Gordon C. Everstine
Raymond S.-C. Cheng
Comput. Mech. Office, David Taylor Model Basin, Carderock Div., Naval Surface Warfare Ctr., Bethesda, MD 20084-5000
An approach is described for computing the direct frequency response of structural acoustic systems containing frequency-dependent materials or damping treatments. The frequency dependence of the damping material is treated by approximating its modulus with a second-order polynomial so that the stiffnesses associated with the constant, linear, and quadratic terms can be combined with the stiffness, damping, and mass matrices assembled for the rest of the structure. The mathematically complex stiffness, damping, and mass matrices that result can then be used in coupled finite element/boundary element structural acoustic analyses using a direct frequency sweep.