[M] Added an optional input for using the B bar method

ProcessLib/SmallDeformation/CreateSmallDeformationProcess.cpp

@@ -111,6 +111,9 @@ std::unique_ptr<Process> createSmallDeformationProcess(
         std::copy_n(b.data(), b.size(), specific_body_force.data());
     }
 
+    //! \ogs_file_param{prj__processes__process__SMALL_DEFORMATION__use_b_bar}
+    auto const use_b_bar = config.getConfigParameter<bool>("use_b_bar", false);
+
     auto media_map =
         MaterialPropertyLib::createMaterialSpatialDistributionMap(media, mesh);
     DBUG(
@@ -144,7 +147,8 @@ std::unique_ptr<Process> createSmallDeformationProcess(
         std::move(solid_constitutive_relations),
         initial_stress,
         specific_body_force,
-        reference_temperature};
+        reference_temperature,
+        use_b_bar};
 
     SecondaryVariableCollection secondary_variables;
 

ProcessLib/SmallDeformation/SmallDeformationFEM.h

@@ -226,6 +226,20 @@ public:
             "implemented.");
     }
 
+    BBarMatrixType getDilatationalBBarMatrix() const
+    {
+        if (!(this->process_data_.use_b_bar))
+        {
+            return {};
+        }
+
+        return LinearBMatrix::computeDilatationalBbar<
+            DisplacementDim, ShapeFunction::NPOINTS, ShapeFunction,
+            BBarMatrixType, ShapeMatricesType, IpData>(
+            _ip_data, this->element_, this->integration_method_,
+            this->is_axially_symmetric_);
+    }
+
     void assembleWithJacobian(double const t, double const dt,
                               std::vector<double> const& local_x,
                               std::vector<double> const& local_x_prev,
@@ -256,11 +270,7 @@ public:
         auto const& medium =
             *this->process_data_.media_map.getMedium(this->element_.getID());
 
-        auto const B_dil_bar = LinearBMatrix::computeDilatationalBbar<
-            DisplacementDim, ShapeFunction::NPOINTS, ShapeFunction,
-            BBarMatrixType, ShapeMatricesType, IpData>(
-            _ip_data, this->element_, this->integration_method_,
-            this->is_axially_symmetric_);
+        auto const B_dil_bar = getDilatationalBBarMatrix();
 
         for (unsigned ip = 0; ip < n_integration_points; ip++)
         {
@@ -312,11 +322,7 @@ public:
         auto const& medium =
             *this->process_data_.media_map.getMedium(this->element_.getID());
 
-        auto const B_dil_bar = LinearBMatrix::computeDilatationalBbar<
-            DisplacementDim, ShapeFunction::NPOINTS, ShapeFunction,
-            BBarMatrixType, ShapeMatricesType, IpData>(
-            _ip_data, this->element_, this->integration_method_,
-            this->is_axially_symmetric_);
+        auto const B_dil_bar = getDilatationalBBarMatrix();
 
         for (unsigned ip = 0; ip < n_integration_points; ip++)
         {

ProcessLib/SmallDeformation/SmallDeformationProcessData.h

@@ -51,6 +51,10 @@ struct SmallDeformationProcessData
 
     ParameterLib::Parameter<double> const* const reference_temperature;
 
+    /// An indicator to use the B bar method \cite hughes1980generalization to
+    /// tackle the  volumetric locking.
+    const bool use_b_bar;
+
     std::array<MeshLib::PropertyVector<double>*, 3> principal_stress_vector = {
         nullptr, nullptr, nullptr};
     MeshLib::PropertyVector<double>* principal_stress_values = nullptr;