Problems initializing own constitutive model

[scja1991]

I want to implement a hardening law for plasticity. For this I work with the application ConstitutiveModelsApplication. I replaced the deprecated Python commands and the material models already implemented in this application are now running. I added my plasticity model to the 'add_custom_constitutive_laws_to_python.cpp' file bute get the error AttributeError: 'module 'KratosMultiphysics.ConstitutiveModelsApplication' has no attribute 'VonMisesLinearElasticSwiftPlasticityModel''
My files are listet in 'CMakeLists.txt'.

I am using VisualCode on Windows 11 Pro and Pythonn 3.11.3 on a 64-bit machine.

Has someone a hint where I should look for my fault or what is the right way to find it?

[matekelemen]

Can you plz produce a diff on your applications/ConstutitutiveLawsApplication/CMakeLists.txt and
applications/ConstutitutiveLawsApplication/custom_python/add_custom_constitutive_laws_to_python.cpp and post them here?

[scja1991]

Sure:

---------- applications/ConstitutiveModelsApplication/CMakeLists.txt ----------
@@ -55,6 +55,7 @@ set( KRATOS_CONSTITUTIVE_MODELS_APPLICATION_CORE

${CMAKE_CURRENT_SOURCE_DIR}/custom_models/plasticity_models/hardening_rules/modified_exponential_damage_hardening_rule.cpp
${CMAKE_CURRENT_SOURCE_DIR}/custom_models/plasticity_models/hardening_rules/cam_clay_hardening_rule.cpp
${CMAKE_CURRENT_SOURCE_DIR}/custom_models/plasticity_models/hardening_rules/gens_nova_hardening_rule.cpp
+${CMAKE_CURRENT_SOURCE_DIR}/custom_models/plasticity_models/hardening_rules/swift_hardening_rule.cpp

#utilities
${CMAKE_CURRENT_SOURCE_DIR}/custom_utilities/properties_layout.cpp

applications/ConstitutiveModelsApplication/custom_python/add_custom_constitutive_laws_to_python.cpp
@@ -56,6 +56,7 @@

// Plasticity models
#include "custom_models/plasticity_models/von_mises_linear_elastic_plasticity_model.hpp"
+#include "custom_models/plasticity_models/von_mises_linear_elastic_swift_plasticity_model.hpp"
#include "custom_models/plasticity_models/von_mises_neo_hookean_plasticity_model.hpp"
#include "custom_models/plasticity_models/simo_J2_plasticity_model.hpp"
#include "custom_models/plasticity_models/simo_J2_thermo_plasticity_model.hpp"

[matekelemen]

Right, so far so good. However, it's not enough to include the header of your class, you have to define its bindings manually. You can take a look at the rest of add_custom_constitutive_laws_to_python.cpp for examples. You'll probably have to define your bindings like this:

    py::class_<VonMisesLinearElasticSwiftPlasticityModel, VonMisesLinearElasticSwiftPlasticityModel::Pointer, ConsitutiveLaw>(m, "VonMisesLinearElasticSwiftPlasticityModel")
        .def(py::init<>())
        ;

Details

This is just extra info if you want to know more about python bindings - it's not strictly necessary to understand it to solve your problem at hand.

We're using pybind to create python bindings for C++ classes. You'll need to be fairly comfortable with C++ to understand how pybind works, but in this case, this is all you need to know:

• you have to specify
  • the class you wish to bind VonMisesLinearElasticSwiftPlasticityModel - first template parameter to py::class_
  • the handle type of your class, in this case VonMisesLinearElasticSwiftPlasticityModel::Pointer - second template parameter
  • the base class of your bound class: ConstitutiveLaw (I'm assuming you derived from it) - third template parameter
• you also need to provide the name of your class separately "VonMisesLinearElasticSwiftPlasticityModel"
• you have to define bindings for each member function you wish to invoke from python - including the default constructor, which is what py::init<> is for. The bound class inherits the member functions of its base (ConsitutiveLaw) so you probably don't have to bind anything else, unless you have some custom stuff you want to reach from python.

Pybind uses a fluent interface to define its bindings, so you can chain py::class_::defs to define bindings for multiple member functions.

[matekelemen]

@scja1991 any luck?

[scja1991]

Yes, this was the hint I needed!

[AlejandroCornejo]

I do not know how is maintining the ConstitutiveModelsApp. I am the main developer and maintainer of the ConstitutiveLawsApp. IMO you should check mine since it is currently maintained in the master.

[scja1991]

I took a look at your app. But I didn't fully understand where to implement more hardening rules there.

[AlejandroCornejo]

The hardening rules for plasticity are implemented in here

Kratos/applications/ConstitutiveLawsApplication/custom_constitutive/auxiliary_files/cl_integrators/generic_cl_integrator_plasticity.h

Line 446 in b652b8e

static void CalculateEquivalentStressThreshold(