FUNCTIONAL FATIGUE PROPERTIES OF TINIZRSN BIOCOMPATIBLE SHAPE MEMORY ALLOY

Functional fatigue degrades the superelastic properties of shape memory alloys under cyclic loading. In the presence of geometric stress concentrations, the local stress fields are amplified resulting in local accumulation of irrecoverable strains and consequently loss of functionality. For the biocompatible TiNbZrSn system, grain size and solution treatment temperature play a major role in affecting the level of pseudoelastic strains and their evolution upon cycling. These aspects are quantitatively investigated in this work. Dogbone tensile specimens and samples with drilled circular holes are considered in this work and full field strain measurements are employed to quantitatively evaluate the localization in response leading to loss of functionality.
EXTENDED ABSTRACT