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\subsection{Insertion of Cohesive Elements}
\subsubsection{Dynamics}
As far as dynamic simulations are concerned, cohesive elements are
currently compatible only with the explicit time integration scheme
(see section~\ref{ssect:smm:expl-time-integr}). They do not have to be
inserted when the mesh is generated but during the
simulation. Intrinsic cohesive elements can be introduced at the
beginning of the simulation as follows:
\begin{cpp}
SolidMechanicsModelCohesive model(mesh);
model.initFull();
model.limitInsertion(_x, -1, 1);
model.insertIntrinsicElements();
\end{cpp}
where the insertion is limited to the facets whose barycenter's $x$
coordinate is in the range $[-1,1]$. Additional restrictions with
respect to $y$ and $z$ directions can be added as well. Similarly the
dynamic insertion of extrinsic cohesive elements can be utilized in
the following way:
\begin{cpp}
SolidMechanicsModelCohesive model(mesh);
model.initFull(SolidMechanicsModelCohesiveOptions(_explicit_lumped_mass, true));
model.limitInsertion(_x, -1, 1);
model.updateAutomaticInsertion();
\end{cpp}
in which this time the method \code{limitInsertion} prevents the
cohesive elements to be inserted out of the range $[-1,1]$ in the $x$
direction. In order to check stress and automatically insert elements,
it is necessary to call the function \code{checkCohesiveStress} in the
main loop where \code{solveStep} is:
\begin{cpp}
model.checkCohesiveStress();
model.solveStep();
\end{cpp}
At any time during the simulation, it is possible to access the
following energies with the relative function:
\begin{cpp}
Real Ed = model.getEnergy("dissipated");
Real Er = model.getEnergy("reversible");
Real Ec = model.getEnergy("contact");
\end{cpp}
\subsubsection{Statics}
The only cohesive law that is applicable in this case is the
exponential one (see
section~\ref{ssect:smm:cl:coh-exponential}). However
unloading-reloading cycles are not supported yet. In this case
cohesive elements have to be inserted before creating the
\code{SolidMechanicsModelCohesive} model:
\begin{cpp}
Mesh mesh(spatial_dimension);
mesh.read("implicit_mesh.msh");
CohesiveElementInserter inserter(mesh);
inserter.setLimit(_y, 0.9, 1.1);
inserter.insertIntrinsicElements();
SolidMechanicsModelCohesive model(mesh);
model.initFull(SolidMechanicsModelCohesiveOptions(_static));
\end{cpp}
Also in this case the element insertion can be limited to a given
range thanks to the method \code{setLimit}. The first input parameter
of this method indicates the direction while the other two indicate
the extreme values of the range $[0.9, 1.1]$. In order to compute the
energies, the same functions illustrated for dynamics in the last
section can be used.
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