OlevskySinteringStress.cxx

// Copyright 2023, UChicago Argonne, LLC
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// Software Name: NEML2 -- the New Engineering material Model Library, version 2
// By: Argonne National Laboratory
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#include "neml2/models/solid_mechanics/OlevskySinteringStress.h"
 
namespace neml2
{
register_NEML2_object(OlevskySinteringStress);
 
OptionSet
OlevskySinteringStress::expected_options()
{
  OptionSet options = Model::expected_options();
  options.doc() = "Define the Olevsky-Skorohod sintering stress to be used in conjunction with "
                  "poroplasticity yield functions such as the GTNYieldFunction. The sintering "
                  "stress is defined as \\f$ \\sigma_s = 3 \\dfrac{\\gamma}{r} \\phi^2 \\f$, where "
                  "\\f$ \\gamma \\f$ is the surface tension, \\f$ r \\f$ is the size of the "
                  "particles/powders, and \\f$ \\phi \\f$ is the void fraction.";
 
  options.set<VariableName>("sintering_stress") = VariableName("state", "internal", "ss");
  options.set("sintering_stress").doc() = "Sintering stress";
 
  options.set<VariableName>("void_fraction") = VariableName("state", "internal", "f");
  options.set("void_fraction").doc() = "Void fraction";
 
  options.set<CrossRef<Scalar>>("surface_tension");
  options.set("surface_tension").doc() = "Surface tension";
 
  options.set<CrossRef<Scalar>>("particle_radius");
  options.set("particle_radius").doc() = "Particle radius";
 
  return options;
}
 
OlevskySinteringStress::OlevskySinteringStress(const OptionSet & options)
  : Model(options),
    _s(declare_output_variable<Scalar>("sintering_stress")),
    _phi(declare_input_variable<Scalar>("void_fraction")),
    _gamma(declare_parameter<Scalar>("gamma", "surface_tension")),
    _r(declare_parameter<Scalar>("r", "particle_radius"))
{
}
 
void
OlevskySinteringStress::set_value(bool out, bool dout_din, bool d2out_din2)
{
  if (out)
    _s = 3 * _gamma * _phi * _phi / _r;
 
  if (dout_din)
    _s.d(_phi) = 6 * _gamma * _phi / _r;
 
  if (d2out_din2)
    _s.d(_phi, _phi) = 6 * _gamma / _r;
}
} // namespace neml2