v2_001.m

美国辛辛那提大学的振动教材

% v2_001.m   
%
% This is a script file to solve a sdof system
% given the mass, damping and stiffness terms
% in dimensionless units.  The output includes
% poles, residues (modal coefficients) and both
% time and frequency domain plots of the impulse
% frequency response functions.
 
%**********************************************************************
% Author: Randall J. Allemang
% Date:	18-Apr-94
% Structural Dynamics Research Lab
% University of Cincinnati
% Cincinnati, Ohio  45221-0072
% TEL:  [phone]
% FAX:  [phone]
% E-MAIL: [e-mail]
%*********************************************************************
%
clg, clear
plt=input('Store plots to file (Yes=1): (0)');if isempty(plt),plt=0;end;
mass=input('Mass value: (10)');if isempty(mass), mass=10;end;
stiff=input('Stiffness value: (16000)');if isempty(stiff),stiff=16000;end;
damp=input('Damping value: (10)'); if isempty(damp),damp=10;end;
f=linspace(0,150,500);
H=1.0./((-mass.*f.*f+stiff)+j.*damp.*f);
plot(f,real(H))
pause
plot(f,imag(H))
pause
clear f,H;
pause
a=[mass,damp,stiff]
b=[0,0,1]
[r,p,k]=residue(b,a)
residue = r(1)  
lambda=p(1)        
whos
pause(2)
t=linspace(0,5,500);
xt=residue./2*exp(lambda.*t) + residue'./2*exp(lambda'.*t);
plot(t,xt)
xlabel('Time (Sec.)'),ylabel('Amplitude'),grid
if plt==1,print -deps v2_001a.eps, end;
pause
clear t,xt;
f=linspace(0,150,500);
xf=residue./(j.*f-lambda) + residue'./(j.*f-lambda');
plot(f,abs(xf))
xlabel('Frequency (Hz)'),ylabel('Magnitude'),grid
if plt==1,print -deps v2_001b.eps, end;
pause
semilogy(f,abs(xf))
xlabel('Frequency (Hz)'),ylabel('Log Magnitude'),grid
if plt==1,print -deps v2_001c.eps, end;
pause
plot(f,360./(2.*pi).*angle(xf))
xlabel('Frequency (Hz)'),ylabel('Phase (Deg)'),grid
if plt==1,print -deps v2_001d.eps, end;
pause
plot(f,360./(2.*pi).*angle(xf))
xlabel('Frequency (Hz)'),ylabel('Phase (Deg)'),grid
if plt==1,print -deps v2_001e.eps, end;
pause
plot(f,real(xf))
xlabel('Frequency (Hz)'),ylabel('Real'),grid
if plt==1,print -deps v2_001f.eps, end;
pause
plot(f,imag(xf))
xlabel('Frequency (Hz)'),ylabel('Imaginary'),grid
if plt==1,print -deps v2_001g.eps, end;