Hexagon shaft hub connection

[Sco79]

Hollow shaft, hexagonal connection with hub. Materials and torque on the shaft are known and I'm trying to find out how big the diameters and hexagon length 'b' should be. Surface pressure between shaft and hub also.

Only formula I found was for max. torque, shown in picture. I'm not sure how the polar moment of inertia works in hexagon shaft or how to get the max. torsional shear stress. Any suggestions?

 

[desertfox]

Hi Sco79

Try this site:-

http://www.engineeringtoolbox.com/torsion-shafts-d_947.html

Also in the past I have found the polar moment of inertia
of a hexagon shaft by assuming the across flat dimension is a diameter of a round bar.

drsertfox

 

[desertfox]

A better reference;

http://books.google.co.uk/books?id=...g=atCoZZXWm2rPriRipLYGoG38OeY&hl=en&ei=khWdTP

KLGsL84AaOwvy_DQ&sa=X&oi=book_result&ct=result&resnum=
8&ved=
0CDQQ6AEwBzge#v=onepage&q=torsion%20of%20a%20hexagon%20shaft&f=
false

 

[tbuelna]

Sco79,

Just to clarify: Do you want to know the section properties of the two halves of your joint? Or do you want to know how to obtain the proper shaft hex and hub OD dimensions to handle a given input torque?

The references above will give moments of inertia. But calculating the stresses at the hex joint interface (ie. hub hoop stress, hex flank contact stress, etc.) is a bit more complex.

If you want to properly size the hex joint itself, you will need to specify the materials, class of fit, detailed surface geometries and loading conditions.

Hope that helps.
Terry