Title

Elasto-plastic analysis of stents : texture and grainsize effects on radial strength

Document Type

Thesis

Degree

Master of Science (MS)

Department

Mechanical Engineering

First Advisor's Name

K. H. Wu

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Richard Shoephoerster

Third Advisor's Name

Cesar Levy

Date of Defense

12-2-2003

Abstract

A nonlinear finite element analysis of a stent was performed using ABAQUS® to analyze the elasto-plastic behavior during crimping and deploying of the stent and the effects of material properties on various characteristics like radial strength, recoil and foreshortening. Geomteric and material non-linearities are considered since the crimping and deployment of the stent involves large deformations. The stent is meshed using solid elements brick, wedge and tetrahedral elements to model the stent. An elastic-plastic material model described by von Mises-Hill constitutive model is considered due to the plastic deformations involved.

An entirely new stent was designed and analyzed. Characteristics of the stent like stress concentrations, the elastic recoil and the longitudinal foreshortening after crimping and expansion were computed. The width of the strut of the stent is very small and therefore the grainsize of the material also plays an important part in the radial strength of the stent. Single crystal elastic constants were used to model the grainsize effect on the radial strength of the stent. The effects of changes in grain orientation on the radial strength of the stent were analyzed. The effects of the deployment diameter and the strut thickness on the radial strength of the stent were also analyzed. The data obtained from the finite element analysis was also used to calculate the theoretical fatigue life of the stent.

Identifier

FI14062205

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