Researchers at the Penn State College of Engineering have created patterned fabricated plates with adjustable properties, known as metasurfaces, that regulate surface waves. This type of strategic design is known as the topology optimization method (TOM).

Their newly designed metasurface barrier is made of resonant – or vibrating – structures to prevent plate waves from propagating in a specific area. Surface waves have a long range and can travel a long distance without losing much energy, but the resonant structures of the metasurface barrier can stop them.

These structures are tuned to a specific frequency, they correspond to the predefined target frequency of surface waves propagating over an aluminum plate. The design methodology is formulated as a topology optimization problem using TOM.

The TOM aims to generate a bandgap around a specific frequency, automatically designing optimally engineered resonators to have certain resonance and anti-resonance characteristics.

Parisa Shokouhi, professor of engineering sciences and mechanics, said: “In this paper, we show that the methodology can design resonators for metasurfaces that can suppress plate waves, called Lamb waves, but this method can be extended to design resonant metasurfaces that can control other types of guided waves, regardless of frequency range.”

β€œIt is the first time that TOM – originally conceived in the 1980s to solve structural design problems – has been applied in this way. This systematic design strategy can be further generalized and offers a possible approach to wave management in other areas, such as acoustics.”

Magazine reference:

  1. Daniel Giraldo Guzman et al. Design of resonant elastodynamic metasurfaces to control S0 Lamb waves using topology optimization. JASA Express Letters 2, 115601 (2022); DOI: 10.1121/10.0015123