Unraveling Frequency Effects in Shape Memory Alloys: NiTi and FeMnAlNi

R. Sidharth, A. S.K. Mohammed, W. Abuzaid, H. Sehitoglu

Research output: Contribution to journalArticlepeer-review

Abstract

With the presence of internal interfaces such as the austenite–martensite interface and the internal twin boundaries in the martensite, shape memory alloys (SMAs) can be employed in passive/active damping applications. Due to the latent heat of transformation, a temperature rise/drop during a load/unload cycle is expected to dynamically couple with the mechanical response of the SMA and influence the stress levels of forward/reverse transformation and thus the hysteretic area (i.e. the dissipated energy). Additionally, the temperature change per cycle is a function of loading frequency due to momentary heat transfer effects. To this end, for the first time, we demonstrate a rate insensitive shape memory alloy system, Fe43.5Mn34Al15Ni7.5 which also exhibits near-zero temperature dependent stress–strain response. Contrastingly, we show that Ni50.8Ti, which is widely used commercially, is highly rate sensitive. With straightforward in situ experiments, complemented with thermomechanical modelling, we pinpoint the key material parameter which dictates frequency sensitivity. The corresponding results are then discussed in the light of different mechanisms contributing to the damping capacity of SMAs.

Original languageEnglish (US)
Pages (from-to)235-249
Number of pages15
JournalShape Memory and Superelasticity
Volume7
Issue number2
DOIs
StatePublished - Jun 2021

Keywords

  • Clausius-Clapeyron
  • Damping capacity
  • Entropy of transformation
  • Hysteresis
  • Internal friction
  • Latent heat
  • Superelasticity

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials

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