Talk:Stress relaxation

The plot is wrong. The two points on the vertical axis should be \sigma_0 / E_1 and similarly for the other point, not \sigma_0 * E_1.

also, the plot says "strain", when it is clearly plotting stress (sigma) 64.30.3.122 (talk) 00:32, 24 February 2008 (UTC)

Obukhov relation is wrong
The text states the following :

$$\sigma(t)= \frac { \sigma_0 }{ 1-[1-(t/t*)(1^{1-n})]}$$

But this relation is obviously wrong because of the $$1^{1-n}$$ that is totally useless. From the 1965 paper of Obukhov (The Relationship Between Stress and Deformation of Polymers in the Linear Stress State, Mekhanika Polimerov, Vol. 1, No. 5, pp. 25-29, 1965) he proposes the following : $$\sigma_0 = \sigma(t) \left( 1 - \left( 1-\left( \frac{t_{in}}{t}\right)^{n}\right)^{1-n} \right) $$

But this serves for stress relaxation after an instantaneous loading and unloading.

213.137.179.49 (talk) 08:54, 2 June 2015 (UTC)