The using of mesh/surface/stress/servo command

Submitted by chqiao on Fri, 04/15/2016 - 10:58

Hi all,
After insertion of particles, I want compact the particles with a controlled stress, so I use the mesh/surface/stress/servo command. I followed the instruction of manual and tutorial, but when I using the following commands:

fix sslab all mesh/surface/stress/servo file meshes/slab3_mesh.stl type 3 stress on com 1.75 0. 0.006 &
ctrlPV force axis 0. 0. 1. target_val -10. vel_max 1. ratio 0.01 mode auto
fix tempslab all wall/gran model hertz tangential history mesh n_meshes 1 meshes sslab

I still got an error, tell me should using wall/gran with "mesh/surface/stress/servo", but I already used the wall/gran keyword just like the Shear Cell example do. After checking several times, I didn't know how to correct it.

The error message is :
Reading STL file 'meshes/gate3_mesh.stl'
ERROR: Fix mesh/surface/stress/servo (id sslab): The servo-wall requires a contact model. Therefore, it has to be used for a fix wall/gran too. (../fix_mesh_surface_stress_servo.cpp:302)

Could somebody give me some help? any suggestion will be appreciate!

Best regards

Cheng

jachueire | Mon, 03/13/2023 - 13:36

Hello,
Have you tried "unfixing" the old wall/grain fix you had before fixing the new one?

For ex :
fix tempslab all wall/gran model hertz tangential history mesh n_meshes 3 meshes mesh1 mesh2 mesh3

< - - execute the insertion of grains - - >
unfix tempslab
fix sslab all mesh/surface/stress/servo file meshes/slab3_mesh.stl type 3 stress on com 1.75 0. 0.006 &
ctrlPV force axis 0. 0. 1. target_val -10. vel_max 1. ratio 0.01 mode auto
fix tempslab all wall/gran model hertz tangential history mesh n_meshes 4 meshes mesh1 mesh2 mesh3 sslab