Bio-Inspired Design of PLLA Vascular Stents for Enhanced Radial Mechanical Performance Based on Coconut Palm Microstructures

To improve the radial mechanical performance and reduce the collapse risk of poly(L-lactic acid) (PLLA) vascular stents, this study proposes a novel stent design integrating the negative Poisson’s ratio (NPR) effect with a bio-inspired coconut palm (CP) cell structure. An anisotropic multi-plate crimping model incorporating the Hill yield criterion is developed to accurately capture the radial mechanical behavior of PLLA stents. The effects of different cell configurations on radial stiffness, strength, specific stiffness, and specific strength are investigated, and the deformation mechanisms of different cell structures are revealed. Results indicate that, compared with a typical PLLA stent, the NPR PLLA stent exhibits significantly enhanced radial mechanical performance. Moreover, the multi-cell structures combining CP and NPR cells further improve the radial stiffness and strength of the stent. The coupled deformation effect between the CP and NPR cells effectively suppresses buckling instability, resulting in a more stable crimping process and regular deformation behavior. Based on these findings, a novel NPR-nested CP double-cell structure is proposed with superior radial mechanical performance. Post-deployment performance is further evaluated by analyzing stent recoil and the corresponding arterial mechanical response. This work provides insights and technical guidance for the structural design and radial mechanical enhancement of PLLA vascular stents.