<title>Variations of hybrid damping</title>

Abstract

ABSTRACT Damping is important to structures and can be achieved through the addition of viscoelastic materials (VEM). The dampingof the VEM is enhanced if a constraining layer is attached to the VEM. If this consiraining layer is active, the treatment iscalled active constrained layer damping (ACLD). In the last few years, ACiD has proven to be superior in vibration conirolto active or passive damping. The active element makes ACLD more effective than passive constrained layer damping. Italso provides a fail-safe in case of breakdown of the active element that is not present for purely active control. It is shownthat the conirol effort needed to damp vibration using ACLD can be significantly higher than purely active control. In orderto combine the inherent damping of passive control with the effectiveness of the active element, this paper will exploredifferent variations of active, passive and hybrid damping. Some of the variations include: passive constrained layerdamping (PCLD) separate from active element but on the same side ofbeam, PCLD separate from active on the opposite sideof the beam, and active element underneath PCLD. The discreUzed system equations will be obtained using assumed modesmethod and Lagrange's equation. The damping will be modeled using the Golla-Hughes-McTavish (GHM) method. Theoptimal placement and size of the active, passive, ACLD and hybrid treatments will be found using different schemes. Theissue of overshoot and setthng time of the output and control force using LQR will be addressed, as well as the control effort,passive and active vibration suppression, and LQR cost function. It will be shown that the hybrid treatments are capable ofgreater vibration control for lower control effort for different optimization schemes.Keywords: passive damping, active damping, ACLD, optimal control, hybrid damping, optimal placement and size