It is becoming increasingly important to add damping to structures for vibration and noise control purposes. Most damping falls in two categories: passive damping and active damping. Recently, a new subset of damping was created by combining passive and active damping, thereby producing a hybrid damping treatment. This paper is a review of these damping treatments including the recent advances in the hybrid damping using active constrained layer damping (ACLD) treatment.
"Recent advances in active constrained layer damping treatment", Proc. SPIE 5062, Smart Materials, Structures, and Systems, (14 October 2003); doi: 10.1117/12.514640; https://doi.org/10.1117/12.514640