Robust control of active constrained layer damping

Conventional Passive Constrained Layer Damping (PCLD) treatments with visco-elastic cores are provided with built-in sensing and actuation capabilities to actively control and enhance their vibration damping characteristics. The control gains of the resulting Active Constrained Layer Damping (ACLD) treatments are selected, in this paper, for fully treated beams using the theory of robust controls. In this regard, an optimal controller is designed to accommodate the uncertainties of the ACLD parameters, particularly those of the visco-elastic cores which arise from the variation of the operating temperature and frequency. The controller is also designed to reject the effects of the noise and external disturbances. The theoretical performance of beams treated with the optimally controlled ACLD treatment is determined at different excitation frequencies and operating temperatures. Comparisons are made with the performance of beams treated with PCLD treatments. The results obtained emphasize the potential of the optimally designed ACLD as an effective means for providing broadband attenuation capabilities over a wide range of operating temperatures as compared to PCLD treatments. (C) 1998 Academic Press Limited.