Читать книгу Vibroacoustic Simulation - Alexander Peiffer - Страница 25

Viscous damping is rare in real systems, it only exists if the surface that is connected to liquids moves so slow that no turbulent motion appears. Observation of experiments with damping normally doesn’t show damping that increases with frequency as would be the case with viscous damping. Examples for damping processes are:

 structural or hysteretic damping

 coulomb or dry-friction damping

 velocity-squared or aerodynamic drag damping.

As most systems are lightly damped so that damping can be neglected except near resonance, it is sufficient to approximate the non-viscous damping in terms of equivalent viscous damping. A good way to formulate a criteria that works for all types of damping is to consider the dissipated energy per cycle of vibration. For viscous damping this reads as

With the dissipated energy per cycle ΔEcycle for any particular damping type the equivalent viscous damping cveq can be determined from

(1.56)