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On 11/22/95 Todd Leonard wrote:
>Would capping the ends of the cylinder with a hollow hemispherical 
>shape improve the strength compared to a plate of the same material
>and thickness? If so, is it just not worth doing because of additional 
>manufacturing complexity?

I believe the answer to both questions is yes. First a hemispherical 
end cap does not transfer bending forces (or at least minimizes) into 
the end of the tubular body, if the wall thickness of the end cap and 
body are similar. The walls of the end cap where it joins to the 
cylinderical body tend to deflect inward just like the walls of the 
body. Conversely a flat plate does transfer bending forces as the plate 
deflects inward in the center which tends to rotate the edges of the 
plate. If the end cap is bonded, or tightly fit, to the body it will 
transfer this rotation into the body. A hemisphere would be the 
preferred end closure, but your second question touches on the reality 
of the issue. Hemispherical end caps involve more manufacturing 
complexity. Flat end caps are readily producible, and if sufficiently 
thick will suffice for deep dive light battery cannisters. End cap 
thickness of the presently available lights such as the AUL does not 
appear to be the more limiting factor in the light design. Other 
factors such as out-of-roundness of the body and a bonded lower end cap 
may dominate.

Hope this provides some useful info.

Doug Chapman

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