HOW TO CHECK FOR TORSION

[ARNAR]

How to check the section (bracket fixed as shown below) for torsion ?? any general formula for min thickness??

 

[KootK]

any general formula for min thickness??

Amusing you are.

How to check the section (bracket fixed as shown below) for torsion ??

1) Finite element method if accuracy and lean design are very important and/or justified by the economics of the problem.

2) Discritize the assembly as plate "strips" that will resist torsion by way of opposing flexural couples.

The thing to recognize with plate assemblies is that their behavior is dominated by warping torsion rather than St.Venant torsion. This makes #2 a pretty sensible path.



I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[WARose]

Where is it supported? The one hole that doesn't have a force on it? (It may not be in torsion if that is the case (and those loads are of equal magnitude).)

As far as analysis goes.....you may want to get AISC's Design Guide #9.

 

[ARNAR]

@WARose : The Bracket supported on the holes that doesn't have force on it (As you said) and loads are not equal (only in one leg and the other is very small or negligible). Any general formula for finding the stress or min thickness of the member ??

 

[rb1957]

Torsion on the back face (T = Force*e) is easy to analyze (flat sheet in torsion, T/(1/3*b*t^2).

It's much less easy to see how the brkt will resist the torsion due to the offset load (RH screw = torsion in the plane of the face of the brkt).

another day in paradise, or is paradise one day closer ?

 

[ARNAR]

@rb1957 : T/(1/3*b*t^2 gives what ?? any general formula for min thickness??

 

[klaus.]

NO

 

[rb1957]

if you don't know, there's no point in telling you. If you understood, you'd be able to answer your question.

Please read a text book.

another day in paradise, or is paradise one day closer ?

 

[DaveAtkins]

3T/bt^2 is the shear stress due to pure torsion. I agree with rb1957--that is how I would check the back plate.

DaveAtkins