Why does pure remote rotational displacement results in force reaction

- May 12, 2020 at 9:53 pm
  
  rfn123
  Subscriber
  
  Hello,
  
  I have a question regarding remote displacements and the resulting force/ moment reactions.
  
  I was experimenting a bit with the file provided in this post. I modified it such that I apply a purely rotational remote displacement around the z axis.
  
  As output I probed force and moment reactions as bounding condition at the point of displacement. Since it is a purely rotational displacement, I would expect only non-zero moment values (Mz). However, the force reaction additionally states a non-zero force.
  
  When further experimenting, I found out that in "Details of Remote Displacement", when I set X Y Z Components to free, the force disappears. Can someone explain why this happens?
  
  PS. It seems that I cannot insert any images, when clicking on upload after browsing, nothing happens. Is this the right procedure to insert images?
- May 13, 2020 at 3:07 am
  
  peteroznewman
  Subscriber
  
  Your expectations were wrong.
  
  If X is free and the solution shows there is movement in the X direction, setting a constraint of X=0 will require a reaction force to achieve that constraint.
  
  Only in a very special case where X is free but the solution shows there is no movement in the X direction will setting a constraint of X=0 require no force.
  
  The Insert Image button was temporarily broken, but it is working now.