ElasticityInterface.h

// Copyright 2024, UChicago Argonne, LLC
// All Rights Reserved
// Software Name: NEML2 -- the New Engineering material Model Library, version 2
// By: Argonne National Laboratory
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#pragma once
 
#include "neml2/models/solid_mechanics/elasticity/ElasticityConverter.h"
#include "neml2/base/MultiEnumSelection.h"
#include "neml2/tensors/Scalar.h"
#include "neml2/base/OptionSet.h"
#include "neml2/base/TensorName.h"
 
namespace neml2
{
template <class Derived, std::size_t N>
class ElasticityInterface : public Derived
{
public:
  static OptionSet expected_options();
 
  ElasticityInterface(const OptionSet & options);
 
protected:
  void declare_elastic_constant(ElasticConstant);

  std::array<ElasticConstant, N> _constant_types;

  std::array<const Scalar *, N> _constants;

  std::array<bool, N> _need_derivs;
 
private:
  std::vector<TensorName<Scalar>> _coefs;

  const std::vector<ElasticConstant> _coef_types;

  std::vector<bool> _coef_as_param;

  std::size_t _counter = 0;
};
 
} // namespace neml2

// Implementation
 
namespace neml2
{
template <class Derived, std::size_t N>
OptionSet
ElasticityInterface<Derived, N>::expected_options()
{
  OptionSet options = Derived::expected_options();
 
  MultiEnumSelection type_selection({"LAME_LAMBDA",
                                     "BULK_MODULUS",
                                     "SHEAR_MODULUS",
                                     "YOUNGS_MODULUS",
                                     "POISSONS_RATIO",
                                     "P_WAVE_MODULUS",
                                     "INVALID"},
                                    {static_cast<int>(ElasticConstant::LAME_LAMBDA),
                                     static_cast<int>(ElasticConstant::BULK_MODULUS),
                                     static_cast<int>(ElasticConstant::SHEAR_MODULUS),
                                     static_cast<int>(ElasticConstant::YOUNGS_MODULUS),
                                     static_cast<int>(ElasticConstant::POISSONS_RATIO),
                                     static_cast<int>(ElasticConstant::P_WAVE_MODULUS),
                                     static_cast<int>(ElasticConstant::INVALID)},
                                    {"INVALID"});
  options.add<MultiEnumSelection>("coefficient_types",
                                  type_selection,
                                  "Types for each parameter, options are: " +
                                      type_selection.join());
 
  options.add<std::vector<TensorName<Scalar>>, FType::PARAMETER>(
      "coefficients", "Coefficients used to define the elasticity tensor");
 
  options.add<std::vector<bool>>(
      "coefficient_as_parameter",
      {true},
      "Whether to treat the coefficients as (trainable) parameters. Default is true. Setting this "
      "option to false will treat the coefficients as buffers.");
 
  return options;
}
 
template <class Derived, std::size_t N>
ElasticityInterface<Derived, N>::ElasticityInterface(const OptionSet & options)
  : Derived(options),
    _coefs(options.get<std::vector<TensorName<Scalar>>>("coefficients")),
    _coef_types(options.get<MultiEnumSelection>("coefficient_types").as<ElasticConstant>()),
    _coef_as_param(options.get<std::vector<bool>>("coefficient_as_parameter"))
{
  if (_coefs.size() != N)
    throw NEMLException("Expected " + std::to_string(N) + " coefficients, got " +
                        std::to_string(_coefs.size()) + ".");
  if (_coef_types.size() != N)
    throw NEMLException("Expected " + std::to_string(N) + " coefficient types, got " +
                        std::to_string(_coef_types.size()) + ".");
  if (_coef_as_param.size() != 1 && _coef_as_param.size() != N)
    throw NEMLException("Expected 1 or " + std::to_string(N) +
                        " entries in coefficient_as_parameter, got " +
                        std::to_string(_coef_as_param.size()) + ".");
 
  if (_coef_as_param.size() == 1)
    _coef_as_param.resize(N, _coef_as_param[0]);
 
  // Fill out _constants, _constant_types, and _constant_names by sorting the coefficients according
  // to the order defined by ElasticConstant
  declare_elastic_constant(ElasticConstant::LAME_LAMBDA);
  declare_elastic_constant(ElasticConstant::BULK_MODULUS);
  declare_elastic_constant(ElasticConstant::SHEAR_MODULUS);
  declare_elastic_constant(ElasticConstant::YOUNGS_MODULUS);
  declare_elastic_constant(ElasticConstant::POISSONS_RATIO);
  declare_elastic_constant(ElasticConstant::P_WAVE_MODULUS);
 
  // Figure out which coefficients need derivatives
  for (std::size_t i = 0; i < _constant_types.size(); i++)
    _need_derivs[i] = (Derived::nl_param(neml2::name(_constant_types[i])) != nullptr);
}
 
template <class Derived, std::size_t N>
void
ElasticityInterface<Derived, N>::declare_elastic_constant(ElasticConstant ptype)
{
  for (std::size_t i = 0; i < _coefs.size(); i++)
  {
    if (_coef_types[i] == ElasticConstant::INVALID)
      throw NEMLException("Invalid coefficient type provided for coefficient " + std::to_string(i) +
                          ".");
 
    if (_coef_types[i] != ptype)
      continue;
 
    if (std::find(_constant_types.begin(), std::next(_constant_types.begin(), _counter), ptype) !=
        std::next(_constant_types.begin(), _counter))
      throw NEMLException("Duplicate coefficient type provided for coefficient " +
                          std::to_string(i) + ".");
 
    const auto pname = neml2::name(ptype);
    const auto * pval = _coef_as_param[i]
                            ? &Derived::template declare_parameter<Scalar>(
                                  pname, _coefs[i], /*allow_nonlinear*/ true)
                            : &Derived::template declare_buffer<Scalar>(pname, _coefs[i]);
 
    if (_counter >= N)
      throw NEMLException("Too many coefficients provided.");
    _constant_types[_counter] = ptype;
    _constants[_counter] = pval;
    _counter++;
 
    return;
  }
}
} // namespace neml2