Role of the Wall Layer in 3D-Printed Composites under the Salt Spray Condition

Abstract

While the mechanical strength of 3D-printed composites is an area of active research, few studies have considered their application to the marine industry. In particular, the role of wall layers is an issue because of their lack of the contribution to the mechanical strength although they help prevent water penetration. In this study, experiments were performed to investigate the effects of salt spray exposure on the mechanical strength of continuous fiber 3D-printed composites with and without the wall layer. Specimens were printed using continuous fiber filaments in the same direction as the loading direction with and without a wall layer. The period of salt spray exposure was set to 15 and 30 days, and the saltwater absorption rate was calculated for each specimen. Tensile tests were performed to determine the effect of the exposure period on the tensile modulus and strength. The results showed that the tensile strength decreased with an increasing exposure period and that the presence of the wall layer reduced the rate of decrease in the mechanical strength. The results confirmed that a wall layer prevents the penetration of saltwater, which may facilitate the potential application of 3D-printed composites in the marine industry.