Tire idea

[FuzzyDice]

im making this thread cause Ciro convinced me to

i got a little idea in my mind and i dont know if could work.

basically we put electroactive polymer (EAP) into a tire. electroactive polymer is contracting if voltage is applied on them. they use them to build artificial muscles
(http://en.wikipedia.org/wiki/Electroactive_polymers)

and why we need EAP in tire? so this is a part that i dont really know if could work but idea is that we use EAP to control the tire contact surface. ideally we can go from slick when we need traction to some pattern when we have wet road.

general idea was to go from slick when we need a lot of traction (for example when car is starting to move) to some other pattern when when car is already moving and we want to maintain that speed so we should lower the traction. again im not sure if we need lower traction (friction coefficient) when car is driving 100km/h on a highway and i dont know whats the difference between friction coefficient in slick tires and some pattern tires.

would this work?

well if doesnt work with friction coefficient changes it still could work with changing tire contact surface depending on dry or wet condition

[WhiteBlue]

Welcome FuzzyDice, nice idea. I surely would ad another parameter to the long requirement list for tyre materials. I'm not a polymer scientist but my impression is that we are discussing a very specialized niche market with two very different special purpose solutions. those are supposed to be replaced by one solution with new technology. Special solutions are usually developed because they are superior solutions to a problem. I would have my doubt that going back to a uniform tyre would give such a big advantage. It only is conceivable if the tyre would have equal and better performance in both dry and whet. beside the different shape requirement it would also necessitate different hardnesses and working temperature ranges of the tyre. all that is very difficult to imagine. perhaps it would be more interesting for road cars. drivers hate to change tyres. they do not even check the tyre pressure. in F1 they do that more frequently.

[checkered]

Hi, FuzzyDice, your

idea certainly sounds promising. Automotive technology, despite some amazing advances and huge investment, has oftentimes been a bit complacent. What you suggest should excite race engineers and road car designers alike, the prospect of controllable/reactive contact patch/pattern grip could ease many other challenges and enable different solutions throughout the vehicle. I guess there are many ways to achieve such morphing ability, EAPs being one candidate. Sufficient resources should be put in place to make a feasibility analysis and determine the range within which such technology provides an advantage. Somewhere down the optimisation curve "traditional" tyres will lose out to a superior product.

[Jersey Tom]

Tire tread compounds, race in particular, are a very special formulation depending on series, track, type of car, etc. Who is to say an EAP would have any traction?

Beyond that, tire compounds have different operating ranges. Consider an autocross tire, designed to operate at high temp, vs a winter tire designed to operate when much colder. Same happens with tires in hot dry conditions vs cold wet. Massive difference. A magically appearing pattern won't save you. You'd be much faster just pitting and switching to intermediates.

[Ciro Pabón]

Thanks, FuzzyDice. First, for making public your excellent idea, second for bringing this new material to the attention of the forum. Third, welcome, I did not notice your previous posts.

Jersey_Tom has a point, but he has to consider that this material does not need to be on the contact patch itself, it could take the role of the cords embedded in the tyre.

I'd say that the development of significant forces is still in its infancy. I was amused by the Armwrestling Match of EAP Robotic Arm Against Human mentioned in your link, but the amount of force developed by the robot was very low. The human contender defeated easily the robot:



The human was able to generate 10 kilograms of force while the robots went up to 100 grams.

I thought you were talking about nitinol alloys or something similar, when we discussed this in a PM. I found after a short search that memory shape alloys are already used in several patents for tyres.

I would say that a changing tyre cord stress, if feasible, would be most useful. For example, tyres that make themselves narrower at cruising speed will save gas. Besides the obvious application for regular cars, this could be critical in a race, where fuel weight is truly important, not to mention the aerodynamic advantage that a thinner tyre would have at high speeds.

It could also be used to control the width of the tyre, which is regulated, so you could use softer compounds without fear of exceeding the maximum regulated width because of deformation after the tyre wears, something that has actually happened. I have already said to you, in PMs, that maybe this is a patentable idea.

I think there are many other possible applications in a car, not only in its tyres. Brake boosters, where a diaphragm is used nowadays, come to my mind. I don't know if other members can come up with other uses for the material. Here is the picture that could bring some ideas, also taken from the link you mention:

[FuzzyDice]

well EAP wouldnt be in contact with the road it would in the tire.

idea came up for fuel savings cause of this raging gas prices and i see it more suitable for everyday cars and not for racing where we have extreme conditions and extreme performance requirements

[Metar]

I can still see a potential advantage in racing-conditions: If such tyres were made in Formula 1, for example, we could see a whole new kind of Intermediate tyres. Under rain, it could run as a regular Intermediate tyre, with the full rain-thread, but as soon as it dries enough, it could start to "smooth out" and become less and less "Intermediate" and closer to "Slick"... Saving teams the hassle of an extra stop, by minimizing part of the performance-disadvantage that Intermediates have in almost-dry weather. Obviously, Dry compounds would still have an advantage - but a smaller one.

[Jersey Tom]

Wouldn't work, metar. For the reasons I stated above. If you wanted to somehow magically change the tread pattern youd have to load the tread with this stuff. And when on a drying track teams switch from intermediates to slicks, its less about pattern and more about compound. Even low level racing drivers learn this quickly.. on a drying track you drive OFF the dry line (in a wet area) on the straights to keep the compound cool. Otherwise you will just blister or shred the compound. And I can't imagine this EAP stuff is as grippy as a race compound anyway, so whatever advantage you'd gain with a little more of an open or closed tread pattern would be blown away by overall grip level.

But assuming you could put this stuff in the tire.. in the cords or what have you.. you wouldn't want to make the whole tire just "shrink." Otherwise it would pop off the wheel, and all the rubber in the tread that isn't EAP would just wrinkle up. But supposing you could even just use it to change the tension in the cords and adjust how much the tire changes shape.. like a drag tire.. what does that even gain you? Tire would become a bit narrower but taller. Area exposed to the air remains the same, so you don't gain any aero advantage.

[Ciro Pabón]

I don't know, Tom, "there are many ways to kill a flea". What about this, for example?

http://www.freepatentsonline.com/EP0909665.html

Using Nitinol you can get a "good penetration of elastomeric material between the wires", something hard to imagine at first sight. This material is similar. Cann't you think of any diaphragms in your racing cars? I couldn't think of something beyond boosters. I'm sure the forum can think of some use for a polymer that can shrink.

About the aero, you don't have to use the material across the whole surface or you could collapse/expand wrinkles, like many animals do.

[Belatti]

...idea came up for fuel savings cause of this raging gas prices and i see it more suitable for everyday cars and not for racing where we have extreme conditions and extreme performance requirements

mmm...

1) We would have to compare the electrical energy used to feed those electrodes vs. the energy saved becaused reduced contact patch.
2) Beyond that i don´t know if I would feel comfortable driving at 120kph on a freeway with the contact patch the size of a bicycle. The implementation of such tire would require a fast response control system in order the return to the max grip condition when you need it.

[Ciro Pabón]

The links explain that the effect of point 1 raised by Belatti is negligible: the thing does not need to be continuously fed, just for the time of the expansion/contraction, then it holds for itself (at least for a kind of the material).