Experimental observations on rate-dependent cyclic deformation of super-elastic NiTi shape memory alloy

Qianhua Kan, Chao Yu, Guozheng Kang, Jian Li, Wenyi Yan

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63 Citations (Scopus)

Abstract

Based on the strain-controlled cyclic tension-unloading tests at various strain rates (3.3 ×10 −4 –3.3 ×10 −2 /s), the effect of strain rate on the uniaxial cyclic deformation of a super-elastic NiTi shape memory alloy (SMA) was investigated. It is concluded that ap- parent degeneration of super-elasticity occurs during the cyclic loading, i.e., the residual strain and transformation hardening increase, but the start stress of forward transforma- tion and the maximum responding stress decrease with the increasing number of cycles and strain rate, and finally reach to their saturated states after certain cycles. Although the dissipation energy per cycle decreases progressively during the cyclic loading and is saturated after certain cycles, it does not change monotonically with the increasing strain rate. Moreover, the temperature oscillation is observed due to the internal heat production from the inelastic dissipation and transformation latent heat, and the extent of tempera- ture variation increases monotonically with the increasing strain rate, which is the physical nature of rate-dependent cyclic deformation of the NiTi SMA.
Original languageEnglish
Pages (from-to)48 - 58
Number of pages11
JournalMechanics of Materials
Volume97
DOIs
Publication statusPublished - 1 Jun 2016

Keywords

  • NiTi shape memory alloy
  • Super-elasticity
  • Cyclic deformation
  • Rate-dependence
  • Internal heat production

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