Porous Shape Memory Alloy: 3D Reconstitution and Numerical Simulation of Superelastic Behavior

摘要

As a new class of metallic foam materials have attracted increasing interest in different fields of engineering. They are particularly versatile because of their interesting mechanical and physical properties: relative low density makes it possible to obtain a high stiffness/weight radio, existence of cavities results in the abilities of energy absorption and of damping, and also gives them thermal and acoustic insulation properties. As a well-known material for reversible inelastic deformation, shape memory alloys (SMA) have been paid attention on over last few years. They possess two important properties: superelasticity and shape memory effect. Cellular structures in SMAs are particularly interesting for their potential to provide superelasticity and shape memory effect in a lightweight material. In this work, 3D foam CAD structure of NiTi material is reconstituted using ellipsoid cell units. A "taking" and "placing" algorithm based on uniform distribution and normal distribution is adopted for the reconstitution process of Representative Volume Element (RVE). In the RVE, dimensions, positions, and orientations are all random. A constitutive model for shape memory alloy including phase transformation, martensitic reorientation and twins accommodation is used to simulate by the finite element analysis the superelastic behavior of the SMA foam. In order to show the efficiency of the proposed methodology, some applications are presented to simulate the compression of shape memory alloy foam. The effects of porosity, size, orientation, and ratio of long and axes short of the unit cell on the superelastic behavior of porous material are discussed.