Creep is the slow, permanent deformation of a solid under stress. Unlike ordinary plastic deformation, which generally occurs after stress exceeds the elastic limit, creep can occur below that limit if the stress acts for a sufficiently long time. It becomes more pronounced when a material remains at high temperature or near its melting point. Many materials, including metals, plastics and rocks, exhibit creep under suitable conditions.
The creep rate is related to material properties, loading time, loading temperature and loading structural stress. At present, there is no widely recognized unified theory of material creep. The creep micromechanisms of different materials are different and require further research. The creep mechanism of polycrystalline materials is mainly atomic diffusion and intergranular slip. Therefore, creep tends to be analyzed from the microscopic level, and sometimes creep can still be used as an advantage.
Creep intergranular slip
Creep, English is also Creep. "Rolling Bearing Damage and Failure Terminology, Characteristics and Causes" summarizes the creep of rolling bearings as follows: If the bearing ring is installed on the shaft or in the bearing seat, the clamping force is insufficient and causes the ring to move relative to its supporting surface (creep). Smearing (also called gluing) will occur on the inner and outer diameter surfaces of the bearing or the supporting surfaces of the shaft and bearing seat holes. Because there is a small difference in the diameter of the two parts, there is also a small difference in their circumference.
Therefore, the radial load relative to the rotation of the ferrule causes the two parts to come into contact at a series of consecutive points, and the two contacting parts rotate relative to each other at a slight differential speed. This rolling motion of the ferrule relative to its supporting surface at a slight difference in rotational speed is called "creep". The research on the mechanism of rolling bearing creep is relatively in-depth, and the research by many foreign scholars is relatively thorough. Creeping is a form of damage to rolling bearings and is a macroscopically visible movement.
Ferrule deformation caused by creeping movement
Source: Bearing Magazine
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