Suspension

[Subu]

which suspension system will be better for F1 car ?And what is torsional rigidity in suspension system??

[Owen Thomas]

Well, there are various types of suspension setups, but I suppose your super specific question requires an equally accurate and lengthy response. It should be noted that the front and rear suspension setups are usually identical, which is convenient since I wouldn't want you to read too much http://fsae.com/groupee_common/emoticons/icon_wink.gif.

Lets start from the wheels and move towards the chassis:

First, you have your control arms. These bad boys should be DIRECTLY connected to the wheel hub and ALWAYS be in bending (an extreme case is best, and many teams use this to provide down force). One can never be too creative with the geometry and number of these control arms, so there's a wide variety to be found on all the winning cars. As for materials, you want something super light weight, because that's unsprung mass just screaming to be cut down. Most teams use wooden dowels painted a cool colour, but it has been speculated that the top teams use Ostrich bones (usually from the leg). This can be risky, however, as the ductility of said bones sharply decreases with freshness.

Next up, bell cranks. Well, there's really only one type of bell crank that people ever use, since it always ends up providing the same motion ratio anyways, but basically take the shape of an N64 controller and connect the pushrod, anti roll bar linkage and the springs to the grips. Obviously weight and aesthetics are critical for material selection, so soft precious metals like gold are the primary choice.

The anti roll bar is usually integrated into the steering links for maximum efficiency. Back in the '80s F1 had dynamic systems which provided active weight transfer to the unladen wheel by moving a large steel block from one side of the driver compartment to the other. While technically still the best anti roll setup, this was banned because teams began using super dense metals which were often very radioactive in nature.

Finally we arrive at the springs. It used to be that people used something called a "damper" to keep the spring from oscillating excessively after suspension travel, but the Red Bull team made that obsolete in 2008 by putting their springs directly in tension. Since then this has become the standard, as it reduces weight and provides a smoother ride. The spring rate required is directly proportional to the drivers hand characteristics and shape, as this dictates their driving style. F1 teams put a lot of time and resources into accurately measuring and manicuring a drivers hands for optimal performance tuning of the suspension.

As for torsional rigidity of the suspension system as a whole, teams keep this a closely guarded secret. It is speculated that a complex equation involving the product of the mass and acceleration vector is used in conjunction with a supercomputer to find the ideal number. Here in FSAE we are limited to a suspension torsional rigidity of 207 GPa or 273.15 lbf/in*R in imperial units, so we don't know all that much about it.

I hope this gave you some insight as to what makes the best suspension systems in Formula 1. I know how hard it is to find good pictures on google or any kind of literature on vehicle dynamics, so I really hope this helped http://fsae.com/groupee_common/emoticons/icon_biggrin.gif.

Cheers,

[PatClarke]

Mr Thomas,
You have too much time on your (manicured) hands http://fsae.com/groupee_common/emoticons/icon_smile.gif http://fsae.com/groupee_common/emoticons/icon_smile.gif

Pat

[Kirby]

now challenging anyone to put their chassis stiffness as Nm/rad or lbf-in/rad in design report.