Inverse right Cauchy-Green strain
= Inverse right Cauchy-Green strain
{title2=$E^{(-2)}=(I-C^{-1})/2$}
For $C=F^TF$, differentiation of $C^{-1}$ gives $\dot E^{(-2)}=F^{-1}DF^{-T}$. Its reference-power conjugate is $T^{(-2)}=F^T\tau F$. In a convected coordinate basis $g_I=Fe_I$, these are the covariant components of the <Kirchhoff stress tensor>. The <second Piola-Kirchhoff stress tensor> instead gives its contravariant components, since $\tau=T^{(2)}_{IJ}g_I\otimes g_J$.