Computational modeling of stent failure during crimping and deployment in coronary arteries

Crimping and deployment of coronary stents involve severe finite deformations, multibody contact, and complex loading-unloading sequences that critically influence their structural integrity and long-term performance. This study presents a 3D phase-field fracture framework for simulating the onset and evolution of metal stent failure during crimping and balloon-assisted deployment in coronary arteries modeled as an anisotropic, hyperelastic material. The proposed framework combines finite-strain elastoplasticity with a phase-field description of ductile fracture, implemented as a dedicated user element (UEL) in Abaqus and validated against experimental stress-strain data for stainless steel stents to accurately capture plastic deformation, damage initiation, and softening. In parallel, a second UEL is developed for the arterial wall, incorporating anisotropic hyperelasticity to represent the layered mechanical response of intima, media, and adventitia. Fully coupled simulations of the stent-balloon-artery system reproduce the complete crimp-hold-release and expansion sequence, explicitly capturing contact interactions, stress localization at crowns and connectors, and progressive damage accumulation under realistic physiological conditions. The simulations reveal that fracture is initiated already during the crimping phase and continues to evolve during balloon expansion, resulting in localized damage zones, residual stresses, and elastic recoil after balloon deflation. Comparative analyses of representative stent designs (e.g., open-cell and closed-cell configurations with varying strut thickness and geometry) demonstrate how design features, loading paths, and arterial anisotropy govern damage evolution, failure progression, and post-deployment mechanical performance. The proposed model establishes a robust computational framework for failure-aware evaluation of coronary stents under finite strains, providing new insights for optimizing stent design and deployment strategies. The corresponding source code in this study is openly available at https://doi.org/10.25835/666phabc to support further research.