Ride rate, Roll rate calculation : part 2

part 1

5. Select the static deflection and corresponding frequency from the graph.


(2π wF)2 W2 = KRF

(2π wR)2 W4 = KRR

wF = front ride frequency

KRF = ride rate front

W1 = static weight on front inner tire

W2 = static weight on front outer tire

W3 = static weight on rear inner tire

W4 = static weight on rear outer tire

Rear drive cars have front natural frequency higher than rear suppose if for 2.5 inch travel rear ride frequency in taken 108 cpm then it is advisable to take front ride frequency upto 115 cpm.

6. KØF = (KRF × tF2 × Ø) / (2Ø)  (unit=N-m/rad)

KØF = Roll rate of front.

tF = front track width

Ø = roll angle

Simillarly calculate KØR by taking rear datas.

7. Roll gradient

Ø / Ay = (-W × H) / (KØF + KØR)

8. Weight transfer on the front axle due to lateral acceleration

WF = Ay (W / tF) {[( H × KØF) / (KØF + KØR)] + [( b × ZRF) / l]}

H = height of cg from roll axis.

h = cg height

b = distance of cg from rear axle

a = distance of cg from front axle

ZRF = Roll axis height above the ground

simillarly calculate the weight transfer on the rear axle due to lateral acceleration.


This post was written by BAJA Tutor

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