Experimental investigation on 3D printed lightweight sandwich structures for energy absorption aerospace applications

One of the ongoing challenges in aeronautics is the development of increasingly lighter structures. This has become a crucial goal because structural lightening means improving aircraft performance in terms of speed, manoeuvrability, fuel efficiency, and at the same time reducing manufacturing and service costs. The aerospace industry continues to focus more and more on this goal and every improvement in technology and materials can bring significant advantages in performance, efficiency, and safety of aircraft. The present work is part of this framework, as it analyses the feasibility of achieving very high weight reduction in sandwich panels using a new manufacturing approach. It introduces an experimental limited sensitivity analysis on the mechanical responses of composite sandwich structures for shock -absorption applications lightened by appropriately setting a specific additive manufacturing process parameter: the infill value. The investigated sandwich structures are characterised by a core Designed for Additive Manufacturing (DfAM) in order to maximise their performance in terms of energy-to-weight ratio and damping of impact loads. The material chosen for the inner part of the sandwich structure (core and internal face sheets) is polypropylene (PP) while the external face sheets are in Carbon Fibre Reinforced Polymers (CFRP). By comparing the post-impact responses at 20 J impact of three sandwich configurations with the same external shape but different material layer densities related to different setting of the infill parameter in the frame of the printing process, the work proves that this approach leads to lightening of this specific sandwich structures by up to 28% and at the same time improves their structural effectiveness in terms of energy absorption characteristics. The comparison was made by relating specific absorption indices, force-time and force-displacement graphs and CT scans. (c) 2023 Elsevier Masson SAS. All rights reserved.