[Mat] added accessors for Ehlers damage internal variables

MaterialLib/SolidModels/Ehlers-impl.h

@@ -742,6 +742,33 @@ SolidEhlers<DisplacementDim>::integrateStress(
         tangentStiffness)};
 }
 
+template <int DisplacementDim>
+std::vector<
+    std::pair<std::string,
+              typename MechanicsBase<DisplacementDim>::InternalVariableGetter>>
+SolidEhlers<DisplacementDim>::getInternalVariables() const
+{
+    return {
+        {"damage.kappa_d",
+         [](typename MechanicsBase<
+             DisplacementDim>::MaterialStateVariables const& state) -> double {
+             assert(dynamic_cast<StateVariables<DisplacementDim> const*>(
+                        &state) != nullptr);
+             auto const& ehlers_state =
+                 static_cast<StateVariables<DisplacementDim> const&>(state);
+             return ehlers_state.damage.kappa_d();
+         }},
+        {"damage.value",
+         [](typename MechanicsBase<
+             DisplacementDim>::MaterialStateVariables const& state) -> double {
+             assert(dynamic_cast<StateVariables<DisplacementDim> const*>(
+                        &state) != nullptr);
+             auto const& ehlers_state =
+                 static_cast<StateVariables<DisplacementDim> const&>(state);
+             return ehlers_state.damage.value();
+         }}};
+}
+
 }  // namespace Ehlers
 }  // namespace Solids
 }  // namespace MaterialLib

MaterialLib/SolidModels/Ehlers.h

@@ -238,6 +238,10 @@ public:
         typename MechanicsBase<DisplacementDim>::MaterialStateVariables const&
             material_state_variables) override;
 
+    std::vector<std::pair<std::string, typename MechanicsBase<DisplacementDim>::
+                                           InternalVariableGetter>>
+    getInternalVariables() const override;
+
 private:
     NumLib::NewtonRaphsonSolverParameters const _nonlinear_solver_parameters;
 

MaterialLib/SolidModels/MechanicsBase.h

@@ -10,8 +10,10 @@
 #pragma once
 
 #include <boost/optional.hpp>
+#include <functional>
 #include <memory>
 #include <tuple>
+#include <vector>
 
 #include "ProcessLib/Deformation/BMatrixPolicy.h"
 
@@ -104,6 +106,15 @@ struct MechanicsBase
                     KelvinVector const& sigma_prev,
                     MaterialStateVariables const& material_state_variables) = 0;
 
+    using InternalVariableGetter =
+        std::function<double(MaterialStateVariables const&)>;
+
+    virtual std::vector<std::pair<std::string, InternalVariableGetter>>
+    getInternalVariables() const
+    {
+        return {};
+    }
+
     virtual ~MechanicsBase() = default;
 };