set different boundary conditions for nanobeam

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1

Dear lammps users,

I’m trying to simulate nanobeam with different boundary conditions(clamped-clamped, clamped-free and pinned-pinned).
For clamped boundary, I just group the regions and do simulations without the regions, which I think is clamped. Otherwise I think I could set force as null null null or 0 0 0.

For pinned boundary conditions, I am not really sure how to do. Should I setforce as 0 in horizontal and vertical direction and null in z direction, which allows rotating.

Thanks very much
YQ

2

Hi everyone,

Just wondering if there is someone who can give me a hand on that.I am not sure if my thoughts are correct.

A lot of thanks
Yueqiang

3

For clamped-clamped, you could define small regions at the ends of your nanobeam and use setforce to prevent all movement of those atoms (a material in a clamp can’t move, right?). For clamped-free, you would have one region at one end of the nanobeam which prevents those atoms from moving. For pinned-pinned, it sounds reasonable to me to set groups at the corners of your nanobeam and then use setforce as you describe.

4

Hi Will,

Thanks for your reply, that explains it.

Warm regards
Yueqiang