<title>Modeling of strain energy absorption in superelastic shape memory alloys</title>

Abstract

The mechanical behavior of shape memory alloys (SMA) can be separated into two distinct categories: the shape memory effect and the superelastic effect. When loaded, the superelastic SMA undergoes a stress-induced martensitic transformation that will result in a large recoverable strain. Upon unloading, the undergoes a large hysteresis loop that makes the superelastic SMA an excellent candidate for strain energy absorption. This large strain energy absorption capability has been used to improve the impact tolerance of composites in related work. It is to further understand this strain energy absorption capability in composites that a 1D model to evaluate the energy absorption of superelastic shape memory alloy under bending and tension loading is developed using the Euler-Bernoulli beam theory. This theoretical model gives quantitative relations between the martensite fraction, the applied load, and the strain energy absorbed in the SMA. As expected, the superelastic SMA as demonstrated a very high strain energy absorption capability, demonstrating the advantage of using superelastic SMA to absorb strain energy. The closed form solution of the strain energy absorption capability of SMA bars provides a useful tool in the design of energy dissipation applications of superelastic SMA.