Identification of reduced and uncoupled models in vibroacoustical experimental modal analysis

To control the noise level of passenger compartment is one of the important design issues in fields such as automobile and manned aerospace. An uncoupled model of the acoustic part extracted from the coupled vibroacoustical system is significant for predicting and improving the vehicle noise performance. The objective of this work is to build mass, stiffness, and damping matrices of a reduced equivalent system which exhibits the same behavior as the full size one. An extension of the least-square complex frequency-domain (LSCF) method is introduced specifically for vibroacoustical identification. The QR decomposition is subsequently performed to obtain a reduced model whose behavior is as close as possible to the measurement. The properness condition enforcement method employed here provides the optimal eigenvectors, which can be safely used to reconstruct the equivalent system. A simulated case study is proposed to illustrate the application of this approach.