The behaviors of structural waves (axial, shear and bending) are studied in multi-material beams and single material plates using the method of characteristics (MOC). The characteristics equations in one dimensional problems are extended and derived to cover the two dimensional problems and to make the method be applicable to study the wave behavior in plates.
The results showed that the structural waves changed their forms during their propagation in the multi-material beams and some reduction is occurred in the natural frequency of the beam. The propagation of structural waves in plates showed same behavior as in beams, so the propagation in two directions can be separated and each direction can be considered individually as one dimensional problem to simplify the characteristics equations and saving the computing time and solution techniques.

KEYWORDS: Beams, Method of Characteristics, Plates, Structural waves and Vibration.