The variational theory of complex rays for the calculation of medium-frequency vibrations

A new approach called the "variational theory of complex rays" (VTCR) is de veloped for calculating the vibrations of weakly damped elastic structures in the medium-frequency range. here, the emphasis is put on the most fundam ental aspects. The effective quantities (elastic energy, vibration intensit y, ets.) are evaluated after solving a small system of equations which does not derive from a finite element discretization of the structure. Numerica l examples related to plates show the appeal and the possibilities of the V TCR.