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arXiv · 2505.01977

Quasi-BICs due to symmetry mismatch in architected elastic plates

Adib Rahman·Sean Perkins·Raj Kumar Pal
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Abstract

We report the existence of quasi-bound modes in the continuum (quasi-BICs) in architected elastic plates based on a square lattice. The structure consists of topologically trivial and nontrivial lattices, forming an interface and maintaining C2 symmetry. Carefully engineered interface gives rise to center quasi-BICs. We show how the mismatch in symmetry between the Bloch modes of the lattice and the defect modes confine them at the defect center, resulting in quasi-BICs. Our analysis begins with a square lattice-based spring-mass system. Finite element simulations on an architected plate comprising of slender curved and straight beams to achieve the desired stiffness variation predict quasi-BICs analogous to those in the discrete model. These predictions are validated with Laser Doppler vibrometry based experiments, confirming the presence of a quasi-BIC in the structure. The concept of quasi-BICs arising from modal symmetry mismatch paves the way for achieving localized modes in elastic structures, with potential applications as resonators.

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Adib Rahman, Sean Perkins, Raj Kumar Pal. 2025-05-04. Quasi-BICs due to symmetry mismatch in architected elastic plates. https://arxiv.org/abs/2505.01977

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