So in the end, I'm not sure what has been proven or disproven, it was a fun little exercise, but really with the particulars of this material not exactly known, and the material that's really in question being different in the first place, it is nearly unusable data...
With that said, here's what I did.
Bolts...
Holes were tapped at a theoretical 77% with a "H" drill (.2660") in a drill press, fixtured and tapped with a manual tap head, threads were checked with a thread gauge and tested good. With the exception of hole #4, holes were at 2D from edges and each other, hole 4 was at ~1.5D from one edge and this should not have been a significant factor.
'Should be obvious, but a new bolt was used for each test.
Typical starting position
While it's very subtle and very hard to see in the videos (especially with me moving around and jumping, the threads start to give up around ~1400PSI (~6125lbf), beyond this, the threads are effectively trash, despite the ultimate failure at a higher pressure.
Results:
- 1625PSI = 1625PSI * 4.375in = 7110lbf
- 1625PSI = 1625PSI * 4.375in = 7110lbf
- 1700PSI = 1700PSI * 4.375in = 7438lbf
- 1600PSI = 1600PSI * 4.375in = 7000lbf
~7165lbf average
Calculated @ 8775lbf Ultimate Tensile strength
Actual Ultimate Tensile Failed @ ~82% (This is easily accounted for in a bad or non-existent material temper.)
Yield @ ~70%
Be sure to turn off YouTube potato resolution
Bolt #1
Bolt #2
Bolt #3
Bolt #4
That is all, you may now return to reality....
