Workpiece atoms penetrating tool

LAMMPS LAMMPS General Discussion
1

Hi, I am trying to simulate elliptical vibrated cutting of CuZr using diamond tool.
Workpiece: CuZr
Tool: C

Picture 1 (orthogonal cutting):
1

Picture 2 (elliptical vibrated cutting):
3

I realised that there was no problem at all with orthogonal cutting but when I applied elliptical vibration to my tool, workpiece atoms started to penetrate my tool.

Potentials:
Cu-Zr: eam
C-C: rigid (no potentials)
C-Cu, C-Zr: lennard-jones

I tried using morse potentials for C-Cu, C-Zr as well but it didnt help.
From what I observed, I suspect that it is the cutting speed that causes the penetration, as vibrating speed is definitely way higher than tool speed during orthogonal cutting.
I have discussed with someone familiar with LAMMPS but his feedback was to try different potentials. So far, I find it not useful.

It would be great if someone could provide some thoughts/guidance. Thank you in advance.

2

This is more likely due to the way how you move your tool.

3

Hi Dr @akohlmey, thank you fo your reply.

Here is a comparison between elliptically and diagonally cutting the moment the tool comes in contact with the workpiece.
Elliptical:
4
diagonal:
5

I used command velocity for orthogonal/diagonally cutting, and fix move for elliptically cutting.
I guess this is what you meant and I believe this is the root cause as well.

orthogonal tool motion: velocity tool set -1.0 0.0 0.0 sum yes units box
elliptical tool motion:
variable Vx equal …
variable Vy equal …
fix 1 tool move variable NULL NULL NULL v_Vx v_Vy NULL

May I ask for suggestions on what options do I have, in order to realise elliptical motion and also avoiding atoms penetration at the same time?
Thank you very much.

4

There is not enough information here to make any specific statements.

5

Hi Dr @akohlmey , my problem has been solved, and it was due to error: one or more atoms are time integrated more than once. Thank you very much.

6

Lesson: always take warnings in your output seriously and only ignore them if you are dead certain they may be ignored in your specific case.

7

Noted. Thank you very much, Dr @akohlmey .