Originally Posted by
Brian
Yep, you're correct. With a clean fracture right in the middle of the tube it sounds like a buckling failure, and increasing the thickness of the tubing exponentially increases the buckling strength as you are increasing the radius of inertia of the bar. It isn't a linear relationship but rather a quartic one with respect to the inner and outer radii. Assuming everything else constant, the thicker pole (.625", .038" thickness) will be ~390% stronger than the thinner (.433", .030" thickness) for buckling loads.
Force-wise, for 7000 series aluminum, the thicker pole will buckle at 460 lbf with the thinner pole buckling at 117 lbf (which is well within reason for an adult getting into a hammock!).
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