I am starting with the bending beam benchmark and changing the material model from the Viscoelastic module to Visco Plastic module so we can play with plasticity. This model has 4 composition fields - the first three are form the stress components and the last one is to define the location of the beam. The first test we wanted to do to make sure we “translated” the material models correctly was to replicate the visco-elastic benchmark just using the Visco Plastic module.
When changing the material model we came across a strange issue that causes the run to abort in the first time step. The trigger seems to be whether only one a value is entered for a material model parameter, e.g., :
set Elastic shear moduli = 1.0e11
AND multiple values are entered for a different variable, e.g.,
set Prefactors for dislocation creep = 0.5e-18, 0.5e-18, 0.5e-18, 0.5e-18, 0.5e-24
This causes the run to abort in the Stokes Solve of the first time-step. However, if I instead set, I set:
set Elastic shear moduli = 1.0e11, 1.0e11, 1.0e11, 1.0e11, 1.0e10
Then this runs without a problem.
In these two cases, the other viscosity parameters were set as
set Stress exponents for dislocation creep = 1.0 set Activation energies for dislocation creep = 0.0 set Activation volumes for dislocation creep = 0.0
So it seems weird that we need to specific the values of the elastic moduli for all compositions, but we don’t have to do this for the other flow law parameters.
BUT (here’s the weird part), going from the successful run, I try to do this:
set Stress exponents for dislocation creep = 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 set Activation energies for dislocation creep = 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 set Activation volumes for dislocation creep = 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
It aborts before entering the first time-step.
My understanding is that for all these parameters, I can choose (independently) if I set one value to be used by all compositions or set a list of values for each composition + background.
So, something strange seems to be going on. All three test were run with everything else exactly the same. The one that does not abort behaves exactly as expected (e.g, exactly like the output from Viscoelastic since we are replicating that set-up using Visco Plastic)
I’ve attached a file showing a snippet of part of the Visco Plastic subsection and then output of the run. I’ve also uploaded the full prm.
let me know if this is an issue I should open on git.,