Intended for engineers who deal with vibrations of rods and shells in their everyday practice but who also wish to understand the subject from the mathematical point-of-view, the results contained here concerning high-frequency vibrations may be new to many. The book serves equally well as an advanced textbook, while remaining of interest to mathematicians who seek applications of the variational and asymptotic methods in elasticity and piezoelectricity. Only a minimum knowledge in advanced calculus and continuum mechanics is assumed on the part of the reader.