Sniffer tool detects surface contaminants
Adhesive bonding is a common assembly method for carbon fibre-reinforced polymers (CFRPs) in the aerospace industry. Recent research has shown contamination by different fluids severely affects mechanical properties of CFRP bonding. Detecting surface contaminants on CFRP panels before repairing bonds is thus crucial for applying efficient surface treatment. The EU-funded project 'In-field CFRP surfaces contamination assessment by artificial olfaction tool' (ICARO) developed a compact, easy-to-operate handheld tool for identifying, discriminating and quantifying potential surface contaminants. Contaminated CFRP samples could be identified before bonding and selected to undergo a further cleaning stage to avoid developing possible weak bonds. The project contributed to Europe's Clean Sky initiative for greener aircraft through use of composites to reduce weight. Mainly relying on solid-state chemical sensor arrays, the prototype electronic nose coupled their sensing capabilities with pattern recognition technologies. The latter are able to analyse the odorant fingerprint and thus perform identification and quantification tasks. Scientists investigated different sensing technologies for analysing complex gas mixtures (mainly hydraulic fluids, release agents or runway deicing fluids). They examined their capability to react to volatiles emitted by potential contaminants as well as limited drift behaviour in a controlled environment. Ad hoc pattern recognition software components were investigated, developed and trained for fast olfactive fingerprint analysis. The tool has been tested following common maintenance and repair scenarios. Results showed that that the ICARO electronic nose was affected by environmental influences in the measurement phase. However, thanks to the developed calibration methodology, it was able to distinguish among the targeted fluid substances. Named after Icarus, a character in Greek mythology, the developed prototype helped to highlight the potential role of electronic nose technology in the aerospace industry.
Keywords
Electronic nose, aerostructures, adhesive bonding, carbon fibre-reinforced polymer, surface contaminant, chemical sensor, pattern recognition
