Lightweight sensors for airframes
The air transportation industry has been responding to public concerns about pollution and climate change. Clean Sky is a multi-project joint initiative between the aviation industry and the European Commission aimed at developing and marketing new green aircraft technologies. Funded by the EU, the project 'Strain monitoring in composite stiffened panels using sensors' (STRAINMON) was part of Clean Sky. The project aimed to develop procedures for implementation of a structural health monitoring system, based on fibre-optic Bragg grating (FOBG) sensors and strain gauges. The new system was to be installed onto a carbon-fibre reinforced polymer fuselage stiffened panel. The purpose of the FOBG sensor was to monitor structural integrity of impacted and fatigued panels under compression loading. The advantage of the new technology over current monitoring systems is weight-saving. The two-member consortium ran from January to August 2012. The project set eight technical goals, amounting to defining system requirements, manufacturing a test rig and testing. Work resulted in the team developing a method for embedding the sensors in the structure, which is related to the autoclave manufacturing process. In developing the method, the group paid special attention to entry/exit points, and to definition of appropriate sensors. A suitable testing plan was developed, then associated testing rigs were designed and built. Two panels were struck with low-force impact, and subjected to static and fatigue testing using the project's system. The FOBG data matched conventional testing systems, meaning that the FOBG sensors may be an adequate alternative. STRAINMON successfully demonstrated that FOBG sensors can be integrated into composite aircraft structures, while also effectively monitoring structure strain. Use of the sensors will mean weight reduction, meaning savings on fuel and reduced pollution, and reduced maintenance intervals.
Keywords
Lightweight sensors, airframe, Clean sky, aviation industry, composite stiffened panel, structural health monitoring, fibre-optic Bragg grating, strain gauge, carbon fibre reinforced polymer, fuselage, compression loading, autoclave manufacturing
