《汽车理论》第四章作业MATLAB部分

clc

close all

%空载(no load)-1 ;满载(full load)-2

m1=4080; m2=9290;

hg1=0.845; hg2=1.170;

L=3.950;

a1=2.100; a2=2.950;

b1=L-a1; b2=L-a2;

beta=0.38;

%利用附着系数与制动强度的关系曲线

z=0:0.01:1;

phi_f1=L*beta.*z./(b1+z*hg1);%前轮利用附着系数(空载)

phi_r1=L*(1-beta).*z./(a1-z*hg1);%空载时后轮利用附着系数(空载)

phi_f2=L*beta.*z./(b2+z*hg2);%前轮利用附着系数(满载)

phi_r2=L*(1-beta).*z./(a2-z*hg2);%后轮利用附着系数(满载)

phi=z;%最理想情况

figure(1);

plot (z, phi_f1,'g--', z, phi_f2,'g-',z, phi_r1,'b--',z, phi_r2,'b-',z, phi,'k-');

axis([0,1,0,1]);grid on;box off;axis square;

title('利用附着系数与制动强度的关系曲线');

xlabel('制动强度 z/g');

ylabel( '利用附着系数{\phi}');

%ECE 法规要求界限

hold on;

z1=0.2:0.01:0.8;z2=0.15:0.01:0.3;z3=0.3:0.01:1;

phi1=(z1+0.07)/0.85;

phi2=z2-0.08;phi3=z2+0.08;phi4=(z3-0.02)/0.74;

plot (z1, phi1,'r-.',z2,phi2,'r-.',z2,phi3,'r-.',z3,phi4,'r-.')

legend('{\phi}_{f}(空载)','{\phi}_{f}(满载)','{\phi}_{r}(空载)','{\phi}_{r}(满载)','{\phi}=z','ECE 法规要求界限');

legend( 'Location', 'northwest');

%制动效率曲线

Ef1=z./phi_f1*100;

Er1=z./phi_r1*100;

Ef2=z./phi_f2*100;

Er2=z./phi_r2*100;

figure(2);

plot (phi_f1, Ef1,'k', phi_rl, Er1,'k',phi_f2, Ef2,'b',phi_r2, Er2,'b');

axis([0,1,0,100]);

grid on;

box off;

axis square;

title('制动效率曲线');

xlabel('附着系数{\phi}');

ylabel('制动效率(%)');

text(0.25,90,'E_f');

text(0.6,88','满载');

text(0.8,90,'E_r');

text(0.7,65,'空载');

text(0.72,72,'E_r');