Active-passive hybrid constrained layer for structural damping augmentation

A new surface-damping concept with an active-passive hybrid constraining la yer (HCL) is proposed to improve the damping performance of traditional act ive constrained layer (ACL) systems. instead of using a pure piezoelectric constraining layer, passive and active materials are used together to const rain the viscoelastic material layer. A generic model of the HCL treatment is presented Nondimensional equations of motion and boundary and connecting conditions are derived. The closed-form solutions to the equations are dev eloped and analyzed. Tabletop tests are also performed to verify the feasib ility of the nerv damping concept. It is shown that by properly selecting a passive constraining material and assigning appropriate lengths for the ac tive and passive constraining parts, HCL can outperform a system with a pur e active PZT coversheet, both in terms of its fail-safe ability and closed- loop damping performance. [S0739-3717(oo)01503-8].