Adaptive or morphing capable aircraft wings and wing sections have been proved to deliver better adaptability, reliability and overall efficiency throughout their flight regime. Their capability of enhancing flight performance has attracted researchers to explore new designs and methods for morphing. Morphing wings can be customized for improved performance based on flight requirements as opposed to conventional fixed wings. This work is part of the Smart-X project that deals with the in-flight performance optimisation, load alleviation and flight dynamic control of a smart morphing wing. This research describes the design and implementation of load monitoring and shape sensing technology for the Smart-X morphing wing demonstrator with the objective to understand better the performance of the morphing wing.

Many shape sensing methods have been developed over the years with technologies including fibre optics, piezoelectric and visual methods like fringe projection. Among them, optical fibre based sensors are preferred not only in the field of aerospace but also for civil engineering, oil and gas and medical applications. Over other shape sensing methods, fibre optic sensing has advantages including being light weight and flexible, immune to EMI and having a discreet profile when being either surface mounted or embedded in the structure. Their shape sensing capabilities have been extensively reported. The current state of the art for shape estimation using optical fibres are distributed fibre optic sensors, multiple fibre sensing or multiple fibre core sensing. These techniques tend to either require expensive interrogators or intricate fibre optic manufacturing methods. On the other hand, the method proposed in this research uses a standard single core fibre Bragg grating (FBG) sensor and is also configured with the least amount of sensors making it comparatively inexpensive.

The fibre optic method presented in this work combines the hybrid interferometry and FBG spectral sensing principle as reported in our earlier work. The shape sensing analysis involves the usage of an initial calibration procedure followed by a novel algorithm for the required parameter estimation.

The test specimen is a composite 1.8 m morphing wing demonstrator manufactured as part of the Smart-X project. It features 6 independent morphing trailing edge sections with optical fibres running through each of them. These sections are allowed to deflect up to 30 mm while allowing a rotation of 40 degrees at the root of the trailing edge.  Another set of fibres ran along the span of the wing . The small design space and multiple fibres posed a challenge for the sensor layout. The wing was tested in the Open Jet Facility (OJF) low-speed wind tunnel, up to a speed of 35 m/s. 

The end result of these tests was to determine the deflection and shape of the morphing trailing edge sections. This was carried out with a focus on bending and torsional deformations of each of the separate sections as well as the wing as a whole due to static and dynamic loading. A successful wind tunnel test was conducted where the response of the sensors were recorded with respect to the morphing. The results of finite element modelling were compared with the wind-tunnel tests and an analysis was made of the displacement and shape estimation capabilities of the novel shape sensing system.


Multi-Modal Fibre Optic Shape Sensing for the Smart-X Morphing Wing Demonstrator

Division / Sponsors: 
Aerospace Division

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2020/volume/84027

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