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Eigenvector problem with complex conjugate eigenvalues

3 Ansichten (letzte 30 Tage)
Enterprixe
Enterprixe am 8 Apr. 2017
Beantwortet: Torsten am 10 Apr. 2017
Hello, im solving here a viscous damping problem. As you can see det(A) is the equation that must be solved in order to obtain the eigenvalues of the problem. My issue is after having all 10 eigenvalues (20 with their conjugates) i do not know exactly how to make MATLAB calculate me the eigenvectors of the problem, given that im not using the 'eig' command.
M=[1 0 0 0 0 0 0 0 0 0;
0 1 0 0 0 0 0 0 0 0;
0 0 1 0 0 0 0 0 0 0;
0 0 0 1 0 0 0 0 0 0;
0 0 0 0 1 0 0 0 0 0;
0 0 0 0 0 2 0 0 0 0;
0 0 0 0 0 0 3 0 0 0;
0 0 0 0 0 0 0 3 0 0;
0 0 0 0 0 0 0 0 4 0;
0 0 0 0 0 0 0 0 0 1];
K=[1 -1 0 0 0 0 0 0 0 0;
-1 3 0 0 0 0 -2 0 0 0;
0 0 3 -1 0 0 0 -2 0 0;
0 0 -1 1 0 0 0 0 0 0;
0 0 0 0 1 -1 0 0 0 0;
0 0 0 0 -1 3 -2 0 0 0;
0 -2 0 0 0 -2 8 -4 0 0;
0 0 -2 0 0 0 -4 11 -5 0;
0 0 0 0 0 0 0 -5 10 -5;
0 0 0 0 0 0 0 0 -5 5];
F=[1 -1 0 0 0 0 0 0 0 0;
-1 2 0 0 0 0 -1 0 0 0;
0 0 0 0 0 0 0 0 0 0;
0 0 0 0 0 0 0 0 0 0;
0 0 0 0 0 0 0 0 0 0;
0 0 0 0 0 0 0 0 0 0;
0 -1 0 0 0 0 2 -1 0 0;
0 0 0 0 0 0 -1 1 0 0;
0 0 0 0 0 0 0 0 0 0;
0 0 0 0 0 0 0 0 0 0];
f=2/50;
m=8;
k=2000;
Mv=m*M;
Fv=f*F;
Kv=K*k;
syms s phi
A=s^2*Mv +s*Fv+ Kv;
r=det(A);
s=double(subs(solve(r)));
for i=1:20
A=s(i)^2*Mv +s(i)*Fv+ Kv;
eqn= A*phi==0;
Mod(i)=double(subs(solve(eqn,phi)));
end

Akzeptierte Antwort

Torsten
Torsten am 10 Apr. 2017
null(A) might help:
https://de.mathworks.com/help/matlab/ref/null.html
Best wishes
Torsten.

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