Fixed Expansion of a Cylinder/Coil

[paulbenson4290]

Hi, 

I am looking to simulate the stresses on a cylinder (or a coil) when subjected to fixed radial expansion. 

I have a cylinder with an ID of Ø17.5mm that has opposing castellated cuts to turn it into a type of radial spring. I'd like to know what stress (and ideally what pressure) is produced when this is expanded so the ID of the part is Ø19.5.

I'm using a non-linear static analysis.

When I try the "Enforced Motion" option, with a fixed distance of 1mm normal to the ID of the part, it just moves the whole cylinder 1mm in one direction and doesn't apply any stress.

I tried to use just 1/4 of the part and move the two cut faces of the quarter 1mm each (parallel to the cut direction in the relevant x and z direction) but I can't constrain it in a way I think will produce meaningful results without getting a "Singularity" error. 

I can change the pressure on the ID to refine to the point I get (about) 1mm (radially, 2mm on diameter) of movement and record the stress but I'm attempting to improve the current design and this is time-consuming to repeat so I would like to use Enforced motion if possible.

Any ideas?

Regards,

Paul.    

[John_Holtz · Accepted solution]

Hi Paul,

I did not know that the enforced motion could be applied in a normal direction. I learned something new today!

But considering that the geometry where the enforced motion is applied ALSO needs to have a constraint in the same direction, and I know that constraints cannot be applied "normal to the surface", how did you apply a constraint to the face with the enforced motion?

The usual method is to create a cylindrical coordinate system, and apply the enforced motion and constraint in the radial direction. This article describes creating the coordinate system and applying constraints in the new coordinate system: How to represent 2D axisymmetric elements in Nastran In-CAD. Hopefully you can adapt the article for your needs.