Multi-field induced reconfigurable point defect state of flexural waves in magnetostrictive phononic crystals plates

Point defect state of phononic crystals (PCs) has attracted increasing interest owing to the unique characteristics of wave localization. However, the effectively and dynamically multi-field realization of point defect state of elastic waves in complex environments is still a challenge. We propose a magnetostrictive PC plate aiming to dynamically achieve the reconfigurable point defect state of flexural waves by adjusting magnetic, mechanical and thermal loadings. The controllable band gap can be successfully induced by changing the multi-field loadings. Subsequently, we design three Schemes to induce the reconfigurable point defect without altering the structure, i.e., magnetic-induced, thermal-induced and multi-field (magnetic and thermal) induced Schemes, respectively. The numerical and experimental results show that for the magnetic and thermal-induced Schemes, the frequency of point defect state increases monotonically with the increase of the defect magnetic field and temperature, respectively. By adjusting the magnetic and thermal distributions, the reconfigurable location of point defect can be obtained, the frequency decreases as the number of cells increases. This study provides a guidance for realizing the reconfigurable point defect state of elastic waves, which can be beneficial for the customized requirement of wave localization devices like wave guiding, monitoring and energy harvesting.