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      02-02-2013, 02:16 PM   #370
Skunk
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Drives: E93 M3
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Quote:
Originally Posted by ADV.1 Matt View Post
[font=Arial][color="#A9A9A9"]
This is just poor design with fundamental engineering flaws which make this dangerous. I'll talk about it below.

Quote:
Originally Posted by phillegal View Post
I think somewhere (either in this thread or a similar one) it has been mentioned that not every wheel is TUV certified because that would be extremely expensive. You do not need to test every offset, rim size etc. as long as for each style (or similar enough styles), at least one wheel is tested. FEA can (assuming you know what you're doing) reasonably test the other sizes/offsets. Arguably, rim to rim, the amount of material and method in which they are produced does not vary greatly. As long as one rim passes certification, it does lend greatly to the notion that all rims produced by that manufacturer should also pass.

On the other hand, if a manufacturer has zero certifications, there are no ways to assess if ANY of its wheels are safe. Therefore third-party verification is necessary.

I don't think it's misleading, but rather that a lot people are not very bright. 6>0
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.

Quote:
Originally Posted by x5mad View Post
If you look carefully the "certified" wheel on the right bounces much more than the one on the left. Ie the bed which the fake wheel sits on is more rigid whilst the one on the right is not. Therefore the load put on the fake wheel is greater. Less movement of the bed means greater forces put on the wheel itself.
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="https://www.youtube-nocookie.com/embed/rOEBR3DcqN0" frameborder="0" allowfullscreen></iframe>[/u2b]

Quote:
Originally Posted by THE TECH View Post
Forged or not, wheels shouldn't do that.
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.

Quote:
Originally Posted by db71 View Post
I could tell you how tire size and offset add or subtract from the test standard also. I will say it does not take a degreed engineer to make wheels that pass tests. That would be like saying its takes an architect to build a house.
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.

Quote:
Originally Posted by mikesis View Post
My intention is to help the community better understand engineering and to take it seriously. My concerns are for the community and not me personally so feel free to respond on this thread so everyone can benefit from your response.

BUYER'S BEWARE: It is your responsibility to be informed and make an educated decision on your wheels purchase. There are a lot of wheel companies out there. Make sure you purchase your wheels from a company where wheels are engineered, designed, tested and certified and are transparent about it. Where a quality/testing certificate can be issued upon request. Pricing does not determine quality. The most expensive could be the worst, and more affordable ones could actually be better.
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.
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Last edited by Skunk; 02-02-2013 at 02:22 PM. Reason: Trying to get the youtube video to properly embed