i know applications such as honda use cast steel or iron spindles but does anyone make aluminum spindles and how feasible is it for a race application?
This thread seems rather persistant. I'll add one more comment, anyway.
Motorsports is a contest measured in hundredths of seconds or less. A 15% reduction in weight? Well I would think that IS significant. Most professional teams, especially F-1, would positively KILL, and invest millions, for a 1% advantage!
Sure, the question becomes with aluminium, how are you going to make it, and how are you going to design it? With Ti it's easy, if it looks like the steel part it'll be strong enough, but with Al that won't work.
Cheers
Greg Locock
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would carbon fiber have enough durability in that type of application where load is constantly varied.
Is carbon fiber becoming the answer to most strength/wieght issues?
I hope you guys will continue to respond to this thread.
Yes it has the durability, when properly designed and made.
Not for mass production (cost), and not for small budgets (too hard to design and make). I think a spindle would be one of the worst things to make from CF, as it combines high loads, restricted packaging, and a lot of hardpoints in a small area. It can be done, obviously. Having gone to all that trouble you've saved maybe another 2 kg ie 0.5 kg per corner) on a short spindle car. There are much better weight saving opportunities on most cars.
Cheers
Greg Locock
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Carbon fibre can have quite good fatigue resistance if designed correctly, it has a very high flex mod and good tensile strength. It compares with steel on a size for size basis and easily beats steel on a weight for weight basis.
HAVING SAID THAT, I do agree with Greg, specifically for the following reasons:-
It has VERY LOW ELONGATION AT BREAK, hence the design is extremely critical of even distribution of stress.
Packaging restrictions can force stress concentration areas into the design.
The resin that binds the fibres is degraded by heat, the extent of the degradation depends on the particular resin.
The properties are VERY DEPENDANT ON FIBRE ORIENTATION.
Properties quoted for a single fibre cannot be extrapolated into a composite structure, as the load is never shared equally with all the fibres in the cross section of the composite. Also the resin matrix plays a part in the properties of the composite.
Often data sheets quote the properties of a single fibre, not the properties of a composite.
Even data sheets quoting data for composites use data from a perfectly oriented sample, made under ideal conditions and with a test piece designed to optimise the properties. This is rarely if ever achieved in the real world, and many designs and processes fall far short of data sheet properties.
My recommendations.
Use good steel, remove as much excess from the design as possible, then use it to your hearts content.
Use aluminium, save some weight, but check it regularly for cracks.
If you have an F1 level of budget, experiment with carbon fibre prototypes, but expect breakages until, when and if you sort it out. Do extensive testing where neither life nor limb are threatened by a failure.
Regards
eng-tips, by professional engineers for professional engineers
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Pat, we amature builders/racers cannot escape your logic. Those of us who do not operate on $100,000,000 budgets per year (that's not an exageration!) would all tend to agree with you. However...
Greg, based on Norm Peterson's post above...I looked at the photo and article...not practical IMO but then there are plenty of impractical solutions to auto design problems that sell rather well on the open market. Racing tends to weed out those solutions in short order. Alternative material for critical components must, above all, work safely---cost is often secondary. In amature racing I see mostly steel, forgings or fabrications. This is not to say that amatures do not use Al or Ti spindles, just that I have not personally seen them in common use.
Composites are great. Carbon fibre body parts for my race cars would be wonderfull for much needed weight savings (I have grown rather large in my old age)---NOT on my racing budget, anyway. ;-)
The failure of a CF suspension part was very graphically demonstrated during the latest F1 race on the final lap.
K. Raikkonen was leading when he flat spotted a tire that caused a severe vibration in the right front suspension. The vibration resulted in a a very dramatic failure of the CF suspension. If you were watching closely the initiation of the failure was vividly demonstrated by a flash as one of the upper suspension arms failed.
I have seen this particular failure mode several times early on during the development of CF especially in high speed flywheels as they disintegrated with explosive force.
Yeah, I watched it. Stupid rule, the tire change thing. Could have caused a disaster.
I also noted that my estimate of cost for a F-1 season was a bit low...$400,000,000 and UP seems to be the current fugure!!! Sheesh :-(
I watched the Indy and the Nurburg race and I found the F-1 still rather boring (a parade punctuated by brief "events") from a television point of view but the coverage was totally superior to the ABC (Absolutely Boring Coverage) broadcast of Indy. I have been to both types of open wheeled racing and, in person (I "worked" Long Beach GP T-1 drivers right at the last F-1 race there in the 80's), F-1 racing is rather more exciting. I also find NASCAR oval stuff totally boring, but the road racing is super!
I am NOT much of a spectator in motor sports.
Aluminum spindles/knuckles:
GM is using them in late-model midsize fwd cars...(USA, anyhow)
Of course, being fwd, there is no 'carrot' to support the bearings, and the loads are applied to the heart of the piece.
I found out when doing a brake job on my '03 Buick Regal. Used a file on a parting line, just to meke sure it wasn't just a shiny coating. -Nope- it's Al!
cheers
Jay
