Fiber-Optic Strain Gauge Calibration And Dynamic Flexibility Transfer Function Identification In Magnetic Bearings

Historical attempts to measure forces in magnetic bearings (MBs) have experienced limited success as a result of relatively high uncertainties. Recent advances in strain-gauge technology have provided a new method for measuring MB forces. Fiber-optic strain gauges (FOSGs) are roughly 100 times more sensitive than conventional strain gauges and are not affected by electro-magnetic interference. At the Texas A&M University (TAMU) Turbomachinery Laboratory, installing FOSGs in MBs has produced force measurements with low uncertainties. Dynamic flexibility transfer functions (DFTFs) exhibiting noticeable gyroscopic coupling have been identified and compared with finite element predictions. Comparison has verified the effectiveness of using MBs as calibrated exciters in rotordynamic testing. Many applications including opportunities for testing unexplained rotordynamic phenomena are now feasible.