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

Abstract

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.