I think in the simplified calculation the moment of inertia should be taken to be I = 1/3 M L^2 where M = 272.5 is the total mass of the structure. Then K/I = 3K/(ML^2) = 66.97, which is close to the value given by Elmer.
-- Mika
I think in the simplified calculation the moment of inertia should be taken to be I = 1/3 M L^2 where M = 272.5 is the total mass of the structure. Then K/I = 3K/(ML^2) = 66.97, which is close to the value given by Elmer.
Springs and DOFs are enumerated in the same way. To understand the enumeration, the "rotational" DOFs should not be thought of as (approximate) rotations, but in the first place they just give the components of the partial derivative of the displacement field with respect to the normal coordinate, with the components being evaluated with respect to the basis of the global coordinate frame.