Cylindrical coordinates in Ansys workbench 12 1

[EngTipX]

I am new to this forum although I have read some posts. Please bear with me.
Question:
- How to display results in radial (use of cylindrical coordinate) direction? Radial stresses, Shear stress in r-theta, radial deformations...

I have been able to add a cylindrical coordinate system.

 

[flash3780]

Try creating a cylindrical coordinate system and scoping your results to that, rather than the global coordinate system. You can select the cylindrical coordinate system where you output your stress results.

 

[EngTipX]

Thanks flash, I have been able to insert a cylindrical coordinate system.
In the results I added a normal stress and shear stress. In the details, I picked the cylindrical coordinate system. The results are different than those of normal and shear stress if the details were Global coordinates.
I am not 100% sure since when picking normal axis choices were x, y or z!
I try to verify by modeling a thin pressure vessel and comparing radial and hoop stresses to known sigma-theta=Pr/t sigma-r=-p/2
however the results were not conclusive.

 

[flash3780]

I'd start with a simple case to make sure that you understand the interface correctly.

 

[EngTipX]

Thanks flash,

I thought pressure vessel was a simple case but you are right. It is not a simple one to fully understand the interface and make sure I am using it correctly.

Sorry (nothing crosses my mind) Any ideas of a simple case of radial, hoop and shear (r-theta) stress verification !?

 

[flash3780]

A pipe?

 

[EngTipX]

-Here is what I did;
A cylinder of R=10, t=.1 and P=100

for modeling purposes a quarter of the model and symmetry around x and y

Pre-known results: Hoop stresses "Sigma-theta"=Pr/t= 100*10/.1= 10,000
I was able to verifiy this result while using normal stress with y orientation and cylindrical coordinate. The stresses were between 9928.9 and 10091.

Pre-known results: Radial stresses "sigma-r"=-P=-100
I had problems with this I picked the cylindrical coordinate and X orientation. The results were NOT nicely distributed. They were like strips along the z axis. The strip values on the interior were -141 to -79. I would have expected -100 all over the interior face without any varied distribtion.

The cylindrical coordinate was inserted with Global Coordinates 0,0,0 and the prinicpal axis x defined by global x axis.

I tried another problem of pure torsion but results were confusing.

 

[flash3780]

It sounds like you've got a problem with the definition of your coordinate system. You should be able to see a graphical representation of it showing what X, Y and Z represent (it's color coded).

 

[EngTipX]

Thanks flash,
Here is how I defined the new coordinate system (cylindrical coordinate)
Type: Cylindrical
Origin: Global Coordinate
Principal axis: x defined by global x
Orientation about axis: picked z axis
defined by: default ......on this one I just tried
defined by: global z......gave me same answers

 

[EngTipX]

An update still not quiet sure

-the x (radial), y (axial) and z (tangential) directions

I thought
-the x (radial), y (tangential) and z (axial) directions

That is at least how they were displayed on the screen while creating the coordinate besides I picked the orientation to be around z axis