71:
63:, which describes how polymers strain under constant stress. Experimentally, stress relaxation is determined by step strain experiments, i.e. by applying a sudden one-time strain and measuring the build-up and subsequent relaxation of stress in the material (see figure), in either extensional or shear
43:
Since relaxation relieves the state of stress, it has the effect of also relieving the equipment reactions. Thus, relaxation has the same effect as cold springing, except it occurs over a longer period of time. The amount of relaxation which takes place is a function of time, temperature and stress
89:
places these elements in parallel. Although the
Maxwell model is good at predicting stress relaxation, it is fairly poor at predicting creep. On the other hand, the Voigt model is good at predicting creep but rather poor at predicting stress relaxation (see
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generated in the structure. This is primarily due to keeping the structure in a strained condition for some finite interval of time hence causing some amount of plastic strain. This should not be confused with
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materials have the properties of both viscous and elastic materials and can be modeled by combining elements that represent these characteristics. One viscoelastic model, called the
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are stress relaxing, and the kinetics of stress relaxation have been recognized as an important mechanical cue that affects the migration,
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predicts behavior akin to a spring (elastic element) being in series with a dashpot (viscous element), while the
694:
Chaudhuri, Ovijit; Cooper-White, Justin; Janmey, Paul A.; Mooney, David J.; Shenoy, Vivek B. (27 August 2020).
540:{\displaystyle \sigma (t)={\frac {1}{b}}\cdot \log {\frac {10^{\alpha }(t-t_{n})+1}{10^{\alpha }(t-t_{n})-1}}}
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level, thus the actual effect it has on the system is not precisely known, but can be bounded.
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a) Applied step strain and b) induced stress as functions of time for a viscoelastic material.
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fashion. This nonlinearity is described by both stress relaxation and a phenomenon known as
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Vegener et al. use a power series to describe stress relaxation in polyamides:
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The following non-material parameters all affect stress relaxation in polymers
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To model stress relaxation in glass materials
Dowvalter uses the following:
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under constant strain. Because they are viscoelastic, polymers behave in a
40:, which is a constant state of stress with an increasing amount of strain.
401:{\displaystyle \sigma (t)=\sum _{m,n}^{}{A_{mn}^{m}(\epsilon '_{0})^{n}}}
696:"Effects of extracellular matrix viscoelasticity on cellular behaviour"
757:
T.M. Junisbekov. "Stress
Relaxation in Viscoelastic Materials" (2003)
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64:
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Stress relaxation calculations can differ for different materials:
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Meyers and Chawla. "Mechanical
Behavior of Materials" (1999)
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is the maximum stress at the time the loading was removed (
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Temperature (isothermal vs non-isothermal conditions)
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233:{\displaystyle \sigma (t)={\frac {\sigma _{0}}{1-}}}
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47:Stress relaxation describes how polymers relieve
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125:To generalize, Obukhov uses power dependencies:
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644:Standard Linear Solid Model
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263:{\displaystyle \sigma _{0}}
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720:10.1038/s41586-020-2612-2
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560:{\displaystyle \alpha }
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659:Kelvin–Voigt material
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25:stress relaxation
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113:of embedded
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79:Viscoelastic
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87:Voigt model
57:non-Hookean
665:References
555:α
529:−
513:−
502:α
473:−
462:α
451:
445:⋅
420:σ
376:ϵ
344:
307:∑
291:σ
252:σ
214:−
195:∗
176:−
167:−
154:σ
136:σ
101:and most
53:nonlinear
775:Category
738:32848221
628:See also
384:′
65:rheology
729:7676152
708:Bibcode
274:), and
103:tissues
761:
736:
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700:Nature
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547:where
243:where
109:, and
49:stress
33:strain
29:stress
634:Creep
115:cells
61:creep
38:creep
759:ISBN
734:PMID
679:ISBN
571:and
97:The
724:PMC
716:doi
704:584
448:log
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
