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Re: [cracklover] More Alien Test Results (Lots of pics, very bandwidth intensive):
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jt512
Jun 17, 2009, 2:29 AM
Views: 9875
Registered: Apr 12, 2001
Posts: 21904
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cracklover wrote: Aric, the trouble I'm having is that I don't see any correlation between effective cam angle and the point at which the cam slipped.
We wouldn't expect to see a correlation between cam angle and the applied force at which the cam slipped. Accoding to Vaino Kodas's equations, there is no relationship between the applied force at which a cam would slip cam angle. If the cam angle is less than a critical value, the cam will not slip at any applied force; if the cam angle is greater than the critical value, the cam will slip at any applied force.
In reply to: For example, here are the cams for which I was able to determine an effective cam angle, ordered by angle. I've broken them down into thirds for the purpose of getting averages: sample rating failure failure angle RATING Soft avg failure avg rating
Mode kN % Lobes kN %
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3 12 braze 9.3 14 77.50% Y (not counted due to braze failure)
23 9.8 pulled 6.8 15 69.39% Y 11.24 90.94%
1 12 pulled 10.6 16 88.33% Y
15 12 pulled 13.5 16 112.50% Y/N
6 15.5 pulled 14 16 90.32% Y/N
9 12 pulled 11.3 17 94.17% N
14 12 broke cable 12.1 17 100.83% Y 11.86 94.38%
8 12 pulled 11.1 18 92.50% Y/N
18 12 broke cable 12 18 100.00%
2 15.5 pulled 11.4 18.5 73.55% N
21 12 pulled 12.6 19 105.00% N
12 12 broke cable 12 19 100.00% Y
17 12 pulled 11.8 20 98.33% Y
20 12 pulled 9.9 21 82.50% N 11.36 89.82%
19 12 pulled 12.6 21 105.00% Y
16 12 broke cable 14 21 116.67% Y/N
7 8.25 pulled 5.25 22 63.64% Y
4 15.5 pulled 12.6 22 81.29% N
5 15.5 pulled 13.8 23 89.03% N Now you could make the argument that the cam angle in and of itself is not high enough to cause these cams to rip, but in conjunction with the very soft lobes on some of the cams, the effective angle quickly grows until it gets too high and the cam slips out of the fixture.
I wonder if it isn't so much a function of the flat spots on the cam increasing the cam angle as it the flat spots making the cam essentially no longer a cam. Would you expect something like this...
...to really work like a cam? Or maybe it would. After all hexes hold in parallel cracks.
Jay
(This post was edited by jt512 on Jun 17, 2009, 3:07 AM)
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Post edited by jt512
() on Jun 17, 2009, 3:07 AM
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