Non-planar material-extrusion additive manufacturing of multifunctional sandwich structures using carbon-reinforced polyetheretherketone (PEEK)

Additive Manufacturing (AM), and especially Material -Extrusion Additive Manufacturing (MEAM), can provide light structures with high mechanical performances for aerospace applications using fiber reinforced hightemperature resistant thermoplastics (HTRT). Non -planar AM allows to manufacture curved parts with a better approximation of their curvature than cartesian AM. In this paper, we additively manufactured a proof of concept of multi-functional non -planar sandwich panel for aircraft casing using a 6-degree of freedom (6-DOF) robotic platform in a custom heating enclosure, using 30 wt% carbon-reinforced polyetheretherketone (PEEK). Curved beams manufactured using planar and non -planar deposition techniques were manufactured using a custom heating enclosure and reinforced HTRT. The measured surface deviation of the non -planar curved beam (NPCB) was 31% lower than the planar curved beam (PCB). Due to the non -planar deposition that led to a better alignment of the layers along the specimen, the effective stiffness measured during 3 -point bending tests was also increased by similar to 28% compared to PCB, showing the importance of a non -planar deposition. Additively manufactured non -planar sandwich panels containing an acoustic core and two types of microscaffolds (30% infill microscaffold and 74% infill walled microscaffold) were characterized through optical microscopy and 3 -dimension (3D) scanner measurements. The 6-DOF robotic platform, combined to the heating enclosure, allowed to print a portion of a non -planar carbon fiber reinforced PEEK sandwich panel to present the versatility of the structures that could be printed with this setup. The use of non -planar reinforced HTRT structures could find applications in the aerospace field for aircraft noise reduction structures, but also in the biomedical domain for the manufacturing of biocompatible PEEK scaffolds.