Design of M-shaped bistable structure and its application on high radial strength polymer stent

• An M-shaped bistable structure was designed to enhance the radial strength of biodegradable polymer vascular stents. • The M-shaped bistable structure breaks through the limitations of idealized conditions, establishing a mechanical theory model for free boundary conditions. • Theoretical modeling and finite element analysis confirmed the superior mechanical performance of the bistable stent design. • The radial support strength of the bistable polymer stent increased by 214 % compared to the honeycomb stent. This work proposes a novel bistable structure with free-end boundary conditions, breaking through the limitations of traditional idealized bistable structures and offering enhanced applicability in engineering applications. By establishing a theoretical model of the M-shaped bistable structure under free boundary conditions, the accuracy of the design was validated through finite element simulations and experimental prototyping. When applied to vascular stent, this study innovatively compensates for the lack of material properties with structural properties. The structure solves the key problem of poor mechanical properties of polymer stents relying on their own elastic-plastic deformation through the bistable properties, and significantly improves the radial support strength. Comparative studies with conventional honeycomb stents and other biodegradable polymer stents further highlight the advantages of the proposed design. The results demonstrate that the free-end bistable structure not only solves the collapse problem of polymer stents but also provides a versatile design framework for broader engineering applications requiring high mechanical performance and structural adaptability.