Electrically controllable and reversible coupling degree in a phononic crystal with double piezoelectric defects.

• This is the first attempt to achieve tunable defect bands for double defect cases. • Coupling degree between double defects is controllable without altering structures. • Electrically controllable coupling is valid regardless of double defect settings. • The analytical approach reduces computation time for predicting coupling degrees. Research in the field of phononic crystals (PnCs) has traditionally focused on single defects for energy localization and frequency-selective filtering. Recent attention has turned to exploring double defects to expand frequency options. Advancements in this area have introduced differently patterned double defects, which can be either coupled or decoupled. Yet, the conventional mechanical approach locks in double-defect characteristics early in the design process. To overcome this limitation, this study proposes a novel electrical control method to adjust the coupling degree between double defects for the first time. By attaching bimorph piezoelectric elements with respective inductive circuits to defects, this work offers a flexible means of manipulating their interaction, allowing them to interactively behave as double defects or independently function as single defects, depending on the user's purpose, even after mechanical design finalization. Through analytical and numerical models, the proposed approach is comprehensively validated, demonstrating its effectiveness in two scenarios of double defects with identical and different structural configurations. Two main contributions of this work are as follows. First, this is the first attempt to achieve electrically controllable and reversible coupling degrees of double defects. Second, the developed analytical model enables the rapid prediction of tunable defect-band frequencies, thereby reducing computational time. We believe this research opens new avenues for dynamically controlling defective PnC behaviors, promising advancements in applications like structural health monitoring, prognostics health and management, and medical imaging. [ABSTRACT FROM AUTHOR]