Extension test. Fix the left edge completely and apply a displacement of $0\mathrm{.}1$ in the $\backslash ($ x $\backslash )-$direction to the right edge. The nodes on the right edge cannot move in the $\backslash ($ y $\backslash )-$direction. That is$,$ the displacements of the nodes on the left and right edges are completely prescribed.Shear test. Fix the bottom edge completely and apply a displacement of $0\mathrm{.}1$ in the $\backslash ($ x $\backslash )-$direction to the top edge. The nodes on the top edge cannot move in the $\backslash ($ y $\backslash )-$direction. That is$,$ the displacements of the nodes on the top and bottom edges are completely prescribed.Expansion test. Prescribe non$-$homogeneous Dirichlet boundary conditions on all the nodes on the boundary of the body as follows. Prescribe the displacement in the $\backslash ($ x $\backslash )-$direction at each boundary node to be exactly $0\mathrm{.}1$ times the $\backslash ($ x $\backslash )-$coordinate of the node. Similarly, prescribe the displacement in the $\backslash ($ y $\backslash )-$direction at each boundary node to be exactly $0\mathrm{.}1$ times the $\backslash ($ y $\backslash )-$coordinate of the node. For instance the bottom left corner with the coordinates $\backslash ((0,0)\backslash )$ remains completely fixed and the top right corner displaces $0\mathrm{.}1$ in each $\backslash ($ x $\backslash )$ and $\backslash ($ y $\backslash )$ direction.