Evaluation of durability of 3D-printed multi-material parts for potential applications in structures exposed to marine environments

Traditional methods of manufacture require the assembly of individual components to create multi-material structures, leading to increased costs and weight, as well as potentially reduced usable lifetimes. However, there are numerous applications that cannot be realized using conventional manufacturing techniques, as they need a multi-material approach. Additive manufacturing presents a ground-breaking opportunity to fabricate components that combine diverse materials in a single part or incorporate three-dimensional gradient areas throughout the entire cross-section of the component. The utilization of additive manufacturing has transcended its initial prototype phase and has garnered attention for its potential in facilitating low-scale production of products employed across various areas, including underwater field, such as components of the underwater acoustic recorder used by the Brazilian Navy. In this study, the durability of 3D-printed multi-material parts for potential applications in structures exposed to marine environments was investigated. Multi-material sandwich structures with outer layers made of ABS and a PLA core were fabricated using a Fused Deposition Modeling (FDM) 3D printer. Three different configurations were studied, varying the number of ABS layers (one, three and five layers of ABS were used). The ageing process was carried out in seawater for 60 days. Tensile and flexural tests were used to measure the mechanical properties of both unaged (control) and aged specimens. As expected, the highest water absorption was observed in the PLA samples, while the lowest in ABS samples. For the multi-material samples the lower absorption was found for the one layer ABS samples. For the unaged samples, the mechanical properties (tensile and flexural) varied as a function of varying the number of ABS layers, while for the aged samples, a plateau tendency was observed.