Discussion: punch connection of aluminum T-shape flange and FRP web

[Jonmiller]

I am designing a composite I-beam: two aluminum T-shape flanges with short double stems and flat fiberglass reinforced plastic (FRP) sheet as web. The FRP web will insert to the narrow channel between the double stems. I am thinking using circular punch 2-3" O.C. to connect the FRP web to aluminum T-shape flanges. Could anyone suggest a better, really easier and more reliable mechanical connnection? Any input and discussion are greatly appreciated.

By the way, the composite I-beam is quite small, 3" (depth) x 0.5" (width). The thickness of FRP is about 0.110". The aluminum flange is about 0.080" and the short stem is 0.060". The load is appoximately 25-40 lbf/ft.

Any input about book references for design/summary of mechanical connection is appreciated.

Thank you,

 

[40818]

What do you mean by circular punch?? You say that the loading is 25-40lbf/ft, but you give little details on the loading type. You need to determine (amongst other things) the interface loads between the aluminium and the FRP web.
I cant really see the benefits of the FRP web in the aluminium caps, not sure of your situation, but thermal loads might put a downer on your idea.

 

[berkshire]

When you consider the difference between the coefficients of expansion of the FRP and the aluminum You may want to use a slotted hole in one of the parts.
B.E.

 

[Jonmiller]

A circle punch is similar to a dimple on a flat sheet. Basically, I try to use punches to hold the double short aluminum stems and FRP web together to transfer/resist shear vertical and horizontal forces between the alum stems and FRP web.

The expansion and contraction between FRP and aluminum is not a problem cause the coefficients of FRP sheet and aluminum are quite close each other. The major consideration to use FRP web is to get much better thermal-break web to improve thermal resistance. The loading is uniform loading of 25-40 lbf/ft acting at the top aluminum flange.

What I am looking for is to figure out easy and cheap mechanical connection method to hold these three pieces together to form a perfect composite I-beam. I try to figure out whehter there is any other easy and cheap method except punch method.

Thanks for you guys' input.

 

[wes616]

see thread327-197112



Wes C.
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