mesh/surface/stress/servo and rotation problem

Any chance your initial rotation angle and axis aren't quite aligned properly? Is the origin for the rotation axis set properly for this geometry? If the origin is actually at the bottom of your cell, you probably aren't rotating around the axis you think you are.

I do have a script for a shearcell that is copied below.

Best regards,
Chris

# Shear cell

# Preliminaries
units si
atom_style sphere
atom_modify map array sort 0 0
boundary f f f
newton off
communicate single vel yes

# Declare domain
region reg block -0.325 0.325 -0.325 0.325 -0.001 0.071 units box
create_box 2 reg

#neighbor 0.002 bin
neigh_modify delay 0 #every 1 check no page 1000000 one 1000

# Material properties and interactions
fix m1 all property/global youngsModulus peratomtype 1.0e7 1.0e7
fix m2 all property/global poissonsRatio peratomtype 0.25 0.25
fix m3 all property/global coefficientRestitution peratomtypepair 2 0.5 0.5 0.5 0.5
fix m4 all property/global coefficientFriction peratomtypepair 2 0.5 0.5 0.5 0.5
fix m5 all property/global coefficientRollingFriction peratomtypepair 2 0.1 0.1 0.1 0.1

# Physics
pair_style gran model hertz tangential history rolling_friction cdt
pair_coeff * *

# Integrator
fix integrator all nve/sphere

# Gravity
fix grav all gravity 9.81 vector 0.0 0.0 -1.0

# Import mesh from cad:
fix cad1 all mesh/surface/stress file shear_cell.stl type 1 scale 0.001 stress on
fix cad2 all mesh/surface/stress file bottom_plate.stl type 1 scale 0.001 stress on
fix ins_mesh all mesh/surface/planar file factory.stl type 1 scale 0.001
fix geometry all wall/gran model hertz tangential history mesh n_meshes 2 meshes cad1 cad2 rolling_friction cdt

# Timestep
timestep 0.00002

# Thermo settings
thermo_style custom step atoms ke cpu
thermo 50000
thermo_modify norm no

# Particle insertion
fix pts1 all particletemplate/sphere 1 atom_type 1 density constant 4000 radius constant 0.003
fix pdd1 all particledistribution/discrete 63243 1 pts1 1.0
fix ins1 all insert/stream seed 123481 distributiontemplate pdd1 nparticles 4421 &
particlerate 5000 overlapcheck yes vel constant 0. 0. -2. &
all_in yes insertion_face ins_mesh extrude_length 0.02

run 100000

fix pts2 all particletemplate/sphere 1 atom_type 2 density constant 4000 radius constant 0.001
fix pdd2 all particledistribution/discrete 45324 1 pts2 1.0
fix ins2 all insert/stream seed 431524 distributiontemplate pdd2 nparticles 119366 &
particlerate 120000 overlapcheck yes vel constant 0. 0. -2. &
all_in yes insertion_face ins_mesh extrude_length 0.02

run 100000

fix cad3 all mesh/surface/stress/servo file top_plate.stl type 1 scale 0.001 stress on &
com 0 0 0.05 axis 0 0 1 ctrlPV force target_val -0.1 vel_max 1.0 kp 0.1 ki 0.0 kd 0.0
fix geometry2 all wall/gran model hertz tangential history mesh n_meshes 1 meshes cad3 rolling_friction cdt

# Settle the plate on top of the particles
run 200000

# start shearing
fix movecad all move/mesh mesh cad2 rotate origin 0. 0. 0. axis 0. 0. 1. period 20.0

# shearing
run 15000000