v2_016.m

美国辛辛那提大学的振动教材

% v2_016.m   
%
% This is a script file to solve a sdof system
% given the mass, damping and stiffness terms
% in dimensionless units when the damping is varied.
% The output includes
% poles, residues (modal coefficients) and 
% frequency domain plots of the
% frequency response functions.
%
% SDOF System, Change of Damping
% Figures for UC-SDRL-CN-20-263-662, Chapter 2
 
%**********************************************************************
% 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;
pi=3.14159;
mass=input('Mass value: (10)');if isempty(mass),mass=10;end
stiff=input('Stiffness value: (1600)');if isempty(stiff),stiff=1600;end
idamp=input('Initial Damping value: (2)');if isempty(idamp),idamp=2;end
f=linspace(0,50,300);
hold off;
for i=1:10
damp=idamp + (i-1).*2
a=[mass,damp,stiff];
b=[0,0,1];
[r,p,k]=residue(b,a);
residu= r(1); 
lambda=p(1);       
xf=residu./(j.*f-lambda) + residu'./(j.*f-lambda');
semilogy(f,abs(xf))
hold on;
end
xlabel('Frequency (Rad/Sec)'),ylabel('Log Magnitude'),grid
title('Effect of Changing Damping')
if plt==1,print -f1 -deps v2_016a,end;
pause
hold off;
clg;
for i=1:10
damp=idamp + (i-1).*2
a=[mass,damp,stiff];
b=[0,0,1];
[r,p,k]=residue(b,a);
residu= r(1); 
lambda=p(1);       
xf=residu./(j.*f-lambda) + residu'./(j.*f-lambda');
scale=360.0/(2.0*pi);
plot(f,scale.*angle(xf))
hold on;
end
xlabel('Frequency (Rad/Sec)'),ylabel('Phase (Deg)'),grid
if plt==1,print -f1 -deps v2_016b,end;
hold off;