Fibre-optic measurement of strain and shape on a helicopter rotor blade during a ground run: 2. Measurement of shape

Abstract Optical fibre strain and shape measurement sensors were deployed on a rotor blade during full-speed helicopter ground run, with real-time data wirelessly streamed from hub-mounted sensor interrogators. In part 2 of 2-part paper series, two-dimensional direct fibre-optic sensing (DFOSS), using segment interferometry-based interrogation is investigated. The concept change visualisation over one rotation period displacement surfaces introduced the usefulness DFOSS to gain additional insights by determining operational modal frequencies independently for both horizontal vertical vibration directions demonstrated.