Blind pop rivet tensile strength

[OccamzRazor]

The tensile strength is often related to the "pull out strength" of the rivet. Rivets will almost always fail in shear first but there are cases where the rivet being used is tougher than the plate and the plate will crush or tear(thick steel rivet and thin aluminum plate for example). It usually requires more strength to pull a rivet out than to shear it which is what the datasheet is letting you know. The reason you do not use a rivet for a tensile example is because you rarely use one rivet in an application so adding multiple rivets makes the force to shear in that joint increase whereas the pullout force for that ONE rivet still remains about the same no matter how many you add because you are only relying on the head of the rivet and the friction in the expanded joint to hold it in. If separation occurs then shear will most likely happen and cause failure.

Joe is spot on about dynamic and cyclical loads where vibration or fully reversed loading occurs. These types of loading conditions in the real world are treated with a high factor of safety (6 to 12 times) over static loads and more often than not are exactly what you experience on a robot during competition.

Our robot chassis this year was all riveted construction with only two joint welds. http://www.yetirobotics.org/wp/our-robot/

We sheared the riveted angle plate that stops our gravity claw twice during competition so we added more rivets to fix it at worlds since it was a 2 minute fix. Once one rivet shears it usually unzips and breaks the rest of them soon after as the kids got to see.

Hope that helps!

[GreyingJay]

With respect to rivet material, I was reading somewhere that said you should choose the same material of rivet as the material you are fastening, e.g. aluminum rivets for aluminum plates.

I can understand wanting thermal expansion properties to be the same for construction of long-term, permanent structures like vehicles. But does this apply for FRC robot construction? In other words - why wouldn't I always use, say, steel rivets, for strength?

[asid61]

Originally Posted by GreyingJay

With respect to rivet material, I was reading somewhere that said you should choose the same material of rivet as the material you are fastening, e.g. aluminum rivets for aluminum plates.

I can understand wanting thermal expansion properties to be the same for construction of long-term, permanent structures like vehicles. But does this apply for FRC robot construction? In other words - why wouldn't I always use, say, steel rivets, for strength?

I would argue that aluminum rivets will work just as well as steel ones for most applications in FRC. We avoid steel rivets because it is difficult to drill them out. Any time we would have to use steel, we just switch to a screw.

[Mike Marandola]

Originally Posted by GreyingJay

With respect to rivet material, I was reading somewhere that said you should choose the same material of rivet as the material you are fastening, e.g. aluminum rivets for aluminum plates.

I can understand wanting thermal expansion properties to be the same for construction of long-term, permanent structures like vehicles. But does this apply for FRC robot construction? In other words - why wouldn't I always use, say, steel rivets, for strength?

Not really in FRC, but it humid environments it is best to use similar metals to prevent galvanic corrosion.



Source

[philso]

Originally Posted by GreyingJay

With respect to rivet material, I was reading somewhere that said you should choose the same material of rivet as the material you are fastening, e.g. aluminum rivets for aluminum plates.

I can understand wanting thermal expansion properties to be the same for construction of long-term, permanent structures like vehicles. But does this apply for FRC robot construction? In other words - why wouldn't I always use, say, steel rivets, for strength?

We ended up using some 3/16" steel rivets in this years robot. The aluminum ones held up just as well and were lighter. We probably had to cut some extra "speed holes" due to the steel rivets we used.