On the transient impact response of a structure made of shape memory alloy

On the transient impact response of a structure made of shape memory alloy. In this paper, some improvements in the RL model are presented in order to solve transient dynamics problems. the initial model, based on the therm mechanics behaviour of alloy coupled with the heat equation has been implemented in a finite-element code for low frequency dynamics in previous works. Using this non linear model for transient dynamics (structural response to impact excitation) leads to non-physical solutions or to non convergence of the time integration algorithm. These behaviours are clue to strong non-linearities of equations that govern the transformation kinetics between both phases (austenite/martensite). Adding a relaxation term in differential equations allows the algorithms to converge without disturbing the original system. this term can be associated to a physical effect which is the propagation velocity of the phase transformation, classically considered as instantaneous in static or quasi-static simulations. The results are shown using a 2D structure excited by an impact force.