Propagation of harmonic waves in a plate of variable thickness

The authors have constructed an interfaced spectral problem under conditions of bi - orthogonality for a viscoelastic plate with variable thickness. The spectral problem describing distribution of flexural flat waves in a wave guide has been also formulated. Numerical solutions of spectral problems have been calculated on computer by the program complex based on the method of orthogonal condensation by S. K. Godunov combined with the Müller's method.