adding reference to emerging paper

git-svn-id: https://svn.dealii.org/trunk@29138 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/examples/step-42/doc/results.dox b/deal.II/examples/step-42/doc/results.dox
index fda88e8108c0941ea81a93a0ea18b2ae42a5be25..c9753f6f8d93a185962e7f476b6001221470bb23 100644 (file)
--- a/deal.II/examples/step-42/doc/results.dox
+++ b/deal.II/examples/step-42/doc/results.dox
@@ -935,12 +935,19 @@ last 4 or 5 newton iterations.
 </table>
 
 The picture shows the adaptive refinement and as well how much a cell is
-plastified druing the contact with the ball. In the middle - where the
-mesh is finest - you can see the hollow caused by the ball. The blue
+plastified druing the contact with the ball. Remember that we consider the
+norm of the deviator part of the stress in each quadrature point to
+see if there is elastic or plastic behavior. In the middle of the top - 
+where the mesh is finest - you can see the hollow caused by the ball. The blue
 color means that this cell contains only elastic quadrature points in
 contrast to the red cells in which all quadrature points are plastified.
 Since we used trilinear ansatz functions each cell contains eight
-of these points which may or may not be elastic or plastic.  
+of these points which may or may not be elastic or plastic.
+
+For further details see the work of Frohne, Heister, Bangerth: EFFICIENT
+NUMERICAL METHODS FOR THE LARGE-SCALE, PARALLEL SOLUTION OF ELASTOPLASTIC CONTACT
+PROBLEMS, preprint.
+
 
 <a name="extensions"></a>
 <h1>Possibilities for extensions</h1>