ComputeMeanThermalExpansionEigenstrainBase.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 "ComputeMeanThermalExpansionEigenstrainBase.h"
#include "Function.h"
 
defineLegacyParams(ComputeMeanThermalExpansionEigenstrainBase);
 
InputParameters
ComputeMeanThermalExpansionEigenstrainBase::validParams()
{
  InputParameters params = ComputeThermalExpansionEigenstrainBase::validParams();
  params.addClassDescription("Base class for models that compute eigenstrain due to mean"
                             "thermal expansion as a function of temperature");
  return params;
}
 
ComputeMeanThermalExpansionEigenstrainBase::ComputeMeanThermalExpansionEigenstrainBase(
    const InputParameters & parameters)
  : ComputeThermalExpansionEigenstrainBase(parameters)
{
}
 
void
ComputeMeanThermalExpansionEigenstrainBase::computeThermalStrain(Real & thermal_strain,
                                                                 Real & instantaneous_cte)
{
  const Real small = libMesh::TOLERANCE;
 
  const Real reference_temperature = referenceTemperature();
  const Real & current_temp = _temperature[_qp];
  const Real current_alphabar = meanThermalExpansionCoefficient(current_temp);
  const Real thexp_current_temp = current_alphabar * (current_temp - reference_temperature);
 
  // Mean linear thermal expansion coefficient relative to the reference temperature
  // evaluated at stress_free_temperature.  This is
  // \f$\bar{\alpha} = (\delta L(T_{sf}) / L) / (T_{sf} - T_{ref})\f$
  // where \f$T_sf\f$ is the stress-free temperature and \f$T_{ref}\f$ is the reference temperature.
  const Real alphabar_stress_free_temperature =
      meanThermalExpansionCoefficient(_stress_free_temperature[_qp]);
  // Thermal expansion relative to the reference temperature evaluated at stress_free_temperature
  // \f$(\delta L(T_sf) / L)\f$, where \f$T_sf\f$ is the stress-free temperature.
  const Real thexp_stress_free_temperature =
      alphabar_stress_free_temperature * (_stress_free_temperature[_qp] - referenceTemperature());
 
  // Per M. Niffenegger and K. Reichlin (2012), thermal_strain should be divided
  // by (1.0 + thexp_stress_free_temperature) to account for the ratio of
  // the length at the stress-free temperature to the length at the reference
  // temperature. It can be neglected because it is very close to 1,
  // but we include it for completeness here.
 
  thermal_strain =
      (thexp_current_temp - thexp_stress_free_temperature) / (1.0 + thexp_stress_free_temperature);
 
  const Real dalphabar_dT = meanThermalExpansionCoefficientDerivative(current_temp);
  const Real numerator = dalphabar_dT * (current_temp - reference_temperature) + current_alphabar;
  const Real denominator =
      1.0 +
      alphabar_stress_free_temperature * (_stress_free_temperature[_qp] - reference_temperature);
  if (denominator < small)
    mooseError("Denominator too small in thermal strain calculation");
  instantaneous_cte = numerator / denominator;
}