×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Applying torque to a shaft

Applying torque to a shaft

Applying torque to a shaft

(OP)
My question might sound very simple but I can't think of a the right answer:

I have a shaft, a very simple cylindrical shape, with a spline at the bottom. This spline is connected to another component and the torque is 32,000 lb in. Where would you apply the torque? On the side of the teeth of the spline? Because that's where the torque will be applied in real life. Any other suggestion?

RE: Applying torque to a shaft

Well, if it is applied there in real life then do the same in the analysis. Or model this part attached to the spline (that I guess transmits the torque to the shaft) and apply torque on it. Of course this will require proper contact between the part and spline. Anyway you will need coupling constraints to apply torque on the boundary of solid body.

RE: Applying torque to a shaft

(OP)
The shaft has the spline that will interact with splines of another component. Refer to Fig 1 of this free paper, I have exactly the same model.I'm bothering of simulating the shaft only (so I have only the grey part of Figure 1). Now, the torque should be 32,000 in lb since I have an engine of 260 HP at 256 rpm that moves two shafts.

I created an RP and this RP is coupled with the surfaces of the splines that will touch the splines of the external component. I apply the Torque on the reference point. The solution seems to make sense in terms of pure distribution, but I have way too much stress and I can't figure out why (700 ksi!!) so I'm wondering if I applied the load in the proper way. The shaft is a pretty thick piece of AISI 4140 and it is used already with that HP and rpm so I'm pretty sure I'm making a mistake somewhere.

Any tips is greatly appreciated.

RE: Applying torque to a shaft

What are the boundary conditions - how did you constrain this model ? Can you attach a picture with BC and the one with results ?

Make sure that all units are correct. Almost 5 GPa stress indeed seems really off. Also it would be a good idea to do some rough approximation with analytical formulas for stepped shafts subjected to torsion. There are some equations for splines too.

RE: Applying torque to a shaft

(OP)
hope the links works:
This is the part so you have an idea of the component. The far right is fixed as BC
https://files.engineering.com/getfile.aspx?folder=...

In the middles of the two splined I put the RP and it is coupled wih 1 surface of each tooth of each spline
https://files.engineering.com/getfile.aspx?folder=...

general results: this is a different version and stresses are not real
https://files.engineering.com/getfile.aspx?folder=...

Zoom out on the highest stresses area
https://files.engineering.com/getfile.aspx?folder=...

hope this helps!

RE: Applying torque to a shaft

It would be more realistic to replace fixed constraint with supports simulating bearings. This should reduce stresses by eliminating overstiffening. However the results are so high in this case that probably there is another serious error. That’s why I suggested to check all units (common mistake) and perform simplified hand calculations. They should give you an idea of the stress values that can be expected in this model.

RE: Applying torque to a shaft

(OP)
I agree, quick hand calculation with a constant section hollow tube result in 17 ksi which is very good. I can't think of anything else beside the wrong application of the load and I'm trying to find a way out. Units to me seem to be correct, I'll double check them one more time.

Thanks

RE: Applying torque to a shaft

In the mechanics of materials books you can also find examples for stepped shafts as well as notch stress concentration factors. However it's clear that the results are too high. Check if the reaction moment at the support is equal to applied torque just for sure.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

White Paper - The Criticality of the E/E Architecture
Modern vehicles are highly sophisticated systems incorporating electrical, electronic, software and mechanical components. Mechanical systems are giving way to advanced software and electronic devices, driving automakers to innovate and differentiate their vehicles via the electric and electronic (E/E) architecture. As the pace of change accelerates, automotive companies need to evolve their development processes to deliver and maximize the value of these architectures. Download Now
White Paper - Model Based Engineering for Wire Harness Manufacturing
Modern cars, trucks, and other vehicles feature an ever-increasing number of sophisticated electrical and electronic features, placing a larger burden on the wiring harness that enables these new features. As complexity rises, current harness manufacturing methods are struggling to keep pace due to manual data exchanges and the inability to capture tribal knowledge. A model-based wire harness manufacturing engineering flow automates data exchange and captures tribal knowledge through design rules to help harness manufacturers improve harness quality and boost efficiency. Download Now
White Paper - Modeling and Optimizing Wire Harness Costs for Variation Complexity
This paper will focus on the quantification of the complexity related costs in harness variations in order to model them, allowing automated algorithms to optimize for these costs. A number of real world examples will be provided as well. Since no two businesses are alike, it is the aim of this paper to provide the foundational knowledge and methodology so the reader can assess their own business to model how variation complexity costs affect their business. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close