PSI - Issue 53

C.T. Duarte et al. / Procedia Structural Integrity 53 (2024) 299–308 Duarte et al./ Structural Integrity Procedia 00 (2023) 000–000

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Keywords: Additive manufacturing; multi-material; ageing; mechanical properties

1. Introduction Additive Manufacturing (AM), commonly known as 3D printing, is a manufacturing process that constructs objects by adding material, typically through layer-by-layer deposition, controlled by computer numerical commands (CNC) (Shanmugam, V. et al. 2021). AM boasts a range of characteristics that render it highly competitive, such as the ability to create geometries impossible to achieve through traditional manufacturing processes, significant reduction in raw material usage, and minimal material waste. This technology encompasses various techniques, each with specific attributes concerning materials, printing precision, speed, equipment cost, surface finish quality, among others (Syrlybayev, D. et al. 2021). With the ongoing development and widespread adoption of AM, it is now possible to create multi-material systems and multifunctional components in a single continuous step, known as Multi-material Additive Manufacturing. This approach involves combining two or more materials to enhance the overall performance of a component, expanding the applications of plastics that were previously limited by certain thermal, mechanical, or chemical characteristics (Zheng, Y. et al. 2021) (Bandyopadhyay, A. and Heer, B. 2018). The applications of 3D printing are extensive, spanning industries such as aerospace, medical, automotive, fashion and even the food industry (Ngo, T. D. et al. 2018; Cavalcanti, D. K. K., de Queiroz, H. F. M., and Banea, M. D. 2023; de Mendonça, A. et al. 2022). Its contributions also extend to the naval industry, as evidenced in the Submarine Noise Level Monitoring Project in the Pre-Salt region. In this project, researchers from the Navy Research Institute (IPqM) developed an Autonomous Submarine Signal Acquisition System (SAASS) and used 3D printing to manufacture support components. The SAASS is deployed in the sea for a period of 60 days, during which the 3D printed parts are exposed to environmental conditions. Despite the variety, the most used materials are Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA). ABS is widely adopted due to its combination of characteristics, including an appropriate melting temperature, low specific weight, and good mechanical, thermal and chemical resistance (Cavalcanti, D. K. K., de Queiroz, H. F. M., et al. 2022; Cavalcanti, D. K. K., Neto, J. S. S., et al. 2022). It is worth noting that ABS also has the advantage of significantly lower moisture absorption compared to PLA, which is a crucial factor in many applications (Kakanuru, P. and Pochiraju, K. 2020). On the other hand, PLA, being a biodegradable polymer, offers an environmentally friendly alternative to petrochemical-based polymers, with good mechanical properties, processing capability, and thermal stability. However, it is important to note that PLA can degrade more readily when exposed to high temperatures and humidity for extended periods of time (Chamas, A. et al. 2020) (Harris, M. et al. 2019) (Wickramasinghe, S., Do, T., and Tran, P. 2020). Therefore, a sandwich based structure, similar to a composite interlaminar reinforcement is feasible with a focus on decreasing water uptake and degradation (de Seixas, G. et al. 2023). Considering this context, the aim of this research is to examine the effectiveness of utilizing multi-materials in extending the lifespan of components manufactured through multi-material additive manufacturing, with a focus on the combination of PLA and ABS for maritime applications. The architecture was divided into PLA core and ABS covering sandwiches to investigate the impact of hybridization and ageing on mechanical properties.

Table 1. Mechanical properties of the materials (Cavalcanti, D., Banea, M., and Queiroz, H. d. 2020). Material Tensile strength (MPa) Flexural modulus (GPa)

Tensile strain (%)

PLA 1.75 mm ABS 1.75 mm

53 29

3.50 0.26

6

18