Papers and Parametres Related With RotBondPrms

Asked by Jiadun Liu

Hi All,

(1) Could someone recommend me some RotBondPrms-related papers which describe the formula used in this Rot Bond model?
(2) Should I set parameter "torsionK" if I run a 2D simulation?

Best regards,
Jiadun

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Dion Weatherley (d-weatherley) said :
#1

Hi Jiadun,

1) The best paper on the implementation of the RotBondPrms interaction is:
Wang, Y.C. (2008) "A new algorithm to model the dynamics of 3-D bonded rigid bodies with rotations", Acta Geotechnica, DOI 10.1007/s11440-008-0072-1

2) The value of torsionK for 2D simulations is not important as the torsion component of the net moment acting on a particle will be zero. However, for the purposes of documenting your simulation script, I recommend setting torsionK=0.0 explicitly for 2D simulations involving RotBondPrms.

Cheers,

Dion

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Jiadun Liu (liujiadun) said :
#2

Thanks Dion Weatherley, that solved my question.

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Jiadun Liu (liujiadun) said :
#3

Hi Dion,

I found an shear cell example https://www.dropbox.com/sh/yrrpenz7gc8ewbq/AADDU5cMRMHJ7yulWBOgg9i6a?dl=0.

My question is that How the modulus in RotBondPrms are scaled to stiffnesses in this 2D case, and what are the units in shearCell.prm.

Thank you very much for your help.

Best regards,
Jiadun

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Launchpad Janitor (janitor) said :
#4

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

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Jiadun Liu (liujiadun) said :
#5

Hi Dion,

I found that the initial equilibrium distance is the sum of radii of the two bonded particles in RotBondPrms rather than their initial positions.

If two particles with a non-zero gap between them are bonded together, then there will be an attractive force.

An example of two bonded particles is in https://www.dropbox.com/sh/ddhncm21gs5r924/AACJEw5KBUA9S5L0kh0xSkwHa?dl=0.

In the two-bonded particles example, the gap is 0.00002 while the radii are both 1.0. The bond stiffness Kn = 100000.0, Ks = 40000.
if the shear displacement is 0.01, then the numerically obtained bond normal and shear are 400.1 and 2.49998. These forces are obtained on the assumption that the initial distance between the two bonded particles are 2.0 rather than 2.00002.

How to avoid such an error?

Best regards,
Jiadun

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Launchpad Janitor (janitor) said :
#6

This question was expired because it remained in the 'Open' state without activity for the last 15 days.