[0065] Based on the above constructed shell element structure, a closed boundary is constructed by combining the intercostal muscles 203 and the inner surface of the ribs 202. The continuity between different mesh types is ensured by splitting elements and merging nodes, and the normal directions of the shell elements forming the boundary need to be the same.

[0066] Finally, since the generated closed surface is usually irregular and there will be mesh transitions of different shapes, tetrahedral elements are mostly used for filling. After filling, the repeated shell elements on the closed surface of the defined area are deleted, and the shell elements of the thoracic suture surface 201, the spinal envelope surface 206, and the diaphragm structure 207 are retained; the inside of the heart 302 and the aorta 301 are also filled with tetrahedral elements. After filling, the model is as shown in the appendix Figure 5 shown.

[0067] S3: According to the material properties of the fluid filling in the human chest, set the fluid-structure interaction characteristics between the structural mesh and the fluid mesh to obtain a finite element model of the human chest with fluid-structure interaction characteristics; where S3 includes:

[0068] S3-1: Select an empty material that defines the state equation of the hydraulic model to represent blood as the material property of the tetrahedral elements filled in the heart 302 and the aorta 301.

[0069] S3-2: Use a rubber material that can define the load curve as the material property of the tetrahedral elements filled inside the chest cavity to represent the soft tissues inside the chest cavity.

[0070] S3-3: Use the *ALE_MULTI-MATERIAL_GROUP to group the ALE filling parts with the same characteristics. The ALE filling parts with the same characteristics include the filling of soft tissues inside the chest cavity and the filling of blood in the heart 302 and the aorta 301.

[0071] S3-4: Use the *CONSTRAINED_LAGRANGE_IN_SOLID keyword to define the fluid-structure interaction effect between the two mesh structures between the Lagrangian structural mesh and the ALE fluid mesh; the ALE fluid mesh includes the fluid meshes filled into the soft tissues inside the chest cavity and the blood in the heart 302 and the aorta 301; the Lagrangian structural mesh includes the organ wall mesh structure in contact with the ALE fluid mesh.

[0072] In this embodiment, since blood is an approximately incompressible fluid, an empty material that defines the state equation of the hydraulic model is selected to simulate the properties of the blood in the heart 302 and the aorta 301. The state equation of the hydraulic model constrains the volume change of the fluid through the pressure-volume relationship. Specifically, when the heart 302 / aorta 301 deforms due to impact, the internal pressure surges suddenly, reflecting the hydrostatic pressure effect of the blood in real physiology. For example, the sudden increase in pressure caused by the sudden reduction in the chamber volume of the heart 302 under blunt impact;

[0073] The empty material used here refers to a material without initial stress, which defines the fluid behavior only through the state equation and focuses on transmitting pressure loads rather than structural stiffness.

[0074] Therefore, by using the empty material that defines the state equation of the hydraulic model and combining it with the cavity structure of the heart 302 / aorta 301 modeled previously, the blood filling material can be coupled with the surrounding soft tissues (Lagrangian grid) through the ALE algorithm, enabling the simulation of fluid-structure interaction, such as the pressure reaction of the blood on the heart wall during heartbeat or impact.

[0075] For the soft tissue filling material in the thoracic cavity, a rubber material that can define the load curve is selected. This is because the soft tissues in the thoracic cavity have highly nonlinear mechanical behaviors, and the stress-strain load curve of the rubber material can accurately reproduce its large deformation characteristics. At the same time, the rubber material that can define the load curve can input different stress-strain curves in a definable way, so as to better fit the mechanical properties of different soft tissue parts. For example, the lung tissue is softer and requires low stiffness, while the intercostal muscle 203 is tougher and requires high stiffness.

[0076] Therefore, the blood material in the heart 302 / aorta 301 and the soft tissue material in the thoracic cavity mentioned above are constructed into an ALE fluid grid, and the organ wall in contact with the ALE fluid grid, such as the heart 302 wall, belongs to the Lagrangian structural grid. For the fluid-structure coupling characteristics between the Lagrangian structural grid and the ALE fluid grid, the *CONSTRAINED_LAGRANGE_IN_SOLID keyword is used for definition. The specific implementation process is as follows: The surface nodes of the Lagrangian structure are used as the master nodes, and the surface nodes of the ALE fluid are used as the slave nodes. One-to-one or one-to-many node couplings are established through geometric projection at the structure-fluid section, thus forming constraints between the Lagrangian structural grid and the ALE fluid grid. Subsequently, when the Lagrangian structure deforms, the master nodes drag the slave nodes to transfer the displacement boundary conditions. For example, when the heart 302 contracts, it squeezes the blood, and the fluid pressure reacts on the master nodes through the slave nodes, converting into structural stress. For example, the stress concentration on the heart 302 wall caused by the blood impact.

[0077] Therefore, in the finite element model of the human chest constructed in this application, in the simulation of chest blunt injury, the *CONSTRAINED_LAGRANGE_IN_SOLID keyword is used as the digital link connecting biomechanical structures and physiological fluids, which not only realizes the two-way physical process of heart 302 squeezing blood-pressure reaction injury, but also through the accurate node pairing of anatomical structures, enables the model to reproduce the specific injuries observed clinically, thereby improving the accuracy of the research results in blunt injury impact research.

[0078] The above are only the embodiments of the present invention. Specific structures and characteristics and other common knowledge well known in the art are not described in detail here. Those of ordinary skill in the art know all the common general technical knowledge in the technical field to which the invention belongs before the application date or the priority date, can know all the prior art in this field, and have the ability to apply the conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, combine their own abilities to complete and implement this solution. Some typical well-known structures or well-known methods should not become an obstacle for those of ordinary skill in the art to implement this application. 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 also be made, and these 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 and other records in the specification can be used to interpret the content of the claims.

Claims

1. A modeling method for a finite element model of the human chest and abdomen with fluid-structure interaction characteristics, characterized in that: Including: S1: Obtain human medical image data to construct a human chest finite element model with anatomical features; S2: Based on the outer surface of the organs in the thoracic cavity and the inner surface of the thoracic cavity, use shell elements to generate the boundaries defining the void area, fill the defined void area with solid elements to obtain the defined area, and delete the repeated shell elements in the defined area, retaining the shell elements with structural grid features; S3: According to the material properties of the fluid filling in the human chest, set the fluid-structure interaction characteristics between the structural grid and the fluid grid to obtain a human chest finite element model with fluid-structure interaction characteristics.

2. A modeling method for a human chest and abdomen finite element model with fluid-structure interaction characteristics according to claim 1, characterized in that: The S1 includes: S1-1: Obtain the point cloud information of the human medical image file and reconstruct the geometric surface of the chest anatomical structure in sequence; S1-2: Based on the geometric surface, construct a human chest finite element model with anatomical features including ribs, sternum, vertebrae, intercostal muscles, lungs, heart, aorta, and skin.

3. A method for modeling a finite element model of the human chest and abdomen with fluid-structure interaction characteristics according to claim 2, characterized in that: The S1-2 includes: S1-2-1: Use quadrilateral shell elements to model the outer surface structures of the ribs, sternum, and intercostal muscles, and the entire skin layer; use hexahedral elements to model the internal structures of the ribs, sternum, and intercostal muscles; S1-2-2: Use triangular shell elements to model the outer surface structures of the lungs and vertebrae, and use tetrahedral elements to model the internal structures of the lungs and vertebrae; S1-2-3: Based on the injury characteristics of the heart and aorta in blunt chest trauma, use triangular shell elements to model the outer surface structures of the heart and aorta, use tetrahedral elements to model the inner surface structures of the heart and aorta, and establish the mutual connections between the heart and aorta, and between their internal cavity structures and cavities according to the anatomical structure.

4. A modeling method for a human chest and abdomen finite element model with fluid-structure interaction characteristics according to claim 3, characterized in that: In the S1-2-3, establishing the mutual connections between the heart and aorta, and between their internal cavity structures and cavities according to the anatomical structure specifically means: Based on the cavity anatomical features of the left atrium, left ventricle, right atrium, and right ventricle in the heart, model the cavity wall through triangular shell elements; Based on the anatomical features of the connection between the left ventricle of the heart and the aorta, use tetrahedral solid elements to model the connection between the aorta and the left ventricle; Based on the anatomical features of the ascending aorta, aortic arch, and descending aorta of the aorta, connect them at the joints of the ascending aorta, aortic arch, and descending aorta through co-nodes.

5. A modeling method for a human chest and abdomen finite element model with fluid-structure interaction characteristics according to claim 4, characterized in that: The S2 includes: S2-1: Use shell elements to construct the diaphragm structure, close the lower end of the thoracic cavity with the diaphragm structure simulated by shell elements according to the positions of the thoracic and abdominal organs, and combine and fill the shell elements on both sides of the diaphragm structure by translation to obtain the overall shell element structure of the diaphragm; S2-2: Use shell elements at the position of the first rib to suture the neck opening to generate a suture surface, and use translated triangular shell elements on the back of the thoracic vertebra to construct an envelope surface at the thoracic vertebra. The suture surface and the envelope surface are made of elastic materials; S2-3: Construct a closed defined void area according to the overall shell element structure of the diaphragm in combination with the inner surfaces of the intercostal muscles and ribs; S2-4: Fill the voids that define the void region with tetrahedral elements to obtain the defined region. After the filling is completed, delete the repeated shell elements on the closed surface of the defined region, and retain the shell elements of the suture surface on the chest cavity, the spine envelope surface, and the diaphragm structure.

6. A modeling method for a finite element model of the human chest and abdomen with fluid-structure interaction characteristics according to claim 5, characterized in that: In S2-1, the specific positions of the thoracic and abdominal organs are as follows: According to the positions of the lungs and the liver, the periphery of the diaphragm structure is connected to the ends of the ribs and the lower boundaries of the costal cartilages; the diaphragm is made of a fabric material.

7. A method for modeling a finite element model of the human chest and abdomen with fluid-structure interaction characteristics according to claim 6, characterized in that: S3 includes: S3-1: Select an empty material that defines the state equation of the hydraulic model to represent blood, and use it as the material property of the tetrahedral elements filled in the heart and the aorta. S3-2: Use a rubber material that can define the load curve as the material property of the tetrahedral elements filled inside the chest cavity, representing the soft tissues inside the chest cavity. S3-3: Use the *ALE_MULTI-MATERIAL_GROUP to group the ALE filling parts with the same characteristics. The ALE filling parts with the same characteristics include the filling of the soft tissues inside the chest cavity and the filling of the blood in the heart and the aorta. S3-4: Use the *CONSTRAINED_LAGRANGE_IN_SOLID keyword to define the fluid-structure interaction effect between the two mesh structures between the Lagrangian structural mesh and the ALE fluid mesh; the ALE fluid mesh includes the fluid meshes filled into the soft tissues inside the chest cavity and the blood in the heart and the aorta; the Lagrangian structural mesh includes the organ wall mesh structure in contact with the ALE fluid mesh.

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