Autori: E.Dilonardo, M. Nacucchi, F.De Pascalis, M.Zarrelli, C.Giannini 
Rivista: Composites Science and Technology Elsevier Ltd.
Anno di Pubblicazione: 2019
Volume:    Volume 113-2015

Nowadays, in the aircraft sector, the continuous request of lighter components, necessary to reduce energy consumption and production costs, has motivated the replacement of ferrous and non-ferrous materials with polymer-based composites. With these purposes, fewer components and boltless assembly through the large-scale one-shot construction using carbon fibre-reinforced plastic (CFRP) have been developed. Specifically, beyond the use of only a CFRP monolithic core, for some parts of large-scale construction and particular loading conditions, the application of a sandwich structure results to be more effective. The aim of the current study was to develop a versatile, non-destructive (ND) inspection strategy to evaluate the structure of two different aircraft composite configurations which are widely used for structural elements, respectively layered composite and sandwich structure. X-ray computed tomography (CT) has been proposed as a flexible method for assessment of porosity levels in CFRP components in both types of configuration, permitting to investigate the volume distribution of the individuated pores/voids, giving an interactive 3D exploration and quantitative analysis of porosity by the complete 3D volume rendering of the analysed composites. Moreover, specific data analysis could supply detailed information on size, shape and position of pores or defect or misalignment which could be a valuable indication for damage tolerant design methodology or local stress analysis. This presented non-destructive approach based on CT can be a good alternative to standard destructive methods based on the acid digestion or 2D microscopy for porosity evaluation in composite, especially for severe stressed element in aerospace structure. Of course, the X-ray nano- CT cannot substitute the ultrasounds test for analysing full scale components, but it can be complementary to ultrasounds to provide accurate quantitative results on small samples used as references.