DAMPERS: Vibration damping can be added to a structure in many ways to reduce excessive resonant behavior. The most common type is material-based damping created by straining visco-elastic materials (VEM) in either shear or tension/compression. Performance is optimized by selecting a VEM with maximum loss factor in the temperature and frequency range of interest, and with a stiffness range that maximizes strain energy in the damping element. Vibration damping requires optimization through material selection, treatment design and placement to ensure good performance.
ABSORBERS/BARRIERS: For conditions involving excessive radiated noise, a common countermeasure is to enclose the noise source with acoustic absorbing materials to reduce noise levels before they are transmitted to the receiver. Often a dense barrier layer is incorporated to reduce the transmission of noise through the enclosure. Design parameters like foam type, thickness and cover films laminated to the foam are adjusted to achieve good acoustic absorption over the needed frequency range.
ISOLATORS: A common method to mitigate vibration transmission is to insert compliant materials that isolate and de-couple the vibration. These isolating materials are converted into many geometries in a wide range of parts from die-cut isolation gaskets, grommets, bumpers or cushions, to molded rubber components. The isolator is selected to be as compliant as possible and with optimum damping to control unwanted amplification.
