LIGGGHTS-INL cohesion bond model

Hello, I’m a graduate student who has just started working with LIGGGHTS.

I’m trying to implement the Hertz–bond model from Clara Sangrós Giménez’s (2018) paper, but I’m running into difficulties, so i tried to ask to her but her email address was invalid. So i’m posting here to ask for help. The model I’m aiming to reproduce combines the standard Hertz contact model with the bonded-particle model from Potyondy’s paper “A bonded-particle model for rock.” Since LIGGGHTS-PUBLIC includes the Hertz model but not the bond model, I took cohesion_model_bond.h from LIGGGHTS-INL and modified it so that the bond-creation criteria match those in Giménez’s paper. (I confirmed that this INL file also follows Potyondy’s bond model.). Also I modified hertz model following Giménez’s assumption.

Based on this customization, I ran simulations and plotted the z-direction force on the nanoindenter. The values are roughly 12 times lower than those reported in the paper. I have checked the unit conversions multiple times and haven’t found any obvious mistakes, so I suspect the issue may lie in my customized cohesion_model_bond.h. If possible, I would really appreciate your thoughts on which part of the implementation might be wrong or what I should look at more carefully.

Thank you very much.

Attachments: papers,the simulation script, the customized cohesion_model_bond.h, nanoindentor stl file, the nanoindenter output .txt file, and the plotted graph