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In materials science, creep (sometimes called cold flow) is the tendency of a solid material to undergo slow deformation while subject to persistent mechanical stresses.It can occur as a result of long-term exposure to high levels of stress that are still below the yield strength of the material.
Creep increases with temperature and it is more common when a material is exposed to high temperatures for a long time or at the melting point of the material. Creep machines are used to understand the creep of materials and determine which type can do the job better, which is important when making and designing materials for everyday uses.
In materials science, Nabarro–Herring creep (NH creep) is a mechanism of deformation of crystalline materials (and amorphous materials [1]) that occurs at low stresses and held at elevated temperatures in fine-grained materials. In Nabarro–Herring creep, atoms diffuse through the crystals, and the rate of creep varies inversely with the ...
Dislocation creep is a deformation mechanism in crystalline materials. Dislocation creep involves the movement of dislocations through the crystal lattice of the material, in contrast to diffusion creep , in which diffusion (of vacancies) is the dominant creep mechanism.
L. M. Kachanov [5] and Y. N. Rabotnov [6] suggested the following evolution equations for the creep strain ε and a lumped damage state variable ω: ˙ = ˙ ˙ = ˙ where ˙ is the creep strain rate, ˙ is the creep-rate multiplier, is the applied stress, is the creep stress exponent of the material of interest, ˙ is the rate of damage accumulation, ˙ is the damage-rate multiplier, and is ...
In materials science, Coble creep, a form of diffusion creep, is a mechanism for deformation of crystalline solids. Contrasted with other diffusional creep mechanisms, Coble creep is similar to Nabarro–Herring creep in that it is dominant at lower stress levels and higher temperatures than creep mechanisms utilizing dislocation glide. [ 1 ]
In phase (IP) thermo-mechanical loading (when the temperature and load increase at the same time) is dominated by creep. The combination of high temperature and high stress is the ideal condition for creep. The heated material flows more easily in tension, but cools and stiffens under compression.
Downhill creep, also known as soil creep or commonly just creep, is a type of creep characterized by the slow, downward progression of rock and soil down a low grade slope; it can also refer to slow deformation of such materials as a result of prolonged pressure and stress.