Shape optimization of stress concentration-free lattice for self-expandable Nitinol stent-grafts

Abstract

In a mechanical component, stress-concentration is one of the factors contributing to reduce fatigue life. This paper presents a design methodology based on shape optimization to improve the fatigue safety factor and increase the radial stiffness of Nitinol self-expandable stent-grafts. A planar lattice free of stress concentrators is proposed for the synthesis of a stent with smooth cell shapes. Design optimization is systematically applied to minimize the curvature and reduce the bending strain of the elements defining the lattice cells. A novel cell geometry with improved fatigue life and radial supportive force is introduced for Nitinol self-expandable stent-grafts used for treating abdominal aortic aneurism. A parametric study comparing the optimized stent-graft to recent stent designs demonstrates that the former exhibits a superior anchoring performance and a reduction of the risk of fatigue failure.

A Re-Engineered Software Interface and Workflow for the Open-Source SimVascular Cardiovascular Modeling Package

“…In addition, they offer a means to quantify mechanical stimuli triggering mechanobiologic responses such as vessel wall remodeling and aneurysm initiation and progression [9,30]. Furthermore, one can efficiently perform multiple simulations while systematically varying geometric and physiologic parameters for surgical planning, medical device design, and optimization [31][32][33][34][35][36][37].…”

The Wall Apposition Evaluation for a Mechanical Embolus Retrieval Device

“…They are also confirmed to stay in the safe domain of Nitinol alloy. It has been speculated that the former highest peak MPS appears on the basis of unsmooth geometry [ 17 ] and a tiny connecting section in the microstructure.…”

Stent fabric fatigue of grafts supported by Z-stents versus ringed stents: An in vitro buckling test

“…76 Major research reports have highlighted the benefits of shape optimization of the metallic frame but the main achievement was the treatments used to make the Nitinol resistant to corrosion. 77,78 However, the interaction between the Nitinol frame and the fabric sleeve was overlooked in the analysis of explanted AneuRx devices by Zarins et al. 79 This device is supported by diamond-shaped stents, whose tips can perforate the fabric.…”