first Kernel for #74, approximate P->P+dP and drop order 2 or higher

include/kernels/InducedPBulkEnergyDerivativeEighth.h

@@ -0,0 +1,64 @@
+/*
+   This file is part of FERRET, an add-on module for MOOSE
+
+   FERRET is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+   For help with FERRET please contact J. Mangeri <mangeri@fzu.cz>
+   and be sure to track new changes at github.com/mangerij/ferret
+
+**/
+
+#ifndef INDUCEDPBULKENERGYDERIVATIVEEIGHTH_H
+#define INDUCEDPBULKENERGYDERIVATIVEEIGHTH_H
+
+#include "Kernel.h"
+
+class InducedPBulkEnergyDerivativeEighth;
+
+template<>
+InputParameters validParams<BulkEnergyDerivativeEighth>();
+
+class InducedPBulkEnergyDerivativeEighth: public Kernel
+{
+public:
+
+  InducedPBulkEnergyDerivativeEighth(const InputParameters & parameters);
+
+protected:
+  virtual Real computeQpResidual();
+  virtual Real computeQpJacobian();
+  virtual Real computeQpOffDiagJacobian(unsigned int jvar);
+
+  const unsigned int _component;
+  const VariableValue & _polar_x;
+  const VariableValue & _polar_y;
+  const VariableValue & _polar_z;
+  const unsigned int _induced_polar_x_var;
+  const unsigned int _induced_polar_y_var;
+  const unsigned int _induced_polar_z_var;
+  const VariableValue & _induced_polar_x;
+  const VariableValue & _induced_polar_y;
+  const VariableValue & _induced_polar_z;
+  const MaterialProperty<Real> & _alpha1;
+  const MaterialProperty<Real> & _alpha11;
+  const MaterialProperty<Real> & _alpha12;
+  const MaterialProperty<Real> & _alpha111;
+  const MaterialProperty<Real> & _alpha112;
+  const MaterialProperty<Real> & _alpha123;
+  const MaterialProperty<Real> & _alpha1111;
+  const MaterialProperty<Real> & _alpha1112;
+  const MaterialProperty<Real> & _alpha1122;
+  const MaterialProperty<Real> & _alpha1123;
+};
+#endif //INDUCEDPBULKENERGYDERIVATIVEEIGHTH_H