Shape-memory alloys as macrostrain sensors

The present paper studies the feasibility, through physical experimentation, of efficient and low-cost macrostrain sensors, based on shape-memory alloy technologies. The motivation of this work is to explore the intrinsic relation between electrical resistivity and strain, associated with the development of the stress induced martensitic transformation in superelastic shape-memory alloys. This property enables the material to endure deformations up to 8% without any residual strains, making shape-memory alloy wires excellent candidates for kernel elements in innovative strain transducers with dynamic ranges 4 to 5 times larger than the currently available strain transducers. An experimental prototype of a beam with a set of SMA macrostrain sensors is presented, featuring a timed scanning sequential algorithm to successfully perform the resistance readings. The aim of this work is to provide an additional insight into the potential of SMAs in new macrostrain measurement applications.