汽车理论matlab作业

一、确定一轻型货车的动力性能。1）绘制汽车驱动力与行驶阻力平衡图；2）求汽车最高车速与最大爬坡度；3）绘制汽车行驶加速度倒数曲线；用计算机求汽车用Ⅱ档起步加速行驶至70km/h所需的加速时间。已知数据略。（参见《汽车理论》习题第一章第3题）解题程序如下:用Matlab语言(1)绘制汽车驱动力与行驶阻力平衡图m1=2000;m2=1800;mz=3880;g=9.81;r=0.367;CdA=2.77;f=0.013;nT=0.85;ig=[5.562.7691.6441.000.793];i0=5.83;If=0.218;Iw1=1.798;Iw2=3.598;Iw=2*Iw1+4*Iw2;fori=1:69n(i)=(i+11)*50;Ttq(i)=-19.313+295.27*(n(i)/1000)-165.44*(n(i)/1000)^2+40.874*(n(i)/1000)^3-3.8445*(n(i)/1000)^4;endforj=1:5fori=1:69Ft(i,j)=Ttq(i)*ig(j)*i0*nT/r;ua(i,j)=0.377*r*n(i)/(ig(j)*i0);Fz(i,j)=CdA*ua(i,j)^2/21.15+mz*g*f;endendplot(ua,Ft,ua,Ff,ua,Ff+Fw)title('汽车驱动力与行驶阻力平衡图');xlabel('ua(km/h)');ylabel('Ft(N)');gtext('Ft1')gtext('Ft2')gtext('Ft3')gtext('Ft4')gtext('Ft5')gtext('Ff+Fw')(2)求最大速度和最大爬坡度fork=1:175n1(k)=3300+k*0.1;Ttq(k)=-19.313+295.27*(n1(k)/1000)-165.44*(n1(k)/1000)^2+40.874*(n1(k)/1000)^33.8445*(n1(k)/1000)^4;Ft(k)=Ttq(k)*ig(5)*i0*nT/r;ua(k)=0.377*r*n1(k)/(ig(5)*i0);Fz(k)=CdA*ua(k)^2/21.15+mz*g*f;E(k)=abs((Ft(k)-Fz(k)));endfork=1:175if(E(k)==min(E))disp('汽车最高车速=');disp(ua(k));disp('km/h');endendforp=1:150n2(p)=2000+p*0.5;Ttq(p)=-19.313+295.27*(n2(p)/1000)-165.44*(n2(p)/1000)^2+40.874*(n2(p)/1000)^3-3.8445*(n2(p)/1000)^4;Ft(p)=Ttq(p)*ig(1)*i0*nT/r;ua(p)=0.377*r*n2(p)/(ig(1)*i0);Fz(p)=CdA*ua(p)^2/21.15+mz*g*f;af(p)=asin((Ft(p)-Fz(p))/(mz*g));endforp=1:150if(af(p)==max(af))i=tan(af(p));disp('汽车最大爬坡度=');disp(i);endend汽车最高车速=99.0679km/h汽车最大爬坡度=0.3518（3）计算2档起步加速到70km/h所需时间fori=1:69n(i)=(i+11)*50;Ttq(i)=-19.313+295.27*(n(i)/1000)-165.44*(n(i)/1000)^2+40.874*(n(i)/1000)^3-3.8445*(n(i)/1000)^4;endforj=1:5fori=1:69deta=1+Iw/(mz*r^2)+If*ig(j)^2*i0^2*nT/(mz*r^2);ua(i,j)=0.377*r*n(i)/(ig(j)*i0);a(i,j)=(Ttq(i)*ig(j)*i0*nT/r-CdA*ua(i,j)^2/21.15-mz*g*f)/(deta*mz);if(a(i,j)=0)a(i,j)=a(i-1,j);endif(a(i,j)0.05)b1(i,j)=a(i,j);u1(i,j)=ua(i,j);elseb1(i,j)=a(i-1,j);u1(i,j)=ua(i-1,j);endb(i,j)=1/b1(i,j);endendx1=u1(:,1);y1=b(:,1);x2=u1(:,2);y2=b(:,2);x3=u1(:,3);y3=b(:,3);x4=u1(:,4);y4=b(:,4);x5=u1(:,5);y5=b(:,5);plot(x1,y1,x2,y2,x3,y3,x4,y4,x5,y5);title('加速度倒数时间曲线');axis([0120030]);xlabel('ua(km/h)');ylabel('1/aj');gtext('1/a1')gtext('1/a2')gtext('1/a3')gtext('1/a4')gtext('1/a5')fori=1:69A=ua(i,3)-ua(69,2);if(A1&A0)j=i;endB=ua(i,4)-ua(69,3);if(B2&B0)k=i;endif(ua(i,4)=70)m=i;endendt=ua(1,2)*b(1,2);forp1=2:69t1(p1)=(ua(p1,2)-ua(p1-1,2))*(b(p1,2)+b(p1-1,2))*0.5;t=t+t1(p1);endforp2=j:69t2(p2)=(ua(p2,3)-ua(p2-1,3))*(b(p2,3)+b(p2-1,3))*0.5;t=t+t2(p2);endforp3=k:mt3(p3)=(ua(p3,4)-ua(p3-1,4))*(b(p3,4)+b(p3-1,4))*0.5;t=t+t3(p3);endt=t+(ua(j,3)-ua(69,2))*b(69,2)+(ua(k,4)-ua(69,3))*b(69,3)+(70-ua(m,4))*b(m,4);tz=t/3.6;disp('加速时间=');disp(tz);disp('s');加速时间=29.0585s二、计算与绘制题1中货车的1）汽车功率平衡图；2）最高档与次高档的等速百公里油耗曲线。已知数据略。（参见《汽车理论》习题第二章第7题）解题程序如下:用Matlab语言m1=2000;m2=1800;mz=3880;g=9.81;r=0.367;CdA=2.77;f=0.013;nT=0.85;ig=[5.562.7691.6441.000.793];i0=5.83;If=0.218;Iw1=1.798;Iw2=3.598;n1=[8151207161420122603300634033804];Iw=2*Iw1+4*Iw2;nd=400;Qid=0.299;forj=1:5fori=1:69n(i)=(i+11)*50;Ttq(i)=-19.313+295.27*(n(i)/1000)-165.44*(n(i)/1000)^2+40.874*(n(i)/1000)^3-3.8445*(n(i)/1000)^4;Pe(i)=n(i)*Ttq(i)/9549;ua(i,j)=0.377*r*n(i)/(ig(j)*i0);Pz(i,j)=(mz*g*f*ua(i,j)/3600.+CdA*ua(i,j)^3/76140.)/nT;endendplot(ua,Pe,ua,Pz);title('汽车功率平衡图)');xlabel('ua(km/h)');ylabel('Pe,Pz(kw)');gtext('I')gtext('II')gtext('III')gtext('IV')gtext('V')gtext('P阻')forj=1:5fori=1:8Td(i)=-19.313+295.27*(n1(i)/1000.0)-165.44*(n1(i)/1000.0)^2+40.874*(n1(i)/1000.0)^3-3.8445*(n1(i)/1000.0)^4;Pd(i)=n1(i)*Td(i)/9549;u(i,j)=0.377*n1(i)*r/(ig(j)*i0);endendb(1)=0.17768*Pd(1)^4-5.8629*Pd(1)^3+72.379*Pd(1)^2-416.46*Pd(1)+1326.8;b(2)=0.043072*Pd(2)^4-2.0553*Pd(2)^3+36.657*Pd(2)^2-303.98*Pd(2)+1354.7;b(3)=0.0068164*Pd(3)^4-0.51184*Pd(3)^3+14.524*Pd(3)^2-189.75*Pd(3)+1284.4;b(4)=0.0018555*Pd(4)^4-0.18517*Pd(4)^3+7.0035*Pd(4)^2-121.59*Pd(4)+1122.9;b(5)=0.00068906*Pd(5)^4-0.091077*Pd(5)^3+4.4763*Pd(5)^2-98.893*Pd(5)+1141.0;b(6)=0.00035032*Pd(6)^4-0.05138*Pd(6)^3+2.8593*Pd(6)^2-73.714*Pd(6)+1051.2;b(7)=0.00028230*Pd(7)^4-0.047449*Pd(7)^3+2.9788*Pd(7)^2-84.478*Pd(7)+1233.9;b(8)=-0.000038568*Pd(8)^40.00075215*Pd(8)^3+0.71113*Pd(8)^245.291*Pd(8)+1129.7;u1=u(:,1)';u2=u(:,2)';u3=u(:,3)';u4=u(:,4)';u5=u(:,5)';B1=polyfit(u1,b,3);B2=polyfit(u2,b,3);B3=polyfit(u3,b,3);B4=polyfit(u4,b,3);B5=polyfit(u5,b,3);forq=1:69bh(q,1)=polyval(B1,ua(q,1));bh(q,2)=polyval(B2,ua(q,2));bh(q,3)=polyval(B3,ua(q,3));bh(q,4)=polyval(B4,ua(q,4));bh(q,5)=polyval(B5,ua(q,5));endfori=1:5forq=1:69Q(q,i)=Pz(q,i)*bh(q,i)/(1.02*ua(q,i)*7.05);endendplot(ua(:,4),Q(:,4),ua(:,5),Q(:,5));title('四档五档等速百公里油耗图');xlabel('ua(km/h)');ylabel('Qs(L/100km)');三、改变1.3题中轻型货车的主减速器传动比，做出0i为5.17、5.43、5.83、6.17、6.33时的燃油经济性—加速时间曲线，讨论不同0i值对汽车性能的影响。Matlab程序：m1=2000;m2=1800;m=3880;r0=0.367;gt=0.85;f=0.013;CDA=2.77;i0=5.83;If=0.218;Iw1=1.798;Iw2=3.598;Ig5=[5.562.7691.6441.000.793];Ig0=[5.175.435.836.176.33];B=[1326.8-416.4672.379-5.86290.17768;1354.7-303.9836.657-2.05530.043072;1284.4-189.7514.524-0.511840.0068164;1122.9-121.597.0035-0.185170.0018555;1141.0-98.8934.4763-0.0910770.00068906;1051.2-73.7142.8593-0.051380.00035032;1233.9-84.4782.97