Active control of structurally radiated sound from an elastic cylindrical shell

Abstract

A numerical and experimental study was presented on active control of structurally radiated sound from an elastic cylindrical shell. An analytical model was developed for the active structural acoustic control (ASAC) of the cylindrical shell. Both global and local control strategies were considered. The optimal control forces corresponding to each control strategy were obtained by using the linear quadratic optimal control theory. Numerical simulations were performed to examine and analyze the control performance under different control strategies. The results show that global sound attenuation of the cylindrical shell at resonance frequencies can be achieved by using point force as the control input of the ASAC system. Better control performance can be obtained under the control strategy of minimization of the radiated sound power. However, control spillover may occur at off-resonance frequencies with the control strategy of structural kinetic energy minimization in terms of the radiated sound power. Considerable levels of global sound attenuation can also be achieved in the on-resonance cases with the local control strategy, i.e., minimization of the mean-square velocity of finite discrete locations. An ASAC experiment using an FXLMS algorithm was implemented, agreement was observed between the numerical and experimental results, and successful attenuation of structural vibration and radiated sound was achieved.