(CLD) Constrained Layer Damping systems are usually used for very stiff
structures. A sandwich is formed by laminating the base layer to the
damping layer and then adding a third constraining layer. When the system
flexes during vibration, shear strains develop in the damping layer.
Energy is lost through shear deformation rather than extension of the
material.

Free-Layer or extension damping: A material is simply attached with a strong
bonding agent or alternately may be troweled on in the case of tar-like damping
materials. Resonant energy is dissipated as a result of extension and
compression of the damping material under flexural stress of the base material.

Vibration Isolation: This method reduces the transmission of vibrational
energy from one system to another. Common isolators are steel springs,
rubber pads or bellows.