damper

A damper is a device that reduces or controls the amplitude of motion, vibration, or flow by dissipating energy, usually as heat. Dampers are used in mechanical systems, buildings, acoustics, and electrical and fluid systems to limit oscillations, absorb shocks, and stabilize performance.

Common types include shock absorbers in vehicles, viscous or fluid dampers that dissipate energy through moving liquids, friction dampers that convert motion into heat, elastic or viscoelastic dampers, and tuned mass dampers that counteract specific vibrational modes. Magnetic and eddy-current dampers use opposing magnetic fields to provide resistance without contact.

In construction and HVAC, dampers regulate air flow in ducts, chimneys, and ventilation systems. Fire dampers are installed to resist the spread of flames through ducts and shafts and are designed to close automatically under high temperatures.

In music, dampers are felt blocks that rest on the strings of a keyboard or stringed instrument to stop vibration; on pianos, the damper pedal lifts the dampers away from the strings to sustain notes.

In electrical engineering and control theory, damping describes the rate at which oscillations decay in a circuit or mechanical system. Rotor damping devices, such as amortisseur windings in synchronous machines, help stabilize motion after disturbances.