Vibration control of fluid-loaded cylindrical shells using active constrained layer damping

The underlying physics of vibration control and resultant radiated sound pressure level are studied for fluid loaded cylindrical shells treated with Active Constrained Layer Damping (ACLD). Performance of enhancing the damping characteristics via reduced vibrations and sound radiation in the surrounding fluid is demonstrated both theoretically and experimentally. A prime motivation for this research is the potential wide applications to reducing the radiated noise for fluid loaded shells such as submarines and torpedoes where acoustic stealth is critical to the effectiveness of their missions.;For the case of fluid loading on an ACLD treated cylindrical shell, the equations of motion are developed that include accounting for the added mass effect of the surrounding water. A finite element model is also developed to predict the acoustic radiation in the surrounding fluid given excitation of the ACLD treated cylinder. This model allows investigation of the effectiveness of ACLD control strategy as well as specifics to the resultant vibration modes of the submerged cylinder. A water tank is constructed that incorporates test cylinders treated with ACLD patches placed for targeting of specific vibration modes. Using this arrangement, the effectiveness of different control strategies is studies using excitation internal to the submerged cylinder, and the radiated sound pressure level in the water is observed. Comparisons are made between the experimental results and the theoretical predictions to validate the finite element model.