Experimental investigation of the pseudoelastic behaviour of NiTi wires under strain- and stress-controlled cyclic tensile loadings

Pseudoelastic NiTi based shape memory alloys (SMA) wires have a good potential in civil engineering applications and often used as dampers in anti-seismic or cable structures when a rate varied cyclic loadings is applied. In accordance with these applications, an experimental characterization of NiTi wires under strain- and stress-controlled cyclic loadings at various strain rates is presented. Based on these loadings, it is shown that the stress-strain response of the material evolves up to a complete stabilization with the increase of the number of cycles. This evolution is accompanied with the degeneration of pseudoelasticity and transformation ratcheting in the case of strain- and stress-controlled mode, respectively. Also, it was found that the cyclic deformation of pseudoelastic NiTi SMA is significantly rate dependent.