Fatigue, Fracture, and Crack Arrest from Bending Induced Pre-strain in Superelastic Nitinol

Abstract The present study evaluates the fatigue and fracture performance of electropolished Nitinol wire apex specimens subjected to a range initial bending crimp/pre-strains determine how behavior may be modified by compressive strains residual stress. Three extrados (tensile) crimp/pre-strain conditions (8, 12, 14.5%) were investigated. Specimens cycled in unidirectional up 10 7 cycles at 37 °C 1.5% mean strain. High observed decrease probability for higher strain amplitudes cycles. Bend intrados cracks initiate arrest 12 14.5%. These arrested lengths corresponding amount far-field load applied. Finally initiation was change from tensile surface (extrados) (intrados) depending on pre-strain