Thermomechanical and electrical response of a superelastic NiTi shape memory alloy cable

Abstract

Superelastic shape memory alloys are a unique class of smart materials that can recover up to 6% strains. Due to their appealing properties such as high energy dissipation and corrosion resistance, several researchers have assessed the use of such materials in numerous applications ranging from biomedical to civil engineering. This article investigates the thermomechanical and electrical response of a NiTi shape memory alloy cable with a complex configuration subjected to cyclic loading of various strain amplitudes ranging from 3% to 7%. The cable consists of several multi-layered strands with a cumulative outer diameter of 5.5 mm. The thermomechanical results indicate a good correlation of the change in cable temperature with the applied strains and maximum stresses. The temperature history can be used to map the degradation pattern of the shape memory alloy cable. In addition, due to the complex geometry of the cable, the global electrical resistance change does not predict the strain/stress state of the cable; however, it can be used to predict the onset of phase transformations.

Design, manufacturing, and testing of a hybrid self‐centering brace for seismic resilience of buildings

“…The mechanical response of the SMA cable, as shown in Figure 4A, exhibits slight degradation under cyclic loading at a constant displacement. This has also been observed in other studies on the SMA cables 33–37 . Previous experimental studies 49,50 reveal that the training of SMA material has a considerable effect on the cyclic stability of the mechanical response.…”

“…This has also been observed in other studies on the SMA cables. [33][34][35][36][37] Previous experimental studies 49,50 reveal that the training of SMA material has a considerable effect on the cyclic stability of the mechanical response. On the other hand, rubble-like viscoelastic materials also show mechanical degradation after experiencing large strains, [51][52][53] that is, the Mullins effect.…”

“…Previous experimental studies have shown that SMA cables possess large levels of recoverable strain and high fatigue life. [34][35][36][37] They are less sensitive to initial imperfections, and exhibit redundant failure mode. Their cost is also considerably lower than a comparable size of monolithic SMA bar.…”

“…SMA cables leverage the outstanding mechanical properties of wires to carry relatively high tensile loads. Previous experimental studies have shown that SMA cables possess large levels of recoverable strain and high fatigue life 34–37 . They are less sensitive to initial imperfections, and exhibit redundant failure mode.…”

NiTi SMA Superelastic Micro Cables: Thermomechanical Behavior and Fatigue Life under Dynamic Loadings

“…The NiTi SMA micro cable and the reference element reached a low cycle fatigue life, which is of the order of 10 3 cycles [ 1 ]. For reference, Sherif and Ozbulut [ 12 , 20 ] observed the first failures around the 3 × 10 3 cycles in a superelastic multi-layered NiTi cable under tension mode at 7% strain amplitude.…”