Design and optimization of local acoustic response in mid-frequency vibro-acoustic systems

Abstract

Most research about vibro-acoustic optimization focuses on the reduction of the global acoustic response in mid- and even high-frequency ranges. The noise control in concerned local domains inside the acoustic cavity also deserves to be studied. This article deals with a local acoustic optimization in the framework of statistical modal energy distribution analysis (SmEdA) aiming at reducing the noise in concerned local domains of mid-frequency vibro-acoustic systems. As a recently proposed method, SmEdA processes modal energies of the coupled subsystems rather than the subsystem energies directly and permits extending analytical frequency to mid-frequency range. Using a post-processing technique, the local information involving the distributions of kinetic and potential energies inside the acoustic cavity can be estimated. In the optimization model, the acoustic energy in concerned local domains of the cavity is taken as the objective function, considering the constraint on structural weight. By optimizing the thickness distribution of the structural subsystem, the local acoustic response is significantly reduced. The effectiveness of the optimization procedure and the corresponding local acoustic sensitivity technique are illustrated by the given numerical examples. Optimization results indicate: (a) the developed optimization procedure is more effective in reducing the local acoustic response compared with the global acoustic optimization; (b) the modal energies including the kinetic and potential energies in the local acoustic domain tend to be uniformly distributed after optimization.