calculating flanges as stiffners

[fourwheelinyota]

I need to calculate delfection on a plate 36 X 46" under normal vaccum pressure. The only thing is there are 4 flanges around this plate which does not allow me to place a stiffner across it. I know that flanges after being welded in created stiffness but i cannot seem to find anything that will tell me how to calculate this in. calculate the deflection with the added flanges. Any input would be appreciated

 

[prex]

Not sure to understand your setup.
If you have a flat rectangular plate with 4 nozzles (or 4 pad flanges?) placed at some locations over it, then you risk to get a higher deflection with your plate with holes than for a solid plate, though I guess the two deflections would be of the same order of magnitude.
If your problem is to limit deflections, then you definitely must add stiffeners, that would go somehow around the flanges to insure the continuity. Or, if you have nozzles with a generous neck thickness, you can weld the stiffeners to the nozzle necks.

prex

http://www.xcalcs.com

Online tools for structural design

 

[unclesyd]

You might like to checkout this site. Reas the instructions on how to download.

http://euler9.tripod.com/analysis/asm.html

Come back with w little more information as to the type of the flanges.