Existence of Exceptional Body Waves and Subsonic Surface Waves in Monoclinic and Orthotropic Materials

Explicit conditions are given for the existence of an exceptional body wave in monoclinic materials with the symmetry plane at x(1) = 0, x(2) = 0 or x(3) = 0 and in orthotropic materials with the symmetry planes coinciding with the coordinate planes. The non-existence of an exceptional body wave ensures the existence of a subsonic surface wave. If an exceptional body wave exists, explicit conditions are given for the existence of a subsonic surface wave in monoclinic and orthotropic materials except when trL(v) needs to be computed.