COMPLEX ELASTIC-WAVE BAND STRUCTURES IN 3-DIMENSIONAL PERIODIC ELASTIC MEDIA

Propagation of elastic waves can be completely inhibited, irrespective of propagation directions, if oscillation frequencies of elastic wave s fall inside elastic wave band gaps-three-dimensional frequency stop bands of elastic waves generated in three-dimensional periodic elastic materials. The three-dimensional linear vector equation of motion is transformed into a matrix eigensystem and solved numerically by the pl ane wave expansion method. Existence of elastic wave band gaps is theo retically demonstrated for the face centered cubic lattice structure b ased on isotropic materials. The example structure is spherical tungst en scatterers embedded in a polyethylene matrix. Complex elastic wave band structures were also computed for tunneling evanescent waves al s ymmetric points at X and L points. (C) 1997 Elsevier Science Ltd. All rights reserved.