AN ENVELOPE ENERGY-MODEL FOR HIGH-FREQUENCY DYNAMIC STRUCTURES

High frequency structural and acoustic problems require prohibitive co mputational efforts. The tendency, nowadays, is to find a solution in statistical terms (SEA) through an average of the field variables on t he space domain. A limitation of SEA is the loss of any local informat ion. In contrast with SEA, a power flow method [1] can describe a tren d of the energy density along the structure, thus improving the qualit y of the solution. However, in dealing with flexural waves, the power flow neglects the near field contribution: the related solution can so metimes differ considerably from the expected trend. In this paper a h eld trend is obtained in a totally different manner. An envelope energ y is used that describes well the exact solution: specifically, only t he decaying fields, obtained from the projection on the real axis of t he damped bending wavenumbers are accounted for, while the propagating components are omitted. Simulated results are presented and compared with exact and approximate solutions. (C) 1995 Academic Press Limited.