2D triangular anti-trichiral structures and auxetic stents with symmetric shrinkage behavior and high energy absorption

Abstract

In this study, 2D triangular anti-trichiral structures and auxetic stents, under compression, were introduced. The cores of the anti-trichiral structures were the equilateral triangles. The deformation mechanisms in 2D structures were based on the rotation of the triangles and bending of the ligaments. A parametric study was carried out to investigate the dependence of the Poisson's ratio to the triangle edge lengths. The most auxeticity, with the values of υyz = −0.55 and υzy = −1.6, was obtained in the structure in which the triangle edge lengths were considered 13 mm. Next, the auxetic stents with the aims of uniform shrinkage behaviors as well as high energy absorption were introduced. For this purpose, the equilateral triangles were distributed on the cylindrical surfaces along with the peripheral and longitudinal directions. Under compression, the stent with 15mm triangle edge lengths possessed uniform shrinkage behavior, and the values of Poisson's ratio were measured υzx = −2.2 and υzy = −2.19. Finally, the comparisons between triangular and conventional anti-trichiral stents were performed. It was observed that the lateral displacements, as well as energy absorption of the triangular stents were twice and three times as high as the conventional anti-trichiral stents respectively.