Ride rate, Roll rate calculation : part 2

part 1

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

(2π w_F)² W₂ = K_RF

(2π w_R)² W₄ = K_RR

w_F = front ride frequency

K_RF = 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. K_ØF = (K_RF × t_F² × Ø) / (2Ø)  (unit=N-m/rad)

K_ØF = Roll rate of front.

t_F = front track width

Ø = roll angle

Simillarly calculate K_ØR by taking rear datas.

7. Roll gradient

Ø / A_y = (-W × H) / (K_ØF + K_ØR)

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

W_F = A_y (W / t_F) {[( H × K_ØF) / (K_ØF + K_ØR)] + [( b × Z_RF) / 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

Z_RF = Roll axis height above the ground

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

Continue…….