Topological optimization and additive manufacturing method and system for porous bone implant

Abstract

The invention discloses a porous bone implant topological optimization and additive manufacturing method and system. The method comprises the following steps: acquiring mechanical property data of hip joint bones and implant bearing conditions, analyzing bone density distribution characteristics and dynamic load conditions, and constructing bearing characteristics; stress distribution is identified based on finite element analysis, an interface sensitive area is calibrated, and an elastic modulus matching reference is established; variable density topological optimization is adopted to determine porosity gradient distribution, and a three-period minimal curved surface is utilized to perform pore unit configuration screening; the Zr-Nb alloy is subjected to partition forming control through the selective laser melting technology, and the pore communication forming sequence is optimized; a ZrO2-ZnO heterojunction antibacterial coating is constructed on the surface of the porous matrix; and mechanical and antibacterial performance coupling analysis is carried out to establish function partition mapping, and a forming process instruction is output. The problem that mechanical adaptation and antibacterial functions of the porous implant are difficult to consider at the same time is solved, and the prepared implant can meet the bearing requirement and the anti-infection requirement at the same time.

Description

Technical Field

[0001] This invention relates to the field of orthopedic implant manufacturing technology, and in particular to a method and system for topology optimization and additive manufacturing of porous bone implants. Background Technology

[0002] Hip replacement surgery is an effective treatment for conditions such as avascular necrosis of the femoral head and osteoarthritis of the hip. The long-term stability of the implant directly affects the success rate of the surgery and the patient's quality of life. An ideal hip implant needs to meet both mechanical load-bearing and biocompatibility requirements. It must have sufficient strength to support the loads of daily activities while promoting bone ingrowth for biological fixation. However, the elastic modulus of traditional metal implants is much higher than that of human bone. This stiffness mismatch can lead to a stress shielding effect, causing the surrounding bone tissue to gradually absorb and degenerate due to lack of mechanical stimulation, ultimately resulting in implant loosening and failure.

[0003] To address these issues, researchers have attempted to reduce the equivalent stiffness of implants by introducing porous structures to match the mechanical properties of bone tissue. However, existing porous implant design methods have the following shortcomings: First, the pore distribution lacks specificity, failing to differentiate design based on the stress characteristics of the implantation site, making it difficult to balance the load-bearing requirements of high-load areas and the osseointegration requirements of bone contact areas; second, the antibacterial function of porous structures is insufficiently considered, as postoperative infection remains one of the major complications of joint replacement surgery, and relying solely on systemic antibiotic administration is insufficient to achieve an effective drug concentration on the implant surface; third, there is a disconnect between structural design and manufacturing processes, as the ideal configuration obtained through topology optimization often cannot be faithfully reproduced due to limitations in additive manufacturing precision, resulting in discrepancies between designed and actual performance. Summary of the Invention

[0004] This invention discloses a method and system for topology optimization and additive manufacturing of porous bone implants, aiming to solve the problems of insufficient mechanical adaptability, lack of antibacterial function, and disconnect between design and manufacturing in existing porous implant designs. By constructing a complete process technology system from bone mechanical property acquisition, load-bearing boundary analysis, gradient porosity optimization, additive precision forming to antibacterial coating loading, the invention achieves mechanical-antibacterial synergistic optimization design and integrated manufacturing of porous bone implants.

[0005] The first aspect of this invention proposes a method for topology optimization and additive manufacturing of porous bone implants, comprising the following steps: Obtain the mechanical performance data of the hip joint bone and the load-bearing conditions of the implant, and perform boundary condition analysis on the mechanical performance data and the load-bearing conditions to form load-bearing characteristics; Based on the load-bearing characteristics, finite element mechanical analysis is performed to identify stress characteristics. From the stress characteristics, load levels are layered to establish a mechanical benchmark library. Through the mechanical benchmark library, elastic modulus matching detection is performed to generate modulus deviation index. The load-bearing characteristics are subjected to variable density topology optimization to determine the pore gradient distribution. The pore gradient distribution is used to optimize the pore unit configuration to identify the optimal configuration. Based on the optimal configuration, the modulus deviation index is adjusted to form gradient matching parameters. The gradient matching parameters are used to perform additive manufacturing layer forming control to determine the porous matrix forming state. Based on the porous matrix forming state, matrix parameters are generated. The zinc-based coating load and heterojunction interface bonding strength are controlled from the matrix parameters to construct the heterojunction coating structure. A synergy coefficient is extracted by performing mechanical-antibacterial performance coupling analysis on the modulus deviation index and the gradient matching parameter. The ultrasonic response critical point is identified based on the synergy coefficient. An ultrasonic stimulation parameter library is constructed based on the ultrasonic response critical point. The forming process instruction is output by integrating the heterojunction coating structure through the ultrasonic stimulation parameter library.

[0006] A second aspect of this invention provides a porous bone implant topology optimization and additive manufacturing system, comprising: The data acquisition module is used to acquire the mechanical performance data of the hip joint bone and the load-bearing conditions of the implant, and to perform boundary condition analysis on the mechanical performance data and the load-bearing conditions to form load-bearing characteristics. The finite element analysis module is used to perform finite element mechanical analysis based on the load characteristics to identify stress characteristics, establish a mechanical benchmark library by load level stratification from the stress characteristics, and generate a modulus deviation index by performing elastic modulus matching detection through the mechanical benchmark library. The topology optimization module is used to perform variable density topology optimization processing on the bearing characteristics to determine the pore gradient distribution, use the pore gradient distribution to optimize the pore unit configuration to identify the optimal configuration, and adjust the modulus deviation index based on the optimal configuration to form gradient matching parameters. An additive manufacturing module is used to control the additive manufacturing layered forming of the gradient matching parameters to determine the forming state of the porous matrix, generate matrix parameters based on the forming state of the porous matrix, and construct a heterojunction coating structure by controlling the zinc-based coating load and the bonding strength of the heterojunction interface from the matrix parameters. The collaborative control module is used to perform mechanical-antibacterial performance coupling analysis on the modulus deviation index and the gradient matching parameters to extract the collaborative coefficient, identify the ultrasonic response critical point based on the collaborative coefficient, construct an ultrasonic stimulation parameter library based on the ultrasonic response critical point, and output forming process instructions by integrating the heterojunction coating structure through the ultrasonic stimulation parameter library.

[0007] The beneficial effects of this invention are reflected in the following points: First, by acquiring the mechanical property data of the hip joint bones and the load-bearing conditions of the implant, the bone density distribution characteristics and multi-posture load conditions of cortical and cancellous bone are systematically analyzed. A mechanical analysis system covering stress grading, identification of interface sensitive areas, and elastic modulus matching detection is established. This system can accurately set the modulus constraint range of each region for different load-bearing requirements, overcoming the problem of local stiffness mismatch caused by the use of uniform design parameters in traditional methods. Second, a variable density topology optimization method is used to determine the pore gradient distribution. Based on the three-period minimum surface, the pore unit configuration design and mechanical performance verification are carried out. A configuration scheme that balances load-bearing strength and bone ingrowth requirements is selected. The outer surface adopts a configuration with excellent mechanical properties to ensure load-bearing capacity, the interior adopts a configuration with good permeability to promote bone integration, and the transition area adopts a morphological gradient to achieve a smooth performance transition. This makes the stiffness of each region of the implant match that of the adjacent bone tissue, effectively alleviating the stress shielding effect. Finally, laser selective melting technology was used to achieve zoned forming control of the porous matrix. The forming quality was ensured by optimizing pore connectivity and adapting zoned process parameters. A zinc-based heterojunction coating was constructed on the surface of the porous matrix to give the implant antibacterial function. Coupled analysis of mechanical and antibacterial properties was carried out to establish functional zone mapping. Forming process instructions that comprehensively consider load-bearing and antibacterial requirements were output, realizing the integration of porous bone implant design and manufacturing. Attached Figure Description

[0008] The accompanying drawings illustrate specific examples of the technical solutions described in this invention and, together with the detailed embodiments, form part of the specification, serving to explain the technical solutions, principles, and effects of this invention.

[0009] Figure 1 This is a schematic flowchart of a method for topology optimization and additive manufacturing of porous bone implants according to the present invention.

[0010] Figure 2 This is a schematic diagram of the three-period minimal curved pore structure of the present invention.

[0011] Figure 3 This is a schematic diagram of the ZrO2-ZnO heterojunction coating structure of the present invention.

[0012] Figure 4 This is a structural block diagram of a porous bone implant topology optimization and additive manufacturing system according to the present invention.

[0013] Among them: 2a-Gyroid structure unit cell, 2b-Diamond structure, 2c-Schwarz P structure, 2d-mixed configuration, 3a-Zr-Nb porous substrate, 3b-ZrO2 oxide layer, 3c-heterojunction transition region, 3d-ZnO coating. Detailed Implementation

[0014] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0015] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0016] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0017] The technical solutions of the embodiments of this application will be described below.

[0018] like Figure 1 As shown, this embodiment of the invention provides a method for topology optimization and additive manufacturing of porous bone implants, including the following steps S110-S150: Step S110: Obtain the mechanical performance data of the hip joint bone and the load-bearing conditions of the implant, and perform boundary condition analysis on the mechanical performance data and load-bearing conditions to form load-bearing characteristics.

[0019] Specifically, the mechanical properties of the hip joint bones and the load-bearing conditions of the implant were acquired. Three-dimensional images of the patient's hip joint bones were obtained through CT scans, with a slice thickness set to 0.625 mm to ensure sufficient spatial resolution. Based on the mapping relationship between grayscale values ​​and bone density, the elastic modulus and yield strength of each region were calculated, and the elastic modulus, yield strength, and Poisson's ratio were integrated into mechanical property data. In the mechanical property data, the elastic modulus of the cortical bone region ranged from 15-20 GPa, and the Poisson's ratio was approximately 0.3, while the elastic modulus of the cancellous bone region ranged from 0.1-2 GPa, and the Poisson's ratio was approximately 0.2, showing significant differences in the mechanical parameters between the two types of bone tissue. The stress state of the hip joint during the patient's daily activities was collected, including the load direction and load amplitude under typical movements such as standing, walking, climbing stairs, and sitting up. These stress states were integrated into the implant load-bearing conditions. In the load-bearing conditions, the peak load on the hip joint during walking was approximately 3-4 times the body weight, and the peak load during climbing stairs could reach more than 5 times the body weight. When sitting up, the hip joint also had to withstand additional bending moments. Mechanical performance data reflects the load-bearing capacity of the bone itself, while load-bearing conditions reflect the external load conditions that the implant needs to withstand. Together, they form the input basis for boundary condition analysis.

[0020] In some embodiments, the step of performing boundary condition analysis on the mechanical performance data and the load-bearing conditions to form load-bearing features includes: identifying bone density distribution characteristics of cortical bone and cancellous bone from the mechanical performance data to form a bone density mechanical distribution; obtaining multi-posture load conditions from the load-bearing conditions to determine a dynamic load spectrum; performing boundary condition matching between the bone density mechanical distribution and the dynamic load spectrum to obtain a constraint boundary set; and constructing load-bearing features based on the constraint boundary set.

[0021] Bone mineral density (BMD) distribution characteristics of cortical and cancellous bone were identified from mechanical property data to form a BMD mechanical distribution. A 10 GPa elastic modulus was used as the dividing threshold; areas exceeding this threshold were classified as cortical bone, and areas below were classified as cancellous bone. This threshold was chosen based on the essential differences in the microstructure of the two types of bone tissue. The BMD mechanical distribution was represented using a three-dimensional grid, with each grid cell storing the BMD value and corresponding mechanical parameters at that location. The grid size was set to 0.5 mm to ensure sufficient spatial resolution. Mechanical property data from the acetabulum region showed that cortical bone was mainly distributed at the acetabular rim and on the surface of the weight-bearing area, with a thickness of approximately 2-4 mm. Cancellous bone filled the internal space surrounded by cortical bone, exhibiting a typical "hard shell, soft core" structure. This structure allows the bone to maintain strength while possessing relatively light mass. A transition region exists at the junction of cortical and cancellous bone. The BMD mechanical distribution marked the location and width of this transition region, where bone density showed a gradient decreasing from the outside to the inside. The width of the transition region was approximately 1-2 mm. Based on the differences in bone density values ​​of each grid cell in the mechanical performance data, the bone density mechanical distribution divides the hip joint into a high-density load-bearing zone, a medium-density transition zone, and a low-density filling zone. The mechanical performance gradients of the three types of zones are distinct, and their spatial distribution matches the load-bearing path of the bone.

[0022] The dynamic load spectrum was determined by obtaining multi-posture load conditions from load-bearing conditions. Significant differences exist in the force characteristics of the hip joint under different postures. During walking, the load is mainly along the femoral axis and slightly tilted inwards; when climbing stairs, the load direction tilts forward by about 15 degrees; and when standing, the load is relatively stable and has a smaller amplitude. These differences stem from the different coordinated force exertion patterns of muscle groups in each posture. The dynamic load spectrum organizes the load data from the load-bearing conditions in a time-series format. The horizontal axis represents the gait cycle phase, and the vertical axis represents the load component values. The load components include vertical pressure, anterior-posterior shear force, and lateral force in the medial and lateral directions. After processing, the dynamic load spectrum of the walking posture load-bearing condition data exhibits a clear periodic variation pattern. Within a single gait cycle, the load gradually decreases from the peak value when the heel strikes the ground to the trough value during the swing phase, with a peak-to-trough ratio of approximately 3:1. The duration of a single cycle is approximately 1 second. The dynamic load spectrum weights the loads of each posture according to the time proportion of daily activities. Walking posture accounts for approximately 60%, standing posture for approximately 25%, and stair climbing posture for approximately 15%. The weighted result reflects the comprehensive stress condition of the implant during daily use. The number of load cycles in each posture under load conditions is also included in the statistical scope of the dynamic load spectrum. Walking posture generates approximately 6,000-10,000 load cycles per day. Calculated based on the implant's design life of 15 years, the total number of cycles will reach tens of millions of cycles. This cycle frequency places stringent requirements on the fatigue performance of the implant.

[0023] Bone mineral density distribution is matched with the dynamic load spectrum to obtain a constraint boundary set. A clear mechanical constraint relationship needs to be established at the contact interface between the implant and the bone. The constraint boundary set undertakes the mathematical definition of this constraint relationship, transforming the physical contact into boundary conditions usable for finite element analysis. The high-density load-bearing area occupies the main load-bearing surface of the acetabulum in the bone mineral density distribution. The constraint boundary set sets this area as a fixed constraint boundary, restricting the implant's displacement degrees of freedom in three directions at this location, ensuring that the load can be effectively transferred to the bone. The load direction and amplitude of each posture in the dynamic load spectrum are transformed into load boundary conditions of the constraint boundary set. The load is applied to the force-bearing surface of the implant in the form of concentrated or distributed forces, with the application location corresponding to the load application point recorded in the dynamic load spectrum, and the load amplitude set according to the peak value in the dynamic load spectrum. Low-density filling areas correspond to weaker bone support capacity in bone mineral density distribution. The constraint boundary set sets elastic rather than rigid constraints for this region, with constraint stiffness values ​​matching the elastic modulus of cancellous bone, ranging from 0.1 to 2 GPa. This elastic constraint simulates the actual contact state between the implant and cancellous bone. Walking, climbing stairs, and standing postures in the dynamic load spectrum form load case 1, load case 2, and load case 3 in the constraint boundary set, respectively. This multi-case setting ensures the implant can safely bear loads under various daily activities. The constraint boundary set comprehensively integrates the spatial constraint information of bone mineral density distribution with the time-varying load information of the dynamic load spectrum.

[0024] The load-bearing characteristics are constructed based on the constraint boundary set. The mechanical performance requirements of each region of the implant are determined by the constraints it bears. The load-bearing characteristics quantify these requirements, specifying the stiffness and strength levels that each region should achieve. The fixed constraint boundaries in the constraint boundary set mark the main load-bearing areas of the implant. The load-bearing characteristics set high stiffness requirements for these areas, requiring the implant to have sufficient load-bearing stiffness to transfer loads to the bone without excessive deformation. The target elastic modulus is set at 10-15 GPa, close to the stiffness level of cortical bone. The load amplitude of each load condition in the constraint boundary set determines the stress level requirements of the load-bearing characteristics. The calculated theoretical stress must not exceed 60% of the allowable stress of the implant material to retain a safety margin. For titanium alloy materials, the allowable stress is approximately 500 MPa, so the maximum working stress should be controlled within 300 MPa. The elastic constraint boundary corresponds to the deformation coordination region of the bone-implant interface within the constraint boundary set. The load-bearing characteristics set stiffness matching requirements in this region. The local stiffness of the implant should be similar to that of the adjacent cancellous bone to avoid bone resorption caused by stress shielding effects. The target elastic modulus is set to 1-3 GPa. The load-bearing characteristics perform envelope analysis on multiple load conditions of the constraint boundary set to determine the maximum stress and maximum deformation requirements of each region under all conditions. The most unfavorable combination of results from each condition is taken as the design basis. The load-bearing characteristics ultimately output the target elastic modulus range, target porosity range, and target load direction for each region of the implant. These three parameters respectively constrain the stiffness design, porous structure design, and material orientation design of the implant.

[0025] Step S120: Based on the load-bearing characteristics, perform finite element mechanical analysis to identify stress characteristics, establish a mechanical benchmark library by load level stratification from the stress characteristics, and generate a modulus deviation index by performing elastic modulus matching detection through the mechanical benchmark library.

[0026] Specifically, stress characteristics were identified through finite element mechanical analysis based on the load-bearing characteristics. In the load-bearing characteristics, the high-stiffness requirement region with a target elastic modulus of 10-15 GPa had its initial material property value set to 12 GPa in the finite element model, while the stiffness matching region with a target elastic modulus of 1-3 GPa had its initial value set to 2 GPa. After importing the three-dimensional geometric model of the implant into the finite element analysis software, tetrahedral elements were used for mesh generation, with an element size set to 0.3 mm to ensure calculation accuracy. The target load-bearing direction in the load-bearing characteristics determined the direction of load application: the primary load-bearing direction was along the normal to the acetabular weight-bearing area, and the secondary load-bearing direction was along a direction inclined 15 degrees anterior-posteriorly. Boundary conditions were set according to the fixed and elastic constraints defined in the load-bearing characteristics. The fixed constraint was applied to the contact surface between the implant and the cortical bone, and the elastic constraint was applied to the contact surface between the implant and the cancellous bone. The stiffness of the elastic constraint corresponded to the cancellous bone modulus recorded in the load-bearing characteristics. Stress characteristics are automatically generated after the finite element method (FEM) solution is completed. They are displayed as contour maps showing the stress distribution across the implant space, and the von Mises equivalent stress, maximum principal stress, and minimum principal stress values ​​for each node are recorded in a data table. The target porosity range in the load-bearing characteristics affects the equivalent mechanical properties of the implant; regions with higher porosity have lower equivalent stiffness, which manifests as relatively lower stress levels but larger deformations in the stress characteristics. The stress characteristics record the stress distribution results under various working conditions, facilitating envelope analysis and peak value extraction.

[0027] In some embodiments, establishing a mechanical benchmark library by stratifying load levels from the stress characteristics includes: separating the stress peak and stress gradient from the stress characteristics to form a stress grading table; identifying and marking interface sensitive areas of stress concentration at the bone-implant interface in the stress grading table; setting the elastic modulus matching range for each load interval based on the stress grading table and the interface sensitive areas to obtain modulus constraint conditions; and constructing a mechanical benchmark library based on the modulus constraint conditions.

[0028] A stress grading table is constructed by separating the peak stress and stress gradient from the stress characteristics. The von Mises equivalent stress at the chamfered edge of the acetabular cup reaches a peak of 280 MPa in the stress characteristics, while the stress peak around the fixing screw hole is approximately 240 MPa. These locations of geometric abrupt changes are typical stress concentration areas. The stress grading table classifies the peak stress into three levels according to their numerical values: the stress level in the high-stress zone exceeds 50% of the material's allowable stress, i.e., over 150 MPa; the stress level in the medium-stress zone is between 20% and 50% of the allowable stress, i.e., 60-150 MPa; and the stress level in the low-stress zone is less than 20% of the allowable stress, i.e., less than 60 MPa. The stress gradient is the ratio of the stress difference between adjacent nodes to their distance in the stress characteristics. A large gradient value indicates that the stress changes drastically within a short distance, which can easily lead to the initiation of fatigue cracks. The stress grading table synchronously records the stress gradient level of each region. Regions with a gradient exceeding 50 MPa / mm are marked as high gradient regions, regions with a gradient between 20 and 50 MPa / mm are marked as medium gradient regions, and regions with a gradient below 20 MPa / mm are marked as low gradient regions. The spatial information of stress distribution in the stress characteristics is transferred to the stress grading table and organized in matrix form. The row index corresponds to the spatial grid cell number, and the column index corresponds to the stress level and gradient level. Each cell stores the specific stress value and level label at that location.

[0029] The stress grading table was used to identify and mark sensitive areas at the bone-implant interface based on stress concentration zones. The interface stress in the load-bearing area, as shown in the stress grading table, is 80-120 MPa, falling into the high-stress category, while the interface stress in the non-load-bearing area is only 20-40 MPa, falling into the low-stress category—a difference of 3-4 times. Sensitive areas were first marked at the intersection of the high-stress areas in the stress grading table and the bone-implant interface; these locations have a higher risk of interface failure. Interface locations that simultaneously meet the high stress and high gradient conditions in the stress grading table were marked as Level 1 sensitive areas; those meeting the high stress but low gradient or low stress but high gradient conditions were marked as Level 2 sensitive areas; and those meeting both low stress and low gradient conditions were marked as Level 3 sensitive areas. The stress concentration factor was defined as the ratio of local peak stress to average stress. Locations with a concentration factor exceeding 2.0 in the stress grading table were marked as key areas of concern in the sensitive areas, indicating significantly higher local stress levels than the surrounding areas. The interface sensitive area also records the geometric feature information of each sensitive location, including the radius of curvature, the interface normal angle, and the distance from the edge. Concave corner areas with a radius of curvature of less than 3 mm and edge areas with a distance from the edge of less than 2 mm often correspond to higher stress levels in the stress grading table.

[0030] Modulus constraints are derived by setting the elastic modulus matching range for each load interval based on the stress grading table and the interface sensitive regions. The high-stress areas in the stress grading table correspond to the most stringent load-bearing requirements; the modulus constraint sets the lower limit of the elastic modulus for this region to 8 GPa to ensure that the implant does not yield or deform excessively under peak load. For the primary sensitive regions within the interface sensitive regions, when adjacent to cortical bone, the modulus constraint requires that the difference between the elastic modulus of this region and the cortical bone modulus not exceed 30%, corresponding to a modulus range of 10-20 GPa; when adjacent to cancellous bone, the corresponding modulus range is 0.5-3 GPa. The low-stress areas in the stress grading table have lower load-bearing requirements; the modulus constraint allows for a lower elastic modulus in this region to promote bone ingrowth, with a modulus range set to 1-5 GPa. The lower modulus is achieved through higher porosity. The secondary and tertiary sensitive regions within the interface sensitive regions have relatively relaxed modulus ranges set in the modulus constraint, allowing for optimization adjustments within the 3-12 GPa range. These regions provide greater design freedom for topology optimization. The intermediate stress zone in the stress grading table has a modulus range of 5-12 GPa set in the modulus constraint conditions to balance load-bearing capacity and skeletal integration requirements. The modulus constraint conditions organize the upper and lower limits of the modulus of each region into a constraint matrix, and the matrix elements correspond one-to-one with the stress grading table and the spatial grid of the interface sensitive area.

[0031] A mechanical benchmark library was constructed based on modulus constraints. The high-stress zone constraint of 8-20 GPa (elastic modulus upper and lower limits) was transferred from the modulus constraints to the mechanical benchmark library to form a modulus constraint benchmark, with the modulus ranges of other regions being included simultaneously. In addition to the modulus constraint benchmark, the mechanical benchmark library also sets stress allowance benchmarks. For titanium alloys, the yield strength is 850 MPa; with a safety factor of 1.5, the allowable stress is 567 MPa, further reduced to 300 MPa to consider fatigue life requirements. More stringent stress allowance values ​​were set for key areas of concern marked in the modulus constraints in the mechanical benchmark library; the allowable stress for the first-level sensitive area was reduced to 250 MPa to provide additional safety margin. Deformation allowance benchmarks were also included in the mechanical benchmark library. The relative displacement between the implant and the bone interface must not exceed 150 micrometers to ensure initial stability, and the overall deformation must not exceed 0.5% of the implant's characteristic dimensions. In the modulus constraint conditions, regions with a wide modulus range are marked as optimizable regions in the mechanical reference library. Low-stress regions and third-level sensitive regions are typical optimizable regions. The elastic modulus in these regions can be freely adjusted within the constraint range to achieve optimized design of porous structures. The mechanical reference library organizes data in a hierarchical structure. The first layer is the region index, the second layer is the reference type index including modulus reference, stress reference, and deformation reference, and the third layer contains specific values ​​and their applicable conditions.

[0032] A modulus deviation index is generated through elastic modulus matching detection using a mechanical benchmark library. The modulus constraint benchmarks for each region in the mechanical benchmark library include the upper limit, lower limit, and median value of the target elastic modulus. The median value of the target elastic modulus serves as the benchmark reference for matching detection. The mechanical benchmark library also links to the initial material property values ​​set for each region during finite element analysis; these initial values ​​are used as the actual elastic modulus of the current design in the matching detection. When the actual elastic modulus of a region is 15 GPa while the target value in the mechanical benchmark library is 10 GPa, the modulus deviation index calculates a positive deviation of 50%, indicating that the current design is too stiff. The formula for calculating the deviation index is D = (E_actual - E_target) / E_target × 100%, where E_actual is the current design elastic modulus recorded in the mechanical benchmark library, and E_target is the median value of the target elastic modulus for that region in the mechanical benchmark library. When the actual modulus exceeds the upper or lower limits specified in the mechanical benchmark library, the modulus deviation index is automatically marked as exceeding the limit; exceeding the upper limit is marked as a positive exceedance, and falling below the lower limit is marked as a negative exceedance. The key areas of concern marked in the mechanical benchmark library employ stricter deviation judgment criteria. A deviation index with an absolute value exceeding 15% is deemed to require adjustment, while the judgment threshold for ordinary areas is 25%. Modulus deviation indicators are divided into four levels according to the degree of deviation: conforming to the benchmark corresponds to an absolute value of less than 10%; slight deviation corresponds to an absolute value between 10% and 20%; moderate deviation corresponds to an absolute value between 20% and 35%; and severe deviation corresponds to an absolute value exceeding 35%.

[0033] Step S130: Perform variable density topology optimization on the bearing characteristics to determine the pore gradient distribution, use the pore gradient distribution to optimize the pore unit configuration to identify the optimal configuration, and adjust the modulus deviation index based on the optimal configuration to form gradient matching parameters.

[0034] Specifically, variable-density topology optimization is performed on the load-bearing characteristics to determine the pore gradient distribution. In the load-bearing characteristics, the high-stiffness requirement region with a target elastic modulus of 10-15 GPa corresponds to a lower porosity design, while the stiffness-matching region with a target elastic modulus of 1-3 GPa corresponds to a higher porosity design. The porosity and elastic modulus follow a Gibson-Ashby power-law relationship. Where E is the equivalent elastic modulus of the porous structure, E_s is the elastic modulus of the matrix material, ρ / ρ_s is the relative density (1 minus porosity), and n is the structural correlation index, with a value of approximately 2. Variable density topology optimization uses the target load direction in the load-bearing characteristics as the load input, minimizes structural flexibility as the optimization objective, and uses volume fraction as the constraint condition. The density field is solved using the SIMP method. The pore gradient distribution is generated after the optimization iteration converges and is represented as a three-dimensional scalar field representing the target porosity values ​​at each location within the design domain. The target porosity range in the load-bearing characteristics provides upper and lower limits for the optimization results. The porosity in high-stiffness demand areas is controlled between 30% and 50%, while the porosity in stiffness-matching areas is controlled between 60% and 80%. The pore gradient distribution exhibits a gradient characteristic that gradually increases from the outer surface of the implant to the interior. The porosity of the outer surface is approximately 35% to ensure load-bearing strength, while the internal porosity increases to 75% to promote bone ingrowth and reduce overall stiffness. The pore gradient distribution divides the design domain into several partitions, with relatively uniform porosity in each partition. A smooth transition between adjacent partitions is achieved by setting transition units. The porosity gradient step size within the transition unit is controlled within 10% to avoid stress concentration.

[0035] In some embodiments, the step of using the pore gradient distribution to optimize the pore unit configuration and identify the optimal configuration includes: determining the target porosity of each partition from the pore gradient distribution to form a porosity constraint; performing a three-period minimum surface topology design based on the porosity constraint to obtain a candidate configuration set; performing mechanical bearing performance verification on the candidate configuration set to screen effective configurations; and identifying the optimal configuration from the effective configurations.

[0036] Porosity constraints are formed by determining the target porosity of each zone from the pore gradient distribution. The porosity of the outer surface zone is marked as 35%, the intermediate transition zone as 55%, and the internal filling zone as 75%, covering the main range of porosity variation. Porosity constraints translate the target porosity of each zone into geometric constraints for pore element design. These constraints include a center value for porosity and an allowable deviation range, set at ±5%. The porosity difference between adjacent zones in the pore gradient distribution determines the design requirements of the gradient transition zone within the porosity constraints. A 20% porosity jump transition unit is required between the outer surface zone and the intermediate zone, and between the intermediate zone and the internal zone. Porosity constraints also include limitations on pore size range. Considering the needs of bone cell ingrowth and nutrient transport, the pore size range is set to 300-800 micrometers, with larger pore size designs corresponding to areas with higher porosity in the pore gradient distribution. Wall thickness constraints are incorporated into porosity constraints, with a minimum wall thickness of 150 micrometers to ensure the forming accuracy and structural strength of additive manufacturing. The wall thickness is increased accordingly in areas with lower porosity in the pore gradient distribution.

[0037] Based on porosity constraints, a set of candidate configurations was obtained through the design of three-period minimum surface topologies. For example... Figure 2 As shown, the three-period minimal surface configurations include three basic configurations: Gyroid structure 2a, Diamond structure 2b, and Schwarz P structure 2c. Gyroid structure 2a features a continuously curved helical surface with fully interconnected pores and a smooth surface free of stress concentration points, exhibiting excellent permeability. Diamond structure 2b has a topological feature of tetrahedral node connections, resulting in superior mechanical load-bearing capacity compared to the other two structures. Schwarz P structure 2c features a cubic structure with six-way openings, isotropic pore distribution, and a regular structure. Under porosity constraints, the period length of Gyroid structure 2a corresponding to 35% porosity is calculated to be 1.2 mm, with a wall thickness of 0.35 mm; the period length corresponding to 55% porosity is 1.5 mm, with a wall thickness of 0.25 mm; and the period length corresponding to 75% porosity is 1.8 mm, with a wall thickness of 0.18 mm. In addition to the three basic configurations, the candidate configuration set also includes a hybrid configuration 2d. Hybrid configuration 2d is achieved by using different basic configurations in different zones and implementing morphological gradients at the boundaries. The outer surface zone uses the mechanically superior Diamond structure 2b, the inner zone uses the more permeable Gyroid structure 2a, and the intermediate transition zone achieves a smooth transition of porosity from 35% to 75% through morphological gradients. The pore size range of 300-800 micrometers in the porosity constraint is satisfied by adjusting the periodic parameters of the three-period minimum surfaces; the pore size of each configuration in the candidate configuration set falls within this range. The candidate configuration set contains a total of 12 configuration schemes, including three combinations of single basic configurations in three zones and three hybrid configuration schemes, all of which meet the geometric requirements of the porosity constraint.

[0038] Mechanical load-bearing performance verification was performed on the candidate configuration set to screen for effective configurations. Compressive strength and elastic modulus are two core indicators for mechanical load-bearing performance verification. Each configuration in the candidate configuration set must simultaneously meet the strength and modulus matching requirements to be included as an effective configuration. Finite element analysis was performed on each of the 12 configuration schemes in the candidate configuration set. Each configuration scheme in the candidate configuration set was associated with the load condition information of its respective partition, and the boundary conditions were set according to this associated information. The equivalent elastic modulus and maximum von Mises stress of each configuration were calculated. The screening criteria for effective configurations were that the deviation of the equivalent elastic modulus from the target value should not exceed 20% and the maximum stress should not exceed 80% of the allowable stress of the material. Eight configurations in the candidate configuration set met these criteria. The Diamond configuration showed the highest compressive strength in the candidate configuration set, reaching 180 MPa at 35% porosity, but its high elastic modulus resulted in poor stiffness matching. The Gyroid configuration exhibited good stiffness matching in the candidate configuration set, with an equivalent elastic modulus of 2.1 GPa at 75% porosity, which is close to the modulus of cancellous bone. The effective configurations retained eight schemes from the candidate configuration set, including two single Diamond configurations, two single Gyroid configurations, one single Schwarz P configuration, and three mixed configurations. The four eliminated schemes were mainly due to insufficient strength in the high-porosity region or excessive modulus in the low-porosity region.

[0039] The optimal configuration was identified from the effective configurations. The comprehensive evaluation index weighted and integrated mechanical properties, permeability, and manufacturing feasibility. After calculating the comprehensive evaluation index for each scheme in the effective configurations, they were ranked. The weight for mechanical properties was set to 0.4, with evaluation indicators being modulus matching degree and strength safety factor; the weight for permeability was set to 0.3, with evaluation indicators being pore connectivity and permeability coefficient; the weight for manufacturing feasibility was set to 0.3, with evaluation indicators being minimum characteristic dimension and overhang angle. Each sub-indicator was normalized to the range of 0-1 according to its degree of meeting design requirements. 1 point was awarded for complete compliance, 0 points for complete non-compliance, and partial compliance was calculated using linear interpolation. The comprehensive evaluation index was the sum of the weighted scores of each sub-indicator. Hybrid configuration schemes in the effective configurations performed exceptionally well in the comprehensive evaluation. The hybrid scheme using a Diamond configuration on the outer surface and a Gyroid configuration on the interior had the highest comprehensive evaluation index, reaching 0.87 points. The optimal configuration was determined to be this hybrid scheme. The outer surface zone's Diamond configuration has a period length of 1.2 mm, a wall thickness of 0.35 mm, and a porosity of 35%. The inner zone's Gyroid configuration has a period length of 1.8 mm, a wall thickness of 0.18 mm, and a porosity of 75%. The intermediate transition zone uses a gradual transition between the two configurations to achieve a smooth transition in porosity from 35% to 75%. The second-ranked effective configuration is the full Gyroid configuration, with a comprehensive evaluation index of 0.82, which can be considered as an alternative to the optimal configuration. The geometric parameters, mechanical properties, and permeability parameters of each zone of the optimal configuration are fully recorded, forming the final output of the pore unit configuration design.

[0040] The gradient matching parameters are formed by adjusting the modulus deviation index based on the optimal configuration. In the optimal configuration, the equivalent elastic modulus of the outer surface Diamond partition is 11.5 GPa, which deviates positively by +15% from the target value of 10 GPa recorded in the modulus deviation index for this region. This deviation value is updated from the original record of the modulus deviation index. The equivalent elastic modulus of the inner Gyroid partition is 2.1 GPa, with a deviation of only +5% from the target value of 2 GPa. This region is marked as conforming to the benchmark in the modulus deviation index. The gradient matching parameters summarize the geometric parameters of the optimal configuration and the adjusted modulus deviation index to form the input file for additive manufacturing. The modulus gradient characteristic of the transition partition is presented as a linear transition from +15% to +5% in the modulus deviation index. The gradient matching parameters transform this gradient characteristic into a continuous variation curve of period length and wall thickness. In the optimal configuration, the porosity, pore size, and wall thickness parameters of each partition are sequentially written into the gradient matching parameters. The outer surface partition parameter group has a porosity of 35%, a pore size of 450 μm, and a wall thickness of 350 μm, while the inner partition parameter group has a porosity of 75%, a pore size of 650 μm, and a wall thickness of 180 μm. Regions marked as exceeding limits in the modulus deviation index are assigned a process compensation flag in the gradient matching parameters, indicating that the scanning strategy needs to be adjusted during additive manufacturing to improve forming accuracy. The gradient matching parameters are organized using a hierarchical data structure: the first layer is the partition index, the second layer is the parameter type (including geometric, mechanical, and process parameters), and the third layer is the specific numerical value.

[0041] Step S140: The gradient matching parameters are used to control the additive manufacturing layered forming to determine the porous substrate forming state. Based on the porous substrate forming state, substrate parameters are generated. The zinc-based coating load and heterojunction interface bonding strength are controlled from the substrate parameters to construct the heterojunction coating structure.

[0042] In some embodiments, the step of determining the porous matrix forming state by additive manufacturing layered forming control of the gradient matching parameters includes: reading the pore characteristics of each partition from the gradient matching parameters to determine the layered forming sequence; optimizing the pore connectivity forming sequence according to the layered forming sequence to obtain a connectivity forming scheme; performing laser power and scanning speed adaptation according to the connectivity forming scheme to obtain partition process parameters; and using the partition process parameters to perform Zr-Nb powder layer-by-layer melting forming to determine the porous matrix forming state.

[0043] The porosity characteristics of each partition were read from the gradient matching parameters to determine the layered forming sequence. The outer surface partition was labeled as a Diamond configuration with a period length of 1.2 mm and a porosity of 35% in the gradient matching parameters, while the inner partition was labeled as a Gyroid configuration with a period length of 1.8 mm and a porosity of 75%. The 3D geometric data of both configurations were converted to STL format and imported into the slicing software. The layered forming sequence sliced ​​the implant along the Z-axis at 30-micrometer layer thickness intervals, for a total of approximately 1500 layers, corresponding to an implant height of 45 mm. The morphological gradient characteristics of the transition partitions in the gradient matching parameters were manifested in the layered forming sequence as a continuous change in the configuration contour between adjacent slices, with the diamond-shaped pores of the Diamond configuration gradually evolving into the spiral pores of the Gyroid configuration. The layered forming sequence generated a scanning path for each layer, employing a reciprocating scanning strategy for the solid region, with a scanning interval set to 80 micrometers to ensure sufficient overlap between adjacent melt channels. The boundary coordinates of the pore region in the gradient matching parameters are written into the jump command of the layered forming sequence. The laser power is turned off when it reaches the pore boundary until it leaves the pore region. The layered forming sequence also contains preset values ​​of process parameters for each layer. The outer surface partition corresponds to the high-power parameter group, and the inner partition corresponds to the low-power parameter group. The switching timing of the parameter group corresponds to the partition boundary position in the gradient matching parameters.

[0044] For example, the step of optimizing the pore connectivity forming sequence according to the layered forming sequence to obtain a connected forming scheme includes: locating the pore positions of adjacent layers according to the layered forming sequence to form an interlayer pore reference table; performing pore connectivity analysis on the interlayer pore reference table to identify connected pore groups and isolated pore groups; performing forming sequence rearrangement according to the isolated pore groups to obtain a modified forming sequence; and generating a connected forming scheme based on the connected pore groups and the modified forming sequence.

[0045] Based on the layered forming sequence, the positions of pores in adjacent layers are located to form an interlayer pore reference table. Pore contours from layers 100 to 101 in the layered forming sequence are extracted and superimposed for comparison. The offset of the pore center coordinates and the ratio of the overlapping area are calculated for each layer. The interlayer pore reference table stores the comparison results in matrix form, with row indices corresponding to the pore numbers of layer n and column indices corresponding to the pore numbers of layer n+1. Matrix elements represent the percentage of overlapping area between two pores. The layered forming sequence contains 1500 slices, generating 1499 sets of interlayer reference data, totaling approximately 50MB. Pore pairs with an overlapping area ratio exceeding 70% are marked as strongly connected in the interlayer pore reference table, those between 30% and 70% are marked as weakly connected, and those below 30% are marked as not connected. The interlayer pore reference table also records the center offset distance of each pore pair; pore pairs with an offset distance exceeding 50% of the pore diameter, even with a high overlapping area ratio, still pose a risk of connectivity issues. The interlayer porosity table in the Diamond configuration region of the layered forming sequence shows a periodic alternating pattern of strong and weak connectivity, while the Gyroid configuration region shows a continuous pattern of strong connectivity.

[0046] A porosity analysis was performed on the interlayer porosity table to identify connected and isolated pore groups. The longitudinal connectivity path of each pore was traced from the top to the bottom of the implant. Pore pairs marked with strong connectivity in the interlayer porosity table formed continuous connectivity chains. The connected pore group included all pore chains extending from the top to the bottom, which constitute the main channels for bone ingrowth and nutrient transport. Pores with interrupted connectivity chains in the interlayer porosity table, i.e., pores in one layer that do not have a corresponding strongly or weakly connected pore in the next layer, were classified as isolated pores. All pores in the Gyroid configuration region were classified as connected pores in the interlayer porosity table analysis, achieving a 100% connectivity rate. Approximately 8% of the pores in the Diamond configuration region were classified as isolated pores, mainly distributed in the configuration transition region and near the outer surface edges. Although the pores in an isolated pore group are not locally connected, they still have the functions of structural weight reduction and stress buffering. For connected pore groups, the forming quality should be given priority, while the forming accuracy requirements for isolated pore groups can be appropriately relaxed.

[0047] The modified forming sequence is obtained by rearranging the forming order based on the isolated pore group. The pore locations in the isolated pore group are marked in the original layered forming sequence, and the scanning strategy is adjusted to prioritize the forming of the solid regions surrounding these pores. In the scanning sequence of the layer containing the isolated pore group, the modified forming sequence first completes the melting forming within a range of twice the wall thickness around the isolated pores, and then performs a regular scan of other areas in the layer. The boundary contour of the isolated pores is enhanced with an additional contour-enhancing scan in the modified forming sequence, with a 20% reduction in laser power and a 30% reduction in scanning speed to achieve finer boundary forming quality. Multiple adjacent isolated pores in the isolated pore group are merged in the modified forming sequence, sharing the same set of scanning strategy parameters to improve forming efficiency. The adjustment range of the modified forming sequence from the original sequence is controlled within 15% to avoid excessive changes in the forming sequence leading to an imbalance in heat accumulation distribution. The modified forming sequence maintains the layered structure and parameter preset framework of the original sequence, optimizing only the local scanning sequence and contour strategy.

[0048] A connected forming scheme is generated based on the connected pore group and the modified forming sequence. The continuity path information of the connected pore group is written into the quality monitoring module of the connected forming scheme, and the pores in each layer along the continuity path are monitored during the forming process. The scan path file of the modified forming sequence is integrated into the connected forming scheme to form a complete forming control instruction set. The connected forming scheme sets up three levels of quality checkpoints. The first level checkpoint performs online detection of pore connectivity after every 50 layers of forming, using pore contour recognition based on coaxial molten pool monitoring images. The second level checkpoint is performed at key node layers of the connected pore group, which correspond to the branching or merging positions of the pore connectivity chain. The third level checkpoint performs a CT scan after forming to fully verify pore connectivity. Areas with a continuity rate of less than 95% in the connected pore group are marked as high-risk areas in the connected forming scheme, and the laser power fluctuation in these areas is controlled within ±2% during the forming process. The final output of the connected forming scheme includes an optimized scan path file, a quality checkpoint setting file, and a risk area marking file.

[0049] The partitioning process parameters are obtained by adapting the laser power and scanning speed according to the interconnected forming scheme. The outer surface Diamond partition, with a wall thickness of 350 micrometers, corresponds to a relatively high energy input requirement in the interconnected forming scheme. The partitioning process parameters are set with a laser power of 280W and a scanning speed of 800mm / s. The volume energy density is calculated as E=P / (v·h·t)=280 / (800×0.08×0.03)=145.8J / mm³, where P is the laser power, v is the scanning speed, h is the scanning interval, and t is the layer thickness. The inner Gyroid partition, with a wall thickness of 180 micrometers, corresponds to a relatively low energy input requirement in the interconnected forming scheme. The partitioning process parameters are set with a laser power of 200W and a scanning speed of 1000mm / s, resulting in a volume energy density of 83.3J / mm³. The transition partitions in the interconnected forming scheme employ a linear gradient strategy of power and speed, smoothly transitioning from the outer surface parameter set to the inner parameter set, with the gradient spanning approximately 200 slices. The partitioning process parameters also include scanning strategy settings. The outer surface partitions use a 67-degree rotating scanning strategy to homogenize the residual stress distribution, while the inner partitions use a 90-degree orthogonal scanning strategy to simplify path planning. High-risk areas marked in the connected forming scheme have dedicated parameter groups set in the partitioning process parameters, with laser power reduced by 10% and scanning speed reduced by 15% to improve forming stability.

[0050] The porous matrix forming state was determined by layer-by-layer melt molding of Zr-Nb powder using zoned process parameters. The forming chamber was evacuated to 10 °C. -3 After Pa, high-purity argon is introduced as a protective atmosphere, with the oxygen content controlled below 100 ppm to prevent oxidation of the Zr-Nb alloy. The laser power (280W / 200W) and scanning speed (800 / 1000 mm / s) in the partitioning process parameters are automatically switched according to the partition boundaries, with a switching response time of less than 1 ms. The porous matrix forming state is updated in real time during the forming process, including the molten pool morphology parameters, fusion line characteristics, and dimensional deviation data of the current layer. The outer surface partitions with a volume energy density of 145.8 J / mm³ in the partitioning process parameters form a solid wall structure with a density exceeding 99.5%, and the average grain size of this region is recorded as 15-25 micrometers in the porous matrix forming state. The pore boundaries of the internal partitions show clear and sharp outlines in the porous matrix forming state, and the deviation of the pore size from the design value is controlled within ±30 micrometers. After the partitioned process parameters are fully executed to form all 1500 layers, the forming quality data of the entire implant is summarized by the porous matrix forming state, including the density distribution, porosity distribution, dimensional accuracy distribution and surface roughness distribution of each partition.

[0051] Matrix parameters are generated based on the porous matrix forming state. The density (99.5%), average wall thickness (352 μm), and surface roughness (Ra8 μm) of the outer surface partitions are extracted from the porous matrix forming state and written into the matrix parameters. The matrix parameters are organized using a partitioned structure, with each partition recording both geometric and mass parameters. The measured porosity of the internal partitions in the porous matrix forming state is 73.8%, deviating from the design value of 75% by -1.6%, which is recorded in the mass deviation field of the matrix parameters. Pore connectivity is obtained from the CT scan verification results of the porous matrix forming state; the connectivity of the outer surface Diamond partition is 91.5%, and the connectivity of the internal Gyroid partition is 98.2%, both of which are written into the matrix parameters. The matrix parameters also include the measured mechanical properties of the porous matrix. Compression testing of the specimens yielded an equivalent elastic modulus of 11.2 GPa and a compressive strength of 175 MPa for the outer surface partitions, and an equivalent elastic modulus of 2.0 GPa and a compressive strength of 45 MPa for the internal partitions. Surface morphology data recorded during the porous matrix forming process are transferred to the matrix parameters, including the micro-roughness of the pore wall surfaces, molten pool overlap marks, and the distribution of partially molten powder particles. These surface features will affect the deposition quality of subsequent coatings.

[0052] In some embodiments, the step of constructing a heterojunction coating structure by controlling the zinc-based coating load and heterojunction interface bonding strength from the substrate parameters includes: analyzing the porous surface morphology characteristics from the substrate parameters to determine coating deposition constraints; performing zinc-based coating pore wall permeation loading according to the coating deposition constraints to obtain a coating-substrate composite; performing thermal oxidation treatment on the coating-substrate composite to form a ZrO2-ZnO heterojunction interface; and performing bonding strength testing on the ZrO2-ZnO heterojunction interface to construct the heterojunction coating structure.

[0053] The coating deposition constraints were determined by analyzing the porous surface morphology characteristics from the substrate parameters. A pore wall surface roughness of Ra 8 micrometers corresponds to a medium roughness in the substrate parameters. This roughness is beneficial for the mechanical interlocking between the coating and the substrate but not for uniform coating. The coating deposition constraints stipulate that the upper limit of the coating thickness is three times the surface roughness, i.e., 24 micrometers, to avoid excessive coating thickness leading to pore blockage. The distribution density of partially molten powder particles in the substrate parameters is approximately 15-25 particles per square millimeter. These particles form microscopic protrusions, and the coating deposition constraints require the deposition process to cover the entire surface of the top and root of these protrusions. A pore connectivity rate of 98.2% in the internal Gyroid zone means that the coating solution can penetrate to the inner walls of most pores in the substrate parameters. The coating deposition constraints set a minimum immersion time of 30 minutes for this area to ensure sufficient penetration. The 650-micrometer pore size internal zone in the substrate parameters allows for immersion deposition in the coating deposition constraints, as does the 450-micrometer pore size external surface zone. The coating deposition constraints also specify coating composition requirements, with zinc content controlled at 85%-95% of the total coating weight to ensure sufficient antibacterial activity, and the remaining components being trace alloying elements and unavoidable impurities.

[0054] A coating-substrate composite was obtained by performing a zinc-based coating pore wall permeation loading under coating deposition constraints. The zinc nitrate aqueous solution was prepared at a concentration of 0.5 mol / L, and the pH was adjusted to 4.5-5.0 to ensure the stability and deposition activity of zinc ions. The immersion time of 30 minutes specified in the coating deposition constraints was extended to 45 minutes in the actual process to ensure that the solution penetrated into the deep pores of the internal Gyroid zone. After the porous substrate was immersed in the solution, ultrasonic vibration was applied with a vibration frequency of 40 kHz and a power density of 100 W / L. The ultrasonic cavitation effect promoted the solution to enter the narrow channels and expel air bubbles from the pores. After immersion, the coating-substrate composite was removed and subjected to low-temperature drying at 80°C for 4 hours. After solvent evaporation, zinc salt formed a precursor film on the pore wall surface. The upper limit of 24 micrometers of coating thickness in the coating deposition constraints was achieved by controlling the number of immersions. A single immersion formed a precursor layer of approximately 5 micrometers, and after four repeated immersions, the total precursor thickness of the coating-substrate composite reached 18-22 micrometers. The coating-matrix composite has a grayish-white appearance. The precursor layer is uniformly covered on the inner and outer surfaces of the porous matrix, and the coverage rate exceeds 95% according to sampling tests.

[0055] For example, the step of performing thermal oxidation treatment on the coating-substrate composite to form a ZrO2-ZnO heterojunction interface includes: setting the thermal oxidation temperature and oxidation time for the coating-substrate composite to determine oxidation process parameters; performing surface oxidation according to the oxidation process parameters to form a ZrO2 oxide layer and a ZnO oxide layer; performing interfacial diffusion treatment on the ZrO2 oxide layer and the ZnO oxide layer to form a heterojunction transition region; and characterizing the crystal phase structure of the heterojunction transition region to confirm the construction of the ZrO2-ZnO heterojunction interface.

[0056] The oxidation process parameters were determined by setting the thermal oxidation temperature and time for the coating-substrate composite. The temperature window of 350-450℃ is suitable for zinc salt decomposition and ZnO crystallization. Below 350℃, decomposition is incomplete, leaving organic impurities; above 450℃, ZnO grains grow excessively, and the ZrO2 layer thickens too rapidly. The oxidation process parameters were selected with 400℃ as the oxidation temperature, at which the zinc salt decomposition rate and ZrO2 growth rate are well matched. The oxidation time needs to balance oxidation completeness and coating thickness control. At 400℃, oxidizing the coating-substrate composite for 30 minutes completes zinc salt decomposition, but the ZrO2 layer is only about 50nm thick. After 2 hours of oxidation, the ZrO2 layer thickens to 150nm, and the ZnO layer is fully crystallized. The oxidation process parameters were set with an oxidation time of 2 hours, a heating rate of 5℃ / min to avoid thermal shock, and the furnace pressure maintained at atmospheric pressure during the holding phase. The oxidation process parameters specify that the coating-substrate composite should be suspended during loading to avoid contact with the furnace bottom, which could lead to localized overheating or coating wear. The oxidation process parameters also include atmosphere control requirements: the oxygen partial pressure should be maintained at 0.21 atm (normal air composition), and the humidity should be controlled below 30% relative humidity to prevent water vapor from participating in the reaction.

[0057] The surface oxidation process is performed according to the oxidation parameters to form a ZrO2 oxide layer and a ZnO oxide layer. For example... Figure 3As shown, the heterojunction coating structure, from the inside out, includes a Zr-Nb porous substrate 3a, a ZrO2 oxide layer 3b, a heterojunction transition region 3c, and a ZnO coating 3d. After the heating rate of 5℃ / min in the oxidation process parameters was executed, the coating-substrate composite increased from room temperature to 400℃ within 75 minutes. During the heating process, the zinc salt precursor gradually dehydrated and decomposed. The ZnO oxide layer began to form at 350℃. In-situ XRD monitoring showed that the (100) and (002) diffraction peaks of ZnO first appeared at this temperature and gradually increased with increasing temperature. The formation temperature of the ZrO2 oxide layer was slightly higher than that of ZnO. Oxidation began on the surface of the Zr-Nb porous substrate 3a at approximately 380℃. The oxidation products were mainly monoclinic ZrO2 with a small amount of tetragonal ZrO2. After 2 hours of heat treatment, the ZnO coating 3d reached a thickness of 15-20 micrometers with a grain size of approximately 50-100 nm, exhibiting a typical hexagonal wurtzite structure. The ZrO2 oxide layer 3b reached a thickness of 100-200 nm, forming a metallurgical bond with the Zr-Nb porous substrate 3a, with a significantly higher bonding strength than mechanical bonding. The ZnO coating 3d covered the ZrO2 oxide layer 3b, forming a heterojunction transition region 3c between the two layers. The thickness of the transition region was approximately 50-100 nm. In this region, the solid solution concentration of Zn in ZrO2 gradually decreased from 5 at% at the interface towards the substrate side to 0, and the solid solution concentration of Zr in ZnO gradually decreased from 3 at% at the interface towards the surface side to 0.

[0058] Interfacial diffusion treatment was performed on the ZrO2 oxide layer and the ZnO oxide layer to form a heterojunction transition region. The interfacial diffusion treatment occurred naturally in the later stage of the thermal oxidation holding phase. At 400℃, Zn and Zr atoms underwent short-range diffusion across the interface, with a diffusion coefficient of approximately 10. -18 The thickness of the heterojunction transition region is on the order of m² / s. It is proportional to the square root of the diffusion time, reaching approximately 50-100 nm after 2 hours of heat treatment. In the ZrO₂ oxide layer, Zn atoms are dissolved near the interface, with the Zn content gradually decreasing from 5 at% at the interface to 0 in the bulk phase, forming a compositional gradient. Similarly, Zr atoms are dissolved near the interface in the ZnO oxide layer, with the Zr content gradually decreasing from 3 at% at the interface to 0 in the bulk phase. The crystal structure of the heterojunction transition region exhibits a gradual transition from the monoclinic phase of ZrO₂ to the hexagonal phase of ZnO, with coherent or semi-coherent interfaces between the two phases present within the transition region. The formation of the heterojunction transition region significantly improves the bonding strength between the coating and the substrate, eliminating the weak interfacial layer that might exist when the ZrO₂ oxide layer and ZnO oxide layer are in direct contact.

[0059] The crystal structure of the heterojunction transition region was characterized to confirm the construction of the ZrO2-ZnO heterojunction interface. High-resolution transmission electron microscopy (TEM) was used to observe the cross-sectional sample of the heterojunction transition region. The lattice fringe image clearly showed the epitaxial relationship between the ZrO2 (111) plane and the ZnO (002) plane. The ZrO2-ZnO heterojunction interface exhibited clear and continuous interface lines in the TEM image, with no obvious amorphous layers or pore defects at the interface, indicating good interfacial bonding quality. Selected area electron diffraction (SED) obtained composite diffraction patterns of ZrO2 and ZnO in the heterojunction transition region. The two sets of diffraction spots showed a specific orientation relationship, confirming the existence of epitaxial growth. X-ray photoelectron spectroscopy (XPS) analysis of the chemical state of the heterojunction transition region revealed the binding energy positions and peak shapes of the zirconium (Zr3d) and zinc (Zn2p) peaks, confirming the oxide morphology of ZrO2 and ZnO. Fitting analysis of the O1s peak revealed the existence of the Zr-O-Zn bridging bond. After the crystal phase structure of the ZrO2-ZnO heterojunction interface was characterized and confirmed, the preparation process of the heterojunction coating was completed.

[0060] The bonding strength of the ZrO2-ZnO heterojunction interface was tested to construct a heterojunction coating structure. The scratch test involved applying an increasing load with a diamond indenter to the coating surface and recording the critical load Lc at which the coating peeled off. The critical load test result for the ZrO2-ZnO heterojunction interface sample was Lc = 15.8 N, corresponding to a bonding strength of approximately 35 MPa, significantly higher than the 18 MPa bonding strength of the control sample without a heterojunction interface. The bonding strength of the heterojunction coating structure meets the requirements for implant use. ISO 13779 standard specifies a lower limit of 15 MPa for the bonding strength of calcium phosphate coatings; zinc-based coatings should follow this standard. As a supplementary verification to the scratch test, the tensile test was performed. An epoxy resin adhesive was used to bond the test column to the coating surface, and after curing, it was stretched vertically until the coating peeled off. The tensile peel strength of the ZrO2-ZnO heterojunction interface sample was 32 MPa. Analysis of the peel surface showed that the fracture mainly occurred within the ZnO layer rather than at the interface, proving that the interfacial bonding strength of the heterojunction coating structure is higher than the cohesive strength of the coating itself. The final parameters of the heterojunction coating structure are summarized as follows: ZrO2 layer thickness 150 nm, ZnO layer thickness 18 μm, heterojunction transition region thickness 80 nm, interfacial bonding strength 35 MPa, and coating coverage 97%.

[0061] Step S150: Perform mechanical-antibacterial performance coupling analysis on the modulus deviation index and gradient matching parameters to extract the synergy coefficient, identify the ultrasonic response critical point based on the synergy coefficient, construct an ultrasonic stimulation parameter library based on the ultrasonic response critical point, and output forming process instructions by integrating the heterojunction coating structure through the ultrasonic stimulation parameter library.

[0062] In some embodiments, the step of extracting synergy coefficients by performing mechanical-antibacterial performance coupling analysis on the modulus deviation index and the gradient matching parameters includes: selecting mechanical fitness parameters from the modulus deviation index to determine mechanical performance constraints; obtaining pore structure characteristics from the gradient matching parameters to form coating bearing constraints; performing functional partitioning mapping between the bearing area and the antibacterial area according to the mechanical performance constraints and the coating bearing constraints to obtain a functional partitioning map; and conducting multi-objective coupling analysis based on the functional partitioning map to obtain synergy coefficients.

[0063] Mechanical performance constraints are determined by selecting mechanical fit parameters from the modulus deviation index. Regions with a slight deviation (10%-20%) are rated as good, those with a moderate deviation (20%-35%) as acceptable, and those with a severe deviation (over 35%) as unacceptable. The mechanical fit parameters are extracted from the three-level evaluation results of the modulus deviation index: a deviation of +15% in the outer surface zone corresponds to a good grade, a deviation of +12% in the transition zone corresponds to a good grade, and a deviation of +5% in the internal zone also corresponds to a good grade. Mechanical performance constraints transform the mechanical fit parameters into design constraints. Regions rated as good are allowed adjustments within ±10% of the current modulus; regions rated as acceptable require a 5%-15% correction towards the target value; and regions rated as unacceptable require a redesign of the pore structure. Regions marked as exceeding limits in the modulus deviation index are subject to mandatory correction requirements in the mechanical performance constraints. Positively exceeding limits require increased porosity to reduce the equivalent modulus, while negatively exceeding limits require decreased porosity or increased wall thickness to increase the equivalent modulus. The mechanical performance constraints also include stress safety margin requirements; the working stress in each region must not exceed 60% of the allowable stress. Regions in the modulus deviation index with stress levels approaching this limit are marked as stress-sensitive areas in the mechanical performance constraints.

[0064] Pore ​​structure characteristics were extracted from gradient matching parameters to form coating load-bearing constraints. Porosity, pore size, and wall thickness were extracted from the gradient matching parameters section by section: 35% / 450μm / 350μm for the outer surface section, 55% / 550μm / 260μm for the transition section, and 75% / 650μm / 180μm for the inner section. The coating load-bearing constraints determined the upper limit of the coating load capacity for each section based on the pore structure characteristics. The upper limit of the coating thickness was set to 10% of the wall thickness to avoid excessive occupation of structural space; the upper limit of the coating thickness for the outer surface section was 35 micrometers, and for the inner section it was 18 micrometers. The inner section with a porosity of 75% in the gradient matching parameters provided the largest specific surface area. The coating load-bearing constraints calculated the coating area per unit volume for this section to be 12.5 mm² / mm³, significantly higher than the 6.8 mm² / mm³ for the outer surface section. Pore ​​size affects the penetration depth and uniformity of the coating solution. The coating load constraints stipulate that areas with pore sizes smaller than 300 micrometers are unsuitable for immersion coating. In the gradient matching parameters, the pore sizes of all zones are greater than 450 micrometers, meeting the immersion coating requirements. The coating load constraints also consider the impact of pore connectivity on coating uniformity. Areas with connectivity below 90% may have uneven coating coverage. In the gradient matching parameters, the internal Gyroid zone has a connectivity of 98.2%, and the outer surface Diamond zone has a connectivity of 91.5%, both meeting the coating uniformity requirements.

[0065] A functional zoning diagram is obtained by mapping the load-bearing and antibacterial zones based on mechanical performance constraints and coating load-bearing constraints. The functional requirements of the implant are spatially differentiated. The load-bearing area primarily functions as a mechanical support zone, while the bone contact area primarily functions as an antibacterial and ossification zone. The functional zoning diagram visualizes these differentiated requirements. Locations marked as stress-sensitive areas in the mechanical performance constraints are designated as load-bearing functional zones in the functional zoning diagram. The design of these zones prioritizes mechanical performance, with coating thickness controlled to the lower limit to minimize impact on structural strength. Areas with a specific surface area greater than 10 mm² / mm³ in the coating load-bearing constraints are designated as antibacterial functional zones in the functional zoning diagram. These areas fully utilize the large pore wall space to load the ZnO coating, maximizing the release of antibacterial active substances. Areas with good mechanical fit in the mechanical performance constraints and a specific surface area between 8-10 mm² / mm³ in the coating load-bearing constraints are designated as composite functional zones in the functional zoning diagram. These areas simultaneously undertake both mechanical support and antibacterial functions, requiring a balance between the two. The functional zoning diagram is presented as a three-dimensional color cloud map. Red indicates that the load-bearing functional area occupies approximately 70% of the area of ​​the outer surface zoning, blue indicates that the antibacterial functional area occupies approximately 80% of the area of ​​the inner zoning, and purple indicates that the composite functional area occupies approximately 60% of the area of ​​the transition zoning. The zoning boundaries of the functional zoning diagram coincide with the gradient change areas of mechanical performance constraints and coating load-bearing constraints, and the width of the boundary transition zone is approximately 2-3 mm.

[0066] Synergy coefficients were obtained through multi-objective coupling analysis based on the functional zoning diagram. During the construction of the functional zoning diagram, attribute parameters such as modulus deviation, porosity, and coating surface area per unit volume for each zone were pre-stored. These attribute parameters were recorded along with the zone index for direct use in subsequent coupling analysis. The multi-objective coupling analysis needs to consider both mechanical load-bearing capacity and antibacterial coating design objectives. These two objectives have an inverse relationship within the limited structural space: increasing porosity increases the coating adhesion area but reduces structural stiffness; increasing wall thickness increases load-bearing capacity but reduces the coating load space. The load-bearing functional zone occupies the main position on the outer surface of the functional zoning diagram. The optimization objective for this region is primarily minimizing modulus deviation, with maximizing coating load as a secondary objective, and the objective weight allocation is 0.7:0.3. The antibacterial functional zone occupies the main position in the internal space of the functional zoning diagram. The optimization objective for this region is primarily maximizing coating load, with minimizing modulus deviation as a secondary objective, and the objective weight allocation is 0.3:0.7. The composite functional zone is located in the transition area of ​​the functional zoning diagram, and a balanced weight of 0.5:0.5 is used to consider both functional requirements. The synergy coefficient is calculated based on the association attributes of each partition in the functional zoning diagram, and the calculation formula is as follows: Where α and β are the target weight coefficients and α+β=1, D is the modulus deviation value of the functional zoning diagram recorded for that zone, D_max is the maximum allowable deviation value of 35%, P is the porosity of the functional zoning diagram recorded for that zone, P_max is the maximum porosity of 80%, and S is the coating surface area per unit volume of the functional zoning diagram recorded for that zone, S_max is the maximum surface area of ​​12.5 mm² / mm³. The synergy coefficient ranges from 0 to 1. The closer the value is to 1, the better the two objectives can be met under the current weight configuration. The closer the value is to 0, the more conflicting the two objectives are, making it difficult to achieve both simultaneously.

[0067] The ultrasonic response critical point was identified based on the synergy coefficient. Under ultrasonic stimulation, the ZnO coating exhibits a piezoelectric effect, releasing reactive oxygen free radicals. A nonlinear response relationship exists between ultrasonic parameters and antibacterial effect; the ultrasonic response critical point marks the key inflection point on the response curve. Regions with high synergy coefficients have sufficient coating load, requiring lower ultrasonic intensities to elicit adequate antibacterial activity; the corresponding ultrasonic response critical point is located in the low-intensity range. Regions with low synergy coefficients have limited coating load, requiring higher ultrasonic intensities to achieve effective antibacterial concentrations; the corresponding ultrasonic response critical point is located in the high-intensity range. The antibacterial functional region has a high synergy coefficient; the ultrasonic response critical point corresponds to an ultrasonic intensity of 30 mW / cm², a frequency of 1 MHz, and an action time of 10 minutes, with the antibacterial efficiency exceeding 90% for the first time under this parameter combination. The load-bearing functional region has a lower synergy coefficient; the ultrasonic response critical point corresponds to an ultrasonic intensity increased to 80 mW / cm², a frequency of 1.5 MHz, and an action time extended to 20 minutes, with the higher ultrasonic energy compensating for the insufficient coating load in this region. The synergy coefficient of the composite functional area is moderate. The ultrasonic response critical point corresponds to an ultrasonic intensity of 50 mW / cm², a frequency of 1 MHz, and an action time of 15 minutes, with parameter settings between the former two. The ultrasonic response critical point also marks the upper limit threshold of ultrasonic intensity. Exceeding this threshold and continuing to increase the ultrasonic intensity will not significantly improve the antibacterial effect but may damage surrounding normal tissues. The upper limit threshold for the antibacterial functional area is 100 mW / cm², and the upper limit threshold for the load-bearing functional area is 150 mW / cm².

[0068] An ultrasound stimulation parameter library was constructed based on ultrasound response critical points. Ultrasound response critical point parameter groups for three functional zones were entered into the ultrasound stimulation parameter library one by one, forming zoned ultrasound treatment plans. The ultrasound stimulation parameter library uses a three-layer structure to organize the data. The first layer is the spatial location of the ultrasound response critical point corresponding to the functional zone index; the second layer is the parameter type index, including intensity parameters, frequency parameters, time parameters, and safety thresholds; and the third layer contains specific values ​​and applicable conditions. Parameter records for the antibacterial functional zone were transferred from the ultrasound response critical point to the ultrasound stimulation parameter library: intensity 30-100mW / cm², frequency 1-1.5MHz, single treatment time 10-20 minutes, daily treatment frequency 2-3 times, treatment cycle 7-14 days. The upper limit threshold of the ultrasound response critical point marker is set as a mandatory constraint in the ultrasound stimulation parameter library; the ultrasound device automatically limits the amplitude when this threshold is reached. The ultrasound stimulation parameter library also includes a parameter gradation strategy. In the early postoperative period, a lower intensity of 30 mW / cm² is used to avoid stimulating new tissue. Starting two weeks postoperatively, the intensity is gradually increased to 50 mW / cm², reaching the optimal intensity corresponding to the ultrasound response critical point at four weeks postoperatively. For the load-bearing functional area, due to the limited coating load, the ultrasound stimulation parameter library sets an enhancement mode for this area, increasing the intensity to 1.2 times the ultrasound response critical point (96 mW / cm²) and the frequency to 1.5 MHz to increase the tissue penetration depth of the ultrasound energy. The completeness of the ultrasound stimulation parameter library is verified by the coverage index; all functional zones and all treatment stages have corresponding parameter combinations recorded.

[0069] The forming process instructions are generated by integrating the heterojunction coating structure using an ultrasonic stimulation parameter library. The ultrasonic parameter requirements for each zone in the library are transmitted back to the coating design. The low strength requirement of the antibacterial functional zone means that the coating thickness can be set to an upper limit of 18 micrometers to maximize zinc ion storage. The high strength requirement of the load-bearing functional zone means that the coating needs to have a higher piezoelectric response coefficient to generate sufficient active oxygen within a limited thickness. The parameters of 150 nm ZrO2 layer thickness, 18 micrometer ZnO layer thickness, and 35 MPa interfacial bonding strength in the heterojunction coating structure are confirmed and locked in the forming process instructions. These parameters have been verified in S140 to meet the design requirements. The forming process instructions integrate the process parameters for porous substrate forming and coating preparation. The substrate forming part includes parameters such as laser power 280W / 200W, scanning speed 800 / 1000 mm / s, and layer thickness 30 μm. The coating preparation part includes parameters such as impregnation concentration 0.5 mol / L, impregnation time 45 minutes, oxidation temperature 400℃, and oxidation time 2 hours. The partition information in the ultrasonic stimulation parameter library is converted into partition boundary coordinates of the processing path in the forming process instruction, with the boundary positions of the outer surface Diamond partition and the inner Gyroid partition precisely defined. The quality inspection standards for the heterojunction coating structure are written into the quality control module of the forming process instruction: coating thickness deviation is controlled within ±15%, interfacial bonding strength is not less than 30 MPa, and coating coverage is not less than 95%. The final output of the forming process instruction is a machine-readable G-code file and a process card document. The G-code file is directly imported into the laser selective melting equipment for processing, and the process card document is used by operators for process parameter verification and quality traceability. The ultrasonic stimulation parameter library is delivered as an appendix with the forming process instruction for subsequent clinical use in ultrasound treatment plans.

[0070] To implement the above-described method embodiments, a method for topology optimization and additive manufacturing of porous bone implants is provided to achieve the corresponding functional and technical effects. See also... Figure 4 , Figure 4 This diagram illustrates a structural block diagram of a porous bone implant topology optimization and additive manufacturing system 400 according to an embodiment of this application. For ease of explanation, only the parts relevant to this embodiment are shown. The porous bone implant topology optimization and additive manufacturing system 400 provided in this embodiment includes: The data acquisition module 401 is used to acquire the mechanical performance data of the hip joint bone and the load-bearing conditions of the implant, and to perform boundary condition analysis on the mechanical performance data and the load-bearing conditions to form load-bearing characteristics. Finite element analysis module 402 is used to perform finite element mechanical analysis based on the bearing characteristics to identify stress characteristics, establish a mechanical benchmark library by load level stratification from the stress characteristics, and generate a modulus deviation index by performing elastic modulus matching detection through the mechanical benchmark library. Topology optimization module 403 is used to perform variable density topology optimization processing on the bearing characteristics to determine the pore gradient distribution, use the pore gradient distribution to optimize the pore unit configuration to identify the optimal configuration, and adjust the modulus deviation index based on the optimal configuration to form gradient matching parameters. The additive forming module 404 is used to control the additive manufacturing layered forming of the gradient matching parameters to determine the forming state of the porous matrix, generate matrix parameters based on the forming state of the porous matrix, and construct the heterojunction coating structure by controlling the zinc-based coating load and the bonding strength of the heterojunction interface from the matrix parameters. The collaborative control module 405 is used to perform mechanical-antibacterial performance coupling analysis on the modulus deviation index and the gradient matching parameters to extract the collaborative coefficient, identify the ultrasonic response critical point based on the collaborative coefficient, construct an ultrasonic stimulation parameter library based on the ultrasonic response critical point, and output forming process instructions by integrating the heterojunction coating structure through the ultrasonic stimulation parameter library.

[0071] The aforementioned porous bone implant topology optimization and additive manufacturing system 400 can implement a porous bone implant topology optimization and additive manufacturing method according to the above-described method embodiments. The options in the above method embodiments are also applicable to this embodiment, and will not be detailed here. The remaining content of this application's embodiments can be referred to the content of the above method embodiments, and will not be repeated in this embodiment.

[0072] The above embodiments are not an exhaustive list based on the present invention, and there may be many other embodiments not listed. Any substitutions and improvements made without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A method for topology optimization and additive manufacturing of porous bone implants, characterized in that, include: Obtain the mechanical performance data of the hip joint bone and the load-bearing conditions of the implant, and perform boundary condition analysis on the mechanical performance data and the load-bearing conditions to form load-bearing characteristics; Based on the load-bearing characteristics, finite element mechanical analysis is performed to identify stress characteristics. From the stress characteristics, load levels are layered to establish a mechanical benchmark library. Through the mechanical benchmark library, elastic modulus matching detection is performed to generate modulus deviation index. The load-bearing characteristics are subjected to variable density topology optimization to determine the pore gradient distribution. The pore gradient distribution is used to optimize the pore unit configuration to identify the optimal configuration. Based on the optimal configuration, the modulus deviation index is adjusted to form gradient matching parameters. The gradient matching parameters are used to perform additive manufacturing layer forming control to determine the porous matrix forming state. Based on the porous matrix forming state, matrix parameters are generated. The zinc-based coating load and heterojunction interface bonding strength are controlled from the matrix parameters to construct the heterojunction coating structure. A synergy coefficient is extracted by performing mechanical-antibacterial performance coupling analysis on the modulus deviation index and the gradient matching parameter. The ultrasonic response critical point is identified based on the synergy coefficient. An ultrasonic stimulation parameter library is constructed based on the ultrasonic response critical point. The forming process instruction is output by integrating the heterojunction coating structure through the ultrasonic stimulation parameter library.

2. The method according to claim 1, characterized in that, The step of performing boundary condition analysis on the mechanical performance data and the load-bearing conditions to form load-bearing characteristics includes: The bone density distribution characteristics of cortical bone and cancellous bone are identified from the mechanical property data to form a bone density mechanical distribution. The dynamic load spectrum is determined by obtaining multi-attitude load conditions from the aforementioned load-bearing conditions; The bone density mechanical distribution is matched with the dynamic load spectrum to obtain a constraint boundary set; Based on the constraint boundary set, bearer features are constructed.

3. The method according to claim 1, characterized in that, The step of establishing a mechanical benchmark library by classifying load levels from the stress characteristics includes: The stress peak value and stress gradient are separated from the stress characteristics to form a stress classification table; The stress grading table is used to identify and mark the stress concentration areas at the bone-implant interface, specifically the sensitive areas of the interface. Based on the stress grading table and the interface sensitive area, the elastic modulus matching range of each load interval is set to obtain the modulus constraint conditions. A mechanical benchmark library is constructed based on the aforementioned modulus constraints.

4. The method according to claim 1, characterized in that, The step of using the pore gradient distribution to optimize the pore unit configuration and identify the optimal configuration includes: The target porosity of each zone is determined from the pore gradient distribution to form porosity constraints; Based on the porosity constraint, a set of candidate configurations is obtained by designing the topology of the three-period minimum surface. Perform mechanical load-bearing performance verification on the candidate configuration set to screen for effective configurations; Identify the optimal configuration from the effective configurations.

5. The method according to claim 1, characterized in that, The step of determining the porous matrix forming state by controlling the additive manufacturing layered forming of the gradient matching parameters includes: The pore characteristics of each partition are read from the gradient matching parameters to determine the layered forming sequence; Based on the layered forming sequence, the pore interconnection forming order is optimized to obtain an interconnection forming scheme; Based on the aforementioned interconnection forming scheme, laser power and scanning speed are matched to obtain partitioning process parameters; The porous matrix forming state is determined by layer-by-layer melting and forming of Zr-Nb powder using the aforementioned partitioning process parameters.

6. The method according to claim 1, characterized in that, The process of constructing a heterojunction coating structure by controlling the zinc-based coating load and heterojunction interface bonding strength from the matrix parameters includes: The coating deposition constraints are determined by analyzing the porous surface morphology characteristics based on the substrate parameters. A coating-matrix composite is obtained by performing pore wall permeation loading of the zinc-based coating according to the coating deposition constraint; The coating-matrix composite is subjected to thermal oxidation treatment to form a ZrO2-ZnO heterojunction interface; The bonding strength of the ZrO2-ZnO heterojunction interface was tested to construct the heterojunction coating structure.

7. The method according to claim 1, characterized in that, The step of extracting synergistic coefficients through mechanical-antibacterial performance coupling analysis of the modulus deviation index and the gradient matching parameter includes: Mechanical performance constraints are determined by selecting mechanical fit parameters from the modulus deviation index; The pore structure features are obtained from the gradient matching parameters to form the coating bearing constraint; Based on the mechanical performance constraints and the coating bearing constraints, a functional partitioning diagram is obtained by performing functional partitioning mapping between the bearing area and the antibacterial area; Based on the functional zoning diagram, a multi-objective coupling analysis is performed to obtain the synergy coefficient.

8. The method according to claim 5, characterized in that, The step of optimizing the pore connectivity forming sequence based on the layered forming sequence to obtain a connectivity forming scheme includes: Based on the layered forming sequence, the positions of pores in adjacent layers are located to form an interlayer pore reference table; A pore connectivity analysis was performed on the interlayer pore reference table to identify connected pore groups and isolated pore groups; A modified forming sequence is obtained by rearranging the forming sequence based on the isolated pore group; A connected forming scheme is generated based on the connected pore group and the modified forming sequence.

9. The method according to claim 6, characterized in that, The process of thermally oxidizing the coating-matrix composite to form a ZrO2-ZnO heterojunction interface includes: The oxidation process parameters are determined by setting the thermal oxidation temperature and oxidation time for the coating-substrate composite. Surface oxidation is performed according to the oxidation process parameters to form a ZrO2 oxide layer and a ZnO oxide layer; An interfacial diffusion treatment is performed on the ZrO2 oxide layer and the ZnO oxide layer to form a heterojunction transition region; The crystal structure of the heterojunction transition region was characterized to confirm the construction of the ZrO2-ZnO heterojunction interface.

10. A porous bone implant topology optimization and additive manufacturing system, characterized in that, include: The data acquisition module is used to acquire the mechanical performance data of the hip joint bone and the load-bearing conditions of the implant, and to perform boundary condition analysis on the mechanical performance data and the load-bearing conditions to form load-bearing characteristics. The finite element analysis module is used to perform finite element mechanical analysis based on the load characteristics to identify stress characteristics, establish a mechanical benchmark library by load level stratification from the stress characteristics, and generate a modulus deviation index by performing elastic modulus matching detection through the mechanical benchmark library. The topology optimization module is used to perform variable density topology optimization processing on the bearing characteristics to determine the pore gradient distribution, use the pore gradient distribution to optimize the pore unit configuration to identify the optimal configuration, and adjust the modulus deviation index based on the optimal configuration to form gradient matching parameters. An additive manufacturing module is used to control the additive manufacturing layered forming of the gradient matching parameters to determine the forming state of the porous matrix, generate matrix parameters based on the forming state of the porous matrix, and construct a heterojunction coating structure by controlling the zinc-based coating load and the bonding strength of the heterojunction interface from the matrix parameters. The collaborative control module is used to perform mechanical-antibacterial performance coupling analysis on the modulus deviation index and the gradient matching parameters to extract the collaborative coefficient, identify the ultrasonic response critical point based on the collaborative coefficient, construct an ultrasonic stimulation parameter library based on the ultrasonic response critical point, and output forming process instructions by integrating the heterojunction coating structure through the ultrasonic stimulation parameter library.

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