Evaluation of a new approach for modelling full ring stent bundles with the inclusion of manufacturing strains

Kyriakou, Faidon and Bow, David and Dempster, William and Brodie, Robbie and Nash, David (2020) Evaluation of a new approach for modelling full ring stent bundles with the inclusion of manufacturing strains. Annals of Biomedical Engineering, 48 (1). pp. 144-156. ISSN 0090-6964

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    Abstract

    Ring stent bundles have been used in several biomedical stent-graft devices for decades, yet in the published literature, the numerical models of these structures always present significant simplifications. In this paper, a finite element (FE) ring stent bundle has been developed and evaluated with a combination of beam and surface elements. With this approach, the shape, the global stiffness and the strains of the structure can all be well predicted at a low computational cost while the approach is suitable for application to non-symmetrical, patient-specific implant simulations. The model has been validated against analytical and experimental data showing that the manufacturing strains can be predicted to a 0.1% accuracy and the structural stiffness with 0–7% precision. The model has also been compared with a more computationally expensive FE model of higher fidelity, revealing a discrepancy of 0–5% of the strain value. Finally, it has been shown that the exclusion of the manufacturing process from the simulation, a technique used in the literature, quadruples the analysis error. This is the first model that can capture the mechanical state of a full ring stent bundle, suitable for complex implant geometry simulations, with such accuracy.