Tunable metamaterial beam with shape memory alloy resonators: Theory and experiment

We investigate and experimentally validate the concept of bandgap tuning in a locally resonant metamaterial beam exploiting shape memory alloy (SMA) resonators. The underlying mechanism is based on the difference between the martensitic phase (low temperature) and austenitic phase (high temperature) elastic moduli of the resonators, enabling a significant shift of the bandgap for a sufficient temperature change. Experimental validations are presented for a base-excited locally resonant metamaterial beam with SMA resonators following a brief theoretical background. It is shown that the lower bound of the bandgap as well as the bandwidth can be increased by 15% as the temperature is increased from 25 degrees C to 45 degrees C for the specific SMAs used in this work for concept demonstration. The change in the bandgap lower bound frequency and its bandwidth is governed by the square root of the fully austenitic to fully martensitic elastic moduli ratio, and it could be as high as 70% or more for other SMAs reported in the literature. Published by AIP Publishing.