Plane harmonic waves in orthorhombic thermoelastic materials

Keeping in view the increased usage of orthorhombic materials in the develo pment of advanced engineering materials such as fibers and composites and o ther multilayered media, the aim of the present paper is to give a detailed account of the plane harmonic generalized thermoelastic waves in orthorhom bic materials. According to the frequency equation, the four waves, a quasi -longitudinal, two quasi-transverse, and a quasi-thermal wave, can propagat e in an orthorhombic crystal. When plane waves propagate along the axis of an orthorhombic solid, then only the longitudinal and thermal waves are cou pled, whereas the transverse waves get decoupled from the rest of the motio n. For plane waves propagating in one plane of the solid, only the SH wave in that plane remains purely transverse and gets decoupled from the rest of the motion and vice versa. The other three waves are coupled and get modif ied due to thermal variations and relaxation time. The particle paths and s tability of the waves have been discussed and the results verified numerica lly. These have been represented graphically for single crystals of solid h elium and cobalt material. (C) 2000 Acoustical Society of America. [S0001-4 966(99)06912-X].