Pore gradient discrete embedded type composite bone tissue modeling method

Abstract

The invention discloses a porosity gradient discrete embedded type composite bone tissue modeling method. The method comprises the following steps: establishing a three-phase composite bone tissue geometric model of cortical bone, cancellous bone and cortical bone with discrete random pores; establishing material constitutive models of a cortical bone model and a cancellous bone model in the three-phase composite bone tissue geometric model; and performing grid division on the three-phase composite bone tissue geometric model to obtain a composite bone tissue model. According to the porosity gradient discrete embedded type composite bone tissue modeling method, the composite structure of the bone tissue in transition from cortical bone to cancellous bone can be effectively simulated, the accuracy of bone model simulation is improved, and the problem of constitutive homogeneous distortion of an existing bone tissue cutting simulation material is solved.

Description

Technical Field

[0001] The invention relates to the technical field of bone tissue modeling, and in particular to a pore gradient discrete embedded composite bone tissue modeling method. Background Art

[0002] Studying the biomechanical properties of bone tissue can provide a theoretical basis for orthopedic surgery and is the key to further optimizing surgical operations and improving surgical quality. However, with the development and deepening of related research, the limitations of bone tissue as an experimental material have gradually emerged. It is very difficult to obtain bone tissue materials, and the quantity is difficult to meet the requirements. The emergence of the finite element model of bone tissue not only effectively avoids the above problems, but also can intuitively display the real-time change information of various physical quantities such as stress, strain, and temperature. At the same time, it also has certain advantages in experimental costs. Therefore, the finite element model of bone tissue has gradually become an important research method.

[0003] Studies on the anatomical structure of human bone tissue have shown that bone tissue is mainly composed of cortical bones on both sides and cancellous bones in the middle. The cortical bone is compact, while the cancellous bone is porous and spongy, playing an absolutely dominant role in bone tissue. However, existing bone tissue models often compare bones to engineering materials such as wood and steel, ignoring the effects of their anatomical structure and material constitutive model on mechanical properties. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the existing bone tissue model cannot take into account the detailed composite bone tissue anatomical structure and the realization of finite element simulation, and to provide a pore gradient discrete embedded composite bone tissue modeling method based on the structural characteristics of the pore gradient change of the composite bone tissue, which can effectively simulate the composite structure of the bone tissue transition from cortical bone to cancellous bone, improve the accuracy of bone model simulation, and solve the problem of constitutive homogeneity distortion of existing bone tissue cutting simulation materials.

[0005] In order to achieve the above object, the present invention provides a pore gradient discrete embedded composite bone tissue modeling method, comprising the steps of:

[0006] S1. Establish a three-phase composite bone tissue geometric model of "cortical bone, cancellous bone and cortical bone" with discretized random pores;

[0007] S2. Establishing the material constitutive model of the cortical bone model and the cancellous bone model in the three-phase composite bone tissue geometric model;

[0008] S3. Meshing the three-phase composite bone tissue geometric model to obtain a composite bone tissue model.

[0009] The three-phase composite bone tissue geometric model of "cortical bone, cancellous bone and cortical bone" is established by secondary development of Abaqus software using Python language, including:

[0010] Based on Abaqus / Python software, a .rpy script file is developed to create cancellous bone tissue modeling based on discretized random pores;

[0011] Compile an Abaqus plug-in to visualize the code language of the .rpy script file and obtain a cancellous bone model;

[0012] The cancellous bone model generated by secondary development in Abaqus software and the rectangular cortical bone model directly generated in the part plate were imported into Auto-CAD software and combined to form a three-phase composite bone tissue geometric model with a gradient random pore structure.

[0013] The secondary development based on Abaqus / Python software can create a .rpy script file that can create cancellous bone tissue modeling based on discretized random pores, including:

[0014] Call the random function CircleByCenterPerimeter to randomly generate a set of circular pores (R i ,x i ,y i ), R i ,x i ,y i Respectively represent the radius and coordinate value of the circular pore;

[0015] The generated circular pores (R i ,x i ,y i ) and the existing matrix center[(R q ,x q ,y q )], if the circular pore (R i ,x i ,y i ) and any circle (R q ,x q ,y q ) is smaller than the set optimal gap G, then return to the previous line of commands to regenerate a new set of circular pores (R i ,x i ,y i ) and perform intersection determination again until a circular hole (R i ,x i ,yi ), and then the circular hole (R i ,x i ,y i ) is stored in the existing matrix center[] to obtain the .rpy script file that can create cancellous bone tissue modeling based on discretized random pores.

[0016] The Abaqus plug-in is compiled to perform visual processing on the code language of the .rpy script file to obtain a cancellous bone model, including:

[0017] Use UltraEdit software to open the generated .rpy script file in the working directory of the Part module in Abaqus / CAE; filter according to the function name and parameter value to obtain the script function and expression for drawing rectangles and circles, and check whether there are any problems with the rewritten script file by trial running;

[0018] Use RSG to build plug-ins and create different GUI interfaces under the RSG Dialog Builder section of the Plug-ins menu;

[0019] The .rpy script file is bound in the GUI interface to realize the visual processing of the code language of the .rpy script file to obtain the cancellous bone model.

[0020] The cortical bone model and the cancellous bone model are combined to form a composite bone tissue geometric model with a gradient random pore structure, including:

[0021] The cancellous bone model with discretized random pores and the rectangular cortical bone models on both sides were imported into Auto CAD software for modification and combination to form a composite bone tissue geometric model with discretized random pores.

[0022] The established composite bone tissue geometric model is rectangular, and its size parameters are set as follows: horizontal total length 10mm, height 4mm, stretching width 3mm, the width of the cortical bone model is 1.25mm, the total length of the cancellous bone model is 7.5mm, and the width of the two outer areas of the cancellous bone model is 1mm. The pore radius ranges from 0.1-0.2mm, and the minimum pore interval is 0.1mm; the medial area width of the cancellous bone model is 5.5mm, the pore radius ranges from 0.3-0.5mm, and the minimum pore interval is 0.1mm.

[0023] Wherein, in step S2, the material constitutive models of the cortical bone model and the cancellous bone model are established in Abaqus / Explicit, including:

[0024] The Brittle-Cracking constitutive model, in which brittle behavior is dominant, was selected as the material constitutive model for the cortical bone model and the cancellous bone model.

[0025] The material parameters of the material constitutive models of the cortical bone model and the cancellous bone model are set to obtain the material constitutive models of the cortical bone and the cancellous bone.

[0026] The cortical bone material parameters of the material constitutive model of the cortical bone model are set as follows: density 1.8×10 - 9 t / mm 3 , Young's modulus 2.2×10 -4 MPa, Poisson's ratio 0.4, fracture energy 1.374N / mm, cracking strain 0.2%, failure stress 219MPa, shear retention factor 2, failure displacement 0.001mm, specific heat capacity 1.26×10 9 mJ / (t·℃), import coefficient 0.56mJ / (s·℃);

[0027] The cancellous bone material parameters of the material constitutive model of the cancellous bone model are set as follows: density 5.5×10 - 10 t / mm 3 , Young's modulus 1.1×10 -4 MPa, Poisson's ratio 0.3, fracture energy 2.912N / mm, cracking strain 0.2%, failure stress 110MPa, shear retention factor 2, failure displacement 0.001mm, specific heat capacity 1.26×10 9 mJ / (t·℃), introduction coefficient 0.18mJ / (s·℃).

[0028] Wherein, in step S3, the meshing of the three-phase composite bone tissue geometric model is completed in Abaqus / CAE, including:

[0029] The overall geometric model of the three-phase composite bone tissue adopts a global unilateral seeding method, and the hexahedral mesh is selected as the mesh unit shape of the three-phase composite bone tissue geometric model. The mesh unit type is the C3D8RT unit with reduced integration, explicit, linear, and temperature-displacement coupling. The style grid size is set, and the standard structural meshing method is used for network division of the cortical bone model, and the sweeping meshing method is used for the cancellous bone model.

[0030] Wherein, in the meshing step of the three-phase composite bone tissue geometric model, the mesh size is set to 0.2.

[0031] The present invention divides bone tissue into cortical bone and cancellous bone according to its physiological and anatomical structure, function and respective biomechanical properties, establishes finite element models of cortical bone and cancellous bone respectively, selects a more accurate material constitutive model according to the material properties, and finally establishes a pore gradient discretized embedded composite bone tissue, which can be used to accurately realize finite element simulation of bone tissue. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flow chart of the pore gradient discrete embedded composite bone tissue modeling method of the present invention;

[0033] Figure 2 The flowchart of generating and verifying the discretized random pore characteristic parameters of the present invention is as follows;

[0034] Figure 3 A schematic diagram of generating random pores for the Abaqus random pore plug-in of the present invention;

[0035] Figure 4 A schematic diagram of a composite bone tissue geometric model with gradient discretized random pores constructed according to an embodiment of the present invention;

[0036] Figure 5 A calculation flow chart for parameter setting of the Brittle-Cracking constitutive model of the present invention;

[0037] Figure 6 A schematic diagram of the discretized random pore composite bone tissue geometric model constructed in an embodiment of the present invention after meshing. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the present invention to clearly and completely describe the technical solutions in the present invention. Obviously, the examples described are only part of the embodiments of the invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making innovative work are within the scope of protection of the present invention.

[0039] See also Figure 1 As shown, the pore gradient discrete embedded composite bone tissue modeling method of the embodiment of the present invention includes the following steps:

[0040] S1. Establish a three-phase composite bone tissue geometric model of "cortical bone, cancellous bone and cortical bone" with discretized random pores;

[0041] S2. Establishing the material constitutive model of the cortical bone model and the cancellous bone model in the three-phase composite bone tissue geometric model;

[0042] S3. Meshing the three-phase composite bone tissue geometric model to obtain a composite bone tissue model.

[0043] In the embodiment of the present application, the three-phase composite bone tissue geometric model of "cortical bone, cancellous bone and cortical bone" is established by secondary development of Abaqus software using Python language, including:

[0044] Based on Abaqus / Python software, a .rpy script file is developed to create cancellous bone tissue modeling based on discretized random pores;

[0045] Compile an Abaqus plug-in to visualize the code language of the .rpy script file and obtain a cancellous bone model;

[0046] The cancellous bone model generated by secondary development in Abaqus software and the rectangular cortical bone model directly generated in the part plate were imported into Auto-CAD software and combined to form a three-phase composite bone tissue geometric model with a gradient random pore structure.

[0047] In the embodiment of the present application, the secondary development based on Abaqus / Python software can create a .rpy script file that can create cancellous bone tissue modeling based on discretized random pores, including:

[0048] Call the random function CircleByCenterPerimeter to randomly generate a set of circular pores (R i ,x i ,y i ), R i ,x i ,y i Respectively represent the radius and coordinate value of the circular pore, such as Figure 3 As shown, the given range is a rectangular area Xmax, Ymin, Figure 3 On the interface shown, you can select the maximum radius Rmax of the circular pore, the minimum radius Rmin, the optimal distance G, and the maximum number of circular pores N1, in mm.

[0049] like Figure 2 As shown, interference judgment is performed on the generated circular pores:

[0050] The generated circular pores (R i ,x i ,y i ) and the existing matrix center[(R q ,x q ,y q )], if the circular pore (R i,x i ,y i ) and any circle (R q ,x q ,y q ) is smaller than the set optimal gap G, then return to the previous line of commands to regenerate a new set of circular pores (R i ,x i ,y i ) and perform intersection determination again until a circular hole (R i ,x i ,y i ), and then the circular hole (R i ,x i ,y i ) is stored in the existing matrix center[] to obtain the .rpy script file that can create cancellous bone tissue modeling based on discretized random pores.

[0051] Specifically, Figure 2 As shown, enter X max ,Y min , R max , R min , G, N1, generate random circular pores (R i ,x i ,y i ), R i ∈[R min ,R max ,],x i ∈[R i +G,X max -R i -G],y i ∈[R i +G,Y max -R i -G], i represents the circular pore number; then enter the steps:

[0052] Determine whether i is equal to 0. If so, proceed to the next step and add a circular hole (R i ,x i ,y i ) to the existing matrix center[(R q ,x q ,y q )], then after adding 1 to i, determine whether i is greater than or equal to N1. When i ≥ N1, output the circular pore R that meets the minimum or optimal gap. q ,x q ,y q , when i≥N1 is not true, return to generate a random circular hole (Ri ,x i ,y i ) steps;

[0053] If i is not equal to 0, then judge (x i -x q ) 2 +(y i -y q ) 2 ≥(R i +R q +G) 2 Is it true? If so, add a circular hole (R i ,x i ,y i ) to the existing matrix center[(R q ,x q ,y q )], otherwise, after adding 1 to i, determine whether i is greater than or equal to N1. When i ≥ N1, output the circular pore (R q ,x q ,y q) , when i≥N1 is not true, return to generate a random circular hole (R i ,x i ,y i ) steps.

[0054] In the embodiment of the present application, the Abaqus plug-in is compiled to visualize the code language of the .rpy script file to obtain a cancellous bone model, including:

[0055] Use UltraEdit software to open the generated .rpy script file in the working directory of the Part module in Abaqus / CAE; filter according to the function name and parameter value to obtain the script function and expression for drawing rectangles and circles, and check whether there are any problems with the rewritten script file by trial running;

[0056] Use RSG to build plug-ins and create different GUI interfaces under the RSG Dialog Builder section of the Plug-ins menu;

[0057] The .rpy script file is bound to the GUI interface to realize the visual processing of the code language of the .rpy script file to obtain the cancellous bone model.

[0058] It should be noted that in the above steps, if the rewritten script file is checked for problems through a trial run, then return to the aforementioned script file step and re-modify the script function. If there are no problems, then proceed to the following step of creating a different GUI interface.

[0059] In the embodiment of the present application, the cortical bone model and the cancellous bone model are combined to form a composite bone tissue geometric model with a gradient random pore structure, including:

[0060] The cancellous bone model with discretized random pores and the rectangular cortical bone model on both sides were imported into the Auto CAD software and modified and combined, as shown in Figure 4 The lower figure shows the cancellous bone model in the middle and the cortical bone models on both sides. Figure 4 The upper middle diagram corresponds to the actual bone tissue structure.

[0061] In the embodiment of the present application, the established composite bone tissue geometric model is rectangular, and its size parameters are set as: horizontal total length 10mm, height 4mm, stretching width 3mm, wherein the width of the cortical bone model is 1.25mm, the total length of the cancellous bone model is 7.5mm, wherein the width of the two outer regions of the cancellous bone model is 1mm, the pore radius ranges from 0.1-0.2mm, and the minimum pore interval is 0.1mm; the width of the inner region of the cancellous bone model is 5.5mm, the pore radius ranges from 0.3-0.5mm, and the minimum pore interval is 0.1mm.

[0062] In the embodiment of the present application, in step S2, the material constitutive model of the cortical bone model and the cancellous bone model is established in Abaqus / Explicit, including:

[0063] The Brittle-Cracking constitutive model, in which brittle behavior is dominant, was selected as the material constitutive model for the cortical bone model and the cancellous bone model.

[0064] The material parameters of the material constitutive models of the cortical bone model and the cancellous bone model are set to obtain the material constitutive models of the cortical bone and the cancellous bone.

[0065] In the embodiment of the present application, the Brittle-Cracking constitutive model is composed of three parts: Brittle Cracking, Brittle Shear and Brittle Failure, which correspond to the crack damage initiation, crack damage evolution and unit failure deletion of the material, respectively. At the same time, the linear elastic process of the material is represented by Young's modulus and Poisson's ratio. The calculation process of the Brittle-Cracking constitutive model is as follows: Figure 5 As shown, where E is the Young's modulus of the material, σ t is the material limit stress, σ i Calculate stresses for materials, is the material cracking strain, is the maximum cracking strain of the material, and the calculation process includes the following steps:

[0066] First, relevant material parameters are input, and then a material calculation point is compressed under external influence, and the compression process is differentiated into n finite compression processes, where the time second corresponding to a single compression process is a time increment step. Before compression, the time increment counter is initialized to 0, and then compression is performed by adding 1 to multiple time increments. After the compression of n finite compression processes is completed, that is, after the compression of n time increments is completed, the calculation results are output to obtain the corresponding material parameters.

[0067] Among them, in the i-th time increment, the theoretical compression of the material calculation point is e i In the compression process, when the compression is not completed, determine whether the calculation point is damaged, or determine whether the calculation point is invalid. When the calculation point is determined to be invalid, delete the material calculation point and output the calculation result.

[0068] If the calculation is judged to be without damage, σi=E×ei is calculated according to the elastic compression process; if the calculation point is not failed, the damage degree is calculated according to

[0069] Among them, whether the calculation point is invalid is determined according to the formula Judgement, if If it holds, the calculation point is considered to be valid, otherwise it is considered to be invalid.

[0070] Among them, judging whether the calculation point is damaged is based on the formula E×e i ≥σ t Judge, if E×e i ≥σ t If it holds, the calculation point is considered damaged, otherwise it is considered that there is no damage.

[0071] By setting the material parameters in the above manner, the material parameters of the material constitutive model of the cortical bone model and the cancellous bone model are obtained.

[0072] In the embodiment of the present application, the cortical bone material parameters of the material constitutive model of the cortical bone model are set as follows: density 1.8×10 -9 t / mm 3 , Young's modulus 2.2×10 -4 MPa, Poisson's ratio 0.4, fracture energy 1.374N / mm, cracking strain 0.2%, failure stress 219MPa, shear retention factor 2, failure displacement 0.001mm, specific heat capacity 1.26×10 9 mJ / (t·℃), import coefficient 0.56mJ / (s·℃);

[0073] The cancellous bone material parameters of the material constitutive model of the cancellous bone model are set as follows: density 5.5×10 - 10t / mm 3 , Young's modulus 1.1×10 -4 MPa, Poisson's ratio 0.3, fracture energy 2.912N / mm, cracking strain 0.2%, failure stress 110MPa, shear retention factor 2, failure displacement 0.001mm, specific heat capacity 1.26×10 9 mJ / (t·℃), introduction coefficient 0.18mJ / (s·℃).

[0074] In the embodiment of the present application, in step S3, the meshing of the three-phase composite bone tissue geometric model is completed in Abaqus / CAE, including:

[0075] The three-phase composite bone tissue geometric model adopts a global unilateral seeding method as a whole. The hexahedral mesh is selected as the mesh unit shape of the three-phase composite bone tissue geometric model. The mesh unit type is the C3D8RT unit with reduced integration, explicit, linear, and temperature-displacement coupling. The style grid size is set. The cortical bone model is meshed using the standard structural meshing method, and the cancellous bone model is meshed using the sweeping meshing method. After the network is divided, Figure 6 As shown, in the meshing step of the three-phase composite bone tissue geometric model, the mesh size is set to 0.2.

[0076] The present invention divides bone tissue into cortical bone and cancellous bone according to its physiological and anatomical structure, function and respective biomechanical properties, establishes finite element models of cortical bone and cancellous bone respectively, selects a more accurate material constitutive model according to the material properties, and finally establishes a pore gradient discretized embedded composite bone tissue, which can be used to accurately realize finite element simulation of bone tissue.

[0077] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the attached claims rather than the above description, and it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention.

[0078] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A composite bone tissue modeling method with pore gradient discrete embedded, characterized in that: Includes steps: S1. Establish a three-phase composite bone tissue geometric model of "cortical bone, cancellous bone and cortical bone" with discretized random pores; S2. Establishing the material constitutive model of the cortical bone model and the cancellous bone model in the three-phase composite bone tissue geometric model; S3. Meshing the three-phase composite bone tissue geometric model to obtain a composite bone tissue model.

2. The pore gradient discrete embedded composite bone tissue modeling method according to claim 1, characterized in that: The three-phase composite bone tissue geometric model of "cortical bone, cancellous bone and cortical bone" is established by secondary development of Abaqus software using Python language, including: Based on Abaqus / Python software, a .rpy script file is developed to create cancellous bone tissue modeling based on discretized random pores; An Abaqus plug-in was compiled to visualize the code language of the .rpy script file to obtain a cancellous bone model; The cancellous bone model generated by secondary development in Abaqus software and the rectangular cortical bone model directly generated in the part plate were imported into Auto-CAD software and combined to form a three-phase composite bone tissue geometric model with a gradient random pore structure.

3. The pore gradient discrete embedded composite bone tissue modeling method according to claim 2, characterized in that: The secondary development based on Abaqus / Python software can create a .rpy script file that can create cancellous bone tissue modeling based on discretized random pores, including: Call the random function CircleByCenterPerimeter to randomly generate a set of circular pores (R i ,x i ,y i ), R i ,x i ,y i Respectively represent the radius and coordinate value of the circular pore; The generated circular pores (R i ,x i ,y i ) and the existing matrix center[(R q ,x q ,y q )] in each circle (R q ,x q ,y q ) to make an intersection judgment. If the circular pore (R i ,x i ,y i ) and any circle in the existing matrix center[] is smaller than the set optimal gap G, then return to the previous line of commands to regenerate a new set of circular pores (R i ,x i ,y i ) and perform intersection determination again until a circular hole (R i ,x i ,y i ), and then the circular hole (R i ,x i ,y i ) is stored in the existing matrix center[] to obtain the .rpy script file that can create cancellous bone tissue modeling based on discretized random pores.

4. The pore gradient discrete embedded composite bone tissue modeling method according to claim 2, characterized in that: The Abaqus plug-in described above is used to visualize the code language of the .rpy script file to obtain a cancellous bone model, including: Use UltraEdit software to open the generated .rpy script file in the working directory of the Part module in Abaqus / CAE, filter it according to the function name and parameter value, obtain the script function and expression for drawing rectangles and circles, and check whether there are any problems with the rewritten script file by trial running; Use RSG to build plug-ins and create different GUI interfaces under the RSG Dialog Builder section of the Plug-ins menu; The .rpy script file is bound to the GUI interface to realize the visual processing of the code language of the .rpy script file to obtain the cancellous bone model.

5. The pore gradient discrete embedded composite bone tissue modeling method according to claim 2, characterized in that: The cortical bone model and the cancellous bone model are combined to form a composite bone tissue geometric model with a gradient random pore structure, including: The cancellous bone model with discretized random pores and the rectangular cortical bone models on both sides were imported into Auto CAD software for modification and combination to form a composite bone tissue geometric model with discretized random pores. The established composite bone tissue geometric model is rectangular, and its size parameters are set as follows: horizontal total length 10mm, height 4mm, stretching width 3mm, the width of the cortical bone model is 1.25mm, the total length of the cancellous bone model is 7.5mm, and the width of the two outer areas of the cancellous bone model is 1mm. The pore radius ranges from 0.1-0.2mm, and the minimum pore interval is 0.1mm; the medial area width of the cancellous bone model is 5.5mm, the pore radius ranges from 0.3-0.5mm, and the minimum pore interval is 0.1mm.

6. The pore gradient discrete embedded composite bone tissue modeling method according to claim 1, characterized in that: In step S2, the material constitutive models of the cortical bone model and the cancellous bone model are established in Abaqus / Explicit, including: The Brittle-Cracking constitutive model, in which brittle behavior is dominant, was selected as the material constitutive model for the cortical bone model and the cancellous bone model. The material parameters of the material constitutive models of the cortical bone model and the cancellous bone model are set to obtain the material constitutive models of the cortical bone and the cancellous bone.

7. The pore gradient discrete embedded composite bone tissue modeling method according to claim 6, characterized in that: The cortical bone material parameters of the material constitutive model of the cortical bone model are set as follows: density 1.8×10 -9 t / mm 3 , Young's modulus 2.2×10 -4 MPa, Poisson's ratio 0.4, fracture energy 1.374N / mm, cracking strain 0.2%, failure stress 219MPa, shear retention factor 2, failure displacement 0.001mm, specific heat capacity 1.26×10 9 mJ / (t·℃), import coefficient 0.56mJ / (s·℃); 8. The pore gradient discrete embedded composite bone tissue modeling method according to claim 6, characterized in that: The cancellous bone material parameters of the material constitutive model of the cancellous bone model are set as follows: density 5.5×10 -10 t / mm 3 , Young's modulus 1.1×10 -4 MPa, Poisson's ratio 0.3, fracture energy 2.912N / mm, cracking strain 0.2%, failure stress 110MPa, shear retention factor 2, failure displacement 0.001mm, specific heat capacity 1.26×10 9 mJ / (t·℃), introduction coefficient 0.18mJ / (s·℃).

9. The pore gradient discrete embedded composite bone tissue modeling method according to claim 1, characterized in that: In step S3, the meshing of the three-phase composite bone tissue geometric model is completed in Abaqus / CAE, including: The overall geometric model of the three-phase composite bone tissue adopts a global unilateral seeding method, and the hexahedral mesh is selected as the mesh unit shape of the three-phase composite bone tissue geometric model. The mesh unit type is the C3D8RT unit with reduced integration, explicit, linear, and temperature-displacement coupling. The style grid size is set, and the standard structural meshing method is used for network division of the cortical bone model, and the sweeping meshing method is used for mesh division of the cancellous bone model.

10. The pore gradient discrete embedded composite bone tissue modeling method according to claim 9, characterized in that: In the meshing step of the three-phase composite bone tissue geometric model, the mesh size is set to 0.2.

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