An envelope energy model for high frequency dynamic structures

High frequency structural and acoustic problems require prohibitive computational efforts. The tendency, nowadays, is to find a solution in statistical terms (SEA) through an average of the field variables on the space domain. A limitation of SEA is the loss of any local information. In contrast with SEA, a power flow method [1] can describe a trend of the energy density along the structure, thus improving the quality of the solution. However, in dealing with flexural waves, the power flow neglects the near field contribution: the related solution can sometimes differ considerably from the expected trend. In this paper a held trend is obtained in a totally different manner. An envelope energy is used that describes well the exact solution: specifically, only the decaying fields, obtained from the projection on the real axis of the 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.