Detection and quantification of composite surface contaminants with an e-nose for fast and reliable pre-bond quality assessment of aircraft components.

Composite Fiber Reinforced Polymers (CFRP) are at the basis of the so called green aircraft production. In order to exploit the full potential of CFRPs for lightweight structures in aeronautic industry, there is a strong need to apply adhesive bonding as the appropriate joining technology to load-critical CFRP primary structures. Up to now, it is not possible to reach this important goal because of the unavailability of an adequate quality assurance concept (e.g. pre-bond surface inspection) which guarantees the safety of the adhesive joint and therefore enables certification. Surface contamination is a primary concern for joint quality severely limiting the robustness of the adhesion.In this work we show how an electronic nose solution could be designed and used as a non-destructive tool for pre-bond surface inspection. An ad-hoc pattern recognition system is also devised for ensuring a fast and reliable assessment of contamination status by combining real time classifiers and implementing a reject option. Results show that e-nose can be a reliable choice for a first line low cost NDT tool in aerospace CFRP assembly and maintenance scenarios.