ABSTRACT
Evaluating the dynamic properties of rotor systems in an early design stage requires simulation. At the Chair of Applied Mechanics at the Technical University of Munich, the rotor simulation program AMrotor was developed using Timoshenko-beam elements to discretize the rotor. Components with non-linear reaction forces can be added on the right-hand side of the equation to the external loads. This requires considering the differential equations in the time domain. In order to get an approximate solution, direct time integration is used, as it is applicable for systems with general excitation.
In this work, different time integration schemes are applied to a rotor system and validated with experimental results from an academic test rig.
Examples of Runge-Kutta, backward differentiation formula and Newmark methods are implemented in the rotor simulation program. The methods are compared using Fourier transforms of resulting displacements and validated using experimental frequency response functions.
Experiments are performed on a rotor test rig, which consists of a simple rotor levitating in active magnetic bearings. A discrete PID controller, which is included in the simulation, controls the electric current in the electromagnets to stabilize the rotor.
This discussion helps the user of a finite element rotor simulation code to decide for a suitable time integration method. Finding a fast and reliable integration method can drastically improve the simulation speed, making the code suitable for real-time simulation. In a next step, the code may be used for real-time hybrid sub-structuring (Hardware-in-the-Loop).
