Nonlinear Statistical Energy Analysis modelling of a complex structural-acoustic system

Active noise control has been extensively studied with the aim of improving the acoustic comfort in vehicles. The current state-of-art feed-forward road noise reduction systems are limited by nonlinearities in the transmission path between the sensors and the acoustic response in the car cabin, due to nonlinear characteristics of the components in the suspension system. The aim of the present work is to explore key physical nonlinear characteristics of the vibro-acoustic response of a car by adopting a Statistical Energy Analysis (SEA) approach. A nonlinear structural-acoustic system excited with band filtered Gaussian noise has been designed to study the dependency of the dynamic response to on the degree of nonlinearity. Experimental data has shown that both structural and acoustic responses are dependent on the amplitude of the input at the driving point. Following an SEA approach, the structural subsystem has been modelled as a dissipative mechanism, allowing the derivation of a first-order equation of motion with nonlinear stiffness. Numerical solutions of the nonlinear equation are in good agreement with experimental data. The SEA model is being extended to include the acoustic response of the nonlinear system.