Dynamic Modulus
Viscoelasticity is studied using dynamic mechanical analysis, applying a small oscillatory stress and measuring the resulting strain.
- Purely elastic materials have stress and strain in phase, so that the response of one caused by the other is immediate.
- In purely viscous materials, strain lags stress by a 90 degree phase lag.
- Viscoelastic materials exhibit behavior somewhere in the middle of these two types of material, exhibiting some lag in strain.
Complex Dynamic modulus G can be used to represent the relations between the oscillating stress and strain:
where ; is the storage modulus and is the loss modulus:
where and are the amplitudes of stress and strain and is the phase shift between them.
Read more about this topic: Viscoelasticity
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