QUOTE=unterhausen;21590823]When I taught engineering design a couple of years ago, a project cost $3000. I can use a fatigue machine, but I'm not sure that's really the failure mode that builders worry about. I think that probably just hitting a brazed on mount with a hammer and looking for cracks in a microscope would be as good of a test as anything. Just to qualify that, I am totally against that kind of testing for most brazing. I have seen some incredibly inept brazing survive such a test. I have my suspicions about eyelets that fail. I suppose I should do some destructive testing of my work. Not sure where you would publish it,maybe in an open source journal.

Just to be clear, we are talking about eyelets like the ones that come on dropouts. Just about every other kind of rack attachment is beyond safe. I'm pretty sure the difference between built-in and brazed on is ductility. It's also not too hard to braze something like an eyelet and not get full penetration with complete bonding in the center. At least that's my working theory on why people have had brazed on eyelets fail.[/QUOTE]

I was thinking this would be an undergraduate project, mechanical engineering curricula usually has a lab class, often with an "open" experiment at the end for the student to design. Publishing might be limited to Bike Forums!

I agree that almost all brazed on bit failures are due to incomplete penetration, leaving a stress riser.