Limits of Roark's formula for buckling of shell

[mlbtx]

Hello,

I would like to understand what kind of error results from using Roark's formulas for the buckling of a thin tube when the thickness of the wall, in fact, is larger than the the "1/10 of radius" limit for their validity. Are the predictions obtained conservative (undervalue of crush pressure) or dangerous to use (overestimate of crush pressure)?

My thickness to external radius ratio is 1/4 and I am mostly interested in the long tube with free ends case (but interested in the other loading cases as well).

Are there derivations that work for thicker walls?

What does the experimental evidence show?


Thanks,

mlbtx

 

[JoeTank]

You might want to check out ASME VIII. It has rules for thin and thick walled cylinders.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[mlbtx]

Steve. Thanks for that suggestion. Will I find there algebraic equations similar to those I refer to? Or rather a step-by-step process to calculations in order to achieve an ASME-allowed design? (I am more interested in the former at the moment.)

Thanks again,

mlbtx

 

[JoeTank]

ASME has step-by-step calculation procedures

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com