Vibration Control of Tubes With Internally Moving Loads Using Active Constrained Layer Damping

The vibration of a flexible tube with internally moving load is controlled using patches of Active Constrained Layer Damping (ACLD) bonded to the tube surface. The damping characteristics of the tube/ACLD system are modeled by Golla-Hughes-McTavish (GHM) method in order to predict the tube response in the time domain. The transient response of tube/ACLD system is calculated using the finite element method. The predicted response is compared with that of a tube controlled with conventional Passive Constrained Layer Damping (PCLD) treatments. Such comparisons are essential in quantifying the individual contribution of the active and passive damping components to the overall damping characteristics of the system. The predictions of the finite element model are validated experimentally using a cantilevered PVC plastic tube treated with an ACLD patch placed parallel to the tube longitudinal axis. The tube vibration due to an internally moving load is controlled by the ACLD patch using a simple velocity feedback controller. The effectiveness of the controller in damping out the tube vibration is determined experimentally and theoretically for different control gains. Close agreement is obtained between theory and experiments. The results obtained suggest the effectiveness of the ACLD treatment in controlling the vibration of precision pointing systems such as weapon systems.