Exploring nonlinear metasurfaces for low-frequency ground-vibration control

Mitigating low-frequency ground vibrations is increasingly important as urban environments densify and critical infrastructure are placed closer to activities that generate vibration. Conventional mitigation measures are often ineffective at the long wavelengths, motivating the exploration of engineered metastructures capable of manipulating vibration fields at the sub-wavelength scale. This work investigates the numerical and theoretical foundations of nonlinear metawedges—graded arrays of resonant elements whose response is intentionally designed to depart from linear behavior. While linear metawedges rely on local resonance and spatial grading to produce bandgaps, introducing controlled nonlinearities may offer adaptive and amplitude-dependent performance, enabling wider or tunable bandgaps and a form of self-tuning in which the metasurface responds differently depending on vibration intensity. Using time-domain finite-element simulations and simplified nonlinear models, we examine how nonlinear restoring forces influence energy trapping and wave mode conversion. The study focuses on conceptual mechanisms rather than specific performance outcomes, aiming to identify conditions under which nonlinearities can be exploited to enhance wave attenuation or redirect energy more effectively than linear designs.