CosmosWorks 2003 Thin Plate Analysis 1

[Paulhen]

I have recently done an analysis using CosmosWorks 2003 on a 24"x36"x0.018" (26 ga.) plate that is fixed on all 4 edges with a 0.46 psi pressure on the face and is 304 SSTL. I used the mid-surface mesh type with a pretty fine mesh size. The results were very surprising. Cosmos calculated a max deflection of 23" and a max stress of 3.28x10^6 psi (ultimate for 304 is 75000psi per Cosmos). This just seems wrong(24"x30" plate physically tested at 0.36" deflection).

Why is Cosmos producing such a result and is they a way to properly analyze this scenario?

Small Deflection Theory vs Large deflection Theory of Plates???

Any ideas would be helpful.

Thanks Neil

 

[TheTick]

You may want to direct this query to the Finite Element Analysis Engineering forum. Sounds like more of a general FEA question than a COSMOS question.

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Due to illness, the part of The Tick will be played by... The Tick.

http://www.EsoxRepublic.com

 

[ShaggyPE]

Yeah, it is because the plate is a large deflection case. I recently did an FEA using cosmos for a thin film, .0005 thick. It was clamped on all four edges. Under a very small pressure 1X10^-4 psi, it deflected some odd 2000 in. Ha Ha. Interestingly enough, this matched the hand calc. When I used an equation that takes into consideration the "membrane" properties of the system, (essentially the non-linear aspects of the problem), the deflection was on the order of .25 in.

In order to properly do your problem in FEA, you must have the non-linear package. For the equations that will help you do this as a hand calc, do a google search for "Timoshenko plate large deflection"