MaterialBase.h

// $Id$
//==============================================================================
//!
//! \file MaterialBase.h
//!
//! \date Mar 01 2011
//!
//! \author Knut Morten Okstad / SINTEF
//!
//! \brief Base class for material models.
//!
//==============================================================================

#ifndef _MATERIAL_BASE_H
#define _MATERIAL_BASE_H

#include "MatVec.h"

class Vec3;
class Tensor;
class SymmTensor;
class FiniteElement;
class Field;
namespace tinyxml2 { class XMLElement; }
struct TimeDomain;


/*!
  \brief Base class representing a material model of a solid mechanics problem.
*/

class Material
{
protected:
  //! \brief The default constructor is protected to allow sub-classes only.
  Material() {}

public:
  //! \brief Empty destructor.
  virtual ~Material() {}

  //! \brief Parses material parementers from an XML element.
  virtual void parse(const tinyxml2::XMLElement*) {}

  //! \brief Prints out material parameters to the log stream.
  virtual void printLog() const {}

  //! \brief Returns \e false if plane stress in 2D.
  virtual bool isPlaneStrain() const { return true; }

  //! \brief Initializes the material with the number of integration points.
  virtual void initIntegration(size_t) {}
  //! \brief Initializes the material model for a new integration loop.
  virtual void initIntegration(const TimeDomain&) {}
  //! \brief Initializes the material model for a new result point loop.
  virtual void initResultPoints() {}
  //! \brief Defines a point location with some special material properties.
  virtual void addSpecialPoint(const Vec3&) {}
  //! \brief Assigns a scalar field defining the material properties.
  virtual void assignScalarField(Field*, size_t = 0) {}

  //! \brief Evaluates the stiffness at current point.
  virtual double getStiffness(const Vec3&) const { return 1.0; }
  //! \brief Evaluates the plate stiffness parameter at current point.
  virtual double getPlateStiffness(const Vec3&, double) const { return 0.0; }
  //! \brief Evaluates the mass density at current point.
  virtual double getMassDensity(const Vec3&) const { return 0.0; }
  //! \brief Evaluates the heat capacity for given temperature.
  virtual double getHeatCapacity(double) const { return 1.0; }
  //! \brief Evaluates the thermal conductivity for given temperature.
  virtual double getThermalConductivity(double) const { return 1.0; }
  //! \brief Evaluates the thermal expansion coefficient for given temperature.
  virtual double getThermalExpansion(double) const { return 0.0; }

  //! \brief Evaluates the constitutive relation at an integration point.
  //! \param[out] C Constitutive matrix at current point
  //! \param[out] sigma Stress tensor at current point
  //! \param[out] U Strain energy density at current point
  //! \param[in] fe Finite element quantities at current point
  //! \param[in] X Cartesian coordinates of current point
  //! \param[in] F Deformation gradient at current point
  //! \param[in] eps Strain tensor at current point
  //! \param[in] iop Calculation option;
  //!  -1 : Calculate the inverse constitutive matrix only,
  //!   0 : Calculate the consitutive matrix only,
  //!   1 : Calculate Cauchy stresses and the tangent constitutive matrix,
  //!   2 : 2nd Piola-Kirchhoff stresses and tangent constitutive matrix,
  //!   3 : Calculate the strain energy density only.
  //! \param[in] prm Nonlinear solution algorithm parameters
  //! \param[in] Fpf Deformation gradient for push-forward transformation
  virtual bool evaluate(Matrix& C, SymmTensor& sigma, double& U,
                        const FiniteElement& fe, const Vec3& X,
                        const Tensor& F, const SymmTensor& eps,
                        char iop = 1, const TimeDomain* prm = nullptr,
                        const Tensor* Fpf = nullptr) const = 0;

  //! \brief Evaluates the Lame-parameters at an integration point.
  virtual bool evaluate(double&, double&, const FiniteElement&,
                        const Vec3&) const { return false; }

  //! \brief Returns number of internal result variables of the material model.
  virtual int getNoIntVariables() const { return 0; }
  //! \brief Returns an internal variable associated with the material model.
  virtual double getInternalVariable(int, char*, size_t=0) const { return 0.0; }
  //! \brief Returns whether the material model has diverged.
  virtual bool diverged(size_t = 0) const { return false; }
};

#endif