What is the significance of the Stribeck curve?
The Stribeck curve is a fundamental concept in the field of tribology. It shows that friction in fluid-lubricated contacts is a non-linear function of the contact load, the lubricant viscosity and the lubricant entrainment speed.
What is Stribeck number?
In a Stribeck curve the key parameter, against which the coefficient of friction (COF) is plotted, is called the Hersey number. The Hersey number is the dimensionless number obtained from the velocity (m/s) times the dynamic viscosity (Pa∙s = N∙s/m2), divided by the load per unit length of bearing (N/m).
What are the 3 regimes of lubrication?
There are three primary lubrication regimes: Boundary, Mixed, and Hydrodynamic Lubrication.
What is Stribeck equation?
For straight roller bearings, Co = Kd LZ / 5 where L and d are diameter and length of rollers. Stribeck’s equation to determine basic static capacity of ball bearings is based on assumptions specified below: 1) After loading races retain their circular shape and are rigid.
What is Stribeck friction?
The Stribeck friction, FS, is the negatively sloped characteristics taking place at low velocities (see [1]). The Coulomb friction, FC, results in a constant force at any velocity. The viscous friction, FV, opposes motion with the force directly proportional to the relative velocity.
How do you make a Stribeck curve?
The most common and simple technique used to acquire a Stribeck curve is by maintaining two variables (e.g. load and viscosity) and varying the third (e.g. velocity) over an appropriate range so that the contact interface passes through the asperity contact region (boundary) and through the full fluid-film separation ( …
What is full fluid lubrication?
a continuous lubricating film thick enough to completely separate two surfaces. Normally in full fluid-film lubrication oil adheres to the moving part and is drawn into the area between the sliding surfaces, where hydrodynamic processes form a pressure wedge.
What are the rolling contact bearing?
The term rolling contact bearings refers to the wide variety of bearings that use spherical balls or some other type of roller between the stationary and the moving elements. The most common type of bearing supports a rotating shaft, resisting purely radial loads or a combination of radial and axial (thrust) loads.
What is Stribeck velocity?
Stribeck curve is basically a curve between coefficient of friction and bearing number. Bearing number can be defined as sliding velocity, what we are talking about the relative sliding velocity lubricant with viscosity per unit load.
How is the Stribeck curve used in tribology?
Stribeck curve is a fundamental and one of the most widely known concepts in tribology and lubrication fields. The concept represents the friction behavior in lubricated contacts as a function of viscosity of the lubricant, entertainment speed and roughness (sometimes, just roughness).
How does the Stribeck curve relate to friction?
where η is the dynamic viscosity of the fluid, N is the entrainment speed of the fluid and P is the normal load in the tribological contact. Thus, for a given viscosity and load, the Stribeck curve shows how friction changes with increasing velocity.
Who are the pioneers of the Stribeck curve?
Richard Stribeck along with Mayo Hersey are accredited as the pioneer researchers of the 20 th century, who introduced Stribeck curve by extending their work on the topic of friction within the railway industry; however the results of the research were in coherence with the previous researches.
How does the Hersey number relate to the Stribeck curve?
Alternatively, the Hersey number is the dimensionless number obtained from the velocity (m/s) times the dynamic viscosity (Pa∙s = N∙s/m2), divided by the load per unit length of bearing (N/m). Thus, for a given viscosity and load, the Stribeck curve shows how friction changes with increasing velocity.