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

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

Automated summary

This paper investigates the application of optical fibre strain and shape measurement sensors on a rotor blade during a full-speed helicopter ground run. Real-time data is wirelessly streamed from rotor hub-mounted sensor interrogators, and two-dimensional direct fibre-optic shape sensing (DFOSS) using fibre segment interferometry-based interrogation is explored. The concept of visualizing blade shape change over one rotation period using rotation displacement surfaces is introduced, and the usefulness of DFOSS data in determining operational modal frequencies independently for both horizontal and vertical vibration directions of the blade is demonstrated.