The relationship between simple shear and pure shear for a simple fluid without coupling effects

Similarities between simple shear and pure shear or planar extension are exploited to derive equations relating stress in pure shear at constant extension rate to the stress in simple shear at constant shear rate. For the class of materials considered it follows that there are only two independent material functions required to describe simple shear. The relationships derived may also be used to estimate the ratio of first to second normal-stress differences in simple shear using experimental results from pure shear experiments.