Numerical Simulation of Creep Behavior for Catheter obtained under Different Unloading Conditions after Proportional Loading of Tension and Torsion

Abstract

This paper describes the effect of the braids on the creep deformation behavior of a catheter made of soft nylon resin and stainless steel wires. In our previous studies, the creep deformation behavior generated during the loading process has been mainly examined under two or three stages step stress for tension and torsion with different loading history. However, the creep deformation behavior that occurs during unloading process after loading process has not been examined yet. Therefore, in the present study, the creep deformation behavior is investigated focusing on the unloading history for tension and torsion. Especially, in order to reveal the effect of loading history for tension or torsion on the creep deformation behavior generated under step unloading, experiments are performed under different starting times of step unloading and different values of step unloading. Moreover, the numerical simulations of creep deformations when tension or torsion is unloaded after proportional combined loading for tension and torsion are carried out based on the three-element mechanical model that consists of a spring element and a Voight model.