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Creep behavior can be split into three main stages. In primary, or transient, creep, the strain rate is a function of time. In Class M materials, which include most pure materials, primary strain rate decreases over time. This can be due to increasing dislocation density, or it can be due to evolving grain size. In class A materials, which have ...
When the stress is maintained for a shorter time period, the material undergoes an initial strain until a time , after which the strain immediately decreases (discontinuity) then gradually decreases at times > to a residual strain. Viscoelastic creep data can be presented by plotting the creep modulus (constant applied stress divided by total ...
In mechanics, strain is defined as relative deformation, compared to a reference position configuration. Different equivalent choices may be made for the expression of a strain field depending on whether it is defined with respect to the initial or the final configuration of the body and on whether the metric tensor or its dual is considered.
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.
The Maxwell model does not exhibit creep since it models strain as linear function of time. If a small stress is applied for a sufficiently long time, then the irreversible strains become large. Thus, Maxwell material is a type of liquid.
[11] [12] An example of this phenomenon is the thickening of farmer's hands. The remodeling of connective tissues is well known in bones by the Wolff's law ( bone remodeling ). Mechanobiology is the science that study the relation between stress and growth at cellular level.
The general equation for power law creep is as follows, [17] where is a dimensionless constant relating shear strain rate and stress, μ is the shear modulus, b is the Burger's vector, k is the Boltzmann constant, T is the temperature, n is the stress exponent, is the applied shear stress, and is the effective diffusion constant.
Davis's law is used in anatomy and physiology to describe how soft tissue models along imposed demands. It is similar to Wolff's law, which applies to osseous tissue. It is a physiological principle stating that soft tissue heal according to the manner in which they are mechanically stressed. [1]