The performance of balloon expandable stents during deployment is usually assessed computationally. Most stents have a generic feature that entails wavy rings known as "crowns" which are interconnected via structures known as "bridges". A mathematically exact analyses of such wavy rings would provide a benchmark to such computations and offer a clear insight into the deformation of stents. In the present work, an analytical model is developed to estimate the elasto-plastic response of a cylindrical periodic structure made of sinusoidal crowns interconnected by bridges. Two different interconnections are considered that give rise to two distinctive behaviours one of which is auxetic. Elastic-perfectly plastic material is considered. The apparent elasto-plastic response of the cylindrical structure is obtained in a closed-form by exploiting the periodicity along its longitudinal and the circumferential direction. A scaling ansatz is proposed that collapses nonlinear response data for different geometries into a family of master-curves. Such relationship suggests that the most efficient way to increase the apparent stiffness of the structure is to decrease the amplitude of the wavy crowns. (C) 2019 Published by Elsevier Ltd.
Structural analysis of cyclically periodic rings and its application to the mechanics of balloon expandable stents
Bonfanti, Alessandra;
2020-01-01
Abstract
The performance of balloon expandable stents during deployment is usually assessed computationally. Most stents have a generic feature that entails wavy rings known as "crowns" which are interconnected via structures known as "bridges". A mathematically exact analyses of such wavy rings would provide a benchmark to such computations and offer a clear insight into the deformation of stents. In the present work, an analytical model is developed to estimate the elasto-plastic response of a cylindrical periodic structure made of sinusoidal crowns interconnected by bridges. Two different interconnections are considered that give rise to two distinctive behaviours one of which is auxetic. Elastic-perfectly plastic material is considered. The apparent elasto-plastic response of the cylindrical structure is obtained in a closed-form by exploiting the periodicity along its longitudinal and the circumferential direction. A scaling ansatz is proposed that collapses nonlinear response data for different geometries into a family of master-curves. Such relationship suggests that the most efficient way to increase the apparent stiffness of the structure is to decrease the amplitude of the wavy crowns. (C) 2019 Published by Elsevier Ltd.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
