$\newcommand{\Dev}{\operatorname{Dev}}$ $\newcommand{\dev}{\operatorname{dev}}$ $\newcommand{\grad}{\operatorname{grad}}$ $\newcommand{\divg}{\operatorname{div}}$ $\newcommand{\Ei}{\operatorname{Ei}}$ $\newcommand{\tr}{\operatorname{tr}}$

The prestrain update rules for are implemented via non-linear constraints in FEBio. This is done because non-linear constraints automatically participate in FEBio’s augmentation mechanism, which allows the user to update and rerun the time step. The following section details how to setup the update rules in the FEBio input file and discusses the currently supported rules.