oomph::StrainEnergyFunction Class Reference

#include <constitutive_laws.h>

Inheritance diagram for oomph::StrainEnergyFunction:

Public Member Functions
	StrainEnergyFunction ()
	Constructor takes no arguments. More...
virtual	~StrainEnergyFunction ()
	Empty virtual destructor. More...
virtual double	W (const DenseMatrix< double > &gamma)
	Return the strain energy in terms of the strain tensor. More...
virtual double	W (const Vector< double > &I)
	Return the strain energy in terms of the strain invariants. More...
virtual void	derivative (const DenseMatrix< double > &gamma, DenseMatrix< double > &dWdgamma)
virtual void	derivatives (Vector< double > &I, Vector< double > &dWdI)
virtual bool	requires_incompressibility_constraint ()=0

Detailed Description

Base class for strain energy functions to be used in solid mechanics computations.

Constructor & Destructor Documentation

StrainEnergyFunction()

oomph::StrainEnergyFunction::StrainEnergyFunction ( )

inline

Constructor takes no arguments.

{}

~StrainEnergyFunction()

virtual oomph::StrainEnergyFunction::~StrainEnergyFunction ( )

inlinevirtual

Empty virtual destructor.

{}

Member Function Documentation

derivative()

virtual void oomph::StrainEnergyFunction::derivative ( const DenseMatrix< double > &  gamma, DenseMatrix< double > &  dWdgamma  )

inlinevirtual

Return the derivatives of the strain energy function with respect to the components of the strain tensor (default is to use finite differences).

    {
      throw OomphLibError(
        "Sorry, the FD setup of dW/dgamma hasn't been implemented yet",
        OOMPH_CURRENT_FUNCTION,
        OOMPH_EXCEPTION_LOCATION);
    }

References OOMPH_CURRENT_FUNCTION, and OOMPH_EXCEPTION_LOCATION.

derivatives()

virtual void oomph::StrainEnergyFunction::derivatives ( Vector< double > &  I, Vector< double > &  dWdI  )

inlinevirtual

Return the derivatives of the strain energy function with respect to the strain invariants. Default version is to use finite differences

Reimplemented in oomph::GeneralisedMooneyRivlin, and oomph::MooneyRivlin.

    {
      // Calculate the derivatives of the strain-energy-function wrt the strain
      // invariants
      double FD_Jstep = 1.0e-8; // Usual comments about global stuff
      double energy = W(I);
 
      // Loop over the strain invariants
      for (unsigned i = 0; i < 3; i++)
      {
        // Store old value
        double I_prev = I[i];
        // Increase ith strain invariant
        I[i] += FD_Jstep;
        // Get the new value of the strain energy
        double energy_new = W(I);
        // Calculate the value of the derivative
        dWdI[i] = (energy_new - energy) / FD_Jstep;
        // Reset value of ith strain invariant
        I[i] = I_prev;
      }
    }

References i, I, and W().

Referenced by oomph::IsotropicStrainEnergyFunctionConstitutiveLaw::calculate_second_piola_kirchhoff_stress().

requires_incompressibility_constraint()

virtual bool oomph::StrainEnergyFunction::requires_incompressibility_constraint ( )

pure virtual

Pure virtual function in which the user must declare if the constitutive equation requires an incompressible formulation in which the volume constraint is enforced explicitly. Used as a sanity check in PARANOID mode.

Implemented in oomph::GeneralisedMooneyRivlin, and oomph::MooneyRivlin.

Referenced by oomph::IsotropicStrainEnergyFunctionConstitutiveLaw::requires_incompressibility_constraint().

W() [1/2]

virtual double oomph::StrainEnergyFunction::W ( const DenseMatrix< double > &  gamma )

inlinevirtual

Return the strain energy in terms of the strain tensor.

Reimplemented in oomph::GeneralisedMooneyRivlin, and oomph::MooneyRivlin.

    {
      std::string error_message =
        "The strain-energy function as a function of the strain-tensor,\n";
      error_message +=
        "gamma, is not implemented for this strain energy function.\n";
 
      throw OomphLibError(
        error_message, OOMPH_CURRENT_FUNCTION, OOMPH_EXCEPTION_LOCATION);
      return 0.0;
    }

References OOMPH_CURRENT_FUNCTION, OOMPH_EXCEPTION_LOCATION, and oomph::Global_string_for_annotation::string().

Referenced by derivatives(), oomph::MooneyRivlin::W(), and oomph::GeneralisedMooneyRivlin::W().

W() [2/2]

virtual double oomph::StrainEnergyFunction::W ( const Vector< double > &  I )

inlinevirtual

Return the strain energy in terms of the strain invariants.

Reimplemented in oomph::GeneralisedMooneyRivlin, and oomph::MooneyRivlin.

    {
      std::string error_message =
        "The strain-energy function as a function of the strain\n ";
      error_message +=
        "invariants, I1, I2, I3, is not implemented for this strain\n ";
      error_message += "energy function\n";
 
      throw OomphLibError(
        error_message, OOMPH_CURRENT_FUNCTION, OOMPH_EXCEPTION_LOCATION);
      return 0.0;
    }

References OOMPH_CURRENT_FUNCTION, OOMPH_EXCEPTION_LOCATION, and oomph::Global_string_for_annotation::string().

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The documentation for this class was generated from the following file:

• constitutive_laws.h