Real world tests of AN bolt tensile and shear strengths?

Eric S

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Has anyone done any real world tests of AN bolts of different sizes? How much weight would you comfortably hang from an AN3 bolt, an AN4 bolt?

When I’m experimenting on my experimental gyro I tend to overbuild (use a large enough bolt that I KNOW it will not bend or break). But I also hate adding weight. Kind of like using too many straps on a trailer, just to be sure.

I’m testing by lifting heavy objects with single bolts in shear, but my hoist doesn’t have a scale. AN bolts are STRONG!

Eric
 

Sv.grainne

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Has anyone done any real world tests of AN bolts of different sizes? How much weight would you comfortably hang from an AN3 bolt, an AN4 bolt?

When I’m experimenting on my experimental gyro I tend to overbuild (use a large enough bolt that I KNOW it will not bend or break). But I also hate adding weight. Kind of like using too many straps on a trailer, just to be sure.

I’m testing by lifting heavy objects with single bolts in shear, but my hoist doesn’t have a scale. AN bolts are STRONG!

Eric
This should help Data
 

Eric S

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I have the charts. I find it difficult to determine the square inches of round bolts.
 

GeneralPatton

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Dear Eric
i worked most of my pro career as an engineer on high strength tensile equipment. Calibration by NIST AND ASTM STANDARDS ,there is a wealth of data on AN hardware and their shear and tensile values,done by the US military.
Thousands of pages. Free to download. Unless you can generate 100 k pounds
of force psi, any meaningful tests are not possible.
 

Doug Riley

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A couple of articles in the (good old, much missed) PRA magazine detailed destructive tests of gyro rotor heads. In each of these batteries of tests, the AN bolts broke at around their rated strengths.

With the bolted-aluminum structures that are common in gyros, using a bigger-than-called for bolt is likely to weaken the structure, not strengthen it. In most cases, it's the aluminum that will fail first. The bigger the hole, the more aluminum you've lost and the weaker the assembly has become.

That's one big reason why bonded structures are stronger than bolted or riveted ones. No holes.
 

Doug Riley

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Very cool, Bobby. My back issues are in a heap in my garage, in no particular order!

The first of the articles I mentioned is from way back in 1969. The Bay State (Mass.) PRA chapter pulled apart some gimbal rotor heads in a tensile tester.
 

Eric S

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My thanks to all who replied. This quick reference chart is really what I was looking for. I'm happy to report my calculations were correct.

Eric
 

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Eric S

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Let me try that again. Here's the same chart, but higher resolution.
 

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Gyro28866

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I think you will find Grade 5 or grade 8 hardware bolts to be significantly stronger; BUT we do not use them.
An AN Grade bolt will bend and yield under a load and not have a complete/sudden failure like the hardware grade.
I dont care if it looks like a pretzel, as long as it holds the parts together until I am safely back down on the ground!
 
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