FEM, Matlab and the modes of an element

[Arjan82]

Matlab reports these eigenvectors and I do not like the way they look. If I am a first time FE coder and I experiment to see the modes, and get those shapes, NOTHING in them informs me that three of the eigenvectors would have been MORE INFORMATIVE had I seen them as pure translations and one pure rotation. How would I have known this in advance.

Well, the zero-valued eigenvalues is a big give-away... They never occur for fully constraint problems.

 

[Trying2Learn]

Well, the zero-valued eigenvalues is a big give-away... They never occur for fully constraint problems.

And, oddly, THAT was what I wanted to hear. Those last two sentences, were what I was looking for. And, now that you said them, it is obvious. I should have known that.

Thank you for patience (I know I can be stubborn -- sorry if it came across that way).

 

[Arjan82]

Well, we took some detour, but we got there in the end :) All is ok!