The behavior of Nitinol Wire Bundles for Structural Applications

Shape memory alloys (SMA) belong to are a family of smart materials, which undergo diffusionless phase transformations when subjected to thermo-mechanical changes making them ideally suitableed for utilizationuse in several structural engineering applications. Within this class of materials, Ni-Ti (Nickel-Titanium) alloys are alloys are the most commonly used are the predominantly used alloys due to their significant non-linear behaviour they demonstrated by them. Nitinol, one of the Ni-Ti alloys, haspossesses unique properties such as super-elasticity and shape- memory effect, which makes it suitable for damping vibrations transmitted to structures like buildings and bridges structures during high wind and seismic events. This paper presents a selectedion of the results obtained of from a series of tests conducted on Nitinol 55 wires and bundles made from wires having diameters of 0.25, 0.5, 0.55, and 1 mm diameter wires. The tests conducted include microstructure analyses, static tensile tests, hysteresis tests, and cyclic dynamic tests performed on wire bundles of various diameters. It is demonstrated that wires having small diameters wires (0.25 and 0.5 mm) exhibit higher greater ultimate strength compared to with the ones having a larger diameter ones (1 mm). The wire bundles producedmade from these wires displayed hysteretic behaviour under cyclic-dynamic testing conditions confirming their suitability in structural engineering applications.