Control of sound radiation from an active constrained layer damping treated plate into an acoustic cavity using structural intensity approach

Considerable attention has been devoted to actively and passively control of the sound radiating from vibrating plates into closed cavities. With the advent of smart materials, extensive efforts have been exerted to control the vibration and sound radiation from flexible plates using smart sensors/actuators. Active Constrained Layer Damping (ACLD) treatment has been used successfully for controlling the vibration of various flexible structures. The treatment provides an effective means for augmenting the simplicity and reliability of passive damping with the low weight and high efficiency of active controls to attain high damping characteristics over broad frequency bands. The proposed study is investigated using a numerically simulated example consisting of an ACLD treated plate/acoustic cavity system excited by a point harmonic force. In this study, an ACLD treated plate/acoustic cavity coupled finite element model is utilized to calculate the structural intensity and sound pressure radiated by vibrating plates. In the passive control, the optimum placements of ACLD patches are determined by structural intensity of ACLD treated plates and compared to the results obtained by modal strain energy approach. The influence on structural intensity of plate due to damping treatment is investigated.