What would be an appropriate value for the tire slip coefficient. I don't know how to find the lateral force on the tire because i don't have enough information unfortunately.
this is a two part question. the lateral force can be found at post I did in Introductory Physics forum - Calculating G Forces or the Centripical force -Dec27-08, 01:43 AM
tire slip coefficient - Race car tires were invented to contradict Newton's Laws of Friction. Tires can and do generate forces greater than the load applied to it. It can develop acceleratetive force, decellarative force and side force. In the case of combined lateral and longitudinal force, the sum can be considerably greater than the maximum force that can be developed in anyone direction.
It is important to realize that the coefficient of friction is DIMENSIONLESS. It is an indication of the maximum force which can be developed by one tire when compared to another tire under the same conditions. Tire manufactures use this as ONE consideration ( of many) when designing tires relative to performance and handing.
It is important to remember that the force that can be developed by anyone tire is the product of the instantaneous vertical load applied to the tire and the tires maximum coefficient of friction under the existing conditions. Both these factors change constantly with variations of road speed, load transfer, track conditions, tire temperature, and a bunch more stuff. In the lateral sense, we refer to this generated fo
Cornering Power is centrifugal acceleration capability or in a more scientific sense Friction Force (Ff). Friction force equals the Coefficient of Friction (Cf) times the vertical load or force (Fv). Ff=CfFv.
Tire manufacturers do not give out raw data in pounds-force as the units for lateral force so Gs is a convenient unit to show important trends without specific data. rce as the tires CORNERING POWER which is just the old centrifugal acceleration capability.
In the longintudinal sense we call it TRACTION CAPACITY. For this discussion we assume the tires traction capacity to be equal in both directions.
Slip angle of a pneumatic tire is defined as ' the angular displacement between the plane of rotation of the wheel ( direction the rim is pointing) and the path that the rolling tire will follow on the track surface". This path is made up of successive footprints of the contact patch laid down as the tire rolls..( any questions on contact patch?)
In order for the vehicle to change direction, regardless of speed or track banking ( curvature) each of the vehicle's tires must assume some value of SLIP ANGLE.
How and why the tires responds to changes in chassis geometry is a whole nother story so we will skip the part about sidewall distortion, tire compond, tire grip, and all that to address your question - What would be an appropriate value for the tire slip coefficient.
The appropriate value would be the value of the tire that provided the maximum cornering power for that particular road surface or track, with that particular vehicle weight and suspension setting at that temperature at that time of day.
Racing is about compromise. Can you calculate the appropriate value for the tire slip angle coefficient mathematically without knowing the tires composition, content of rubber/synthetic material, side all construction (bias vs. radial) belt material. steel, nylon, Kelvar, sidewall distortion, heat fade, tread construction if any, compound hardness ( durometer).
Also vertical load must be know and to do this you need to know total vehicle weight, percent sprung to unsprung weight, weight transfer percentage versus vehicle speed, degree of track banking ( in cornering as well) weight jacking effect, camber change under load, bump steer impact on toe - out. Caster change, spring deflection under load, control arm impact on motion rate and much more..then throw in the track itself...current temperature, effect of sunlight on track surface, track surface roughness, composition ( concrete and asphalt or all asphalt).
My recommendation is to look up calculating Gs on a skid pad..see above first sentence I wrote. Look over the generic graph attached. Note the passenger car tire works pretty good up to 4 degrees slip angle and to .8 Gs and is generally the results you see in road tests of street cars on a skid pad. You may get to 1 g with a hot corvette and the max you should see with a full blown formula car is 1.4 g without a lot of aero added to it.
frasool - pls. let me know if this helped..confused you or just muddied up things and I will try again
