I just came up to speed on this thread. On the topic of tensile loading of rivets I have a few points to make.
Some manufacturers of structural pulled rivets actually give tensile and shear strengths for their products. Going into squeezed rivets, we know the alloy, its shear strength, and can compute the forces by several failure modes of the rivet, and by referencing the lowest of them, estimate maximum tensile load on such a rivet.
Doing a quick internet search, I found numerous references to design handbooks for various aircraft manufacturers with design guidance on use or rivets in tension. This should not be a surprise to anyone who has looked over a sheet metal airplane wing or, better still, noticed the difference in the top skin between sitting on the ground, and in flight.
On the ground, forces on the skins are small indeed, and the skins appear smooth. Take off and level at cruise speed, and the skin visibly bulges outward. Air inside the wing is typically stationary and at ambient static pressure. Air outside the wing is moving at a velocity near airplane velocity (look in TOWS Appendix I for V/v plots of various foil thickness distributions). This accelerated flow outside is then at pressure substantially lower than ambient. Solve Bernoulli's famous equation to go from local velocity to local pressure. This results in the wings skins being pulled away from the rest of the wing structure. In sheet metal airplanes, the skin is riveted to ribs and usually the spars, with the rivets thus being in tension from this load. Similarly, the tailplanes, control surfaces, and fuselage skin has similar moving air outside, stationary air inside, and the structures being inflated, with rivets holding the skins in place that are under tension.
Clearly, our riveted joints can carry some amount of tension. The result of my brief search indicated a lot of learned folks urging conservatism in design of rivets under tension. So, some designers do use some tension per rivet, and successfully too.
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Billski
