Bearing stress on a rectangular shape on shaft coupling

Question

Bearing stress on a rectangular shape on shaft coupling

eliam (Mechanical)

(OP)

20 Mar 24 08:08

Hello,
I have a shaft under torque,
this shaft is coupled by a rectangular connection to transmit the rotation.
Witch is the maximum bearing stress on the surface in contact in the coupling?

we have:
a= long side
b= short side
L= lenght of connection

I'm drawing a sample for better understanding
Thank you

electricpete (Electrical) · Answer 1 · 2024-04-01 14:01:23

Fwiw I don't think I can help but that never stopped me from providing thoughts before!

I don't see a drawing yet. How does this clamp to or attach to the cylindrical shaft? Or if there is a transition that will need explanation.

Is there a flexible element in the coupling? What speed will it operate at? It strikes me that square cross-section coupling has a resistance to bending in a given stationary direction which will vary as the coupling rotates.... resulting in oscillating reaction loads and vibration.

geesaman.d (Mechanical) · Answer 2 · 2024-04-01 19:10:59

Are you (the OP) describing a rectangular-section key?

eliam (Mechanical) · Answer 3 · 2024-04-02 13:07:22

Here, a picture of square connection:

https://drive.google.com/file/d/1UVrMBpH8odVEkQmY8...

Answer 4

[Post Deleted]

Answer 5

[Post Deleted]

dvd (Mechanical) · Answer 6 · 2024-04-02 17:30:05

There is a big stress concentration at the very small radius where the square section joins the circular section. This is most likely your failure point.

Tmoose (Mechanical) · Answer 7 · 2024-04-02 21:23:02

On six-sided drives ( like a wrench on a hex head cap screw) at times the contact at the corners has received a great deal of attention. Your square drive may have similar loading.
In addition to the transition mentioned by dvd.

example "Flank drive" as probably originated by Snap-On.

https://photos.smugmug.com/MotoIQ/Tech/Sarah-QA/i-...

https://www.transtime-tools.com/data_pics/0001%20(...

https://www.datamp.org/patents/displayPatent.php?p...

As always, if the load is low or the service life is short, you can get away with practically anything.

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Bearing stress on a rectangular shape on shaft coupling