Vehicle Ride 1

Excel-link:

https://docs.google.com/spreadsheets/d/1B4eM0EcO_to97m1UBIuiMZegGH7v9KyTk1fOjWkRVow/edit?usp=sharing

All the calculations are done using excel.

1.Calculate the following parameters. Use the same front and rear spring rates for all three load conditions.

The front sprung mass natural frequency target at design is 1.15 Hz. Keep this fixed

i.Recommended rear sprung mass frequency based on speed and wheelbase at design condition=1.39 Hz

ii.Front sprung mass natural frequency at design. This will essentially be (i).=1.15 Hz

iii.Front spring rate= 28 N/mm

iv.Rear spring rate = 36 N/mm

v.Front sprung mass natural frequencies at

curb = 1.220353258 Hz

GVW = 1.126850422 Hz

vi.Rear sprung mass natural frequencies at

curb = 1.48600077 Hz

GVW = 1.151051247 Hz

vii.Front unsprung mass natural frequency at all three load conditions

curb = 8.770016795 Hz

Half load = 8.770016795 Hz

GVW = 8.770016795 Hz

viii.Rear unsprung mass natural frequency at all three load conditions

curb = 10.89727451 Hz

Half load =10.89727451 Hz

GVW = 10.89727451 Hz

ix.Rear/Front frequency ratio for all three load conditions

curb = 1.217680831

Half load = 1.089275867

GVW = 1.021476519

2.Plot the bump oscillation profile for all three load conditions using the method we developed in class. You can do this in excel. Use e^-t*sin(wt) as a function for the profile.

clear all
close all
clc
%frequencies from excel plot
spring_rate_front=28;
spring_rate_rear=36;
t_wb=0.01

%curb
f_front_c=1.220353258
f_rear_c=1.48600077

time= 0:0.01:3
ct=1;
for t= 0:0.01:3   
     front_amp(ct)=exp(-t)*sin(2*pi*f_front_c*t);
     rear_amp(ct)=exp(-t)*sin(2*pi*f_rear_c*(t-t_wb));
    ct=ct+1
end
figure(1)
plot(time,front_amp)
hold on
plot(time,rear_amp)
grid on
hold off
title('Bump Oscillation_ Curb')
xlabel('time')
ylabel('amplitude')
legend('front','rear')

%half load
f_front_h=1.148985054
f_rear_h=1.251561691

time= 0:0.01:3
ct=1;
for t= 0:0.01:3   
     front_amp(ct)=exp(-t)*sin(2*pi*f_front_h*t);
     rear_amp(ct)=exp(-t)*sin(2*pi*f_rear_h*(t-t_wb));
    ct=ct+1
end
figure(2)
plot(time,front_amp)
hold on
plot(time,rear_amp)
grid on
hold off
title('Bump Oscillation_ Half load')
xlabel('time')
ylabel('amplitude')
legend('front','rear')

%GVW
f_front_g=1.126850422
f_rear_g=1.151051247


time= 0:0.01:3
ct=1;
for t= 0:0.01:3   
     front_amp(ct)=exp(-t)*sin(2*pi*f_front_g*t);
     rear_amp(ct)=exp(-t)*sin(2*pi*f_rear_g*(t-t_wb));
    ct=ct+1
end
figure(3)
plot(time,front_amp)
hold on
plot(time,rear_amp)
grid on
hold off
title('Bump Oscillation_ GVW')
xlabel('time')
ylabel('amplitude')
legend('front','rear')

Output Bump Plots: