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

The MeshDomains section assigns various physical attributes to the element sets of the mesh. For each of the Elements sections in the Mesh section, define a SolidDomain or a ShellDomain section, depending on whether the elements are solid or shells. Each domain also requires a material name that defines the material properties of the domain.