| SECTION II BASIC DISCUSSION OF VIBRATION DAMPING TREATMENTS Damping materials absorb vibrational energy from resonating panels in a direct analogy to sound absorbing materials interacting with noise in the air. By absorbing energy, damping reduces the structure-borne noise radiated from the panel to which it is applied. Damping also reduces the structureborne noise traversing the treated panel and traveling to more remote parts of the boat (structure). Methods of vibration damping include "extensional" and "constrained layer" treatments. Extensional damping materials are applied as a single layer direct to the treated panel. Constrained layer damping materials, are applied sandwiched between the treated panel and an additional cover material, usually of the same material as the treated panel (wood/damper/wood or aluminum/damper/aluminum), but the constraining layer is usually thinner than the treated panel. Damping materials of either type must be intimately bonded to the panels they are intended to damp, so that the vibrational energy of the panel is transmitted to the energy absorbing damping treatment. Selecting the appropriate method of damping for a given surface, is more complicated than the selection of sound absorbing acoustic materials. Following are some guidelines regarding boat surfaces normally found to benefit from the application of damping materials.These gudelines do not hold for all situations and should be reviewed based on the specific application. |