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[Rodrigo Borela <question270524@xxxxxxxxxxxxxxxxxxxxx>]

New question #270524 on Yade:
https://answers.launchpad.net/yade/+question/270524

Dear all,

I am working on the modelling of a problem using the JCFpm contact law on a very dense pack (porosity is about 11%), where I have three phenomena being imposed simultaneously:
1. particle shrinkage, applied using utils.growParticles(shrinkage factor of the order of .9999995)
2. stiffening of the contacts, applied using an iterative loop on O.bodies (b.mat.young*=stiffeningfactor) and an iterative loop on O.interactions (i.phys.kn*=stiffeningfactor and i.phys.ks*=stiffeningfactor) (stiffeningfactor of the order of 1.0000005)
3. increasing tensile strength, applied also using iterative loops on O.bodies and O.interactions following the same procedure as in (2).
I'm using the GlobalStiffnessTimeStepper, where the iteration interval (of about 500-1000 iterations) is the same as the one for when the three phenomena are applied.
The problem I'm experiencing is that the time step has been decreasing at very large rates despite the gentle stiffening+shrinking, for example from 1e-8 to 1e-10 in an iteration interval. At some point, the particles explode or the time step becomes 'nan'.
The work I'm doing is reproducing results from a study that employed PFC, and all of my coefficients and ratios are calculated according to their work.
Has anyone experienced something similar and would have a suggestion to handle this seemingly numerical instability?

Thank you in advance for your time!

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