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matlab script to resolve free vibration analysis

matlab script to resolve free vibration analysis

matlab script to resolve free vibration analysis

(OP)


can some one help me to extend the matlab script in below (which give the solution of dynamic system (2x2)) to resolve system (33x33)


mt=[0 0 30 0;0,0,0,50;30,0,0,0;0,50,0,80];
kt=[-40,0,0,0;0,-50,0,0;0,0,35000,-25000;0,0,-25000, 4000];
Z=inv(mt)*kt;
[V,D]=eig(Z);
disp('Eigenvalues')
DS=[D(1,1),D(2,2),D(3,3),D(4,4)]
disp('Eigenvectors')
V
x0=[0;0;0.01;0];
S=inv(V)*x0;
tk=linspace(0,2,101);
for k=1:101
t=tk(k);
for i=3:4
x(k,i-2)=0;
for j=1:4
x(k,i-2)=x(k,i-2)+(real(S(j))*real(V(i,j))
-imag(S(j))*imag(V(i,j)))*cos(imag(D(j,j))*t);
x(k,i-2)=x(k,i-2)+(imag(S(j))*real(V(i,j))-imag(S(j))*imag(V(i,j)))
*sin(imag(V(i,j))*t);
x(k,i-2)=x(k,i-2)*exp(-real(D(j,j))*t);
end
end
end
plot(tk,x(:,1),'-',tk,x(:,2),':')
title('Free Vibration response of damped system')
xlabel('t (sec)')




Thanks

RE: matlab script to resolve free vibration analysis

3x3 you mean?

RE: matlab script to resolve free vibration analysis

(OP)
I m trying to resolve a problem of simple portale frame restrained at base were each bar is descritized to 4 element (11 node X 3ddl=33 subject to dynamic load, so we can reduce the problem if the bar have just 2 node in this case with the two restrained node at base we can reduce the problem to 6X6
I have no symetric masse (consistent masse) and general viscous dumping

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