Shell or not? And how to apply pressure

Question

Shell or not? And how to apply pressure

smith4464 (Mechanical)

(OP)

28 Sep 11 15:36

I have an FRP ( fiberglass ) form that is being held by several external "clamps" - bracing. Basically the form is a W shape but with the the W vertices flat instead of pointed.

The 'clamps" are aluminum extrusions along length-wise being rigidly held in place by bolts.

There is an internal pressue of 30 psi pushing out of the form and the clamps are there to keep it from deforming to the point of failure, i.e. bubbling "too much" ( more than 1/2" inch ) or outright cracking.

Should I be modeling the FRP W as a shell? it is approx 3/16" thick. And if it is a shell what faces ( inside or out ) do I apply pressure.

I looked up some "numbers" for FRP to try and guesstimate material properties for it so that is not the issue.

Thanks!!!!!!!!!!!!!!!!!!!!!!!

smith4464 (Mechanical) · Answer 1 · 2011-09-28 15:51:51

Oh, maybe I could use some material property numbers for FRP other than those I put into the database...

smith4464 (Mechanical) · Answer 2 · 2011-09-28 18:07:10

Here's the model...

http://files.engineering.com/getfile.aspx?folder=32d27984-05b4-4e6a-99a8-80

kellnerp (Mechanical) · Answer 3 · 2011-09-30 08:53:40

A W shape is amenable to shelling. Unless you can afford 3 elements throught the thickness and maintain decent ratios of one side to the other in the elements go with shells.

FRP may or may not be anisotropic. Don't know if you can deal with that easily. I would assume the beams are pultruded.

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Shell or not? And how to apply pressure