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 Critical bending moment Post Reply Forum
 Posted by: IMoo ® 06/09/2005, 09:26:31 Author Profile Mail author Edit Anyone any idea of the formula to calculate the critical bending moment of a hollow cylinder (eg. a plastic tube) or could point me to text book where I could find this info. Cheers.

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 Re: Critical bending moment Re: Critical bending moment -- IMoo Post Reply Top of thread Forum
 Posted by: zekeman ® 06/10/2005, 09:46:21 Author Profile Mail author Edit You probably mean the yield stress, so you use the formula s=Mc/I where I=moment of inertia, in^4 M= bending moment, lb-in c= outer radius of cylinder s= yield stress in lb/in^2 For the cylinder, I=pi/64(Do^4-Di^2) C=Do/2 If you find the yield stress s, then M=sI/c If this is a design problem you have to put in factor of safety, at least 3, so that your design stress is 1/3 of the yield stress or less and therefore the allowed M is 1/3 of the value calculated above.

 Re: Critical bending moment Re: Re: Critical bending moment -- zekeman Post Reply Top of thread Forum
 Posted by: ex03134 ® 11/26/2005, 09:12:18 Author Profile Mail author Edit hi,im doin something similar, basically im investigating a type of can crusher. i need to know how to calculate a force acting down on a can that is positioned on its side..it looks like a simply supported beam however because its cylindrical in shape i dont know the formula to calculate the force for this...i was wondering if u can help me..thank you

 Re: Critical bending moment Re: Re: Critical bending moment -- ex03134 Post Reply Top of thread Forum
 Posted by: ex03134 ® 11/26/2005, 09:16:30 Author Profile Mail author Edit sorry again..there was a formula you gave to Imoo.Since i'm from england im unsure of what your symbols mean.. I=pi/64(Do^4-Di^2) C=Do/2 what is Do, Di and C?