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12-Amethyst
January 29, 2024
Question

How to apply torsion to a shaft in CSL

  • January 29, 2024
  • 2 replies
  • 3250 views

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?

2 replies

tbraxton
22-Sapphire II
22-Sapphire II
January 29, 2024

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.

 

Blackhawk12-AmethystAuthor
12-Amethyst
January 30, 2024

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
22-Sapphire II
22-Sapphire II
January 30, 2024

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)

17-Peridot
January 30, 2024

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.

SweetPeasHub_0-1706628078228.png

Reference Mohr's circle.

 

Standard Creo Simulate.

SweetPeasHub_1-1706628754631.png

 

 

tbraxton
22-Sapphire II
22-Sapphire II
January 30, 2024

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