Bednar Experts - repad a/b >1.5

[mecmanmike]

Hi,

Newbie to eng-tips. I'm looking to determine maximum loading to a pair of rectangular repads on a shell where the a/b ratio, as defined by Bednar pg. 194, is greater than 1.5. My "copy" of Bednar makes reference to "REF 56", however, my copy of the book is missing the reference section. Can anyone point me in the right direction for determine my equivalent "c" value should be.

One pad is 5"x11" and the other is 5"x22".

I'd like to buy the reference if anyone can point me in the right direction.

Thanks,

Mike

 

[TomBarsh]

Reference 56 is Welding Research Council (WRC) bulletin 107 "Local stresses in spherical and cylindrical shells due to external loadings".

This can be obtained from the WRC website:

http://www.forengineers.org/store.php?crn=65&rn=351&action=show_detail

Listed price is $72.00 (last time I'd checked it was around $150 so I don't know if this is an error or a bargain).

 

[arto]

there's newer versions of 107 - I think #297

 

[TomBarsh]

WRC-297 "Local Stresses in Cylindrical Shells Due to External Loadings on Nozzles-Supplement to WRC Bulletin NO. 107" addresses only hollow circular shells (branch or "nozzle") attached to hollow circular/cylindrical shells. It does not address rectangular attachments.

This newer bulletin does not replace WRC-107 but provides an alternate method of analysis suitable for some applications. WRC-297 is based on an entirely different approach to the analysis than that taken by WRC-107. 107 considers only stresses in the shell; the attachment is generally considered to be a "rigid plug". 297 considers stresses in the flexible nozzle neck as well. 297 also considers a range of diameter-thickness ratios not addressed in 107.

297 is based on Professor Charles Steele's thin shell theory. Primarily, Steele's fortran program FAST2 was used to produce the curves published in 297 (further verified with some FEA and shell of revolution analysis). FAST2 was definitely more flexible than 297: A strict 297 analysis gives stresses at the four cardinal points around the shell-branch intersection only. FAST2 would provide results at angle around the circumference of the branch, and would provide the results along meridional lines on the shell and branch at the given angle. However, the program was not very user-friendly and I do not know if it can even be obtained anywhere.

 

[chicopee]

Here is a little bit more info from reference 56 in my Bednar PV Design Handbook:
Wichman,K.K., A.G. Hopper, and J.L. Marshen. Local stresses in spherical and cylindrical shells due to external loading. WRC Bulletin No. 107,December 1968.