RateIndependentPlasticFlowConstraint.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/RateIndependentPlasticFlowConstraint.h"
 
namespace neml2
{
register_NEML2_object(RateIndependentPlasticFlowConstraint);
 
OptionSet
RateIndependentPlasticFlowConstraint::expected_options()
{
  OptionSet options = Model::expected_options();
  options.doc() = "Solve the consistent plasticity yield envelope by solving the equivalent "
                  "complementarity condition \\f[ r = \\dot{\\gamma} - f^p - "
                  "\\sqrt{{\\dot{\\gamma}}^2 + {f^p}^2} \\f]";
 
  options.set<VariableName>("yield_function") = VariableName("state", "internal", "fp");
  options.set("yield_function").doc() = "Yield function";
 
  options.set<VariableName>("flow_rate") = VariableName("state", "internal", "gamma_rate");
  options.set("flow_rate").doc() = "Flow rate";
 
  return options;
}
 
RateIndependentPlasticFlowConstraint::RateIndependentPlasticFlowConstraint(
    const OptionSet & options)
  : Model(options),
    _fp(declare_input_variable<Scalar>("yield_function")),
    _gamma_dot(declare_input_variable<Scalar>("flow_rate")),
    _r(declare_output_variable<Scalar>(
        options.get<VariableName>("flow_rate").slice(1).on("residual")))
{
}
 
void
RateIndependentPlasticFlowConstraint::set_value(bool out, bool dout_din, bool d2out_din2)
{
  neml_assert_dbg(!d2out_din2, "Second derivative not implemented.");
 
  const auto FB = _gamma_dot - _fp - math::sqrt(_gamma_dot * _gamma_dot + _fp * _fp);
 
  if (out)
    _r = FB;
 
  if (dout_din)
  {
    const auto I = Scalar::identity_map(options());
    _r.d(_gamma_dot) = I - _gamma_dot / math::sqrt(_gamma_dot * _gamma_dot + _fp * _fp);
    _r.d(_fp) = -I - _fp / math::sqrt(_gamma_dot * _gamma_dot + _fp * _fp);
  }
}
 
} // namespace neml2