Investigations Into the Physical Mechanisms That Facilitate Transformation Hysteresis in Shape Memory Alloys
Influences of energy dissipative mechanisms are rationalized using a theoretical approach which combines micro-mechanics and thermodynamics into a thermo-mechanical framework. Models are formulated for the thermal and stress hysteresis based on a thermo-mechanical framework so as to shed light into differential hysteresis magnitudes. Current theoretical formulations consider energy dissipation from a phenomenological point view and satisfy the second law of thermodynamics by considering a dissipative potential. In the current study, an earlier thermo-mechanical formulation is advanced beyond phenomenological considerations to include the effects of micro-scale plasticity. With this, the hysteresis models can account for energy dissipation resulting from strain energy relaxation. The current modeling approach provides intuitive predictions of the experimentally observed behavior particularly a growing hysteresis with increasing stress for NiTi alloys.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign