Non-destructive inspection of CFRP-based aircraft composite elements by X-ray computed tomography

Nowadays, Carbon Fibre Reinforced Polymer (CFRP)-based composites are becoming increasingly widespread in safety-critical components, e.g. load-carrying structures in transportation, such as aviation, due to their good structural performance and excellent lightweight potential. Thus, robust and reliable non-destructive testing (NDT) methods to inspect CFRP-based composites are essential to reduce safety concerns and maintenance costs. Currently, to certify elements to be used for aircrafts the international regulation applies the standard ASTM D 3171-15 test method, based on destructive acid digestion technique, to evaluate the components content and, indirectly, the porosity in the composite element. In this context, the present study demonstrates the versatility, effectiveness and reliability of X-ray computed tomography (CT) as NDT inspection method to evaluate different configurations of aircraft CFRP-based composite elements. X-ray CT provides at the microscale level the individuation and the identification in the reconstructed 3D analysed material of different components (e.g. pores, carbon fibres and polymer matrix), and also the quantification of each detected element.