Trying to draw an F1 suspension in CAD, but..

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daniellammers
1
Joined: Sat Dec 17, 2016 1:22 pm

Trying to draw an F1 suspension in CAD, but..

Post by daniellammers » Mon Jul 17, 2017 6:41 pm

How are the wishbones connected to the car?

It looks like it can't be moved at all.

Does somebody have a schematic?

Image
You won't catch me driving a race car that I have built.

- Colin Chapman

Scootin159
11
Joined: Thu Aug 06, 2009 8:09 pm

Re: Trying to draw an F1 suspension in CAD, but..

Post by Scootin159 » Mon Jul 17, 2017 8:44 pm

You're largely right. They use what's called a "Flexure" joint, which is basically a specially crafted pieces of composite material that is flexible (although still quite stiff) in one dimension, but all but immovable in the other two dimensions. You can somewhat get the idea by grabbing a notepad and trying to bend it - it will bend easily up & down, but it doesn't "compress" much at all, and it doesn't like being "twisted" (in the lateral plane) very much. Twisting in the vertical plane isn't really an issue, since there's always two of them per wishbone.

The reason they use flexures, as opposed to standard spherical bearings, is to eliminate stiction in the suspension. They are quite stiff (stiff enough you can't bend them by hand), so they do provide an element of a spring rate, but that's easily accounted for by just running softer main springs.

I should add that the joint itself is really just built into the end of the wishbone. One end is bonded to the rigid portion of the wishbone, and the other end is bonded to a titanium end piece. That end piece is then rigidly bolted to the chassis. The rectangular piece you see on the chassis where the wishbones connect is just a flexible aerodynamic cover - likely made of some type of thin plastic or rubber. The actual flexure mounting bolts would be under that cover.

daniellammers
1
Joined: Sat Dec 17, 2016 1:22 pm

Re: Trying to draw an F1 suspension in CAD, but..

Post by daniellammers » Mon Jul 17, 2017 9:01 pm

Scootin159 wrote:
Mon Jul 17, 2017 8:44 pm
You're largely right. They use what's called a "Flexure" joint, which is basically a specially crafted pieces of composite material that is flexible (although still quite stiff) in one dimension, but all but immovable in the other two dimensions. You can somewhat get the idea by grabbing a notepad and trying to bend it - it will bend easily up & down, but it doesn't "compress" much at all, and it doesn't like being "twisted" (in the lateral plane) very much. Twisting in the vertical plane isn't really an issue, since there's always two of them per wishbone.

The reason they use flexures, as opposed to standard spherical bearings, is to eliminate stiction in the suspension. They are quite stiff (stiff enough you can't bend them by hand), so they do provide an element of a spring rate, but that's easily accounted for by just running softer main springs.

I should add that the joint itself is really just built into the end of the wishbone. One end is bonded to the rigid portion of the wishbone, and the other end is bonded to a titanium end piece. That end piece is then rigidly bolted to the chassis. The rectangular piece you see on the chassis where the wishbones connect is just a flexible aerodynamic cover - likely made of some type of thin plastic or rubber. The actual flexure mounting bolts would be under that cover.
Thanks for sharing your knowledge!

Do you have actual schematics as well?
You won't catch me driving a race car that I have built.

- Colin Chapman

henry
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Joined: Mon Feb 23, 2004 7:49 pm
Location: England

Re: Trying to draw an F1 suspension in CAD, but..

Post by henry » Mon Jul 17, 2017 9:20 pm

daniellammers wrote:
Mon Jul 17, 2017 6:41 pm
How are the wishbones connected to the car?

It looks like it can't be moved at all.

Does somebody have a schematic?

http://i.imgur.com/D528R00.jpg
They use flexures. Search for "F1 suspension flexures" and have a look at some images.
Fortune favours the prepared; she has no favourites and takes no sides.

e36jon
0
Joined: Mon Apr 25, 2016 1:22 am

Re: Trying to draw an F1 suspension in CAD, but..

Post by e36jon » Mon Jul 17, 2017 9:32 pm

Here's an older Honda F1 suspension flexure:

http://www.racetothefinish.co.uk/media/ ... 4200000000

If you look around in the "suspension" area they have full wishbones with the flexures bonded in too.

scarbs
336
Joined: Wed Oct 08, 2003 8:47 am
Location: Hertfordshire, UK

Re: Trying to draw an F1 suspension in CAD, but..

Post by scarbs » Mon Jul 17, 2017 10:09 pm

Flexures are often mixed with conventional sphericals...

Image

Image


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mycadcae
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Joined: Sun Jan 10, 2010 3:49 pm
Location: Selangor Malaysia

Re: Trying to draw an F1 suspension in CAD, but..

Post by mycadcae » Tue Jul 18, 2017 1:37 pm

can you see view in CAD, what your CAD? used
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Nik Wan, Mechanical Designer, CATIA V5/ Solidworks/Autodesk Inventor/ AutoCAD

PlatinumZealot
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Joined: Thu Jun 12, 2008 2:45 am

Re: Trying to draw an F1 suspension in CAD, but..

Post by PlatinumZealot » Tue Jul 25, 2017 5:58 pm

To make simulations easier you can use all bearing type joints (spherical, roller, bushing etc) instead of flexture. Or you can simulate the flexture joint isolation then input the response into a bearing type joint.
"Raindrops .. drop top!"

Tommy Cookers
381
Joined: Fri Feb 17, 2012 3:55 pm

Re: Trying to draw an F1 suspension in CAD, but..

Post by Tommy Cookers » Tue Jul 25, 2017 7:26 pm

scarbs flexure looks like metal ?

Scootin 159 talks about composite
and the flexure being a significant contributor to the suspension spring rate
has he felt the suspension without its springs etc ?

a typical flexure arrangement provides notionally full compliance in 1 direction ie 1 degree of freedom and rigidity otherwise
a mechanical isolator
Last edited by Tommy Cookers on Wed Jul 26, 2017 7:26 pm, edited 2 times in total.

scarbs
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Joined: Wed Oct 08, 2003 8:47 am
Location: Hertfordshire, UK

Re: Trying to draw an F1 suspension in CAD, but..

Post by scarbs » Tue Jul 25, 2017 9:52 pm

Teams use both carbon or Ti flexures. It's largely a packaging excercise.

Ti flexures can have a T shaped end to bolt to a flat cockpit side. Carbon flexures tend be a blade to go into a slot in the chassis.
Thus the Front Top wishbone often has a Ti "T" fitting, the Lower Wishbone has a carbon blade slotting into the bottom of the tub.