Title
Spatially Resolved Experimental Modal Analysis On High-Speed Composite Rotors Using A Non-Contact, Non-Rotating Sensor
Abstract
Due to their lightweight properties, fiber-reinforced composites are well suited for large and fast rotating structures, such as fan blades in turbomachines. To investigate rotor safety and performance, in situ measurements of the structural dynamic behaviour must be performed during rotating conditions. An approach to measuring spatially resolved vibration responses of a rotating structure with a non-contact, non-rotating sensor is investigated here. The resulting spectra can be assigned to specific locations on the structure and have similar properties to the spectra measured with co-rotating sensors, such as strain gauges. The sampling frequency is increased by performing consecutive measurements with a constant excitation function and varying time delays. The method allows for a paradigm shift to unambiguous identification of natural frequencies and mode shapes with arbitrary rotor shapes and excitation functions without the need for co-rotating sensors. Deflection measurements on a glass fiber-reinforced polymer disk were performed with a diffraction grating-based sensor system at 40 measurement points with an uncertainty below 15 mu rad and a commercial triangulation sensor at 200 measurement points at surface speeds up to 300 m/s. A rotation-induced increase of two natural frequencies was measured, and their mode shapes were derived at the corresponding rotational speeds. A strain gauge was used for validation.
Year
DOI
Venue
2021
10.3390/s21144705
SENSORS
Keywords
DocType
Volume
experimental modal analysis, modal testing, rotating frame, stationary frame, rotor dynamics, rotating structures, optical measurement, diffraction grating sensor
Journal
21
Issue
ISSN
Citations 
14
1424-8220
0
PageRank 
References 
Authors
0.34
0
6
Name
Order
Citations
PageRank
Julian Lich100.34
Tino Wollmann200.68
Angelos Filippatos302.03
Maik Gude402.37
Juergen Czarske500.34
Robert Kuschmierz600.68