Applied Mechanics Lab,
Mechanics and Applied Mathematics group,
Mechanical Engineering,
IIT Kanpur.
Large strain gives true stress,
$\qquad \boldsymbol{\sigma} = \boldsymbol{C} \boldsymbol{\varepsilon} \qquad (1) $
Need to be elastic of course!
If rigid, who cares, it's anyway there.
Find (1) philosophical? That's
MathJax for you.