Viscous damping
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.[1]
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 improve the damping ratio.
- Shock absorbers in cars
- Seismic retrofitting with viscous dampers[2]
- Tuned mass dampers in tall buildings
- Deployment actuators in spacecraft
Single-degree-of-freedom system
In a single-degree-of-freedom system, viscous damping model relates force to velocity as shown below:
[math]\displaystyle{ f=c\dot x }[/math]
Where [math]\displaystyle{ c }[/math] is the viscous damping coefficient with SI units of [math]\displaystyle{ N\cdot s/m }[/math]. This model adequately describes the damping force on a body that is moving at a moderate speed through a fluid.[3] It is also the most common modeling choice for damping.[4]
See also
References
- ↑ Mechanical Vibrations, Rao, 5th ed.
- ↑ Pollini, Nicolò; Lavan, Oren; Amir, Oded (2017). "Minimum-cost optimization of nonlinear fluid viscous dampers and their supporting members for seismic retrofitting" (in en). Earthquake Engineering & Structural Dynamics 46 (12): 1941–1961. doi:10.1002/eqe.2888. ISSN 1096-9845. https://onlinelibrary.wiley.com/doi/abs/10.1002/eqe.2888.
- ↑ Tony L. Schmitz, K. Scott Smith. Mechanical Vibrations: Modeling and Measurement (2e). 2021. pp. 30, 51.
- ↑ Tony L. Schmitz, K. Scott Smith. Mechanical Vibrations: Modeling and Measurement (2e). 2021. p. 52.
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