Vehicle Ride 1

Given data
Wheel Base=2700mm=2.7m
Speed=60mph=26.8224mps
Sprung Mass frequency design front(ff)=1.15Hz

1) Sprung Mass frequency design Rear(fr):-
Time lag= wb/speed=2.7/26.8224=0.101s
Time lag front=1/1.15=0.869
So, Tf=Tr+T_lag
0.869=Tr+0.101
Tr=0.768
Now as we know Tr=1/fr
0.768=1/fr
fr=1.30Hz

2)Sprung Mass frequency design front(ff) already given which is 1.15Hz.

3)Front Spring Rate
Kw=Ks(mr)^2
Ks=Kw/(mr)^2
Ks=245/(0.97)^2
Ks=260.38 N/mm

4)Rear Spring Rate
Kw=Ks(mr)^2
Ks=Kw/(mr)^2
Ks=245/(0.85)^2
Ks=339.1 N/mm

5)Front sprung mass natural frequency at CURB & GVW
As we know, Front sprung mass natural frequency=1/2pi(sqrt(Kr/m))
Ride Rate Kr=(Ks*Kw)/(Ks+Kw)
Kr=(260.38*245)/(260.38+245)
Kr=126.227N/MM=126227 N/m
CURB:-
Total front mass =0.6*1500=900Kg
Total Sprung Mass=900-90=810Kg
ff=1/2pi(sqrt(126227/810))=1.99Hz
GVW:-
Total front mass =0.52*2000=1010Kg
Total Sprung Mass=1040-90=950Kg
ff=1/2pi(sqrt(126227/950))=1.83Hz

6) Rear sprung mass natural frequency at CURB & GVW
As we know, Rear sprung mass natural frequency=1/2pi(sqrt(Kr/m))
Ride Rate Kr=(Ks*Kw)/(Ks+Kw)
Kr=(339.1*245)/(339.1+245)
Kr=142.235N/MM=142235 N/m
CURB:-
Total front mass =600Kg
Total Sprung Mass=600-60=540Kg
ff=1/2pi(sqrt(142235/540))=2.58Hz
GVW:-
Total front mass =960Kg
Total Sprung Mass=960-60=900Kg
ff=1/2pi(sqrt(142235/900))=2.00Hz

7)Front Unsprung mass natural frequency for all three load condition
As we know, Front unsprung mass natural frequency=1/2pi(sqrt(Keuq/m))
Ride Rate Keqe=(Ks+Kw)
Kr=260.38+245
Kr=505.38N/MM=505380 N/m
fus=1/2pi(sqrt(505380/90))=11.93Hz

8)Rear Unsprung mass natural frequency for all three load condition
As we know, Rear unsprung mass natural frequency=1/2pi(sqrt(Keuq/m))
Ride Rate Keqe=(Ks+Kw)
Kr=339.1+245
Kr=584.1N/MM=584100 N/m
fus=1/2pi(sqrt(584100/60))=15.71Hz

8) Rear/ Front Frequency ratio for all load condition
CURB:-Rear/Front=2.58/1.99=1.29Hz
Design:-Rear/Front=1.3/1.15=1.13Hz
gvw:-Rear/Front=2/1.83=1.09Hz