Coupled phase field and mechanics simulations require a MOOSE executable that combined the
tensor_mechanics modules. One such executable can be built under
moose/modules/combined. That directory also contains a set of examples that are worth looking at.
Full coupling between phase field and mechanics goes both ways
The mechanical properties of the system can (and will) be a function of the phase field variables in a tightly coupled simulation.
CompositeElasticityTensoris a tensor that depends on phase field variables in an arbitrary way
ComputeVariableEigenstrainis a tensor with a variable dependent scalar prefactor. It is best used to turn an Eigenstrain on or off depending on a concentration variable.
To couple the phase field equations with mechanics a contribution of the deformation energy (elastic energy) needs to enter the free energy density of the system. The phase field equations should be assembled using the
AllenCahn parsed function kernels which all take the free energy as a Function Material.
ElasticEnergyMaterialwill automatically compute the free energy density contribution using the local stresses and strains.
DerivativeSumMaterialto sum the chemical and elastic free energy contributions to a total free energy (which is then passed to the kernels.