Efficient way to extract eigenvalues/eigenvector matrices
Efficient way to extract eigenvalues/eigenvector matrices
(OP)
Greetings,
I am working with large Abaqus model and I need to extract its eigenquantities and import them into MATLAB.
Is there an efficient way to do this?
So far I have extracted the Mass and Stiffness matrices (keywords *MATRIX GENERATE and *MATRIX OUTPUT), imported them into MATLAB (via bespoke script), applied boundary conditions and use matlab's EIGS to extract the eigenquantities, but this process is slow and prone to errors.
I would like to import those quantities directly from abaqus. I am already able to print nodal outputs in the *.dat file but again, this approach generates a huge structured data file that has to be parsed. Also, I am not sure about the DOFS convention and thus I do not know if the first 6 elements of an eigenvector are the 6DOFs of the first node, the second 6 elements are the 6DOFs of the second node, etc.
Can you please advise on a method that could let me import those quantities in the least painful way?
Thank you in advance.
I am working with large Abaqus model and I need to extract its eigenquantities and import them into MATLAB.
Is there an efficient way to do this?
So far I have extracted the Mass and Stiffness matrices (keywords *MATRIX GENERATE and *MATRIX OUTPUT), imported them into MATLAB (via bespoke script), applied boundary conditions and use matlab's EIGS to extract the eigenquantities, but this process is slow and prone to errors.
I would like to import those quantities directly from abaqus. I am already able to print nodal outputs in the *.dat file but again, this approach generates a huge structured data file that has to be parsed. Also, I am not sure about the DOFS convention and thus I do not know if the first 6 elements of an eigenvector are the 6DOFs of the first node, the second 6 elements are the 6DOFs of the second node, etc.
Can you please advise on a method that could let me import those quantities in the least painful way?
Thank you in advance.





RE: Efficient way to extract eigenvalues/eigenvector matrices
From what I remember, Abaqus does not have the standard capabilities of QR, Householder, etc, but I find that the Lanczos solver is quite fast if you specify a reasonable frequency range and number of eigenvalues to be extracted.
RE: Efficient way to extract eigenvalues/eigenvector matrices
I am doing this because I could not find an efficient way to export eigenvalues and eigenvectors in a readily digestible format. Thus, the question.
Thank you for the interest!
RE: Efficient way to extract eigenvalues/eigenvector matrices
The eigenvalues should be easy to automate to extract from the standard output using python, as for the eigenvectors, I honestly have never looked where/how they are stored.
RE: Efficient way to extract eigenvalues/eigenvector matrices