Yun Zhai

Auxetic tubular lattices provide a potential structural platform for simultaneously tuning radial support, axial dimensional stability, and bending flexibility; however, the coupled effects of topology and geometric parameters on these mechanical responses remain insufficiently understood. In this study, a topology-driven design framework was established for fused deposition modeling (FDM)-printed thermoplastic polyurethane (TPU) tubular lattices. Five auxetic topologies were designed by regulating curvature polarity and structural symmetry, while planar porosity and wall thickness were selected as geometric control parameters. Numerical simulations combined with experimental validation were employed to systematically evaluate axial bending stiffness, radial support force, Poisson’s ratio, and stress distribution. The results demonstrate that geometric curvature promotes radial load transfer through an arch-like mechanism and contributes to stress redistribution, whereas structural symmetry strongly influences axial compliance and auxetic deformation. Planar porosity acts as the dominant macroscopic tuning parameter for overall mechanical performance, while wall thickness provides a secondary fine-tuning mechanism with greater sensitivity to local stress variation. Based on these findings, a hierarchical design strategy integrating topology, planar porosity, and wall thickness is proposed, providing a generalizable approach for tailoring the mechanical performance of FDM-printed elastomeric tubular lattices.

Tantalum (Ta) is an ideal material for orthopedic implants due to its excellent biocompatibility and osseointegration capability, while Voronoi porous structures can mimic the morphology and mechanical properties of trabecular bone. However, establishing quantitative relationships between design parameters and scaffold performance remains challenging. This study systematically investigates the manufacturability, mechanical properties, and structural control methods of Voronoi porous Ta scaffolds fabricated by selective laser melting (SLM). By adjusting point spacing (700-1700 μm) and strut diameter (250-500 μm), Voronoi scaffolds with different configurations were constructed, and a nonlinear mapping model between design parameters and porosity/specific surface area was established (R2 > 0.99). Six groups of Voronoi porous Ta scaffolds with theoretical porosities of 65%-90% were fabricated by SLM. The scaffolds exhibited high purity (>99.95%), α-Ta phase, strut diameter errors of 21-29.2 μm, porosity errors of 1.7%-2.75%, and relative densities of 96.23%-98.03%, indicating good manufacturability. Compression tests showed elastic modulus of 231-1892 MPa and yield strengths of 3.77-30.60 MPa, matching cancellous bone mechanical properties. Finite element simulations showed a good linear correlation with experimental results (R2 > 0.99), and a power-law relationship between porosity and mechanical properties was observed (R2 > 0.96). At the same porosity, altering point spacing or strut diameter did not significantly affect mechanical performance, confirming porosity as the key factor. In summary, Voronoi porous Ta scaffolds show excellent manufacturability and tunable mechanical properties. The established prediction model provides a quantitative basis for efficient design of biomimetic bone scaffolds, advancing clinical translation of personalized porous Ta implants.

Porous bone implants have been extensively studied, with gradient structures receiving increasing attention due to their superior compatibility with bone tissue. However, comparative studies between gradient and uniform structures remain relatively scarce. In this study, selective laser melting (SLM) technology was employed to fabricate a gradient composite Ti6Al4V humeral bone plate, utilizing rhombic dodecahedron and its derived structures as unit cells. By adjusting the porosity parameter range to 22.02–94.37% using the Ashby Gibson formula, the mechanical properties of the porous bone plate were analyzed by varying the porosity parameters and conducting compression tests. The experimental results show that after preparing and compressing the structure, the elastic modulus of the model is controlled between 0.09–5.43 GPa, and the maximum yield strength is 216.1 Mpa. The experimental results demonstrate that, under shear loading, the gradient structure generates stress from the center of mass, with the phenomenon becoming more pronounced as the number of struts aligned with the direction of the applied load increases. This results in the model exhibiting characteristics of good resilience on the outside and a certain degree of rigidity on the inside. Compared to non-gradient models, gradient structures are more effective in controlling the direction of force transmission. Moreover, the elastic modulus of the bone plate is closer to that of natural bone tissue. These findings provide valuable insights for further research into gradient structure models of other rod-shaped unit cells, highlighting the mechanical advantages of gradient structures over uniform ones.

Titanium alloy dental implants play a crucial role in the field of oral rehabilitation. However, the use of solid designs can give rise to mechanical problems such as mismatched compressive elastic modulus with the host bone tissue, resulting in stress shielding and stress concentration. These problems have been a persistent bottleneck in their application effectiveness. To overcome this challenge, this study creatively designed five types of porous structures with cylindrical thin wall based on the Gibson–Ashby theoretical model. The aim is to optimize the mechanical performance of dental implants, enhance their compatibility with the host bone tissue, and utilize selective laser melting technology for precise fabrication of porous structures using Ti6Al4V material. Through a combination of simulation analysis and compression experiments, the stress and strain distributions of the five structures are systematically investigated under different bite conditions. The experimental results demonstrate that all five porous structures designed in this study effectively alleviate stress shielding phenomenon in dental implants, significantly improving the bonding performance between the implants and bone tissue. This meets the clinical implantation requirements and provides strong theoretical support for the application of dental implants in clinical settings.

Vascular stents have many applications in treating arterial stenosis and other vascular-related diseases. The ideal vascular stent for clinical application should have radial support and axial bending mechanical properties that meet the requirements of vascular deformation coordination. The materials used for vascular stents implanted in the human body should have corresponding biocompatibility to ensure that the stents do not cause coagulation, hemolysis, and other reactions in the blood. This study fabricated four types of vascular stents, including inner hexagon, arrowhead, quadrilateral, and outer hexagonal, using fused filament fabrication technology and thermoplastic polyurethane (TPU) as materials. By evaluating the effects of edge width and wall thickness on the radial support and axial bending performance, it was found that the inner hexagonal stent exhibited the best radial support and axial bending performance under the same conditions. The design and fabrication of vascular stents based on 3D printing technology have promising application prospects in personalized customized vascular repair therapy.