Flexible wings 2011

[Ciro Pabón]

So, it's non-linear stress-strain. How's that not plastic? I'm still confused.

About anisotropy, isn't the FIA test made in the three axes?

I demand an explanation, I don't get it, I'm too dumb. I guess I'll have to wait until some smart soul comes up with a clear drawing. This is pretty interesting, btw, because it shows how deep is the "regulation problem".

You know the idea of the Church of Discordianism:

... the more order is imposed the longer it takes for the chaos to arise and the greater the chaos that arises. The idea is not new; it is mentioned in the Tao Te Ching: "the more laws and orders are written, the more thieves there are".

[Tim.Wright]

Ok Ciro,

I too struggle to see how the deflection can be non linear without either plastic deformation, or some internal mechanics.

Here is one possibility I cooked up which uses the mechanics of a preloaded spring plate (in the form of a composite plate) to give a non linear deflection response.



Tim

[bot6]

Tim, you're right on the money on this, it's one of the (many) ways to do this with carbon reinforced polymer laminates.

Ciro, just to make it clearer, "elastic" just means there is no permanent deformation once the load (aero or test) is taken off the wing. It just comes back to its "good as new" position.

As Tim showed, by carefully placing your laminates on the wing using some hollow parts or letting some plies slip relative to others, you can get a non-linear, but still elastic deformation.

Another way to do this is basically the same idea but on a more microstructural level. Using the way the fibers are woven together locally and the density / type of resin you use, you can taylor the behavior of any piece of laminate. It's complicated maths but nothing a good structural engineer can't handle with a powerful computer at hand.

Also, the test is not done in the three axes unfortunately. It's only done vertically, downwards and using a load at only one point on the wing endplate.

I agree with you. However, some pics posted here seem to show that rbr front wing has an higher incidence than what coming from car body rake. I think it could be either of these two:
-incidence increase is a side effect coming from the twist-bend coupling needed to be flexible but rule-compliant
-the wing in the not-flexed position is in a off-design condition, and rotation is required to get to design point (you can fit bigger section in the mandatory endplate rectangle if you raise leading edge, then twisting will adjust incidence to design point)

Right on the money as well mate.

Marekk is right as well, it all comes down to balance at the end of the day. And the interest of such a technology for other teams will strongly depend on that. Ferrari for example seem to be lacking front downforce at high speeds, so do Mercedes maybe to a lesser extent. Renault generate their downforce further forwards than the others thanks to the FEE so should not need a bendy wing as much as the others. It really depends on the concept used by each team...

All of this is quite impressive coupled aero / structural engineering. Illegal, but impressive none the less.

[marcush.]

If it were plastic deformation the wing would bend and stay bent.plastic deformation implies permanent deformation.

clever Fibre orientation copled with the geometrical design of the wings or other structural components will assure the things will do funny things under certain loadcases.As long as you do not overstress the part it will behave in this way forever.
I´m pretty sure RB has not yet mastered full reproduceability of these characteristics.And you can quite often see that those wings do not bend equally left and right .So I guess there is also a lot of tolerance from part to part...If there is so much to be found in lap time with a special characteristic you can preselect components in the workshop and let wonderboy look better than he should....just an idea.

[Richard]

Doh - its all about passing the scrutineering. That applies a vertical load in a defined location. The RB wing satisfies that very limited test

The real world has eccentric vertical loading plus horizontal wind loading. That results in torsion we can see on the end plates.

Its rather easy to design a structure to be stiff under loading in one plane, whilst creating a downward deflection under torsional & eccentric bi-axial loading. The key is to layer the carbon (and analytical model it) to make to match the simple structural concept.

[Ferraripilot]

You make it sound so easy.

To me, their possible and I would think obvious component matching seems to be the clear reason why Vettel was so much quicker than Webber. The two components look identical but their flexing characteristics could be very different with the best of the bunch of course going to Vettel.

[vall]

Doh - its all about passing the scrutineering. That applies a vertical load in a defined location. The RB wing satisfies that very limited test

The real world has ecentirc vertical loading plus horizontal wind loading. That results in torsion we can see eon the end plates.

Its rather easy to design a structure to be stiff under loading in one plane, whilst creating a downward deflection under torsional & eccentric bi-axial loading. The key is to layer the carbon (and analytical model it) to make to match the simple structural concept.

It should be possible in principle, but it is very difficult to police the non-flexing rule when it comes to the FW. It is hard the reproduce the exact distribution of the forces over the FW when the car is moving. What can FIA do? Update the test all the time? Then if a team fails a new invented test, then it would be hard to punish it because they may argue that the FIA test does not reproduce the forces distribution and so they fails the test. So, IMO FIA does the best it could: sets some test rules and if team passes it the cars are declared legal.

[marcush.]

No.
there are full scale winddtunnels capable of windspeeds enough to show these effects.Put the things in the tunnel and measure deflection.
If you intend to bring a new wing prove it does not bend more than allowed.the nose cone is homologated anyways.

By the way:if the nosecone of RedBull is declared illegal due to the bending but it is a homologated part...what can they do then ...season over?

[Tim.Wright]

1. A wind tunnel test for a single component is a massively overcomplicated and also not so accurate way of testing th wings legality. Just because the nose flexes a certain way in the tunnel, doesnt mean it will do the same on the track. Granted it will be more accurate than the current test but there are so many variables in setting up a wind tunnel test, it is just as likely the teams will find their way around that test too. What speed do you test it at? do you include the rest of the car? rolling floor or not? What defintion of flex will you use?

The current test, while slightly inadequate, is very elegant in its simplicity.

2. The nose cone is not homologated. Only the crash structure inside it is. They can update the external control surfaces to a degree without altering the crash structure.

Tim

[Richard]

Yes, you can scrutineer every wing by putting them in a wind tunnel. As I've mentioned before, that would be onerous.

Better to accept the rule as it currently stands and allow ingenuity to find a way to work with it. Surely this sport cries out for ingenuity? Infinite testing will only result in a serious of identical cars with no room for creativity at the boundaries of legality?

Its the same issue about the Melbourne car park run off. Its always been there, cars always use it, the brave venture onto it and win, the foolhardy stray onto and look like idiots as they rejoin over the grass.

Enjoy the ambiguities, that's where the creative folk are found.

[bhall]

Shoot the messenger...

The FIA mandated a slot-gap separator in 2006 when Ferrari was letting the rear wing of the 248F1 flex under load. That, as they say, was that.

So, how about suspension wires to maintain a rigid front wing?

[Richard]

Shoot the messenger...

The FIA mandated a slot-gap separator in 2006 when Ferrari was letting the rear wing of the 248F1 flex under load. That, as they say, was that.

So, how about suspension wires to maintain a rigid front wing?

UGH!

A skid block would be better, but how would you allow for rubbing on kerbs?

I suppose one could stamp on any creative engineering by mandating a stiff core to thw wing that ran from end plate to end plate. Then we would have a spec series. If you want that then watch Indy.

[bot6]

Yes, you can scrutineer every wing by putting them in a wind tunnel. As I've mentioned before, that would be onerous.

Better to accept the rule as it currently stands and allow ingenuity to find a way to work with it. Surely this sport cries out for ingenuity? Infinite testing will only result in a serious of identical cars with no room for creativity at the boundaries of legality?

Its the same issue about the Melbourne car park run off. Its always been there, cars always use it, the brave venture onto it and win, the foolhardy stray onto and look like idiots as they rejoin over the grass.

Enjoy the ambiguities, that's where the creative folk are found.

The rule, as it actually stands, IS breached. Not the bending test one, but the ground bridge one (3.15) and the "no aero device under the reference plane" one.

Quoted three times in this thread already.

The one about "absolutely no flexing" has been scrapped as it was inapplicable.

[747heavy]

So, how about suspension wires to maintain a rigid front wing?

would not be the fist time, we see something like this....

[Ciro Pabón]

Ciro, just to make it clearer, "elastic" just means there is no permanent deformation once the load (aero or test) is taken off the wing. It just comes back to its "good as new" position.

Thanks, bot6. With all due respect I already knew that, I design bridges and other structures for a living.

What I meant is that what the materials I am used to work with in structural design, only behave nonlinearly (I mean, in stress-strain curve) when:

a- They have surpassed the yield point (thus, they have permanent deformations), or
b- They behave plastically (thus, they also have permanent deformations)

I would be grateful if someone explains to me which materials are those that are elastic and behave nonlinearly before the yield point (I do not doubt they may exist, it's just that I don't know them).

To put it in a simple way: all the materials I know (not many, I confess) that become "good as new" after strain, behave linearly.

Very good idea, Tim, thanks. Very, very clever design, I think it behaves similarly to the hinge I described a few pages before (the "kitchen door hinge").

However, any similar solution does not use what I think are exotic, non-linear and at the same time elastic (?) materials.