In other words, it considers how a three-dimensional body deforms if one pushes
into it a rigid obstacle (the contact problem) where deformation is governed
by an elasto-plastic material law (a material that can only accommodate a certain
-maximal stress) that hardens as deformation accumulates. To show we we intend to
+maximal stress) that hardens as deformation accumulates. To show what we intend to
do before going into too many details, let us just show a picture of what the
solution will look like (the deformable body is a cube - only half of
which is actually shown -, the obstacle corresponds
@f{align*}
\label{eq:linearization}
\left(I_{\Pi}\varepsilon(\tilde {\mathbf u}^{i}),
- \varepsilon(\varphi) - \varepsilon(\tilde {\mathbf u}^{i})\right) \geq 0,
+ \varepsilon(\varphi) - \varepsilon(\tilde {\mathbf u}^{i})\right) \geq
+ \left(\left(I_{\Pi}\varepsilon(\tilde {\mathbf u}^{i-1}),
+ \varepsilon(\varphi) - \varepsilon(\tilde {\mathbf u}^{i})\right) -
+ \left(P_{\Pi}(C\varepsilon(\tilde {\mathbf u}^{i-1})),
+ \varepsilon(\varphi) - \varepsilon(\tilde {\mathbf u}^{i})\right)\right),
\quad \forall \varphi\in V^+,
@f}
where the rank-4 tensor $I_\Pi=I_\Pi(\varepsilon^D(\mathbf u^{i-1}))$ given by