SUPPRESSION AND ENHANCEMENT OF ELASTODYNAMIC RADIATION FROM A POINT-SOURCE LOAD IN ELASTIC-WAVE BAND STRUCTURES

We show that propagation of elastic waves can be completely inhibited, irrespective of propagation directions, if oscillation frequencies of elastic waves fall inside elastic wave band gaps-three-dimensional fr equency stop bands of elastic waves generated in three-dimensional per iodic elastic materials. We also develop a classical theory for the ca lculation of radiated fields and energy from a point source load locat ed in three-dimensional periodic elastic media by incorporating the pl ane wave method, dyadic Green's function, Poynting theorem, and tetrah edron k-space integration. The fee structure of tungsten spheres in po lyethylene background is studied as an example. The resulting frequenc y spectra indicate the total inhibition of energy transmission in the elastic wave band gaps and unusual enhancement near the band edges. In addition, the computed data suggest the strong dependency of radiatio n spectra on the source position in the periodic elastic materials. (C ) 1996 American Institute of Physics.