Issue with LEBM in EDEM v2024.1 at Larger Time Steps

jc_794

Hi Altair Community,

I am currently using the Linear Elastic Bonding Model (LEBM) in EDEM v2024.1 following the tutorial in the attached link:
🔗 EDEM Physics Model Tutorial - Linear Elastic Bonded Model

I encountered an issue when increasing the time step from the original 2e-5 to a larger value, such as 5e-5. When using a larger time step, the bonding does not form correctly. However, when I reduce the time step, the bonding builds as expected.

I am curious about the underlying reason behind this behavior. Why does increasing the time step prevent the LEBM model from forming correctly?

Any insights or explanations would be greatly appreciated!

Sincerely,
Jipei

Stephen Cole

Hi,

This isn't unique to the LEBM model but would be the same for all simulations. Typically we consider the particles as elements and will calculate required time-step as Rayleigh time-step

https://help.altair.com/EDEM/topics/appendix/estimate_simulation_time_c.htm

However LEBM and other models like Bonding introduce a secondary element to the simulation, the bond between particles which is a beam like element in it's self, and requires it's own time-step which maybe higher or lower than the Rayleigh time-step value calculated, and we have to use the lowest value.

Higher forces, higher velocities require lower time-step value to be stable. Ultimately we need to know how far the element will move in the given time-step and if this is going to be stable.

I'm sure there are general papers/articles on the same subject as it wouldn't be limited to EDEM.

Regards

Stephen