ScholarWorks@동국대학교

초록

Piezoelectric actuators that leverage defect modes in phononic crystals (PnCs) have the capacity to significantly amplify longitudinal or flexural waves, rendering them a compelling option for nondestructive testing applications. However, conventional PnCs exhibit a deficiency in their inability to adapt their wave-propagation characteristics to changing environments. To address this limitation, the present study incorporates defective PnC-based bending wave actuators within elastic foundations, thereby facilitating mechanical tuning. An analytical model, founded upon the Euler-Bernoulli beam theory and formulated with transfer matrix and S parameter techniques, has been developed to capture both electroelastic coupling and foundation effects. Two practical configurations are examined: (1) a uniform foundation supporting the entire defective PnC, including the piezoelectric defect, and (2) a selective foundation supporting only the intact beams, leaving the defect region free. In both cases, the proposed analytical model accurately predicts the results in band structure and wave-actuation analyses, showing excellent agreement with COMSOL Multiphysics simulations. The following are the most significant findings: (1) the closed-form analytical model validated against COMSOL for rapid parametric design, (2) near-linear tuning of the bandgap and defect-band frequencies via foundation stiffness while retaining strong defect-mode-enabled energy localization, (3) robust defect-mode shapes that sustain large, symmetric strain fields for efficient bending-wave actuation, and (4) enhanced voltage-to-velocity actuation sensitivity and discovery of an additional low-frequency defect mode when the defect region is left unsupported.

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