Material dissipation effects on wave propagation in polycarbonate elastic metamaterial plates

Elastic metamaterials are known for unusual dynamics of elastic waves that is impossible for common engineered composites. This is due to their carefully engineered architecture, generating frequency bandgaps with inhibited wave propagation. However, elastic wave propagation is also influenced by the mechanical properties of constituent materials, e.g., viscous losses present in most polymers.In this study, we report the dynamic mechanical thermal analysis and ultrasonic tests providing data relative to the viscoelastic behavior of polycarbonate – a promising polymer for elastic metamaterial applications. Our results show that material dissipation in the neat polycarbonate is negligibly small. We then manufacture a polycarbonate metamaterial plate and evaluate its dynamic behavior experimentally and numerically, the latter comparing linear elastic and viscoelastic material models. Despite the fact that viscous losses are small in the material, an elastic model is incapable of reliably predicting a bandgap for the analyzed metamaterial plate. Our findings contribute to providing a better understanding of wave propagation in polymer metamaterial plates and emphasize the importance of considering viscous losses in modeling their wave dynamics.