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      02-05-2013, 01:27 PM   #374
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Drives: 08 E92 M3 /07 Z4MR / 99 E36 M3
Join Date: Sep 2011
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Originally Posted by Skunk View Post
This is just poor design with fundamental engineering flaws which make this dangerous. I'll talk about it below.

Okay, so as phillegal kindly pointed out, FEA can reasonably test a design so long as it is performed correctly. What I see from ADV.1 is a design that is very difficult to test. I have a feeling that ADV.1 did not do any sort of analysis on the bolts, because they are clearly in a single shear at the threads of the bolt. Therefore there are huge stress concentrations within the bolts and unless they are dramatically oversized (and some applications do compromise on this, it just has to be accounted for) they will be susceptible to shearing off. Whoever designs their wheels does not understand the basic design principles for fasteners.

Furthermore, the load paths look horrible. I get that people want a certain "look" to their car, but you can honestly make a better design in areas that aren't so visible so you have more direct loading through the spokes and not putting a relatively flat piece of metal in torsion.

And getting back to the second part of phillegal's comment: people value honestly and transparency. If you try to skirt around an issue, you aren't helping yourself. If you are upfront with what your situation is and doing to improve/remedy it, people will not hold that against you.

No, it doesn't mean that. The wheel on the right has higher crystalline refinement, if not being a better alloy in the first place, and therefore the stress-strain curve would go much higher. This would mean that more of the load put into the wheel would stay in the elastic region which would spring back in the opposite direction (think of the wheel acting as a spring) to both the wheel and impact device, rather than have the energy being dissipated through plastic deformation and even fracturing.

If you want a visual representation of this:
[u2b]<iframe width="420" height="315" src="" frameborder="0" allowfullscreen></iframe>[/u2b]

Yes. Forgings just have better crystalline grain refinement and allows for less material to be used if the grain in the direction of the loading, etc. But you can still mess it up, just as you can mess up a cast wheel. You really need to know how to engineer something to make a good product, given what materials and tools you have. And for a lot of these smaller companies, it's probably just one or two people designing all of their wheels; so it wouldn't be unreasonable to assume that if one wheel has issues, the others will as well, no matter how they were formed.

Half-truth...yes, a person can very well learn that wasn't taught to them in school. That still doesn't mean I'd trust just anybody with the design of a house...I'm in California near a fault line, I don't give a crap about an architect; I want to make sure the house is soundly built by a civil engineer who is a certified Professional Engineer.

Very, very true. People come on here to learn about what to do and what not to do. I'll comment where I have expertise and experience and hope people can make the most of it.

And I'm just including the second part because I think that message needs to be emphasized.
Just saw this post now. Thanks very much for your insight, that was a lot of good information.
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