Lateral load on cylinder

[Spoonful]

Hi All

I have a cylinder ( OD, thickness and width known), as shown, is supported at half way, lateral force F1 and F2, say F1=F2.
Would someone advise on some reference on how to find out the max bending moment at the support plane? so I can find out the max bending stress, hence determine the thickness required for F1 and F2.

If break it into quarters. MA= F1/2 *r - Fx * r. F1 is known, how to solve for Fx?. As Fx is also a function of F1, as when F1 is 0, Fx is certainly also 0. Fx only exist as the half cylinder start to tend to deform.

 

[tmschrader]

hello ............."Formulas for stress and strain" by Roarke should have that or a similiar case. I downloaded the book from site some awhile ago.
Or any FEA. Cadre is free, but i do not think it does arches.
Or be conservative and see how thick it is. ie forget Fx.
Or A cantivered beam of length r may give some idea of stiffness

 

[robyengIT]

may be this

 

[WARose]

Someone already suggested Roark's.......for what you have modeled as a arch with a load at the apex (with fixed supports).....that should suffice.

I have to wonder though: do you really have the cylinder supported that way? (I.e. how valid is that assumption?) Seems to me like even if you have that "fixed" point.....you'd have to consider lengths of the cylinder beyond that (i.e. that could rotate).

If it wasn't for those "supports" I'd suggest a pressure vessel handbook.

 

[rb1957]

I like solving things (rather than looking them up in Roark).

Your Ma calc shows the 1/4 arc is like a propped cantilever. So solve for Px as a single redundancy (unit force method).
Or maybe solve for Ma ... Px = P1/2 (two force member)

But you'll need curved beam expressions for stresses and deflections in the 1/4 arc.

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

 

[Spoonful]

I couldn't seems to find a case in Roark's, could anyone suggest the case number?

robyengIT , your attached is very similar to my case, but I could figure out how to use your attachment?

I think it is a different case as to a external pressurerised pressure vessel, as in my case the load is a point load, where with the vessel, the load is uniform distributed pressure load.

To model the quarter as a cantilever beam, meaning ignore Fx, it is too over conservative. The end result lead to very thick material to be used, which is not acceptable.

 

[robyengIT]

so may be these ("Structural analysis of buried pipes - Hornung/Kittel - ed. Bauverlag")

 

[rb1957]

just thinking ... a section view is fine, but how is the base of this cylinder going to react the bending moment (P*offset) ? Moment at the two fixed support points ? yeck ...

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

 

[TimSchrader2]

Hello

Roark Table 9.1 case 11. It gives stress. You can work back to moments and solve any reactions. All of chp 9 is on curved beams and arches.

Or Table 9.3 case 5a for reactions and deflections, but i think working back from case 11 would be easier. Or a FEA.


Note that estimating defl as cant beam is not ignoring Fx. Not sure if this aproximation would be conservative or not.