Deformable Hinges in Suspensions

[LogicPro]

I just read that Scarbs wrote this a few days ago: "flexures have a smaller angular movement & tend to be used on the longer front wishbones, so often sphericals are at the back"

I thought it might be interesting to add here (and I highly regard what Scarbs says )



https://twitter.com/ScarbsF1/status/324618938283614211

[Pierce89]

I didn't know teams still used spherical joints on the inboard end of the wishbones at all. I thought they did EVERYTHING the expensive way.

[riff_raff]

Flexures can be designed to allow a large deflection angle, but like everything else it requires some compromises. A-arms are designed to react suspension loads in tension/compression. In order to allow greater angular deflection with a flexure, the flexure must be made longer and thinner to prevent excessive bending stresses. While a long, thin flexure works OK in tension, it does not work so well in compression, due to buckling.

[Smokes]

what is the fatigue life of a flexture and the failure mode one it fatigues

[Tommy Cookers]

a flexure would be designed for a chosen fatigue life eg 100 hrs, 1000 hrs etc (specified conditions eg suspension travel)
and would be inspected throughout this period
fatigue failure is due to the intermittent extension of (inevitable) cracking, so is preventable by inspection
as with eg the wing spars of a plane

if the flexure is allowed to be significantly stiff relative to the spring stiffness, the flexure can be very long-lasting

this is roughly how the world's first 500 milion cars were
typically the modern flexure/bearing, spring and location arm/wishbone functions were all done by one part (a 'leaf spring')
the highest-stressed part of the spring, being far from the wheel, gave a relatively high proportion of the wheel travel
so it behaved rather like our modern flexure
the rest of the spring gave proportionately less of the wheel travel (despite the designer's ideal)
so it behaved rather like our wishbone/locating arm

[marcush.]

as I understand the lower wishbones of the MG Lola LMP2 had these issues under braking -compression buckling -tendencies that lead to a not so fine behaviour on the brakes.Not sure if all cars were updated ,the Dyson ones were back then .

[marcush.]

A flexure is a design exercise for an Engineer -that´s why it was introduced to Formula 1 one by one John Barnard.
The requirements have to be defined first and then the man with the brains and expertise is designing the part that matches the set of requirements .
Of course there is less parts in a setup like this ,and if you are in control of your processes it is a very neat thing .
Just think about all those staking tools and operations needed to secure a balljoint in its fit ,not even mentioning the bolt securing it to the bracket which is then bolted to the chassis .That´s a lot of buy in hardware not easy to have 100% control
of ,don´t you think?

[Tommy Cookers]

Flexures can be designed to allow a large deflection angle, but like everything else it requires some compromises. A-arms are designed to react suspension loads in tension/compression. In order to allow greater angular deflection with a flexure, the flexure must be made longer and thinner to prevent excessive bending stresses. While a long, thin flexure works OK in tension, it does not work so well in compression, due to buckling.

such a configuration (pictured in LogicPro's post) seems 'naively' limited in applicability, and not optimal for compressive strength

other configurations are conceivable, just one example, the cruciform flexure, has been around for about 600 years

but there is no law that says a suspension flexure's stiffness in bending must not contribute to the wheel rate, it should contribute
that will hugely increase the scope of flexural pivoting, without complexity or increased drag

[peaty]

flexure to be precise .sorry for being nitpicky

for a start:
http://www.smpp.northwestern.edu/savedL ... 27p788.pdf

and closer to formula 1:

http://www.gef.es/Congresos/24/pdf/3-13.pdf
http://www.gef.es/congresos/21/PDF/7-14.pdf

does anybody have these pdf!? thanks!

[e36jon]

Greetings all

Looking at my favorite F1 collectables site they have some relevant suspension bits:

• 2007 Red Bull A-arm with what appears to be carbon flexures

• 2006 Renault 'double' a-arm (So they must be flexing, right?)

• 2007 Honda flexure (Gets bonded to carbon A-arm)

• 2006 Honda flexure (Gets bonded to carbon A-arm)

https://www.racetothefinish.co.uk/mecha ... -with-coa/






Cheers,

Jon

[Billzilla]

flexure to be precise .sorry for being nitpicky

for a start:
http://www.smpp.northwestern.edu/savedL ... 27p788.pdf

and closer to formula 1:

http://www.gef.es/Congresos/24/pdf/3-13.pdf
http://www.gef.es/congresos/21/PDF/7-14.pdf

does anybody have these pdf!? thanks!

I'd like to get a copy as well if possible please.

[CarterHendricks]

http://www.smpp.northwestern.edu/savedL ... 27p788.pdf

http://www.gef.es/Congresos/24/pdf/3-13.pdf
http://www.gef.es/congresos/21/PDF/7-14.pdf

does anybody have these pdf!? thanks!

I'd like to get a copy as well if possible please.

"Wayback Machine" is your friend!

--Carter

[peaty]

Greetings all

Looking at my favorite F1 collectables site they have some relevant suspension bits:

• 2007 Red Bull A-arm with what appears to be carbon flexures

• 2006 Renault 'double' a-arm (So they must be flexing, right?)

• 2007 Honda flexure (Gets bonded to carbon A-arm)

• 2006 Honda flexure (Gets bonded to carbon A-arm)

https://www.racetothefinish.co.uk/mecha ... -with-coa/


Cheers,

Jon

Thanks e36Jon! I was trying to understand the design criteria and, if possible, get some reference values.

[peaty]

http://www.smpp.northwestern.edu/savedL ... 27p788.pdf

http://www.gef.es/Congresos/24/pdf/3-13.pdf
http://www.gef.es/congresos/21/PDF/7-14.pdf

does anybody have these pdf!? thanks!

I'd like to get a copy as well if possible please.

"Wayback Machine" is your friend!

--Carter

Awesome! I forgot about that one! Thank you very much!