Talk:Torsion constant

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TORSION CONSTANT

It would be a great help if worked examples were given with the different equations in this and other related articles. —Preceding unsigned comment added by 89.168.45.137 (talk) 17:00, 31 October 2009 (UTC)[reply]

I have found conflicting values for the polar moment of inertia of an ellipse:

http://www.eformulae.com/engineering/moment_of_inertia.php

gives a formula which looks similar but is really quite different and yields results that make more sense. Could anyone verify this with an engineering text? 72.1.133.102 (talk) 19:14, 16 December 2009 (UTC)Brendan[reply]

The correct formula for an ellipse is 1/4(pi)ab(a^2 + b^2) —Preceding unsigned comment added by 216.174.137.236 (talk) 15:49, 28 December 2009 (UTC)[reply]

That's polar moment of inertia which is not the same as torsion constant for an ellipse. Xcglxdg5uj (talk) 21:06, 26 September 2019 (UTC)[reply]

Commercial Products

Do we really need a list of products that any mildly competent first year engineering student could replicate? Greglocock (talk) 04:45, 20 June 2017 (UTC)[reply]

Suspicious of Torsion Constant for hollow shaft ??

2/3 pi Rt^3 ?? This seems wrong to me but it's been here for years. I suspect it's something like pi/2(R^4-r^4 ) For thin walled that simplifies to 2piR^3t. — Preceding unsigned comment added by 172.58.43.174 (talk) 02:06, 26 August 2022 (UTC)[reply]

pi/2(R^4-r^4) is for a closed circular section. 2/3 pi R t^3 is for an open section, i.e. tube with a slit along its length. ~ Xcglxdg5uj (talk) 04:35, 26 August 2022 (UTC)[reply]

That clears it up, however, perhaps that's a pretty esoteric example (I think your "tube with slit" is much more descriptive) , while hollow shafts are everywhere. Perhaps it would be better to replace it with a hollow shaft as an example. Lwiniarski (talk) 11:09, 27 August 2022 (UTC)[reply]

I would have expected (4pi/3)(R^3)t. Does the shear profile with respect to theta not match the shape of a shear profile in the cross section of a rectangular beam? (i.e. a parabola with a maximum in the middle). That would indicate that for a thin-walled hollow shaft with a single, thin longitudinal cut, the torsion constant would drop to 2/3 of what it would be without the longitudinal cut. So (2/3)2pi(R^3)t?...3919183588... 130.160.192.22 (talk) 14:57, 3 October 2024 (UTC)[reply]

"I would have expected (4pi/3)(R^3)t" for which case? Greglocock (talk) 08:39, 4 October 2024 (UTC)[reply]

Rectangle

If you're correcting the 2nd formula, beware that a and b are half what they are in the 1st formula and table so it's not wrong in that way. But it is confusing and should probably be made consistent. People keep correcting it in isolation without making the rest of the section agree with the changes. Xcglxdg5uj (talk) 19:02, 24 August 2021 (UTC)[reply]

If the formula is changed form what is says in the source, it should probably say so in the text and show how/why those changes were made? 185.69.206.122 (talk) 13:01, 20 April 2023 (UTC)[reply]