How to apply torsion to a shaft in CSL

[Blackhawk]

Hello - I am trying to apply a torsional load  onto a shaft in Creo Simulation Live.  I have tried several methods to apply a torque to the shaft.  For simplicity, I made a 1" diameter shaft that is 2" long.  I have one face fixed.  I tried applying a 37 in-lb moment load to the the opposite face in the z direction which is the axis of the shaft.  The XY shear stress that it returned with this method was extremely high.  Calculating by hand the shear stress should be 188 psi in the shaft.  I have the accuracy set to the maximum.

I then tried applying a force of 74 lbf to a point on the bottom of the face of the shaft in the X direction in order to simulate an equivalent torque of 37 in-lbf.  Please see screenshot.  This resulted in a XY stress of 142 psi.  This result was much closer to the hand calculation of 188 psi, but is still off by 25%.

What is the best method to apply a torque to a shaft in CSL?

[tbraxton]

As of the release of Creo 7.0.0, I believe you can apply a load (moment) to any coordinate system in the model. Have you tried applying a moment to a csys at the relevant location in the model?

Create a local coordinate system anywhere in the model and use it to define the direction of the force. You can select any coordinate system to apply force, moment, gravity, centrifugal, and linear acceleration loads. Define a direction vector by selecting an edge or surface.

[Blackhawk]

I am using Creo 8.  I can select the coordinate system that I am referencing, but you still have to apply the moment to a surface.  There is no option to apply a moment to the coordinate system.

[tbraxton]

In my reply above it does include the requirement of using a surface to define the direction vector. I do not have CSL available at the moment but if you have a csys in the proper position in the model you should be able to select a surface on the model to define the vector direction for the moment.

You can select any coordinate system to apply force, moment, gravity, centrifugal, and linear acceleration loads. Define a direction vector by selecting an edge or surface. Use the link below for clarification. Note you can define a unit vector as well.

Directions to define a moment in CSL:

Moment Load—Creo Simulation Live (ptc.com)

[Blackhawk]

This is basically what I am doing but the results are inaccurate.

[tbraxton]

If you are confident the boundary conditions are accurate and you are questioning the accuracy of the results, then I would inquire with tech support. ANSYS does state that CSL is not as accurate as the ANSYS FEA solver. I would be surprised if CSL is off by the amount you are reporting here for this simple loading condition. 

[SweetPeasHub]

I don't use CSL but fundamentals are critical, which is why I am a bit reluctant about "democratized" and also approximated simulation tools such as CSL. It is more for quick, directional innovation than checking precise performance.

XY shear stress is not the same as maximum shear stress given by the torsional stress equation for a cylinder.

Reference Mohr's circle.

Standard Creo Simulate.

[tbraxton]

This leads to my recollection of my undergraduate solid mechanics professor telling us that Mohr's circle is your friend more than once.