A ONE-DIMENSIONAL MODEL FOR SUPERELASTIC SHAPE-MEMORY ALLOYS WITH DIFFERENT ELASTIC PROPERTIES BETWEEN AUSTENITE AND MARTENSITE

The present work addresses a one-dimensional model able to reproduce t he shape-memory-alloy superelastic behavior, taking into account the d ifferent elastic properties between austenite and martensite. The mode l is based on a single scalar internal variable, the martensite fracti on, for which evolutionary equations in rate form are proposed. The de pendency of the elastic modulus in terms of the martensite fraction is computed through different homogenization techniques. Integration in time leads to the time-discrete evolutionary equations, for which a de tailed analysis in terms of admissible roots is presented, together wi th the expression of the consistent tangent modulus. The solution of t he time-discrete model is approached through a return map algorithm, p roperly modified for the case of phase transitions of the type occurri ng in shape-memory materials. Finally, the ability of the model to sim ulate one-dimensional experimental data is assessed. (C) 1997 Elsevier Science Ltd.