Stent devices made of a lattice with smooth shape cells improving stent fatigue life

摘要

A method for generating a lattice cell shape for a stent comprising generating a unit cell model representing a stent cell to be made of a given material, the unit cell model comprising elements each comprising points defining a G2-continuous curve, setting a weighting factor to a same value for each one of the points, the weighting factor representing a contribution of a corresponding one of the points to a curvature of an optimal curve, determining a curvature of the G2-continuous curve as a function of the weighting factors having the same value, and structurally optimizing the unit cell model by iteratively determining a variable value for the weighting factor value using stress-strain characteristics for the given material, determining a new curvature of the G2-continuous curve as a function of the variable value, and minimizing the new curvature, thereby obtaining an optimized curve corresponding to an optimized lattice cell shape.

主权项

1. A method for generating a lattice cell shape for a stent made of a lattice of a given material comprising:
generating a unit cell model representing the lattice cell, the unit cell model comprising a plurality of geometric primitives interconnected by blending points, each of the geometric primitives defining a G2-continuous curve at the blending points; setting a weighting factor to a same value for each one of the plurality of blending points, the weighting factor representing a contribution of a corresponding one of the plurality of blending points to a curvature of an optimal curve; determining a curvature of the G2-continuous curve as a function of the weighting factors having the same value; and structurally optimizing the unit cell model by iteratively and sequentially: determining a variable value for the weighting factor value for each one of the plurality of blending points, the variable value for the weighting factor value being calculated at each iteration using at least strain characteristics for the given material, determining a new curvature of the G2-continuous curve as a function of the variable value, and minimizing said new curvature, until obtaining an optimized curve corresponding to an optimized shape of the lattice cell; and generating the lattice cell shape for the stent having said optimized shape.