Modelling a Structural-Acoustic Coupled System with an Equivalent Lumped Parameter Mechanical System

This paper describes the way in which a structural acoustic coupled system can be modelled using an equivalent lumped parameter mechanical model. The impedance-mobility approach is first used to model the system, and by relating the physical parameters to equivalent mass and stiffness, lumped parameter models can be derived provided that damping in the acoustic system is neglected in all modes, but the first (zero order) mode. A limitation of this approach, however, is that these simple mechanical models formulated in terms of the uncoupled structural and acoustic modes are only possible for either a single structural mode coupled to many acoustic modes, or a single acoustic mode coupled to many structural modes. These models facilitate physical insight into the dynamic behavior of a lightly-damped structural-acoustic system at frequencies close to the resonance frequencies of the coupled system.