EFFECT OF REVERSIBLE PHASE-TRANSFORMATIONS ON CRACK-GROWTH

In this work, the influence of partial or full reversibility of a stress-induced phase transformation is investigated, both in terms of the size and shape of the transformation zone around the crack tip, and the toughness development during crack growth. The constitutive equations adopted in this study are due to Sun et al. (1991, J. Mech. Phys. Solids 39, 507) and account for transformation-induced dilatant and shear strains. These constitutive equations were designed to model the phase transformations occurring in zirconia ceramics or in shape memory alloys (SMA). The results are obtained by a full field finite element analysis of crack propagation under small scale transformation conditions. The phase transformations considered here tend to give rise to a substantial toughening of the material if the transformation were irreversible. It is shown here that in some cases, the reversibility of the transformation can significantly reduce the toughness increase. A parameter study establishes the sensitivity of this deterioration to characteristics of the constitutive response.