Dynamic Characterization and Control of a Metamaterials-Inspired Smart Composite

The potential to utilize metamaterials concepts to realize smart composites with adaptive mechanical wave manipulation, energy harvesting, and structural health monitoring functionalities was investigated. A proof-of-concept metamaterials-inspired smart composite having CFRP face sheets bonded to additively manufactured polymer cores equipped with harvesting coils and sandwiching a chemically-etched multifunctional plate was fabricated. This plate consists of a periodic array of re-entrant cantilever beam resonators with center-loaded neodymium magnets, which acts as the multifunctional kernel. Experiments demonstrate isolation of a payload from mechanical disturbances within tunable frequency bands. Moreover, energy sequestered by resonators is harvested as useable electrical power. Using a coupled electromechanical harvesting model, predictions for multifunctional responses were obtained and correlated with experiments. The harvesting circuitry doubles as an active control system for the resonators as well as a sensing and monitoring system to detect structural defects. Both offline and online active control algorithms were investigated to reduce phase shift between harvesting coils, thereby improving the efficacy of the harvesting process. Potential applications include use as structural material for equipment or vehicles used in adverse or remote environments, where maximizing energy recovery and structural awareness in addition to payload isolation is desirable.