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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 large amounts of solid solution hardening, strain ...
F.R. Larson and J. Miller proposed that creep rate could adequately be described by the Arrhenius type equation: = / Where r is the creep process rate, A is a constant, R is the universal gas constant, T is the absolute temperature, and is the activation energy for the creep process.
The Voigt model predicts creep more realistically than the Maxwell model, because in the infinite time limit the strain approaches a constant: =, while a Maxwell model predicts a linear relationship between strain and time, which is most often not the case.
When subjected to a step constant stress, viscoelastic materials experience a time-dependent increase in strain. This phenomenon is known as viscoelastic creep. At time , a viscoelastic material is loaded with a constant stress that is maintained for a sufficiently long time period. The material responds to the stress with a strain that ...
Creep is dependent on time so the curve that the machine generates is a time vs. strain graph. The slope of a creep curve is the creep rate dε/dt [citation needed] The trend of the curve is an upward slope. The graphs are important to learn the trends of the alloys or materials used and by the production of the creep-time graph, it is easier ...
A two-dimensional flow that, at the highlighted point, has only a strain rate component, with no mean velocity or rotational component. In continuum mechanics, the strain-rate tensor or rate-of-strain tensor is a physical quantity that describes the rate of change of the strain (i.e., the relative deformation) of a material in the neighborhood of a certain point, at a certain moment of time.
The classical creep curve represents the evolution of strain as a function of time in a material subjected to uniaxial stress at a constant temperature. The creep test, for instance, is performed by applying a constant force/stress and analyzing the strain response of the system.
where σ is the applied stress, E is the Young's modulus of the material, and ε is the strain. The spring represents the elastic component of the model's response. [2] Dashpots represent the viscous component of a viscoelastic material. In these elements, the applied stress varies with the time rate of change of the strain: