Design method, bracket and application of a nickel-titanium alloy super-elastic bionic bone bracket

Abstract

The application discloses a design method of a nickel-titanium alloy super-elastic bionic bone support, the support and application, relates to the technical field of bionic bone support, and can realize high adaptability of the support in a complex physiological environment by introducing the combination of a G-type TPMS bionic structure and a shape memory alloy, has high strain recovery capacity under periodic load, can effectively relieve stress concentration caused by uneven load, and provides stable bone tissue repair support. The nickel-titanium alloy super-elastic bionic bone support provided by the application combines advanced fluid-mass transfer performance optimization design, improves the mechanical property of the support, effectively enhances the biological compatibility and biological activity of the support, and is beneficial to promoting the growth, differentiation and new bone formation of bone cells.

Description

Technical Field

[0001] This invention relates to the field of bionic bone scaffold technology, and in particular to a design method, scaffold, and application of a nickel-titanium alloy superelastic bionic bone scaffold. Background Technology

[0002] Existing bone implant materials, such as titanium alloys and stainless steel, typically have recoverable strain of less than 1%, making it difficult to match the deformation behavior of natural bone. For porous bone implants, the coupling effect of physiological loads and geometric stress concentrations makes them more prone to plastic deformation. This leads to a shift in the scaffold geometry and pore characteristics, causing a redistribution of contact stress and localized stiffness overload, which in turn results in relative micromotion at the interface between the natural bone and the implant.

[0003] Nickel-titanium alloy (NiTi) exhibits superelasticity exceeding 5% and significant energy dissipation capacity due to its reversible martensitic phase transformation. This enables it to effectively balance deformation recovery and damping under cyclic loading conditions compared to other metallic materials.

[0004] However, existing nickel-titanium alloy porous bone scaffolds are prone to irreversible plastic deformation, fatigue damage, and non-optimal synergistic mechanical-mass transfer properties under complex physiological loads and mass transfer conditions. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a design method, scaffold and application of a nickel-titanium alloy superelastic biomimetic bone scaffold, which aims to solve at least one technical problem existing in the prior art.

[0006] This invention proposes a design method for a nickel-titanium alloy superelastic biomimetic bone scaffold, the method comprising: In the original Cartesian coordinate system, a G-type TPMS unit cell is defined in the form of an implicit function. The unit cell coordinate system is rotated around the Y-axis by a preset angle θ, keeping the topological connectivity of the unit cell unchanged and only changing the spatial orientation, to obtain G-type TPMS unit cells with different rotation angles. The rotated G-type TPMS unit cell is periodically translated and replicated in the X, Y, and Z directions with a unit size L, and the number of copies is Nx, Ny, and Nz respectively to form a spatial lattice array. A target volume domain matching the shape of the target scaffold is constructed. Boolean intersection operation is performed on the lattice array and the target volume domain, the intersection part is retained, and the STL model file is exported. Import the STL model file into the corresponding analysis software, establish the corresponding simulation model according to the test requirements, set the appropriate boundary conditions, load parameters and calculation parameters, obtain relevant data on the static bearing performance, dynamic recovery performance and hydrodynamic performance of the bionic bone scaffold through simulation calculation, and form the corresponding performance spectrum to achieve coordinated control of the comprehensive performance of the bionic bone scaffold until the preset performance conditions are met. Import the STL model file into the slicing software, perform layered slicing on the bionic bone scaffold model contained in the STL model file, then set the corresponding forming parameters to generate a forming data file adapted to the laser powder bed melting equipment. Based on the forming data file, a complete three-dimensional bionic bone scaffold is obtained by using a laser powder bed melting device for three-dimensional printing.

[0007] Furthermore, the above-mentioned design method for a nickel-titanium alloy superelastic biomimetic bone scaffold further includes, after the step of defining the G-type TPMS unit cell in the original Cartesian coordinate system using implicit functions, the following: The relative density ρ of the unit cell is controlled by a threshold parameter t, so that the unit cell can be continuously adjusted within a preset relative density range. The rotation angle θ ranges from 0° to 45°, and the relative density ρ ranges from 0.25 to 0.6.

[0008] Furthermore, the design method for the aforementioned nickel-titanium alloy superelastic bionic bone scaffold, wherein the steps of importing the STL model file into the corresponding analysis software, establishing a corresponding simulation model according to the test requirements, setting appropriate boundary conditions, load parameters, and calculation parameters, obtaining relevant data on the static load-bearing performance, dynamic recovery performance, and hydrodynamic performance of the bionic bone scaffold through simulation calculation, and forming corresponding performance spectra, to achieve coordinated control of the comprehensive performance of the bionic bone scaffold until the preset performance conditions are met, include: Import the STL model file into the 3D finite element analysis software to establish a quasi-static uniaxial compression model: Fully constrained boundary conditions were applied to the lower end face of the biomimetic bone scaffold model, and displacement-controlled loads were applied to the upper end face, with a total compressive strain of 10%–30%. The overall stress-strain curve is obtained by converting the reaction force and displacement of the upper end face. The equivalent elastic modulus of the bionic bone scaffold is obtained by the slope of the initial near-linear segment of the curve. The compressive strength of the structure is determined by the yield inflection point or the ultimate stress at the predetermined strain in the stress-strain curve. Quasi-static compression simulations were repeated under different combinations of rotation angle θ and relative density ρ to obtain static load-bearing performance maps of compressive strength and equivalent elastic modulus, which were used to characterize the static load-bearing capacity and anisotropic characteristics of the biomimetic bone scaffold.

[0009] Furthermore, the design method for the aforementioned nickel-titanium alloy superelastic bionic bone scaffold, wherein the steps of importing the STL model file into the corresponding analysis software, establishing a corresponding simulation model according to the test requirements, setting appropriate boundary conditions, load parameters, and calculation parameters, obtaining relevant data on the static load-bearing performance, dynamic recovery performance, and hydrodynamic performance of the bionic bone scaffold through simulation calculation, and forming corresponding performance spectra, to achieve coordinated control of the comprehensive performance of the bionic bone scaffold until the preset performance conditions are met, include: The STL model file was imported into the finite element software containing the constitutive model of shape memory alloys, and the hyperelastic loading-unloading simulation of the NiTi alloy G-type TPMS structure was performed at room temperature. Different target strains were set, and the stress-strain curves and volume-average martensite content of the structure during loading and unloading were calculated. The hysteresis loop area was obtained by integrating the stress-strain curves, and the strain recovery rate was calculated by the residual strain. Dynamic recovery performance spectra of rotation angle, relative density, strain recovery rate and martensitic phase content were obtained to evaluate the shape recoverability and damping energy dissipation level of the biomimetic bone scaffold under cyclic loading.

[0010] Furthermore, the design method for the aforementioned nickel-titanium alloy superelastic biomimetic bone scaffold, wherein the steps of importing the STL model file into the corresponding analysis software, establishing a corresponding simulation model according to the test requirements, setting appropriate boundary conditions, load parameters, and calculation parameters, obtaining relevant data on the static load-bearing performance, dynamic recovery performance, and hydrodynamic performance of the biomimetic bone scaffold through simulation calculation, and forming corresponding performance spectra, to achieve coordinated control of the comprehensive performance of the biomimetic bone scaffold until the preset performance conditions are met, further include: A steady-state incompressible laminar flow equation was established on a biomimetic bone scaffold model. The inlet cross-section velocity, outlet gauge pressure, working fluid, density, and viscosity were set, and the velocity field and pressure field were obtained by solving. The permeability was calculated based on Darcy's law. Simultaneously, the wall shear stress distribution is calculated using the wall tangential velocity gradient.

[0011] Furthermore, in the above-mentioned design method for a nickel-titanium alloy superelastic biomimetic bone scaffold, the method further includes: Target ranges for equivalent stiffness, strain recovery rate, permeability, and average martensite phase content are set respectively, and three independent performance index spaces are defined. A global scan and sensitivity analysis of the rotation angle and relative density design space are performed to identify the geometric variables that dominate stiffness, hyperelastic recovery and permeability-shear performance. The main control variables of static bearing capacity are distinguished from the main control variables of dynamic recovery and mass transfer, so as to decompose the contribution of design variables to the three types of performance. Based on multiple regression or response surface methodology, a predictive model of "design variables - three performance indicators" is constructed. Given the target range of any two performance indicators, the combination of structural parameters that meets the requirements of the third performance indicator is inversely calculated, thereby realizing the decoupled design and inverse prediction between static load-bearing capacity, dynamic hyperelastic recovery capacity and mass transfer performance. The predicted structural scheme is further verified through finite element and flow field simulation, and compared with the mechanical-fluid experimental results of the printed sample to correct the performance prediction model and achieve iterative optimization.

[0012] Furthermore, in the above-mentioned design method for a nickel-titanium alloy superelastic biomimetic bone scaffold, the step of obtaining a complete three-dimensional biomimetic bone scaffold by three-dimensional printing using a laser powder bed melting device based on the forming data file includes: The particle size of the nickel-titanium alloy powder is 15–53 μm, the Ni content is 50.9%, and the forming substrate is a NiTi alloy dense substrate.

[0013] Furthermore, in the above-mentioned design method for the nickel-titanium alloy superelastic biomimetic bone scaffold, the forming parameters include at least layer thickness, scanning path, and scanning rotation angle. The layer thickness is set to 10–40 μm, and the laser scanning path of each layer is rotated 60–75° relative to the previous layer.

[0014] Another objective of this invention is to provide a nickel-titanium alloy superelastic bionic bone scaffold, designed by the design method of the nickel-titanium alloy superelastic bionic bone scaffold described in any one of the above. The bionic bone scaffold has a multi-period inclined support continuous curved pore network formed by a G-type TPMS structure inside, and its shape is a cube or cylinder. The combination of its relative density and orientation angle makes the equivalent elastic modulus of the bionic bone scaffold match the target bone tissue.

[0015] Another objective of this invention is to provide an application of the nickel-titanium alloy superelastic bionic bone scaffold as described above in bone implants. The bone implants are used to repair long bones, flat bones, and irregular bone defects that bear cyclic loads. By adjusting the orientation angle and relative density of the bionic bone scaffold, personalized matching between structural stability, initial support, and long-term functional reconstruction can be achieved for different bone defect sites.

[0016] This invention introduces a multi-angle rotating G-type TPMS biomimetic structure, combined with hyperelastic constitutive modeling and fluid-mass transfer multiphysics simulation, to achieve synergistic control of scaffold geometry, equivalent elastic anisotropy, and permeability / wall shear force. This results in a scaffold with high strain recovery capacity and mechanical-mass transfer properties matching natural bone under cyclic loading, enabling high adaptability of the scaffold in complex physiological environments. It not only has high strain recovery capacity under cyclic loading, but also effectively alleviates stress concentration caused by uneven loading, providing stable support for bone tissue repair. Attached Figure Description

[0017] Figure 1 This is a flowchart of the design method of the nickel-titanium alloy superelastic bionic bone scaffold in the first embodiment of the present invention; Figure 2 This is a schematic diagram of the G-type TPMS unit cell in the design method of the nickel-titanium alloy superelastic biomimetic bone scaffold in the third embodiment of the present invention; Figure 3 This is a schematic diagram of the compressibility of the bionic bone scaffold in the design method of the nickel-titanium alloy superelastic bionic bone scaffold in the third embodiment of the present invention. Figure 4 This is a schematic diagram of the martensite content of the bionic bone scaffold in the design method of the nickel-titanium alloy superelastic bionic bone scaffold in the third embodiment of the present invention. Figure 5 This is a schematic diagram of the mass transfer performance of the bionic bone scaffold in the design method of the nickel-titanium alloy superelastic bionic bone scaffold in the third embodiment of the present invention. Figure 6 This is a schematic diagram of the tissue structure characterization of the bionic bone scaffold in the design method of the nickel-titanium alloy superelastic bionic bone scaffold in the third embodiment of the present invention.

[0018] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0019] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0020] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] Example 1 Please see Figure 1 The figure shows the design method of the nickel-titanium alloy superelastic bionic bone scaffold in the first embodiment of the present invention, the method including steps S10 to S14.

[0023] Step S10: In the original Cartesian coordinate system, define a G-type TPMS unit cell in the form of an implicit function, rotate the unit cell coordinate system around the Y-axis by a preset angle θ, keep the unit cell topological connectivity unchanged and only change the spatial orientation, to obtain G-type TPMS units cell with different rotation angles.

[0024] In the original Cartesian coordinate system, the G-type three-periodic minimal surface (Gyroid) unit cell is defined in the form of implicit functions, abbreviated as G-type TPMS. G-type TPMS is a typical porous, periodic, bicontinuous porous structure, which is widely used in lightweighting, lattice structures, biomimetic porous structures, heat exchange structures, etc. Gyroid structures are typically represented using implicit trigonometric functions. This expression can directly generate continuous, smooth, and periodic TPMS cells. The relative density ρ of the cells is controlled by a threshold parameter t, making ρ continuously adjustable within the range of 0.05 to 0.7. Based on this, the cell coordinate system is rotated around the Y-axis by a preset angle θ, keeping the topological connectivity of the cells unchanged while only changing the spatial orientation, thus obtaining G-type TPMS cells with different rotation angles.

[0025] Step S11: The rotated G-type TPMS unit cell is periodically translated and copied in the X, Y, and Z directions with a unit size L. The number of copies is Nx, Ny, and Nz, respectively, to form a spatial lattice array. A target volume domain matching the shape of the target scaffold is constructed. Boolean intersection operation is performed on the lattice array and the target volume domain, the intersection part is retained, and the STL model file is exported.

[0026] First, based on the G-type TPMS unit cell that has been rotated around the Y-axis by a specific angle θ, this unit cell is used as the smallest repeating unit. In the three orthogonal directions of X, Y, and Z in three-dimensional space, it is periodically translated and replicated with a uniform unit size L. The number of replications in the X direction is Nx, in the Y direction is Ny, and in the Z direction is Nz. Through this proportional and regular array arrangement, a structurally complete, topologically consistent, and three-dimensionally periodic G-type TPMS space lattice array is formed. The overall size of this array can be precisely calculated and determined by the unit size L and the number of replications Nx, Ny, and Nz (i.e., the total size in the X direction is L×Nx, in the Y direction is L×Ny, and in the Z direction is L×Nz). Subsequently, based on the specific shape contour, size requirements and design needs of the target stent (such as medical implants, industrial lightweight components, porous heat dissipation structures, etc.) in the actual application scenario, a "target volume domain" that is completely matched with the shape of the target stent is constructed. This target volume domain is essentially a three-dimensional geometric entity that wraps around or fits the shape of the stent, such as a cube or cylinder, to define the effective range of the final porous structure and avoid the lattice array from exceeding the shape of the stent or not completely filling the target area. Next, a Boolean intersection operation is performed on the constructed G-type TPMS spatial lattice array and the target bulk domain. The core logic of the Boolean intersection operation is to "retain the overlapping part of the two geometric entities and remove the non-overlapping part". Through this operation, the region that overlaps with the shape of the target support can be accurately extracted from the complete lattice array, so as to obtain a porous lattice structure that perfectly fits the contour, size and shape of the target bulk domain. This ensures that the final support has both the porous topological characteristics of G-type TPMS and meets the requirements of shape, size and installation matching in practical applications. Finally, the porous structure data obtained through Boolean intersection operation, which meets the shape requirements of the target support, is exported as an STL model file. STL is a common file format in the field of 3D molding. It only contains the geometric information of the triangular facets and topological connection relationships of the 3D model. It can be recognized and called by mainstream 3D printers, finite element analysis software, computer-aided engineering (CAE) simulation tools and computer-aided manufacturing (CAM) systems, thereby realizing a seamless connection from digital design to actual physical manufacturing and completing the entire process of digital construction of the G-type TPMS support structure.

[0027] For example, such as Figure 2 As shown, the G-type TPMS unit cell is replicated 4, 4, and 4 times in each of the X, Y, and Z directions to obtain a 4L×4L×4L lattice array. A cubic domain with a side length of 8mm is constructed in the array space, and Boolean intersection is performed with the lattice array to obtain a porous structure with an overall cubic shape, which serves as the target geometric model for subsequent simulation and fabrication.

[0028] Step S12: Import the STL model file into the corresponding analysis software, establish the corresponding simulation model according to the test requirements, set the appropriate boundary conditions, load parameters and calculation parameters, obtain relevant data on the static bearing performance, dynamic recovery performance and hydrodynamic performance of the bionic bone scaffold through simulation calculation, and form the corresponding performance spectrum to achieve coordinated control of the comprehensive performance of the bionic bone scaffold until the preset performance conditions are met.

[0029] The process involves importing STL model files into corresponding finite element analysis and fluid simulation software. Based on the different requirements of static mechanical testing, hyperelastic recovery testing, and fluid mass transfer testing, quasi-static compression models, hyperelastic loading and unloading models, and steady-state laminar flow models are established. Adaptive boundary conditions, load parameters, and calculation parameters are set for each simulation model. Static load-bearing capacity data, dynamic recovery performance data, and fluid dynamics performance data of the bionic bone scaffold are obtained sequentially through simulation calculations. Based on simulation data under multiple sets of different structural parameters, static load-bearing capacity performance maps, dynamic recovery performance maps, and fluid dynamics performance maps are generated. According to preset mechanical and mass transfer performance conditions, the comprehensive performance of the bionic bone scaffold is synergistically controlled until all performance characteristics meet the usage requirements.

[0030] Specifically, the STL model file is imported into the 3D finite element analysis software to establish a quasi-static uniaxial compression model: Fully constrained boundary conditions were applied to the lower end face of the biomimetic bone scaffold model, and displacement-controlled loads were applied to the upper end face, with a total compressive strain of 10%–30%. The overall stress-strain curve is obtained by converting the reaction force and displacement of the upper end face. The equivalent elastic modulus of the bionic bone scaffold is obtained by the slope of the initial near-linear segment of the curve. The compressive strength of the structure is determined by the yield inflection point or the ultimate stress at the predetermined strain in the stress-strain curve. Quasi-static compression simulations were repeated under different combinations of rotation angle θ and relative density ρ to obtain static load-bearing performance maps of compressive strength and equivalent elastic modulus, which were used to characterize the static load-bearing capacity and anisotropic characteristics of the biomimetic bone scaffold.

[0031] First, import the STL model file exported in the previous step, which fits the shape of the target support, into professional 3D finite element analysis software (such as ANSYS, Abaqus, etc.). The software will automatically recognize the topological information of the triangular facets of the STL model, and then construct a quasi-static uniaxial compression model for mechanical simulation. The core of quasi-static compression simulation is to simulate the mechanical response of the support under slow, uniform uniaxial pressure, avoid the interference of dynamic loads (such as impact) on the simulation results, and ensure that the data fits the stress scenario of the support in actual application (such as the slow pressure on human bones). Subsequently, boundary conditions and loads consistent with actual stress conditions were applied to the bionic bone scaffold model: a fully constrained boundary condition was applied to the lower end face of the model, restricting all displacements and rotations in the X, Y, and Z directions to simulate the fixed state of the scaffold in actual use (such as the fixation effect with surrounding bones after implantation in the human body); a displacement control load was applied to the upper end face of the model, and the total compressive strain was set to 10%–30%. Displacement control was chosen instead of force control to precisely control the degree of compression and avoid instantaneous model failure due to excessive load. At the same time, the strain range of 10%–30% covers the deformation range that the bionic bone scaffold may actually withstand, ensuring that key mechanical parameters are not missed due to insufficient strain, nor that the structure is destroyed due to excessive strain, thus ensuring the rationality and practicality of the simulation results. Next, using the calculation function of finite element software, the real-time correspondence between the reaction force and displacement of the upper end face during compression was obtained. Then, based on mechanical principles, this reaction force-displacement relationship was converted into a global stress-strain curve—stress was calculated by dividing the reaction force by the cross-sectional area of ​​the support structure, and strain was calculated by removing the actual compression displacement and subtracting the original height of the support structure. This curve can intuitively reflect the mechanical response law of the support structure during uniaxial compression. Based on this, the equivalent elastic modulus of the biomimetic bone support structure was calculated by using the slope of the near-linear segment in the initial stage of the stress-strain curve. The equivalent elastic modulus characterizes the resistance of a material (or structure) to... The core parameter of elastic deformation capacity directly reflects the "hardness" of the stent. The closer its value is to the elastic modulus of natural human bone, the better the biocompatibility and mechanical fit of the stent. At the same time, by identifying the yield inflection point in the stress-strain curve (that is, the turning point where the curve changes from linear to nonlinear, at which point the stent begins to undergo plastic deformation), or the ultimate stress corresponding to the preset strain (such as 10% or 15% strain), the compressive strength of the stent can be determined. The compressive strength is the maximum compressive stress that the stent can withstand. If this value is exceeded, the stent will undergo irreversible plastic deformation or even fracture. It is a key indicator for evaluating the load-bearing capacity of the stent. Finally, to comprehensively characterize the static load-bearing capacity and anisotropic characteristics (i.e., the differences in mechanical properties under different spatial orientations and densities) of the biomimetic bone scaffold, the entire quasi-static compression simulation process was repeated under different combinations of G-type TPMS unit cell rotation angles θ (different orientation angles preset in the previous steps) and scaffold relative density ρ (determined by the implicit function parameters and unit size of the TPMS unit cell, reflecting the porosity and compactness of the scaffold). Each combination of θ and ρ yielded corresponding compressive strength and equivalent elastic modulus data. After systematically organizing these data, a static load-bearing performance spectrum was formed. This spectrum clearly shows the influence of changes in θ and ρ on the mechanical properties of the scaffold, which can not only intuitively reflect the static load-bearing capacity of the scaffold under different conditions, but also clarify its anisotropic characteristics (such as the differences in mechanical properties of the scaffold in the X and Z directions under different rotation angles θ). This provides accurate mechanical data support for subsequent structural optimization of biomimetic bone scaffolds (such as determining the optimal rotation angle and optimal relative density), clinical application selection, or industrial design.

[0032] For example, such as Figure 3 As shown, the biomimetic bone scaffold model designed in this embodiment of the invention is subjected to small strain tensile and shear loads in the X, Y, and Z directions. The equivalent elastic modulus, shear modulus, and Poisson's ratio are obtained by solving the displacement field and stress field. The calculation results show that the equivalent elastic modulus of the structure in the three principal directions is close to that of cancellous bone, which can reduce the stress shielding effect.

[0033] Furthermore, the STL model file was imported into finite element software containing shape memory alloy constitutive models, and a hyperelastic loading-unloading simulation was performed on the NiTi alloy G-type TPMS structure at room temperature. Different target strains were set, and the stress-strain curves and volume-average martensite content of the structure during loading and unloading were calculated. The hysteresis loop area was obtained by integrating the stress-strain curves, and the strain recovery rate was calculated by the residual strain. Dynamic recovery performance spectra of rotation angle, relative density, strain recovery rate and martensitic phase content were obtained to evaluate the shape recoverability and damping energy dissipation level of the biomimetic bone scaffold under cyclic loading.

[0034] In this process, after performing Boolean intersection operations on the lattice array and the target bulk domain and exporting the STL model file, the STL model file is imported into the finite element software with a built-in Lagoudas shape memory alloy constitutive model. The superelastic loading-unloading simulation of the nickel-titanium alloy G-type TPMS structure is then carried out at room temperature.

[0035] During the simulation, target strains of 2% and 4% were set respectively. The stress-strain curves of the support structure during the entire loading and unloading process were calculated, as well as the average martensite content of the overall volume. The hysteresis loop area was obtained by integrating the stress-strain curves, and the strain recovery rate of the support was calculated based on the residual strain values ​​obtained from the simulation.

[0036] By integrating simulation data under different rotation angles and relative densities, a dynamic recovery performance spectrum is obtained, which includes rotation angle, relative density, strain recovery rate, and martensitic phase content. This spectrum can accurately evaluate the shape recovery capability and damping energy dissipation level of the biomimetic bone scaffold under cyclic loading, reflecting the hyperelastic performance of the scaffold.

[0037] For example, such as Figure 4 As shown, the STL model file designed according to the design method proposed in this embodiment of the invention is imported into finite element software containing shape memory alloy constitutive models. The Lagoudas model is used to describe the phase transformation behavior of the NiTi alloy at room temperature. Compressive strains of 2% and 4% are applied to the overall structure, and the stress-strain curves and volume-average martensite content of the structure during loading-unloading are calculated. The results show that the structure can recover almost completely under 4% strain, with residual strain less than 0.2%, indicating that this configuration has good superelastic recovery capability.

[0038] Furthermore, a steady-state incompressible laminar flow equation was established on the biomimetic bone scaffold model. The inlet section velocity, outlet gauge pressure, working fluid, density, and viscosity were set, and the velocity field and pressure field were obtained by solving. The permeability was calculated based on Darcy's law. Simultaneously, the wall shear stress distribution is calculated using the wall tangential velocity gradient. Firstly, based on the constructed three-dimensional model of the bionic bone scaffold, and combined with its actual application scenarios (such as the interaction with body fluids after implantation in the human body), a steady-state incompressible laminar flow equation is established. Steady-state means that the fluid flow state does not change with time, incompressible indicates that the fluid density is constant (which conforms to the characteristics of common working fluids such as human body fluids), and laminar flow corresponds to the state in which each particle moves along the streamline and there is no obvious turbulent disturbance when the fluid flows. This equation is the core mathematical model describing the fluid flow law in the scaffold and can accurately characterize the flow characteristics of the fluid in the porous structure of the scaffold. Subsequently, based on actual testing requirements and application scenarios, a series of suitable fluid dynamic parameters are set: inlet cross-sectional velocity (the flow rate of working fluids such as body fluids entering the stent, which must conform to the physiological flow rate of the human body or the fluid velocity of the actual use scenario), outlet gauge pressure (usually set to standard atmospheric pressure to simulate the pressure environment after the fluid flows out of the stent and ensure stable flow), and the working fluid is specified (such as physiological saline simulating human body fluids, specific fluids simulating nutrient solutions, etc., which must be consistent with the actual application scenario). At the same time, the density and viscosity of the fluid are set (these two parameters are key to affecting fluid flow resistance and velocity distribution, and must be set accurately according to the selected working fluid; for example, the density and viscosity of physiological saline must conform to human physiological parameters). After setting the parameters, the steady-state incompressible laminar flow equation can be solved using finite element analysis software to obtain the complete velocity and pressure field data of the fluid inside the support. The velocity field can intuitively reflect the flow velocity distribution of the fluid in the porous channels of the support, identify which areas have fast flow velocity and which areas have slow flow velocity, and determine whether there are problems such as blockage or poor flow in the support channels. The pressure field can show the pressure change law of the fluid in the support, reflect the magnitude of the resistance when the fluid flows, and provide a basis for evaluating the fluid permeability performance of the support. Based on this, and using Darcy's law (a core law describing fluid flow in porous media, applicable to porous structures like TPMS porous scaffolds), combined with the obtained pressure and velocity field data and the scaffold's geometric parameters (such as porosity and channel size), the permeability of the scaffold was calculated. Permeability is a core indicator characterizing the ability of a porous structure to allow fluid to pass through. Higher permeability indicates lower resistance to fluid flow within the scaffold, which is more conducive to fluid circulation, nutrient delivery, or metabolic waste removal. For biomimetic bone scaffolds, appropriate permeability is key to achieving biocompatibility and clinical application value. Simultaneously, by analyzing the tangential velocity gradient of the fluid at the scaffold wall, the wall shear stress distribution was calculated. Wall shear stress is the tangential force exerted on the scaffold wall by the fluid flow; its uniformity and magnitude directly affect the structural stability (excessive shear stress may lead to scaffold wall wear and fatigue failure) and biocompatibility (appropriate shear stress can promote cell adhesion and proliferation, while excessively high or low stress may inhibit cell growth). The simulation calculation of fluid dynamics performance, combined with the simulation of static load-bearing performance and dynamic recovery performance, constitutes a simulation testing system for the comprehensive performance of the bionic bone scaffold. By acquiring fluid dynamics-related data such as permeability, wall shear stress distribution, velocity field, and pressure field, and combining them with static load-bearing and dynamic recovery data, a complete comprehensive performance spectrum is formed. Then, according to preset performance conditions (such as mechanical parameters that adapt to human bones and fluid parameters that meet physiological needs), the scaffold structure (such as TPMS rotation angle, relative density, pore size, etc.) is coordinated and controlled until all performance indicators meet the preset requirements, ensuring that the bionic bone scaffold has both good mechanical load-bearing capacity and dynamic recovery capacity, as well as fluid dynamics performance that is suitable for actual application scenarios.

[0039] For example, setting the inlet section velocity = The outlet gauge pressure is 0 Pa, and the working fluid is water with a density of 1000. The viscosity is 1×10 -3 Pa·s; the velocity and pressure fields are obtained by solving, and the permeability is calculated based on Darcy's law; at the same time, the wall shear stress distribution is calculated by the tangential velocity gradient of the wall.

[0040] Specifically, such as Figure 5 As shown, the biomimetic bone scaffold model designed in this embodiment of the invention was tested accordingly. The results show that the internal flow channels of the structure have good connectivity, the permeability reaches the level required for bone tissue engineering scaffolds, and the average wall shear stress is within the range that is conducive to osteoblast adhesion and differentiation.

[0041] Step S13: Import the STL model file into the slicing software, perform layered slicing on the bionic bone scaffold model contained in the STL model file, and then set the corresponding forming parameters to generate a forming data file adapted to the laser powder bed melting equipment.

[0042] The process involves importing the performance-verified STL model file into a dedicated slicing software, performing layered slicing on the bionic bone scaffold model within the software, setting forming parameters such as layer thickness, scanning path, and scanning rotation angle according to the requirements of laser powder bed melting, and generating a forming data file that can be directly adapted to laser powder bed melting equipment after the parameter settings are completed.

[0043] In practice, the layer thickness is set to 10–40 μm, and the laser scanning path of each layer is rotated 60–75° relative to the previous layer.

[0044] Step S14: Based on the forming data file, use a laser powder bed melting device to perform three-dimensional printing to obtain a complete three-dimensional bionic bone scaffold.

[0045] The generated forming data file is imported into the laser powder bed melting equipment. The equipment sequentially completes the operations of powder spreading, selective laser melting, and layer-by-layer stacking according to the instructions in the data file, and continues to process until a three-dimensional bionic bone scaffold with a complete external shape and internal structure is constructed.

[0046] For example, a powder bed melting printing device (such as the EOS M100) is used to lay NiTi alloy powder with a particle size of 15–53 μm on a NiTi substrate and melt it layer by layer to form the final shape. The laser power is set to 90 W and the scanning speed is 650 Hz. The laser spot diameter is approximately 40 μm, the layer thickness is 20 μm, and the scanning path for each layer is rotated 67° relative to the previous layer. After printing, the scaffold is separated from the substrate by wire cutting and ultrasonically cleaned with anhydrous ethanol to remove residual powder and wire cutting fluid.

[0047] In summary, the design method of the nickel-titanium alloy hyperelastic biomimetic bone scaffold in the above embodiments of the present invention, by introducing a multi-angle rotating G-type TPMS biomimetic structure and combining hyperelastic constitutive modeling with fluid-mass transfer multiphysics simulation, achieves synergistic control of scaffold geometry, equivalent elastic anisotropy, and permeability / wall shear force. This results in a scaffold with high strain recovery capacity and mechanical-mass transfer properties matching natural bone under cyclic loading, enabling the scaffold to achieve high adaptability in complex physiological environments. It not only has high strain recovery capacity under cyclic loading but also effectively alleviates stress concentration caused by uneven loading, providing stable support for bone tissue repair.

[0048] Example 2 This embodiment also proposes a design method for a nickel-titanium alloy superelastic bionic bone scaffold. The difference between the design method of the nickel-titanium alloy superelastic bionic bone scaffold in this embodiment and the design method of the nickel-titanium alloy superelastic bionic bone scaffold in Embodiment 1 is as follows: The method further includes: Target ranges for equivalent stiffness, strain recovery rate, permeability, and average martensite phase content are set respectively, and three independent performance index spaces are defined. A global scan and sensitivity analysis of the rotation angle and relative density design space are performed to identify the geometric variables that dominate stiffness, hyperelastic recovery and permeability-shear performance. The main control variables of static bearing capacity are distinguished from the main control variables of dynamic recovery and mass transfer, so as to decompose the contribution of design variables to the three types of performance. Based on multiple regression or response surface methodology, a predictive model of "design variables - three performance indicators" is constructed. Given the target range of any two performance indicators, the combination of structural parameters that meets the requirements of the third performance indicator is inversely calculated, thereby realizing the decoupled design and inverse prediction between static load-bearing capacity, dynamic hyperelastic recovery capacity and mass transfer performance. The predicted structural scheme is further verified through finite element and flow field simulation, and compared with the mechanical-fluid experimental results of the printed sample to correct the performance prediction model and achieve iterative optimization.

[0049] First, the core performance objectives of the stent design are clearly defined, and target ranges for four key performance categories are set: equivalent stiffness (corresponding to static load-bearing performance, characterizing the stent's ability to resist elastic deformation, which needs to be adapted to the stiffness of human bones to avoid stress shielding), strain recovery rate (corresponding to dynamic hyperelastic recovery performance, reflecting the hyperelastic advantages of nickel-titanium alloy materials, ensuring that the stent can recover its original shape after being deformed under load, avoiding irreversible damage), permeability (corresponding to mass transfer performance, reflecting the stent's ability to allow body fluids and nutrients to pass through, ensuring cell survival and tissue regeneration after implantation), and average martensite phase content (the core influencing factor of the hyperelasticity of nickel-titanium alloy, directly related to strain recovery rate and stiffness, which needs to be controlled within a reasonable range to ensure the stability of hyperelastic performance). At the same time, these three core performance categories (static load-bearing, dynamic hyperelastic recovery, and mass transfer) are defined as three independent performance index spaces to avoid mutual interference between different performances, laying the foundation for subsequent performance decoupling and variable analysis. Next, a global scan and sensitivity analysis were conducted on the design space comprised of the key design variables of the scaffold—the rotation angle θ of the G-type TPMS unit cell (which affects the spatial orientation and anisotropy of the structure) and the relative density ρ of the scaffold (which affects porosity, stiffness, and permeability). The global scan involved traversing all possible combinations of rotation angles and relative densities within the design space to obtain the three major performance data corresponding to each combination. The sensitivity analysis, through quantitative calculation, identified the geometric variables that play a dominant role in each type of performance (for example, relative density may play a dominant role in equivalent stiffness and permeability, while rotation angle may play a dominant role in stiffness anisotropy and wall shear stress). This allowed for a clear distinction between the main control variables of static bearing capacity, dynamic hyperelastic recovery capacity, and mass transfer capacity (permeability-shear capacity), achieving a precise decomposition of the contribution of design variables to the three types of performance. This avoided performance optimization chaos caused by the cross-influence of variables and made the control direction of each design variable more targeted. Then, based on the large amount of data on the corresponding design variables and performance indicators obtained from the previous global scan, a prediction model of "design variables - three performance indicators" is constructed using multiple regression or response surface methodology. Multiple regression establishes a linear or nonlinear relationship between design variables (rotation angle, relative density) and each type of performance indicator through mathematical fitting. The response surface methodology, by constructing a three-dimensional or multi-dimensional surface model, intuitively presents the influence of changes in design variables on performance indicators. The core value of this prediction model is to achieve "reverse prediction"—that is, given any two performance indicator target ranges (such as setting specific intervals for equivalent stiffness and strain recovery rate), the model can deduce the combination of rotation angle and relative density that can meet the requirements of the third performance indicator (such as permeability). This enables the decoupling design between static bearing capacity, dynamic hyperelastic recovery capability, and mass transfer performance, breaks the bottleneck of mutual constraints among the three types of performance, solves the problem of "optimizing one type of performance leading to the deterioration of another type of performance" in traditional design, and achieves multi-performance synergistic compliance. Finally, to ensure the accuracy of the prediction model and the feasibility of the design scheme, the optimal combination of structural parameters obtained from the prediction model will be further comprehensively verified through finite element simulation (verifying static load-bearing capacity and dynamic recovery performance) and flow field simulation (verifying mass transfer performance such as permeability and wall shear stress) to verify whether the structural scheme truly meets all preset performance targets. Simultaneously, nickel-titanium alloy printed prototypes of the structural scheme will be fabricated, and actual performance data will be obtained through physical mechanics experiments (such as uniaxial compression tests) and fluid experiments (such as permeability tests). The simulation verification results will be compared and analyzed with the experimental test results to identify deviations between the prediction model and actual conditions, thereby correcting the parameters of the performance prediction model and optimizing the model accuracy. Through this iterative optimization process of "prediction-verification-comparison-correction," the design scheme will be continuously improved until the final combination of structural parameters meets all preset performance targets and is compatible with the 3D printing process of nickel-titanium alloy, ensuring the practicality and reliability of the design scheme and providing solid technical support for the large-scale production and clinical application of nickel-titanium alloy hyperelastic biomimetic bone scaffolds.

[0050] In summary, the design method of the nickel-titanium alloy hyperelastic biomimetic bone scaffold in the above embodiments of the present invention, by introducing a multi-angle rotating G-type TPMS biomimetic structure and combining hyperelastic constitutive modeling with fluid-mass transfer multiphysics simulation, achieves synergistic control of scaffold geometry, equivalent elastic anisotropy, and permeability / wall shear force. This results in a scaffold with high strain recovery capacity and mechanical-mass transfer properties matching natural bone under cyclic loading, enabling the scaffold to achieve high adaptability in complex physiological environments. It not only has high strain recovery capacity under cyclic loading but also effectively alleviates stress concentration caused by uneven loading, providing stable support for bone tissue repair.

[0051] Example 3 This embodiment proposes a nickel-titanium alloy superelastic bionic bone scaffold, which is designed by the above-mentioned design method of nickel-titanium alloy superelastic bionic bone scaffold. The bionic bone scaffold has a multi-period inclined support continuous curved pore network formed by a G-type TPMS structure inside, and its shape is a cube or cylinder. The combination of its relative density and orientation angle makes the equivalent elastic modulus of the bionic bone scaffold match the target bone tissue.

[0052] The stent forms a multi-level inclined support network in three-dimensional space, similar to a glass sponge skeleton. It exhibits high damage tolerance and excellent superelastic recovery characteristics under complex loads such as compression, bending and shearing. At the same time, a continuous and unobstructed flow channel network is constructed inside the stent, which enables the effective exchange of nutrients and metabolites.

[0053] like Figure 6 As shown, the microstructure of the printed nickel-titanium alloy hyperelastic biomimetic bone scaffold was characterized. First, typical samples were cut along the forming direction and perpendicular to the forming direction. After mounting, progressive grinding, and mechanical polishing, the forming quality of the scaffold pore walls, the morphology of the molten pool overlap, and the microstructure characteristics were observed using metallographic microscopy and scanning electron microscopy. When necessary, energy dispersive spectroscopy (EDS) was used to detect the local elemental distribution, and X-ray diffraction (XRD) or electron backscattering diffraction (ESD) was used to analyze the phase composition and grain orientation. The results show that the matrix of the shaped scaffold is dominated by the B2 austenite phase. This microstructure is conducive to the reversible stress-induced phase transformation of the scaffold under room temperature compression conditions, thus providing a microstructural basis for its excellent hyperelastic recovery performance.

[0054] Example 4 This embodiment proposes the application of the nickel-titanium alloy superelastic bionic bone scaffold as described above in bone implants. The bone implants are used to repair long bones, flat bones, and irregular bone defects that bear cyclic loads. By adjusting the orientation angle and relative density of the bionic bone scaffold, personalized matching between structural stability, initial support, and long-term functional reconstruction can be achieved for different bone defect sites.

[0055] Among them, the application of the aforementioned nickel-titanium alloy superelastic biomimetic bone scaffold in bone implants is particularly suitable for repairing long bones, flat bones, and irregular bone defects that bear cyclic loads. By adjusting the orientation angle and relative density of the scaffold, personalized matching between structural stability, initial support, and long-term functional reconstruction can be achieved for bone defects in different locations.

[0056] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] Those skilled in the art will understand that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequential list of executable instructions for implementing logical functions, and can be embodied in any computer-readable storage medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable storage medium" can mean any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0058] More specific examples (a non-exhaustive list) of computer-readable storage media include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable storage media can even be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0059] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0060] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A design method for a nickel-titanium alloy superelastic biomimetic bone scaffold, characterized in that, The method includes: In the original Cartesian coordinate system, a G-type TPMS unit cell is defined in the form of an implicit function. The unit cell coordinate system is rotated around the Y-axis by a preset angle θ, keeping the topological connectivity of the unit cell unchanged and only changing the spatial orientation, to obtain G-type TPMS unit cells with different rotation angles. The rotated G-type TPMS unit cell is periodically translated and replicated in the X, Y, and Z directions with a unit size L, and the number of copies is Nx, Ny, and Nz respectively to form a spatial lattice array. A target volume domain matching the shape of the target scaffold is constructed. Boolean intersection operation is performed on the lattice array and the target volume domain, the intersection part is retained, and the STL model file is exported. Import the STL model file into the corresponding analysis software, establish the corresponding simulation model according to the test requirements, set the appropriate boundary conditions, load parameters and calculation parameters, obtain relevant data on the static bearing performance, dynamic recovery performance and hydrodynamic performance of the bionic bone scaffold through simulation calculation, and form the corresponding performance spectrum to achieve coordinated control of the comprehensive performance of the bionic bone scaffold until the preset performance conditions are met. Import the STL model file into the slicing software, perform layered slicing on the bionic bone scaffold model contained in the STL model file, then set the corresponding forming parameters to generate a forming data file adapted to the laser powder bed melting equipment. Based on the forming data file, a complete three-dimensional bionic bone scaffold is obtained by using a laser powder bed melting device for three-dimensional printing.

2. The design method of the nickel-titanium alloy superelastic biomimetic bone scaffold according to claim 1, characterized in that, The step of defining the G-type TPMS unit cell in implicit function form in the original Cartesian coordinate system further includes: The relative density ρ of the unit cell is controlled by a threshold parameter t, so that the unit cell can be continuously adjusted within a preset relative density range. The rotation angle θ ranges from 0° to 45°, and the relative density ρ ranges from 0.25 to 0.

6.

3. The design method of the nickel-titanium alloy superelastic biomimetic bone scaffold according to claim 1, characterized in that, The steps of importing the STL model file into the corresponding analysis software, establishing a corresponding simulation model according to the test requirements, setting appropriate boundary conditions, load parameters and calculation parameters, obtaining relevant data on the static load-bearing performance, dynamic recovery performance and hydrodynamic performance of the bionic bone scaffold through simulation calculation, and forming corresponding performance maps to achieve coordinated control of the comprehensive performance of the bionic bone scaffold until the preset performance conditions are met include: Import the STL model file into the 3D finite element analysis software to establish a quasi-static uniaxial compression model: Fully constrained boundary conditions were applied to the lower end face of the biomimetic bone scaffold model, and displacement-controlled loads were applied to the upper end face, with a total compressive strain of 10%–30%. The overall stress-strain curve is obtained by converting the reaction force and displacement of the upper end face. The equivalent elastic modulus of the bionic bone scaffold is obtained by the slope of the initial near-linear segment of the curve. The compressive strength of the structure is determined by the yield inflection point or the ultimate stress at the predetermined strain in the stress-strain curve. Quasi-static compression simulations were repeated under different combinations of rotation angle θ and relative density ρ to obtain static load-bearing performance maps of compressive strength and equivalent elastic modulus, which were used to characterize the static load-bearing capacity and anisotropic characteristics of the biomimetic bone scaffold.

4. The design method of the nickel-titanium alloy superelastic biomimetic bone scaffold according to claim 3, characterized in that, The steps of importing the STL model file into the corresponding analysis software, establishing a corresponding simulation model according to the test requirements, setting appropriate boundary conditions, load parameters and calculation parameters, obtaining relevant data on the static load-bearing performance, dynamic recovery performance and hydrodynamic performance of the bionic bone scaffold through simulation calculation, and forming corresponding performance spectra to achieve coordinated control of the comprehensive performance of the bionic bone scaffold until the preset performance conditions are met also include: The STL model file was imported into the finite element software containing the constitutive model of shape memory alloys, and the hyperelastic loading-unloading simulation of the NiTi alloy G-type TPMS structure was performed at room temperature. Different target strains were set, and the stress-strain curves and volume-average martensite content of the structure during loading and unloading were calculated. The hysteresis loop area was obtained by integrating the stress-strain curves, and the strain recovery rate was calculated by the residual strain. Dynamic recovery performance spectra of rotation angle, relative density, strain recovery rate and martensitic phase content were obtained to evaluate the shape recoverability and damping energy dissipation level of the biomimetic bone scaffold under cyclic loading.

5. The design method of the nickel-titanium alloy superelastic biomimetic bone scaffold according to claim 4, characterized in that, The steps of importing the STL model file into the corresponding analysis software, establishing a corresponding simulation model according to the test requirements, setting appropriate boundary conditions, load parameters and calculation parameters, obtaining relevant data on the static load-bearing performance, dynamic recovery performance and hydrodynamic performance of the bionic bone scaffold through simulation calculation, and forming corresponding performance spectra to achieve coordinated control of the comprehensive performance of the bionic bone scaffold until the preset performance conditions are met also include: A steady-state incompressible laminar flow equation was established on a biomimetic bone scaffold model. The inlet cross-section velocity, outlet gauge pressure, working fluid, density, and viscosity were set, and the velocity field and pressure field were obtained by solving. The permeability was calculated based on Darcy's law. Simultaneously, the wall shear stress distribution is calculated using the wall tangential velocity gradient.

6. The design method of the nickel-titanium alloy superelastic biomimetic bone scaffold according to claim 5, characterized in that, The method further includes: Target ranges for equivalent stiffness, strain recovery rate, permeability, and average martensite phase content are set respectively, and three independent performance index spaces are defined. A global scan and sensitivity analysis of the rotation angle and relative density design space are performed to identify the geometric variables that dominate stiffness, hyperelastic recovery and permeability-shear performance. The main control variables of static bearing capacity are distinguished from the main control variables of dynamic recovery and mass transfer, so as to decompose the contribution of design variables to the three types of performance. Based on multiple regression or response surface methodology, a predictive model of "design variables - three performance indicators" is constructed. Given the target range of any two performance indicators, the combination of structural parameters that meets the requirements of the third performance indicator is inversely calculated, thereby realizing the decoupled design and reverse prediction between static load-bearing capacity, dynamic hyperelastic recovery capacity and mass transfer performance. The predicted structural scheme is further verified through finite element and flow field simulation, and compared with the mechanical-fluid experimental results of the printed sample to correct the performance prediction model and achieve iterative optimization.

7. The design method of the nickel-titanium alloy superelastic biomimetic bone scaffold according to claim 1, characterized in that, The step of obtaining a complete three-dimensional bionic bone scaffold by three-dimensional printing using a laser powder bed melting device based on the forming data file includes: The particle size of the nickel-titanium alloy powder is 15–53 μm, the Ni content is 50.9%, and the forming substrate is a NiTi alloy dense substrate.

8. The design method of the nickel-titanium alloy superelastic biomimetic bone scaffold according to claim 1, characterized in that, The forming parameters include at least layer thickness, scanning path, and scanning rotation angle; The layer thickness is set to 10–40 μm, and the laser scanning path of each layer is rotated 60–75° relative to the previous layer.

9. A nickel-titanium alloy superelastic biomimetic bone scaffold, characterized in that, The bionic bone scaffold is designed by the design method of nickel-titanium alloy superelasticity according to any one of claims 1 to 8. The bionic bone scaffold has a multi-period inclined support continuous curved pore network formed by a G-type TPMS structure inside. The shape is a cube or cylinder. The combination of its relative density and orientation angle makes the equivalent elastic modulus of the bionic bone scaffold match the target bone tissue.

10. The application of the nickel-titanium alloy superelastic biomimetic bone scaffold as described in claim 9 in bone implants, characterized in that, The bone implant is used to repair long bones, flat bones, and irregular bone defects that bear cyclic loads. By adjusting the orientation angle and relative density of the bionic bone scaffold, personalized matching between structural stability, initial support, and long-term functional reconstruction can be achieved for different bone defect sites.

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