ComputeEigenstrainBase.C

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//* This file is part of the MOOSE framework
//* https://www.mooseframework.org
//*
//* All rights reserved, see COPYRIGHT for full restrictions
//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
//*
//* Licensed under LGPL 2.1, please see LICENSE for details
//* https://www.gnu.org/licenses/lgpl-2.1.html
 
#include "ComputeEigenstrainBase.h"
 
#include "RankTwoTensor.h"
 
defineLegacyParams(ComputeEigenstrainBase);
 
InputParameters
ComputeEigenstrainBase::validParams()
{
  InputParameters params = Material::validParams();
  params.addParam<std::string>("base_name",
                               "Optional parameter that allows the user to define "
                               "multiple mechanics material systems on the same "
                               "block, i.e. for multiple phases");
  params.addRequiredParam<std::string>("eigenstrain_name",
                                       "Material property name for the eigenstrain tensor computed "
                                       "by this model. IMPORTANT: The name of this property must "
                                       "also be provided to the strain calculator.");
  return params;
}
 
ComputeEigenstrainBase::ComputeEigenstrainBase(const InputParameters & parameters)
  : Material(parameters),
    _base_name(isParamValid("base_name") ? getParam<std::string>("base_name") + "_" : ""),
    _eigenstrain_name(_base_name + getParam<std::string>("eigenstrain_name")),
    _eigenstrain(declareProperty<RankTwoTensor>(_eigenstrain_name)),
    _step_zero(declareRestartableData<bool>("step_zero", true))
{
}
 
void
ComputeEigenstrainBase::initQpStatefulProperties()
{
  // This property can be promoted to be stateful by other models that use it,
  // so it needs to be initalized.
  _eigenstrain[_qp].zero();
}
 
void
ComputeEigenstrainBase::computeQpProperties()
{
  if (_t_step >= 1)
    _step_zero = false;
 
  // Skip the eigenstrain calculation in step zero because no solution is computed during
  // the zeroth step, hence computing the eigenstrain in the zeroth step would result in
  // an incorrect calculation of mechanical_strain, which is stateful.
  if (!_step_zero)
    computeQpEigenstrain();
}
 
Real
ComputeEigenstrainBase::computeVolumetricStrainComponent(const Real volumetric_strain) const
{
  // The engineering strain in a given direction is:
  // epsilon_eng = cbrt(volumetric_strain + 1.0) - 1.0
  //
  // We need to provide this as a logarithmic strain to be consistent with the strain measure
  // used for finite strain:
  // epsilon_log = log(1.0 + epsilon_eng)
  //
  // This can be simplified down to a more direct form:
  // epsilon_log = log(cbrt(volumetric_strain + 1.0))
  // or:
  // epsilon_log = (1/3) log(volumetric_strain + 1.0)
 
  return std::log(volumetric_strain + 1.0) / 3.0;
}