Problem when calculate the eigenvector of a pure bending beam.
Hi developer,
I am able to use arpack solver to calculate the correct eigenvectors of a beam. But when I apply y-symmetric constraint (y = 0, R1 = R3 = 0) by many total joints (supposes to have only pure vertical bending, no torsion), no eigenvectors will show anymore. The total joints I apply are shown in the figure, every node at the beam is constrained at y, R1 and R3 with the reference nodes.
I can't figure out why, could you give me any tips on how to calculate the eigenvector of a pure bending beam. BTW I use a general three-node beam, linear viscoelastic generic material.
Thank you for your help. If you need my test cases please let me know.