@incollection{AlberEhehaltMarkertetal.2017, author = {Alber, Oliver and Ehehalt, Ulrich and Markert, Richard and Wegener, Georg}, title = {Experimental observations on rotor-to-stator contact}, series = {Vibration, Control and Stability of Dynamical Systems}, booktitle = {Vibration, Control and Stability of Dynamical Systems}, editor = {Awrejcewicz, Jan}, publisher = {DSTA}, address = {Lodz, Poland}, isbn = {978-83-935312-5-7}, pages = {9 -- 24}, year = {2017}, abstract = {If a flexible rotor contacts its stator, the nonlinearities induced by contact may result in a great variety of vibration phenomena. This article presents experimental results gained at test rigs. Fundamental phenomena are analyzed and discussed. First, a modular kit for rotordynamic experiments is described. The kit allows customizing the properties of rotor and stator that are relevant for the dynamic behavior. The system allows to specify target values for natural frequencies, modal damping, clearance width, contact fric- tion and others. Basic con� gurations based on this kit were used to study the in uence of mass, sti� ness and damping of both rotor and stator, contact fric- tion and misalignment of the stator on the vibration of the rotor-stator system. Extensions of the kit allowed the experimental investigation of systems with a multitude of natural frequencies, highly exible stators and even drop down and overload incidents of rotors supported by active magnetic bearings. The article also analyzes and explains the various vibration phenomena resulting from contact. In particular, resonance diagrams from run-up and run-down processes, orbit plots and frequency spectra are utilized to discuss the dynamic characteristics. The motion types encountered include not only rotor syn- chronous motions, but also multi frequency motions (forward and backward whirl), sub- and super-harmonic motions, motions including sidebands as well as chaotic motions. Emphasis is put on sensitive system parameters and on existence and stability of the various types of motion.}, language = {en} }