indamping

Indamping is a term used in physics and engineering to refer to the internal dissipation of mechanical energy within a vibrating system, as opposed to energy loss due to external interactions with the environment. It arises from the intrinsic properties of materials and internal interfaces that convert kinetic energy into heat during cyclic deformation. Common sources include viscoelasticity in polymers, plastic deformation and dislocation motion in metals, friction between microstructural features, and hysteresis in composites.

Modeling indamping can be done with damping models that attribute loss to intrinsic material properties rather than external fluids. In many cases, internal damping is described by a complex stiffness or complex modulus, where the imaginary part represents energy dissipation per cycle. In practical oscillator models this is sometimes expressed as a damping ratio ζ that has an intrinsic component ζ_internal. Unlike viscous damping from surrounding media, indamping can persist even in vacuum or in well-controlled environments, and it often depends on temperature, frequency, and amplitude (nonlinear damping).

Applications include precision resonators, MEMS devices, seismic damping materials, and components in automotive or aerospace engineering where material damping is critical for controlling resonant responses and fatigue.

Measuring indamping involves dynamic mechanical analysis, resonance experiments, or tests that separate internal from external losses, by varying environmental conditions or using vacuum environments. The quality factor Q is approximately the reciprocal of twice the total damping ratio; reductions in Q reflect higher internal energy dissipation.

See also: damping, internal friction, hysteretic damping, viscoelasticity.