Tire data for suspension design

[koushikatti]

@Tim Wright , yes I do have Milliken. I have gone through the chapter on steady state response . In RCVD all the derivations are done assuming a single track bicycle model. Currently I am trying to formulate similar equations for a two track model including the lateral load transfer.


Regards!

[Tim.Wright]

Ok I got you. so you are accounting for the load dependency of the cornering stiffness?

I was playing around with something similar to this last week. Are you using steering wheel angle as an input, then iterating to find the wheel slips, tyre forces and therefore latacc?

I found it easier to start with Ay as the input, then you immediately know the wheel loads, axle lateral forces and car yawrate. Then the slip angles can be calculated without iteration. theoretically... I actually didn't finish it myself.

[koushikatti]

Yes this is exactly what i am trying to do.

I have decided a vehicle velocity and path radius (hence the lateral accleration) and the aim is to compute the slip angles on the four tires and also the steering angle required for the turn.

[Tim.Wright]

OK, so given that you know that latacc, you know also the front and rear axle lateral forces, to which the sum of the left and the right wheel forces must add up to.

If you write equations for the front and rear axle forces in terms of sideslip and steering angle, you will have 2 equations and two unknowns which you can solve simultaneuously.

FyF = b.m.Ay/L = Fyfl(steer,beta) + Fyfr(steer,beta)
FyR = a.m.Ay/L = Fyrl(beta) + Fyrr(beta)

[koushikatti]

Yes exactly. I have the two equations and the two unknowns. Actually right now I am trying to use an interpolating polynomial to represent tire data (graph of Lateral force Vs slip angle ) for a given Fz (normal force on the tire). So instead of using the tire lateral coefficient I will use the interpolating polynomial to get the lateral force. Once I am done with the interpolation I will be very close to get the solution.

[koushikatti]

Thank you everyone for the help , finally I was able to prepare the excel sheet and see the car steering response for steady state cornering condition.


Regards!