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Rate dependent free energy formulations for dynamically excited superelastic SMA wires
Author(s) -
Kaup Andreas,
Altay Okyay,
Klinkel Sven
Publication year - 2021
Publication title -
pamm
Language(s) - English
Resource type - Journals
ISSN - 1617-7061
DOI - 10.1002/pamm.202000209
Subject(s) - shape memory alloy , sma* , dissipation , materials science , pseudoelasticity , martensite , vibration , phenomenological model , structural engineering , mechanics , control theory (sociology) , computer science , composite material , thermodynamics , acoustics , algorithm , physics , engineering , condensed matter physics , microstructure , control (management) , artificial intelligence
Superelastic shape memory alloys (SMAs) are metallic two‐phase polycrystal alloys. The transformation between austenite and martensite phases allows superelastic SMAs unique hysteretic energy dissipation capacity, which is particularly interesting for the development of new‐type of intelligent vibration control systems for structures. However, in structural control, most of the vibrations occur in high strain rate regimes, which interfere the release of self‐generated heat and cause atomic lattice destabilization and thus influence the hysteretic dissipation. The present work proposes two different strain rate dependent free energy formulations and aims to improve the accuracy of existing one‐dimensional macroscopic models of SMA wires. The approaches are developed and implemented in different continuum thermomechanical frameworks, without impairing the simplicity and robustness of the solution process. The first approach introduces an additional control variable for the entropy evolution. The second approach uses a phenomenological formulation of the latent heat evolution. The proposed formulations are validated by cyclic tensile tests conducted on SMA wires. The results show that the calculations using the new formulations can represent the superelastic SMA wire response more accurately.