Layout optimization of porous sound-absorbing material in mid-frequency vibro-acoustic systems

Abstract

In this paper, a new layout optimization technique is integrated with a statistical modal energy distribution analysis (SmEdA) model to obtain the optimal layout of a porous sound-absorbing material for noise control in mid-frequency vibro-acoustic systems. The considered optimization problem is minimizing the total energy of the internal acoustic cavity within the prescribed frequency range by reasonably positioning porous sound-absorbing material patches under a given volume constraint. The principle of SmEdA is based on the power balance between different modes of coupled structural and acoustic subsystems. A modal strain and kinetic energy (MSKE) method is employed to estimate the acoustic modal damping loss factors that are associated with the energy attenuation between different modes of the coupled subsystems. The developed real-valued optimization formulation provides the feasibility of adopting an accurate sensitivity analysis technique, the complex variable method (CVM). The effectiveness of the optimization procedure is demonstrated through a significant reduction in the total acoustic energy. Additionally, some conclusions with realistic significance are obtained: (a) The optimal material layout creates a more uniform distribution of modal energies in the SmEdA model; (b) The acoustic modes tend to move out of the prescribed frequency band through optimization.