Martensite variant localization effects on fatigue crack growth - the CuZnAl example

Abstract

The paper underscores the difficulty in characterizing crack growth in shape memory alloys with conventional stress intensity approaches even when anisotropy is accounted for. The local displacements deviate significantly from the presumed K solutions because of transformation localization at macro scales extending from the crack tip. Modifications in stress intensity due to variant induced tractions are derived providing an explanation of the extrinsic behavior. Precise displacement and strain measurements are provided to highlight the complexity of deformation and the need for better fracture mechanics models, including crack tip opening displacements, to characterize fatigue crack growth in shape memory alloys.