Actively tunable nonlocal magneto-electro-elastic phononic crystal nanoplates for wave-based nondestructive testing: bandgap engineering and Grey Wolf optimisation

Efficient regulation of elastic-wave dispersion is important for high-frequency wave manipulation, frequency-selective filtering and vibration-control applications. A theoretical framework for the active control and enhancement of elastic-wave bandgaps in nonlocal magneto-electro-elastic phononic crystal (MEE-PC) nanoplates with regularly distributed Terfenol-D/PZT-5 H inclusions incorporated into an epoxy matrix is presented in this work. Kirchhoff plate theory and Eringen’s nonlocal flexibility theory are combined to create a size-dependent multiphysics model, and dispersion relations and band structures are calculated using the Plane Wave Expansion (PWE) approach. Elastic-wave dispersion is rigorously examined in relation to electric loading, nonlocality, mechanical prestress, magnetic potential and geometric characteristics. The findings show that while growing nonlocality lowers bandgap efficiency due to nanoscale softening, external electric and magnetic fields greatly expand the first bandgap and push it towards higher frequency bands through improved magneto-electro-mechanical interaction. The computational model incorporates a Grey Wolf Optimiser (GWO) to increase the first bandgap width from around 30.0 GHz to 81.2 GHz in order to further enhance wave attenuation. The proposed actively tunable phononic crystal provides a theoretical platform for adaptive wave filtering, ultrasonic-wave manipulation, vibration suppression and high-frequency wave-control devices, while its possible use in NDT and structural health monitoring requires further defect-specific investigation.