基于matlab来确定一轻型五档货车的动力性.docx

确定以轻型五档货车的动力性：
解：1.绘制汽车驱动力与行驶阻力平衡图
Matlab编写程序如下
n=600:4000; r=0.367; nt=0.85; f=0.013; CA=2.77; io=5.83; m=3880; g=9.8;
Tq=-19.313+295.27.*n./1000-165.44.*(n./1000).^2+40.874.*(n./1000).^3-3.8445.*(n./1000).^4;
ig1=5.56; Ua1=0.377.*r.*n./(ig1.*io); Ft1=Tq.*ig1.*io.*nt./r;
ig2=2.769; Ua2=0.377.*r.*n./(ig2.*io); Ft2=Tq.*ig2.*io.*nt./r;
ig3=1.644; Ua3=0.377.*r.*n./(ig3.*io); Ft3=Tq.*ig3.*io.*nt./r;
ig4=1.00; Ua4=0.377.*r.*n./(ig4.*io); Ft4=Tq.*ig4.*io.*nt./r;
ig5=0.793; Ua5=0.377.*r.*n./(ig5.*io); Ft5=Tq.*ig5.*io.*nt./r;
Fr=m.*g.*f+(CA/21.15).*Ua5.^2;
plot(Ua1,Ft1,Ua2,Ft2,Ua3,Ft3,Ua4,Ft4,Ua5,Ft5,Ua5,Fr);

2.求最高车速，最大爬坡度及相应附着率
2.1 最高车速Uamax
function Uamax=Uamax(Ua5)
r=0.367; nt=0.85; f=0.013; CA=2.77; io=5.83; m=3880; g=9.8;ig5=0.793; n=Ua5.*ig5.*io./(0.377.*r);
Tq=-19.313+295.27.*n./1000-165.44.*(n./1000).^2+40.874.*(n./1000).^3-3.8445.*(n./1000).^4;
Ft5=Tq.*ig5.*io.*nt./r;
Fr=m.*g.*f+(CA/21.15).*Ua5.^2;
Uamax=Ft5-Fr;
>> x=fzero(@Uamax,99)
x =
99.0834
2.2 最大爬坡度 imax
r=0.367; nt=0.85; f=0.013; CA=2.77; io=5.83; m=3880; g=9.8;
Tq=-19.313+295.27.*n./1000-165.44.*(n./1000).^2+40.874.*(n./1000).^3-3.8445.*(n./1000).^4;
ig1=5.56; Ua1=0.377.*r.*n./(ig1.*io);
i=(Tq.*ig1.*io.*nt./r-m.*g.*f)./(m.*g);
imax=m>> imax
imax =
0.3325
2.3 该爬坡度时的附着率Co
>> a=1.947; L=3.2; hg=0.9; q=0.3325;
Co=q./(a./L+hg.*q./L)
Co =
0.4737

3.绘制加速度倒数曲线，计算二档起步加速至70Km/s的时间
Matlab编写程序如下
n=600:4000; r=0.367; nt=0.85; f=0.013; CA=2.77; io=5.83; m=3880; g=9.8; Iw1=1.798; Iw2=3.598; If=0.218;
Tq=-19.313+295.27.*n./1000-165.44.*(n./1000).^2+40.874.*(n./1000).^3-3.8445.*(n./1000).^4;
ig1=5.56; Ua1=0.377.*r.*n./(ig1.*io); inv_a1=(m+(Iw1+Iw2)./r.^2+(If.*ig1.^2.*io.^2.*nt)./r.^2)./(Tq.*ig1.*io.*nt./r-m.*g.*f-(CA./21.15).*Ua1.^2);
ig2=2.769; Ua2=0.377.*r.*n./(ig2.*io); inv_a2=(m+(Iw1+Iw2)./r.^2+(If.*ig2.^2.*io.^2.*nt)./r.^2)./(Tq.*ig2.*io.*nt./r-m.*g.*f-(CA./21.15).*Ua2.^2);
ig3=1.644; Ua3=0.377.*r.*n./(ig3.*io); inv_a3=(m+(Iw1+Iw2)./r.^2+(If.*ig3.^2.*io.^2.*nt)./r.^2)./(Tq.*ig3.*io.*nt./r-m.*g.*f-(CA./21.15).*Ua3.^2);
ig4=1.00; Ua4=0.377.*r.*n./(ig4.*io); inv_a4=(m+(Iw1+Iw2)./r.^2+(If.*ig4.^2.*io.^2.*nt)./r.^2)./(Tq.*ig4.*io.*nt./r-m.*g.*f-(CA./21.15).*Ua4.^2);
ig5=0.793; Ua5=0.377.*r.*n./(ig5.*io); inv_a5=(m+(Iw1+Iw2)./r.^2+(If.*ig5.^2.*io.^2.*nt)./r.^2)./(Tq.*ig5.*io.*nt./r-m.*g.*f-(CA./21.15).*Ua5.^2);
axis([0 80 0 10]);
plot(Ua1,inv_a1,Ua2,inv_a2,Ua3,inv_a3,Ua4,inv_a4,Ua5,inv_a5);

求加速时间t
r=0.367;io=5.83;n1=4000;nt=0.85;ig=[5.56 2.769 1.644 1.00 0.793];If=0.218;Iw1=1.798;Iw2=3.598;m=3880;g=9.8;f=0.013;CA=2.77;
for i=1:2
Ua=0.377.*r.*n1./(io.*ig(i)):0.00001:0.377.*r.*n1./(io.*ig(i+1));
n=Ua.*io.*ig(i+1)./(0.377.*r);
Tq=-19.313+295.27.*(n./1000)-165.44.*(n./1000).^2+40.874.*(n./1000).^3-3.8445.*(n./1000).^4;
Ft=Tq.*ig(i+1).*io.*nt./r;
Fw=m.*g.*f+(CA./21.15).*Ua.^2;
p=1+(Iw1+Iw2+If.*ig(i+1).^2.*io.^2.*nt)./(m.*r.^2);
inv_a=p.*m./(Ft-Fw);s=0;
s=s+trapz(Ua,inv_a);
end
Ua=0.377.*r.*n1./(io.*ig(3)):0.00001:70;
n=Ua.*io.*ig(4)./(0.377.*r);
Tq=-19.313+295.27.*(n./1000)-165.44.*(n./1000).^2+40.874.*(n./1000).^3-3.8445.*(n./1000).^4;
Ft=Tq.*ig(4).*io.*nt./r;
Fw=m.*g.*f+(CA./21.15).*Ua.^2;
Iw1=1.798;Iw2=3.598;p=1+(Iw1+Iw2+If.*ig(4).^2.*io.^2.*nt)./(m.*r.^2);
inv_a=p.*m./(Ft-Fw);
acctime=(s+trapz(Ua,inv_a))./3.6
acctime =
19.6495

0.4737