Metal-Matrix Composite Metamaterials With Smart Switches Embedded by Ultrasonic Consolidation

This research deals with the development of metal-matrix composite metamaterials with embedded electrical switches made of shape memory nickel-titanium (Ni-Ti) for use in broad-band radio frequency (RF) antennas. We have created an experiment that illustrates how a Ni-Ti ribbon can form an electrical contact that opens and closes depending on the Ni-Ti phase being austenite or martensite. We have conducted finite element analyses that describe the thermal gradients in the ribbon required for effecting the phase change. Since part of the embedded Ni-Ti has to be electrically insulated from the aluminum matrix, we have investigated various insulation techniques and selected one that is both effective and straightforward to implement. In order to realize multiband/broadband metamaterials, it is necessary to seamlessly embed the Ni-Ti switches into the metamaterial for active reconfiguration of the electromagnetic response. To achieve this reconfiguration we utilize ultrasonic consolidation (UC), a new manufacturing technology that uses solid state ultrasonic metal welding (UMW) to create metal parts at relatively low temperatures. Consideration of the proposed RF switch for load-carrying antennas requires an aluminum matrix with structural-grade strength; we have conducted mechanical testing which quantifies the longitudinal tensile, transverse tensile, and shear strength of the UC matrix. Preliminary tests have been completed to evaluate the performance of an antenna device with integrated Ni-Ti switch.