Rotordynamics

The rotor dynamics combines the disciplines of solid state dynamics of rotors, the dynamics of the flow processes in the lubricating gap of bearings as well as in the use of active magnetic bearings, the dynamic mechatronic systems.

The rotor dynamics describes, among other things:

• The amplitude increases in the relative shaft vibration during acceleration and deceleration of rotor - bearing systems. Due to the rotary- (1X ) unbalance excitation resonances at so-called critical speeds are passed through.
• Resonance states with excitation of a rotor by a plurality of speed harmonics. If, for example, a rotor excited by the unbalance drehfrequent (1X ) and by a single face crack at twice the rotational frequency ( 2X ), so there is also resonance at half value of each critical speed. The blades axial turbomachinery and disc-shaped components of steam turbine rotors ( screen vibration) can be excited by much higher speed harmonic in resonance.
• Increase of rotor natural frequencies by the gyroscopic effect of disc-shaped components of rotors and radial impellers. Change of rotor natural frequencies and mode shapes of the rotational speed by the rotational speed depending on the rigidity of the sliding bearing.
• The occurrence of subsynchronous portions of the wave oscillation in achieving and exceeding the stability limit at which the unbalance excited (ie drehfrequente ) wave oscillation is unstable.

The rotor dynamics took a sharp upturn as a technical science with the development and production of steam turbine end of the 19th century. Problems of rotor dynamics had to be solved not only in the development of thermal and hydraulic turbomachinery, but occurred eg also in the development of centrifuges, high speed spindles of spinning machines, with air bearing spindles of drills in dental technology, and in recent decades in the development of hard disk drives on.