Questions about the new flexible GSP model: fiber simulation and breakage capability

MFiX
1

Dear all,

I have been looking into the new flexible GSP model in MFiX. According to the documentation, the explicit flexible GSP model treats virtual bonds as massless viscoelastic springs that can withstand compression/stretching, bending, and twisting. This sounds very promising for simulating non-spherical and deformable particles.

My first question is: based on this description, would the flexible GSP model be suitable for simulating flexible fibers? I am interested in fiber-like particles with significant bending flexibility. Can the current bond formulation capture the typical bending behavior of fibers reasonably well?

My second question is about breakage and fracture. I have seen in the forum that new flexible GSP model can also be extended to model particle breakage or bond fracture when a certain stress or strain threshold is exceeded. Has this capability (e.g., bond breakage allowing the particle to fragment) been implemented in the current version of the flexible GSP model? If yes, how can users enable it? If not, are there any plans to add such a feature in the near future?

Any insights or suggestions would be greatly appreciated.

Thank you very much.

Best regards,

2

Yes, the flexible GSP is able to simulate the fiber-like particle, we have done a cantilever beam bending, twisting, stretching and results agree well with the Euler–Bernoulli beam theory.
For bond breakage, we did not put the keyword setup in GUI, you have to add it by yourself. There are two keywords:

TENSILE_STRENGTH_BOND(N)
SHEAR_STRENGTH_BOND(N)

where N is the phase id, they are set to infinitely large if you do not provide the value in the mfix input file. Note this is a 1D breakage model based on Potyondy, D. O., & Cundall, P. A. (2004)., once the stress of the bond exceeds the tensile or shear strength, the bond breaks and the solver will clear the force and torque history of the virtual bond.

1 Like
3

That’s a fantastic update. I will try out this feature-very interesting.

4

Great! Please let me know if you have any feedback or suggestions after trying it out.