DOT Wheel Tests

[CapriRacer]

I am in the middle of a discussion on DOT tire testing and the subject of wheel tests has come up. A quick look at the FMVSS regulations doesn't seem to reveal any testing requirements for wheel and rims.

So, is there a DOT test for wheels? If so, what is it?

If not, what do wheel manufacturers use? Is there a standard test?

And if you are knowledgeable on the subject, please explain feel free to fill in the gaps.

Thanks in advance.

 

[GregLocock]

There's some SAE tests which you'd be well advised to pass, and then, so far as I know, each manufacturer does their own thing (that is, for the Mercury Capri I was the wheel design engineer at one point and I don't remember any certification tests for the wheels, but that was a long time ago). In Australia we do have further legislatively mandated on-vehicle tests, and on top of that we have some proprietary tests we developed to expose particular issues.

Cheers

Greg Locock


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[bljnv]

There are two main tests done on the wheels namely (a) radial load fatigue test (b) cornering load fatigue test. There are SAE standards governing these tests. Additionally strain gagging test, impact loading tests are done as agreed between customer and manufacturer

 

[CoryPad]

The two fatigue tests are in SAE J328. The other common test is the impact test in SAE J175.

 

[CapriRacer]

Thanks for the responses - and here is what I am getting out of this:

1) There are no government required tests for wheels and wheels alone.

2) SAE has published some tests for wheels

3) These SAE wheel tests are the commonly used wheel tests.

 

[CapriRacer]

Oh and Greg - being the wheel guy on the Mercury Capri - that would be the Mazda version, right? I don't think anyone would still be around from the European version. (but maybe for the Mustang version)

 

[GregLocock]

Yes, the Mazda based one. I was one of 3 wheel engineers from 1990-1992, in particular the 3 spoke turbo 15" wheel taught me a lot.

Yes I think you have it about right so far as homologation tests.

Cheers

Greg Locock


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[CapriRacer]

Greg,

So what did you learn about the 3 spoke wheels that might be of interest to a tire engineer?

 

[Xwheelguy]

I believe in most cases the only difference between minimum requirements in "the big 3" (radial, rotary and impact) SAE specs and what could be required from an auto maker is the number of cycles, determination of a passing or failing test and possibly the methods used to calculate the test loads (mainly for radial and rotary fatigue) as well as additional measurements taken during the testing process to help validate an accurate test (deflection during testing, speed at which impact weight falls, torque loss during radial or rotary, etc.). If memory serves me correctly, SAE requires a minimum of 50K cycles on rotary and radial fatigue testing. Some of the gray areas in determination of what is a pass or failure may also differ between SAE and an auto maker. For example, a crack on a fatigue test may not necessarily be deemed a failure by an auto maker if it does not propagate during additional testing. I cannot recall off the top of my head if pass/failures are well defined in the SAE specs or not.

Also of note may be the road hazard impact test. As a supplier, my former employer was never asked to perform this test, but it was starting to see some discussion and popularity amongst our customer's product engineers. Would have been a real bear to try and design a wheel to pass this test, so I was glad it never was required of us.

As a supplier to 1 of the big 3 and several Japanese auto makers with a former employer, we were never required to perform strain gaging - that was for our own information only to assist in determining if FEA was giving us accurate results.

Tim Flater
NX Designer
NX 8.0.3.4
Win7 Pro x64 SP1
Intel Xeon 2.53 GHz 6GB RAM
NVIDIA Quadro 4000 2GB

 

[GregLocock]

Nothing much, it was mostly a question of how to scan a sculpture into CAD, and controlling the fit of the large, curiously shaped triangular plastic wheel center into the wheel, and matching the paint between the two. One way or another I'd say it was the second most troublesome alloy wheel I dealt with.

Cheers

Greg Locock


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[GregLocock]

Incidentally this test was always a fun one, small explosive charge to wreck the tire

ADR 20—Safety Rims

The function of this Australian Design Rule is to specify wheel ‘Rims' that will retain a deflated tyre in the event of a rapid loss of inflation pressure.

/00—This standard ceased to have effect for new vehicles as from 9 December 2003.




Cheers

Greg Locock


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[CapriRacer]

Tim said: "...... we were never required to perform strain gaging - that was for our own information only to assist in determining if FEA was giving us accurate results."

I think most folks do not understand that computer modeling needs to be verified - as best as it can be done. I remember working with folks on vehicle handling (Adams, if I remember correctly), and while we couldn't verify the vehicle's tip over point (which was the point of the exercise), we could verify the handling characteristics with out-riggers (to prevent a maneuver from going too far.) That was the best that could be done without risking life and limb.

 

[GregLocock]

Yup, we do a test, we model the test, then we remove whatever constraints are in the test to make it safe, from the model , and rerun the model.

I haven't seen a strain gaged wheel, we do a modal test to get dynamic correlation, and measure the wheelhub loads with a wheel force transducer. Since our wheel/suspension killing events (that ADR isn't the most extreme requirement by a long chalk) also destroy instrumentation we've started doing a lot more with cameras.



Cheers

Greg Locock


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[CapriRacer]

Thanks to all for your responses. They were very helpful.