ScholarWorks@숙명여자대학교

초록

Omnidirectional ultrasonic wave manipulation is critical for non-destructive evaluation and structural health monitoring due to its advantage in simultaneous monitoring of broad inspection areas. However, omnidirectionality inherently suffers from energy dissipation with distance, seriously harming inspection quality in the far field. Here, we propose novel elastic meta-super-strates (EMSs) to achieve extraordinary gain in omnidirectional ultrasonic SH wave emission. Each EMS creates dual Fabry-Perot cavities (an internal cavity and an edge cavity) that confine source energy and release it in a highly amplified manner under precise resonance conditions. Multiple EMSs can be overlapped for cumulative amplification, with the total gain proportional to the product of individual impedance ratios. We establish a rigorous theoretical foundation for this emission enhancement using an effective medium model and validate the gain principle with single and multiple EMS configurations. Numerical simulations and experimental results confirm the hyper-gain phenomenon, demonstrating excellent agreement with theoretical predictions. The proposed EMS concept provides a practical approach for enhancing the omnidirectional performance of ultrasonic transducers.

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