[132] Fibre Bragg gratings (FBGs) for I2BS for the UHPE ground test demonstrator
L Wang1, C Holmes1, N Grabham1, T Harvey1, A Weddell1, N White1, D Mouradian2 and T Endres3
1University of Southampton, UK
2Safran Aircraft Engines, France
3Schaeffler Aerospace, Germany
As part of the Clean Sky 2 Integrated Intelligent Bearing Systems (I2BS) project, fibre Bragg gratings (FBGs) have been designed and implemented on full-scale smart bearings to explore its feasibility in monitoring strain changes around the bearing outer ring during flight cycle testing. By monitoring local strain changes around the whole bearing ring, in close proximity to the ball-raceway contacts, it is envisaged that better prediction of bearing health can be achieved. Bragg gratings of uniform apodisation have been direct UV laser written into GF4A photosensitive optical fibre, with a fluence of 1 kJ cm–2 and a length of 5 mm. The optical fibre contains 12 spectrally multiplexed Bragg gratings that are spatially separated by 65 mm and spectrally separated by 5 nm. Integration of the fibre onto the bearing outer ring has been realised through embedding the optical fibre within a groove on the ring and back filling it with epoxy. In addition to the FBGs, the smart bearings are incorporated with multiple sensors including accelerometers, thermocouples and strain gauges to validate the measurements. Smart bearings with and without seeded defects on their inner rings have been tested under simulated UHPE engine flight cycles where axial load and speed vary. The paper focuses on the FBG development and their responses to bearing condition changes. Details of the experimental work and the test results will be presented at the conference.
