Inspection of Carbon Fibre Reinforced Polymers: 3D identification and quantification of components by X-ray CT

In this reported research activity, a quantitatively 3D characterization at microscale of a CFRP reference composite with controlled porosity was performed by micro X-ray CT (mu XCT); the results were compared with the destructive acid digestion analyses, following the procedure reported in the standard test method (ASTM D 3171 15) used to determine the composites' porosity in General Aviation (GA). The mu XCT analyses revealed a pore content of 4.37%v and identified the components, respectively, in 66%w of carbon fibres and 34%w of matrix; all obtained results demonstrated a high correspondence to the theoretical values of porosity (5.0%v) and components (67%w of carbon fibre and 33%w of polymer matrix). Instead, a not complete correspondence of the measures obtained by acid digestion was reported: 4.36%v of porosity, but 57%w of carbon fibre and 43%w of matrix. Therefore, the conformity of the mu XCT results to the theoretical values demonstrated the feasibility and distinctiveness of the proposed NDT method for a rapid and reliable inspection of CRFP components used in GA in substitution of the standard DT and time-consuming digestion procedure. The proposed NDT inspection technique permitted not only the individuation and visualization in the reconstruction of the 3D analysed material of different components (e.g. pores, carbon fibres and polymer matrix) but also the 3D evaluation of the material composition with the identification and quantification of each constituent element.

Automated summary

The reported research activity conducted a quantitatively 3D characterization of a CFRP composite with controlled porosity using micro X-ray CT, showing high correspondence with theoretical values. In contrast, results obtained through acid digestion analysis showed discrepancies with theoretical values. Therefore, the proposed NDT method demonstrated the feasibility of rapid and reliable inspection as a substitute for standard procedures.