McLaren uprights

[Timstr]

Found this pic of the mp4-19 upright (Melbourne).

[seymour]

I'm a little disappointed to see McLaren apparently using a twill weave everywhere. Granted, a lot of these parts are not really structural, but, for instance, the suspension arms and pushrod would undoubtedly benefit from some unidirectional. I can't really imagine why they'd use anything else.

[KJ]

The brake cooling ducts also look like a last minute addition. I don't understand why they don't use a more innovative approach like the Ferrari guys do. Instead they use this aerodymanically inefficient brakduct.

- KJ

[oz_ferrari]

I'm a little disappointed to see McLaren apparently using a twill weave everywhere. Granted, a lot of these parts are not really structural, but, for instance, the suspension arms and pushrod would undoubtedly benefit from some unidirectional. I can't really imagine why they'd use anything else.

Seymour, the nonstructural components are made using a twill weave simply because, they are more drapable and thus easier to lay up, and of course will have strength in several directions. These components are simply easier and quicker (thus cheaper) to make, this way.
As for the suspension, these components will be made mostly in UD carbon, but still require strength in all directions (including the pushrods), they require torsional stiffness as well as the plain bending strength. I have seen pushrods being made up for Jordan and while 95 % of the layup was UD, twill was used on the first (outside) few layups. The lay-ups for the wishbones is extremely complex (over 200 different pieces of carbon!!) and includes UD and a variety of other configurations. Finally twill weave looks great and F1 cars have to look good too, so its worth using it as the first layer, aesthetics are important.

Oz

[seymour]

I'm sure there's lots of uni underneath that twill, but the outer layer is the most heavily stressed, and the aesthetic argument carries absolutely no weight with me.

People think weaves look good because it is signature carbon fiber, but I promise you that if you saw a nice gel coated uni part, you'd be much more impressed.

[scarbs]

great pic where was it from...?

[Timstr]

It is a Ken Sawada original.
http://www.crash.ne.jp/individ/sawada/gprpt/04r01.html
As always, unique pictures!

[KeithYoung]

I met one of those guys at the USGP last year, he wouldnt talk. it was tempting to tie him up and take his outfit and pass hanging around his neck. they get to see some pretty cool stuff.

[Reca]

I'm a little disappointed to see McLaren apparently using a twill weave everywhere.
[...] the suspension arms and pushrod would undoubtedly benefit from some unidirectional. I can't really imagine why they'd use anything else.

One of the reasons is that unidirectional working in compression isn’t very efficient and it’s subjected to risk of instability, the twill wrapped around the UD allows to increase the limit of instability of the UD fibres.

[marcush.]

one question about ud fibres not efficient under compression..are you sure?
The filaments in ud layers are layedouit flat and so they can transmit forces in their orientation perfectly,but forces at different angles they do not transmit well.
If you use woven fabric ,the filaments are not straight they form a series of essesgoing over or under the next filament it comes across.So obviously the load path in comression or tension is not as good as in UD
filaments.
But :stones,debris ,sand and so on do not arrive at these parts in the drirection of the designed loads(tension or compression along the arm),so anything coming up the suspension is very very serious trouble if you use ud fibres on the outside .I think these environmental uncertainties make them wrap their parts with a layer of twill,of course sacrifying that last bit of possible load bearing in the normal path of forces.

[Reca]

Problem is instability of the fibres under compression.
Consider a bar, circular cross section, and quite long compared with the diameter of the section. In traction it works in the same way until it breaks, meaning that it deforms increasing the length and reducing the cross sectional area. On the contrary if you apply a gradually increasing compression, you’ll see a different behaviour depending by the load itself. The rod will deform reducing the length and increasing the area, until it reaches the critical load, then it becomes unstable, it’s unable to balance the load, becomes “wavy” and collapses. The critical load obviously depends by the material (proportional to the elastic modulus) but mainly by the geometry, directly proportional to the cross sectional area and inversely proportional to the square of the “free length” (length between supports) meaning that critical load is low if the rod is long and the diameter is small.
Each fibre in a ud is basically a long rod with a small cross sectional area hence the critical load is very low. The matrix increases it a bit but still isn’t very good, and if you have a fracture in the matrix that would easily lead to the breaking of the part because of instability of fibres.
Wrapping the twill around the ud you are fundamentally introducing more supports on each fibre, reducing the “free length” thus increasing the critical load.

Anyway as I said that’s only one of the reasons. Your suggestion that it’s for protection from debris and stones is another one. Torsional stiffness is another one.

[marcush.]

Now I got it,you are right.thanks.

[marcush.]

one more on the topic:
Why not using Dyneema fabric as the toplayer onthe frontsuspension and the lower rears?

[Reca]

I think Berger would have loved to have several layers of Dyneema on the suspensions arms when Alesi lost the camera car in front of him, but excluding that situation, is it really required ? I don’t know honestly.

[marcush.]

it surely isn´t a bad idea ,as you would not compromise the weight nor the strength of the part just makes it a lot tougher.I don´t think they need the carbonfibre looks in F1 ...