In continuum mechanics, ratcheting, or ratchetting, also known as cyclic creep, is a behavior in which plastic deformation accumulates due to cyclic mechanical or thermal stress.^[1][2]

In an article written by J. Bree in 1967,^[3] the phenomenon of ratcheting is described as "Unsymmetric cycles of stress between prescribed limits will cause progressive 'creep' or 'ratchet(t)ing' in the direction of the mean stress". Ratcheting is a progressive, incremental inelastic deformation characterized by a shift of the stress-strain hysteresis loop along the strain axis.^[4] When the amplitude of cyclic stresses exceed the elastic limit, the plastic deformation that occurs keep accumulating paving way for a catastrophic failure of the structure. Nonlinear kinematic hardening, which occurs when the stress state reaches the yield surface, is considered as the main mechanism behind ratcheting.^[5] Several factors influences the extent of ratcheting including the load condition, mean stress, stress amplitude, stress ratio, load history, plastic slip, dislocation movement, and cells deformations.^[6]

The effect of structural ratcheting can sometimes be represented in terms of the Bree diagram.^[7] Alternative material models have been proposed to simulate ratcheting, such as Chaboche, Ohno-Wang, Armstrong–Frederick, etc.^[6]

Ratcheting is a significant effect to be considered to check permanent deformation in systems which undergoes a cyclic loading. Common examples of such repetitive stresses include sea waves, road traffic, and earthquakes.^[8] Initially it was studied to inspect the permanent deformation of thin, nuclear fuel cans with an internal pressure and temperature gradient while undergoing repetitive non-zero mean stresses.^[3]