Finite Elements in Rotordynamics

Equation of motion of rotating structures may be derived referring to co-rotating as well as fixed reference systems. Correspondingly, different additional matrices must be taken into account in finite element idealization. Symmetry is very important since axisymmetric as well as cyclic-symmetric structures after Coleman transformation may be investigated in fixed coordinates whereas unsymmetric rotors with isotropic support are usually studied in co-rotating coordinates. In the most general case one gets a system of equation with periodic coefficients which may be solved using Floquet's theory.