Calculation of stress intensity factor for an edge cracked shape memory alloy plate

Abstract

In this thesis, the e ect of martensitic transformation on stress intensity factor in an edge cracked shape memory plate loaded under Mode I conditions is studied. J contour integral is evaluated by an explicit technique and the results are compared to those of ABAQUS. It is seen that J integral is path dependent in martensite region at the crack tip. But, it remains path independent in austenic zone. Also a decrease in stress intensity factor due to martensitic transformation at the crack tip is observed. In addition to this, micromechanics based calculations in the literature are reviewed and modi ed to discuss the toughening e ect as a result of phase transformation. Eshelby approach with a weight function method is utilized in order to quantify the decrease in stress intensity factor. Using analytical expressions from literature, transformation e ect on stress intensity factor is also calculated. The orientation of crystals are taken into account by calculating variants and related transformation strains. The assigned orientation is seen to be responsible of di erence in magnitude of stress intensity factor.