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mass and stiffness matrix
Posted Sep 26, 2016, 6:55 p.m. EDT 0 Replies
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I am trying to work with the mass and stiffness matrices exported from a COMSOL model to MATLAB. I have done the Frequency domain analysis (sol1) and Eigenfrequency analysis (sol2). In order to analyse the matrices I have calculated the eigenvalues and compare with those obtained in the eigenfrequency study, but I have found two problems:
- The mass matrix exported from the Frequency Domain study (sol1) is null. Is ther any parameter to set in the study to obtain this matrix?.
- The eigenfrequencies calculated in MATLAB do not match with those obtained in the Eigenfrequency analysis (sol2). I have used the following script:
model=mphload('bars.mph');
MA = mphmatrix(model,'sol2','out',{'K','E'});
K = MA.K;
M = MA.E;
K1 = MA1.K;
M1 = MA1.E;
Kf = full(K);
Mf = full(M);
lambda = real(eig(Kf,Mf));
omega = sqrt(lambda);
f = omega/(2*pi);
f_sorted = sort(real(f));
I will appreciate your assistance,
Kind regards,
Diego
Hello Diego Calero
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