3. Influence of thermoplastic nodules on drilling quality

In this section, we focus on the analysis of drilling machining quality on two types of composite materials. The two types of material studied are carbon/epoxy prepregs. The elementary constituents of the laminated structures are supplied by Hexcel Composites and are referenced respectively, UD T2H 268 150 EH25 NS 35% (noted EH25-T2H) with a fiber content of 58% and an average ply thickness of 0.25 mm and HexPLY UDT 700GC 268 M21 34% (noted M21-T700GC) with a fiber content of 58% and an average ply thickness of 0.26 mm. These two products are roughly equivalent in terms of elastic properties (Young's modulus, Poisson's ratio). However, M21-T700GC is distinguished by the presence of thermoplastic nodules at the interplies, averaging 20 m in diameter and representing around 13% of the matrix mass in the prepreg. The function of these nodules is to initiate crack networks at the interface...