Wheel assembly testing

[ImGone]

I'm looking for some information in regards to testing of wheel assemblies (actually, the balance weights). There doesn't appear to be a lot of standardized test methods or design criteria for what should be expected. Specifically, I would like the loading conditions the assembly will be subjected to through a repeating cycle.

I've seen this "4-5g vertically, 3-4g fore-aft, and 2g laterally" condition mentioned but it doesn't provide what I'm trying to do. The variable I'd like to test is jerk/shock/jolt. Pick your poison, it's called many different things. I'd like to develop a simple repeatable test that will allow me to simulate rough driving conditions (including potholes) to check for wheel balance weight retention. This is a good means to provide assurance that the product will stay on through it's entire life-cycle.

Any help given will be greatly appreciated! Thanks!!!

 

[BrianE22]

I've seen vertical accelerations of greater than 40 g's for pot hole strikes.

 

[ImGone]

I've seen one technical article speak to over 100g's of shock load from potholes. It causes both tire and wheel damage. The problem that exist that I can't find relevant information on is "what is shock load?" It's easy to develop g's but shock has a time element. I really want to know what the time element is. Creeping up on 100g's or doing it quickly is different energy levels.

 

[cibachrome]

Rent a set of load wheels and go play car-car, as we say. Then you will have face validity. You may have to construct a curb strike or sewer scupper out of metal or concrete for a standard reference.

Or call an auto manufacturer. For example, GM has a Tire & Wheel group in Milford with a book of specs on wheels and wheel weights thicker than a phone book. (When they used to make phone books).

 

[BrianE22]

The 40 g's would be after low pass filtering at 50 hz if that helps.

 

[GregLocock]

wheel force transducers won't be worth much after a proper pothole strike. The only way i can get the Test guys to risk instrumentation on potholes is to use strain gauged suspension arms, as they are only 1000 bucks instead of half a million.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[GregLocock]

Oh, the other trick is to measure the loads in the edge of the pothole. Much easier to measure.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[ImGone]

Hmmm.... So that's good to know. Will light weight accelerometers not hold up?

Greg, are you aware of any design criteria around the subject, specifically the shock loads (jerk/jolt) of a typical, low-profile tire, wheel assembly? I found a technical paper abstract, Shock Loading Experiments and Requirements for Electric Wheel Motors on Military Vehicles(SAE 2005-01-0278), that shows 150g's with a pulse width of 10 to 20ms. This is probably overkill for passenger vehicles but at least gives a good baseline for the test apparatus minus having something else available.

 

[GregLocock]

Everything I know is proprietary. I haven't seen a useful public reference. 150 g/s for 20 ms seems to me to be only 3g.

Yes, for wheelweight retention accelerometers would probably be good enough, or at least very helpful.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[ImGone]

I must have misunderstood how to read that. I thought it meant to develop 150g in 10 to 20ms or around 10,000g/s.

Am I correct in assuming that by testing with a shock load that I'm checking the energy level rather than a force? 150g on a 0.25oz balance weight is only 2.3 lbf; that's not much.