[lammps-users] Correct way to include force controlled indenter inside lammps

LAMMPS LAMMPS Mailing List Mirror
1

I was wondering if there is a way to include force-controlled indenter in lammps. In the lammps, the indenter is included by mentioning its position. However, I want the indenter with a fixed force whose value I define, inside the system.

Currently, I am including a large particle with soft-sphere potential and apply force to it. Is this the correct way? (I have included file)

I wonder If I can use a force-interaction as the same -K(r-R)^2 instead of soft sphere potential. Is there any way?

Ankit

in.indent2.min (1.79 KB)

2

I was wondering if there is a way to include force-controlled indenter in lammps. In the lammps, the indenter is included by mentioning its position. However, I want the indenter with a fixed force whose value I define, inside the system.

if you want to have the indenter position to be dependent on the force it applies to the atoms it is in contact with, then you can make its position a variable and and then use fix controller to determine the value based on the force component that you can access from fix indent.

mind you, this is a non-trivial procedure that requires some careful testing and some empirical trial and error iterations to get it to work well.

axel.

3

Thank you so much for the suggestion. I just have one more question

Applying load through a single particle (which should act as indenter) of a very large radius is also a correct way? I have applied force using addforce to this particle and this particle interacts with other particles in the system using soft-sphere potential. (I have attached the image depicting my indenter, which is a yellow colored particle and code to generate it)

Warm Regards,

Ankit

indenter.png

in.indent2.min (1.79 KB)

4

There is no such thing as “the one correct way”. Each of the approaches implement a specific model and mechanism. It is up to you to decide whether this implements the exact behavior that you want to achieve.

5

Dear Axel,

I would like to do something similar to this. How would one go about implementing this as per Axel’s comment:
then you can make its position a variable and then use fix controller to determine the value based on the force component that you can access from fix indent.

Is this done via set or fix move?
Best,

6

I have just provided a small demonstration for moving a wall following a computed property in your other thread.

All required information is in the manual. The rest is up to you