A question about longitudinal tire slip ratio

[wilsonzhang]

The traction force is generated between the tire and road, it has relation with slip ratio, simply, F=Cs, s is slip ratio, which is defined as as a difference between the tire tangential speed and the speed of the axle relative to the road. Question here is how we can find these two velocity in the same time.

 

[GregLocock]

Use a correvit to measure true road speed and a tone wheel on the axle to find the axle speed and a laser height probe to measure the true rolling radius



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[wilsonzhang]

Thank GregLocock for your quick reply. But how can some vehicle dynamic software, such as Adams-car and car-sim , determine the longitudinal tire slip ratio.

 

[GregLocock]

If you know the longitudinal force at the CP, and the vertical force, then you have a look up chart based on the tyre characteristics which tells you the slip ratio. That chart is compiled more or less as I explained above, with the addition of some load-measuring systems.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[danghuang]

Ordinally the slip is computed by tire forward speed Vx, the angular speed revolution rou. And effective rolling radius re.
Slipratio=(Vx-re*rou)/Vx
you can get Vx,re and rou from the Software before you use your tire model.
the tire model just tells the relationship between longitudinal force and slip ratio.