H_∞ control of active constrained layer damping

Conventional passive constrained layer damping treatments with viscoelastic cores are provided with built-in sensing and actuation capabilities to actively control and enhance their vibration damping characteristics. Two configurations of the resulting hybrid treatment are considered in this paper. In the first configuration, the active control and passive operate separately, whereas in the second configuration, the two operate in unison to maximize the energy dissipation characteristics. In this study, three objectives are accomplished. The first objective aims at the design and implementation of robust H_∞ controllers for the separated and unified control strategies. In the second, the performance of the H_∞ controllers at different operating frequencies and temperatures is compared with that of a conventional proportional/derivative controller to demonstrate robustness. Finally, a control effort study involving the H_∞ controllers for the separated and unified control strategies is shown to assess the efficiency of the active control scheme in controlling structural vibration. The results obtained emphasize the potential of the optimally design unified control strategy as an effective means for providing broad-band attenuation capabilities over a wide range of operating temperatures.