FEM optimization with Nitinol.

The present contribution focuses on the structural modelling of Nitinol devices. Apart from a powerful material modelling which should consider the well-known phenomena pseudo-elasticity, pseudo-plasticity and the shape memory effect a computationally efficient finite element implementation is needed. The cost of the numerical simulation depends crucially on the implementation of the material model at the Gauss point level (local level) and on the finite element technology used. Concerning the first point it is meanwhile state of the art to work with a so-called consistent linearization. This is also pursued in the present paper. On the other hand, the question of finite element technology is hardly discussed in the literature on shape memory alloy (SMA) modelling, although it is one of the crucial points. We discuss here a new one Gauss point concept which avoids the well-known "locking" (artificial stiffening) of standard displacement-based formulations and which is even more efficient than many formulations available in commercial codes.