Moving-boundary elastica predicts looped-end braided stent crimping

Looped-ended braided stents are used in vascular interventions owing to their flexibility, conformability, and self-expansion. However, severe crimping into low-profile delivery catheters concentrates bending, crossing-point migration, and geometric crowding at the terminal crowns, producing stresses that classical uniform-braid models cannot resolve. This limitation is critical for bioabsorbable metallic stents, where excessive end-region stress may compromise deliverability or exceed yield limits. To address this gap, this study develops a large-deformation moving-boundary elastica model that represents the terminal crown as a planar elastica with a moving crossing point and predicts maximum bending stress, radial force, and local geometric jamming. The model was verified against finite element simulations spanning stiffness, pitch angle, wire diameter, loop radius, wire number, and stent diameter, and compared with experimental crimping data for a looped-ended Nitinol braided stent. The predictions showed close agreement with finite element stress and radial-force responses throughout the planar sliding regime and followed the measured force trend before stress-induced martensitic transformation. In high-wire-density configurations, deviations marked the transition to out-of-plane crown buckling and defined the planar model limit. The results establish the looped end as a design-limiting region and provide an end-specific framework for rapid loop-end screening before finite element analysis or prototype testing