機械動力學試驗報告

1、機 械 動 力 學 大 作 業(yè) 江西機械 院 系： 機械工程學院專 業(yè)： 機械設計及理論班 級： 4班學 號： 20404151姓 名： 王昌榮 汽車配件網(wǎng)機械動力學課程大作業(yè)實驗任務：觀察激振試驗；進行錘擊試驗，繪制特性曲線圖及數(shù)據(jù)表，并利用所得數(shù)據(jù)對模態(tài)參數(shù)進行識別。儀器設備GF10型功率放大器；XD-18A型超低頻信號發(fā)生器；MO-1251型示波器；PDM-2000數(shù)據(jù)采集分析儀；帶有傳感器的力錘；加速度傳感器。實驗框圖錘擊實驗框圖：力 傳 感 器設備計 算 機濾 波 器A/D前 處 理（放大）濾 波 器適 配 器加速度傳感器器（四）繪制實頻、虛頻、幅頻、相頻及Nyqiust圓圖1繪制實

2、頻、虛頻、幅頻、相頻及Nyqiust圓源程序清單：%原始數(shù)據(jù)讀入-clc;for j=1:4 fid=0; while fid1 switch j case 1 filename=wcry01.txt; case 2 filename=wcry02.txt; case 3 filename=wcry03.txt; case 4 filename=wcry04.txt; end fid,j=fopen(filename,r); if fid=-1 disp(message) end end data_all=fscanf(fid,%g); N=length(data_all); %數(shù)據(jù)長度 fs

3、=2560; %采樣頻率 f=1000; %分析頻率 data_Re=data_all(1:N/2); %前半段數(shù)據(jù)為實頻 data_Im=data_all(N/2+1:N); %后半段數(shù)據(jù)為虛頻 for i=1:N/2 Aw(i)=sqrt(data_Re(i)*data_Re(i)+data_Im(i)*data_Im(i); %幅頻 Qw(i)=atan(data_Im(i)/data_Re(i); %相頻 end figure subplot(221); plot(data_Re(1:400),b); title(實頻特性) subplot(222); plot(data_Im(1:4

4、00),g); title(虛頻特性) subplot(223); plot(Aw(1:400),c); title(幅頻特性) subplot(224); plot(Qw(1:400),r); title(相頻特性) figure plot(data_Re(1:400),data_Im(1:400),k); title(Nyquist特性) end 第一組數(shù)據(jù)繪圖：江西機械 第二組數(shù)據(jù)繪圖：第三組數(shù)據(jù)繪圖第四組數(shù)據(jù)繪圖:2用五點求擬合圓，并計算各階固有頻率，阻尼比：采用第一組數(shù)據(jù)計算：源程序清單：江西機械 clc;fprintf(-采用第1組數(shù)據(jù)計算-n) fid=0;while fid1

5、filename=wcry01.txt; %原始數(shù)據(jù)文件名稱 fid,message=fopen(filename,r); %讀入數(shù)據(jù) if fid=-1 disp(message); endend data_all=fscanf(fid,%g); N=length(data_all); %數(shù)據(jù)長度 %fs=2560; %采樣頻率 %f=1000; %分析頻率 data_Re=data_all(1:N/2); %前半段數(shù)據(jù)為實頻 data_Im=data_all(N/2+1:N); %后半段數(shù)據(jù)為虛頻 for i=1:N/2 Aw(i)=sqrt(data_Re(i)*data_Re(i)+d

6、ata_Im(i)*data_Im(i); %幅頻 end peak_value=zeros(1,3); subpoint=1 40 91 130 131 170; max_data1,peak_value(1)=max(Aw(subpoint(1):subpoint(2); max_data2,peak_value(2)=max(Aw(subpoint(3):subpoint(4); max_data3,peak_value(3)=max(Aw(subpoint(5):subpoint(6); peak_value(2)=peak_value(2)+subpoint(3)-1; peak_v

7、alue(3)=peak_value(3)+subpoint(5)-1; fprintf(n 三階峰值位置分別是：);fprintf(%d %d %dn,peak_value(1),peak_value(2),peak_value(3);m=5; k=(m+1)/2; dataX_curve=zeros(1,m); dataY_curve=zeros(1,m);for j=1:3 peakva=peak_value(j); center_X,center_Y,curve_R,A_mainarray=calc_curve(data_Re,data_Im,peakva); ring_X=zeros

8、(1,628); ring_Y=zeros(1,628); for i=1:628 ring_X(i)=curve_R*cos(i/100)+center_X; ring_Y(i)=curve_R*sin(i/100)+center_Y;end figure plot(ring_X,ring_Y,m); hold on for i=1:m dataX_curve(i)=data_Re(peak_value(j)-k+i); dataY_curve(i)=data_Im(peak_value(j)-k+i); end plot(dataX_curve,dataY_curve,b-*); %繪制擬

9、合圓所取各點 switch j case 1 title(一階五點擬合園法); case 2 title(二階五點擬合園法); case 3 title(三階五點擬合園法); end x1=ring_X(1)+curve_R/10; %x軸繪制 y1=0; x2=ring_X(314)-curve_R/10; y2=0; point_X=x1,x2; point_Y=y1,y2; plot(point_X,point_Y,k,LineWidth,1); y1=ring_Y(157)+curve_R/10; %y軸繪制 x1=0; y2=ring_Y(471)-curve_R/10; x2=0;

10、 point_X=x1,x2; point_Y=y1,y2; plot(point_X,point_Y,k,LineWidth,1); plot(center_X,center_Y,mo); %圓心坐標 x1=ring_X(1)+curve_R/10; %圓對稱軸x y1=center_Y; x2=ring_X(314)-curve_R/10; y2=y1; point_X=x1,x2; point_Y=y1,y2; plot(point_X,point_Y,r-,LineWidth,0.8); y1=ring_Y(157)+curve_R/10; %圓對稱軸y x1=center_X; y2

11、=ring_Y(471)-curve_R/10; x2=x1; point_X=x1,x2; point_Y=y1,y2; plot(point_X,point_Y,r-,LineWidth,0.8); hold off;axis(image); 汽車配件網(wǎng) chord_angle=zeros(1,6); chord_anglem=0; for i=2:m+1 chord_angle1=atan(data_Im(peak_value(j)-k+i-1)/data_Re(peak_value(j)-k+i-1); chord_angle2=atan(data_Im(peak_value(j)-k

12、+i )/data_Re(peak_value(j)-k+i ); chord_angle(i) =abs(chord_angle2-chord_angle1); end chord_anglem,peak_num=max(chord_angle(1:5); %取得最大角度即為最大弦長位置 chord_num=peak_value(j)-k+peak_num; hold on if peak_num=5 %如果固有頻率為第5點則繪制下一點 x1=data_Re(peak_value(j)+k-1); y1=data_Im(peak_value(j)+k-1); x2=data_Re(peak_

13、value(j)+k); y2=data_Im(peak_value(j)+k); point_X=x1,x2; point_Y=y1,y2; plot(point_X,point_Y,b-*); end for i=1:3 %繪制固有頻率與圓心連線 x1=center_X; y1=center_Y; x2=data_Re(peak_value(j)-k+peak_num-i+2); y2=data_Im(peak_value(j)-k+peak_num-i+2); point_X=x1,x2; point_Y=y1,y2; plot(point_X,point_Y,b,LineWidth,0

14、.8); end江西機械 natural_FREQ(j)=(peak_value(j)-k+peak_num)*2.56; %得到各階固有頻率 pkvl_plus =(peak_value(j)+1)+(peak_value(j)-1); pkvl_divid=(peak_value(j)+1)-(peak_value(j)-1); %得到各階阻尼比 damping_ratio(j)=(pkvl_plus-2*k+2*peak_num)*pkvl_divid/2/.(peak_value(j)-k+peak_num)2*(tan(chord_angle(peak_num)/2)+tan(cho

15、rd_angle(peak_num+1)/2);end fprintf(n 各階固有頻率分別是：); %輸出各階固有頻率 disp(natural_FREQ); fprintf(n 各階阻尼比分別是 ：); %輸出各階阻尼比 disp(damping_ratio);程序清單： function center_X,center_Y,curve_R,A_mainarray=calc_curve(data_Re,data_Im,peakva) m=5; k=(m+1)/2; for i=1:m dataX_curve(i)=data_Re(peakva-k+i); dataY_curve(i)=da

16、ta_Im(peakva-k+i); end curve_A=zeros(3,3); curve_B=zeros(3,1); curve_C=zeros(3,1); curve_A(1,1)=dataX_curve*dataX_curve; curve_A(1,2)=dataX_curve*dataY_curve; curve_A(2,2)=dataY_curve*dataY_curve; for i=1:m curve_A(1,3)=curve_A(1,3)+dataX_curve(i); curve_A(2,3)=curve_A(2,3)+dataY_curve(i); curve_B(1

17、 )=curve_B(1)-dataX_curve(i)3-dataX_curve(i)*dataY_curve(i)2; curve_B(2 )=curve_B(2)-dataX_curve(i)2*dataY_curve(i)-dataY_curve(i)3; curve_B(3 )=curve_B(3)-dataX_curve(i)2 -dataY_curve(i)2; end curve_A(2,1)=curve_A(1,2); curve_A(3,1)=curve_A(1,3); curve_A(3,2)=curve_A(2,3); curve_A(3,3)=m; A_mainarr

18、ay=curve_A; curve_C=curve_Acurve_B; center_X=-curve_C(1)/2; center_Y=-curve_C(2)/2; curve_R=sqrt(center_X2+center_Y2-curve_C(3);%子程序結束結果輸出 -采用第1組數(shù)據(jù)計算- 三階峰值位置分別是： 14 326 361 各階固有頻率分別是： 35.8400 837.1200 921.6000各階阻尼比分別是 ： 1.2261 0.0025 0.0017三階擬合圓圖形：江西機械 2求各階主振型，仍然調(diào)用上述求圓心子程序程序清單：clc;file_num=4;main_ar

19、ray=zeros(file_num,3); for ks=1:file_num fid=0; while fid1 switch ks case 1 filename=wcry01.txt; case 2 filename=wcry02.txt; case 3 filename=wcry03.txt; case 4 filename=wcry04.txt; end fid,w=fopen(filename,r); if fid=-1 disp(message) end end data_all=fscanf(fid,%g); N=length(data_all); %數(shù)據(jù)長度 data_Re

20、=data_all(1:N/2); %前半段數(shù)據(jù)為實頻 data_Im=data_all(N/2+1:N); %后半段數(shù)據(jù)為虛頻 for i=1:N/2 Aw(i)=sqrt(data_Re(i)*data_Re(i)+data_Im(i)*data_Im(i); %幅頻 end peak_value=zeros(1,3); subpoint=1 40 91 130 131 170; max_data1,peak_value(1)=max(Aw(subpoint(1):subpoint(2); max_data2,peak_value(2)=max(Aw(subpoint(3):subpoin

21、t(4); max_data3,peak_value(3)=max(Aw(subpoint(5):subpoint(6); peak_value(2)=peak_value(2)+subpoint(3)-1; peak_value(3)=peak_value(3)+subpoint(5)-1; m=5; k=(m+1)/2; for j=1:3 peakva=peak_value(j); center_X,center_Y,curve_R,A_mainarray=calc_curve(data_Re,data_Im,peakva); peak_flag=1; if data_Im(peakva

22、)0; peak_flag=-1; end main_array(ks,j)=curve_R*peak_flag; end end array_max=zeros(1,3); for i=1:3 array_max(i)=main_array(4*i-2); end for i=1:3 for j=1:4 main_array(j,i)=main_array(j,i)/array_max(i); end end for i=1:3 figure plot(main_array(4*i-3):(4*i),m); hold off switch i case 1 title(一階主陣型); case 2 ti