Dear steve,
I alway appreciate your kind support for LAMMPS users.
I have two questions.
- Does following input make the specimen contract naturally in x and y direction ?
boundary m m p (or s s p, f f p)
fix 1 all nvt 77 77 1.0
fix 5 all deform 100 z erate 0.005
When I use PBC along all the three dimensions, ‘fix deform aniso’ command makes that happen.
But when free-surface is included in the simulation, ‘fix deform aniso’ can not be used so I’m trying to find another way to achieve it.
For my experience, above input does not guarantee the natural contraction.
How about your opinion?
If not, can you suggest better way to achieve it ?
- Compression test including free-surface doesn’t work.
boundary m m p (or s s p, f f p)
fix 1 all nvt 77 77 1.0
fix 5 all deform 100 z erate -0.005
Above input is just different with the input that mentioned in the previous question (direction of strain along z-direction is minus)
I hoped that made the compression test but simulation ended in fail printing out the error message, “Final box dimension due to fix deform is < 0.0”
I understand what the error message means but I don’t know how to resolve the problem.
I need your help.
Best,
JongBae Jeon
Comments below.
Steve
Dear steve,
I alway appreciate your kind support for LAMMPS users.
I have two questions.
1. Does following input make the specimen contract naturally in x and y
direction ?
boundary m m p (or s s p, f f p)
fix 1 all nvt 77 77 1.0
fix 5 all deform 100 z erate 0.005
When I use PBC along all the three dimensions, 'fix deform aniso' command
makes that happen.
But when free-surface is included in the simulation, 'fix deform aniso' can
not be used so I'm trying to find another way to achieve it.
For my experience, above input does not guarantee the natural contraction.
How about your opinion?
If not, can you suggest better way to achieve it ?
I don't see anything wrong with the commands above. Movement
in x,y will not be constrained in any way, so I don't
see how the contraction could be un-natural.
2. Compression test including free-surface doesn't work.
boundary m m p (or s s p, f f p)
fix 1 all nvt 77 77 1.0
fix 5 all deform 100 z erate -0.005
Above input is just different with the input that mentioned in the previous
question (direction of strain along z-direction is minus)
I hoped that made the compression test but simulation ended in fail printing
out the error message, "Final box dimension due to fix deform is < 0.0"
I understand what the error message means but I don't know how to resolve
the problem.
Again, the x,y motion should be unconstrained. If you are running
so long that the box length in z vanishes to 0.0, then LAMMPS is
telling you that's not a good idea.
Steve