Numerical and experimental modal analysis of structures under gyroscopic influence in ALE formulation

A test set-up for the modal analysis of gyroscopic, rotationally symmetric systems is presented. It employs laser Doppler vibrometry along with automatic impulse excitation installed on a rotary table and is applied to a glass structure rotating about its figure axis. The effects of gyroscopic influences on the modal behaviour such as the split of eigenfrequencies and the treatment of complex eigenmodes as travelling waves are deduced analytically and shown experimentally. Finally numerical computations using the Arbitrary-Lagrangian-Eulerian (ALE) finite element formulation separating the rigid body rotation from the mesh deformation are conducted. With the combination of analytical, experimental and numerical analysis a broad overview of modal characteristics of gyroscopic systems is given.