Plate Deflection Calulation help
Plate Deflection Calulation help
(OP)
I have a 3/16" plate with a 2x2x3/16 angle iron frame with a pressure of 8psi on the surface as shown in the attached picture.
How do I calculate the max deflection in the plate?
How do I calculate the max deflection in the plate?





RE: Plate Deflection Calulation help
For a long narrow plate, figure a strip of it in the short direction as a beam and use beam formulas.
RE: Plate Deflection Calulation help
RE: Plate Deflection Calulation help
the two important dim'ns are the width and the length of the plate (together with the thickness and the pressure).
another day in paradise, or is paradise one day closer ?
RE: Plate Deflection Calulation help
How would you choose the width of such an arbitrary strip?
RE: Plate Deflection Calulation help
Because OP's loading is even pressure and not a concentrated load, the deflection is the same for the beam method no matter the width. I would choose a width of 1 inch to drop a dimension out of the calculations.
RE: Plate Deflection Calulation help
RE: Plate Deflection Calulation help
RE: Plate Deflection Calulation help
Plus, pencil and paper methods also make small-angle approximations.
RE: Plate Deflection Calulation help
RE: Plate Deflection Calulation help
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Plate Deflection Calulation help
Definitely solvable with formulae, but, jazz330, please first state some more data: supports, dimensions...
prex
http://www.xcalcs.com : Online engineering calculations
http://www.megamag.it : Magnetic brakes and launchers for fun rides
http://www.levitans.com : Air bearing pads
RE: Plate Deflection Calulation help
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Plate Deflection Calulation help
We need more information like measurements, I assumed that is 1x0.2m welded in 4 corners, you will have problems because the deflection is 10.77 mm and von mises stress is 310 MPa. (I assumed that material is A36 too).
P.D.: My english is very bad
RE: Plate Deflection Calulation help
I have done hand calculations and FEA but I get a ridiculous value for Stress and deflection and I may be doing it wrong so any help would be great.
Thanks
RE: Plate Deflection Calulation help
You should better describe the context and the goal of your analysis, as what you described is out of question.
Anyway your source is definitely the Roark, but also other sources online, google 'flat plates in bending' (example here, from the first site below).
If you insist with those dimensions and loading, you'll need to take into account the membrane action, and state whether the boundary is also fixed in the plane of the plate. Here a calc sheet for this condition.
prex
http://www.xcalcs.com : Online engineering calculations
http://www.megamag.it : Magnetic brakes and launchers for fun rides
http://www.levitans.com : Air bearing pads
RE: Plate Deflection Calulation help
Unless the plate gets used once and is then discarded...
STF
RE: Plate Deflection Calulation help
RE: Plate Deflection Calulation help
Assume a deflection of 1", then the plate has formed to a radius of 1152" = (48^2+1)/2
Then hoop stress is 8*1152/0.1875 = 50ksi; so it is looking dodgy,but then maybe 1" dflection is on the small side, given the scale of this plate. a 2" deflection would about 1/2 the stress ... 1/48, about 2% ... not unreasonable.
stiffeners running across the plate (96" long) provide lots of bending strength to the plate, and reduce the stress in the plate.
But, don't count a simple angle to fix the edge, even if you support the standing leg all around the perimeter; the angle would easily "open up". A tube section around the perimeter would give you more fixity (plate bending is torque of the tube ...)
another day in paradise, or is paradise one day closer ?
RE: Plate Deflection Calulation help
RE: Plate Deflection Calulation help
STF
RE: Plate Deflection Calulation help
That small a frame is not sufficient to hold the "drumhead" tension needed.