Multiscale nonlocal effective medium model for in-plane elastic wave dispersion and attenuation in periodic composites

This manuscript proposes a multiscale nonlocal homogenization and a nonlocal effective medium model for in-plane wave propagation in periodic composites accounting for dispersion and attenuation due to Bragg scattering. The nonlocal effective medium model is developed based on the spatial-temporal nonlocal homogenization model that is formulated to capture dispersion within the first Brillouin zone with particularly high accuracy along high symmetry directions. The homogenization model is derived by employing high order asymptotic expansions, extending the applicability of asymptotic homogenization to short wavelength regime, to capture wave dispersion and attenuation. The effective medium model is in the form of a second order PDE with a nonlocal effective moduli tensor that contains the nonlocal features of the homogenization model. The proposed models are derived and numerically verified for in-plane elastic wave propagation in two-dimensional periodic composites. It is shown that the dispersion curves of the spatial-temporal nonlocal homogenization model capture the acoustic branch, the first stop band and the optical branch of longitudinal and shear wave modes. The nonlocal effective medium model predicts transient elastic wave propagation in periodic composites and captures wave dispersion and attenuation within the limits of separation of scales. (C) 2018 Elsevier Ltd. All rights reserved.