In continuum mechanics, viscous damping is a formulation of the damping phenomena, in which the source of damping force is modeled as a function of the volume, shape, and velocity of an object traversing through a real fluid with viscosity.Mechanical Vibrations, Rao, 5th ed.
Typical examples of viscous damping in mechanical systems include: Fluid films between surfaces Fluid flow around a piston in a cylinder Fluid flow through an orifice Fluid flow within a journal bearing
Viscous damping also refers to damping devices. Most often they damp motion by providing a force or torque opposing motion proportional to the velocity. This may be affected by fluid flow or motion of magnetic structures. The intended effect is to bring the damping ratio closer to 1.
Practical examples include: Shock absorbers in cars Seismic retrofitting with viscous dampers Deployment actuators in spacecraft
Single-degree-of-freedom system In a single-degree-of-freedom system, viscous damping models the relatitionship between force and velocity as shown below:
Where is the viscous damping coefficient with SI units of . This model adequately describes the damping force on a body that is moving at a moderate speed through a fluid.Tony L. Schmitz, K. Scott Smith. Mechanical Vibrations: Modeling and Measurement (2e). 2021. pp. 30, 51. It is also the most common modeling choice for damping.Tony L. Schmitz, K. Scott Smith. Mechanical Vibrations: Modeling and Measurement (2e). 2021. p. 52. See also Hysteresis Coulomb damping
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