Mechanical Degradation of 3D Printed PLA in Simulated Marine Environment

Abstract

3D printing technology is gaining continuous attention in many fields due to its suitability for designing complex parts, and naval applications are no exception. However, the real application of these parts in the marine environment is still under consideration and requires several assessments in terms of material degradation. This work evaluates the mechanical degradation of 3D printed parts in a simulated marine environment. For this purpose, the simulated seawater-environment is created, and the samples were immersed in this for 30 days. The tensile properties of these samples were estimated. A biocompatible polylactic acid (PLA) material is used to fabricate selected parts. Initially, a square block and a propeller blade are chosen for the mechanical degradation test. Thereafter, wear-incited mechanical degradation, including friction and surface deformation, of the propeller blade is investigated in detail. A high loading rate tensile test is conducted on the samples to assess the suitability of the printed parts in marine contact applications. The average calculated values of elastic modulus, yield strength and tensile stress of the sample are 1101 MPa, 36.86 MPa and 52.96 MPa. The calculated elongation at break is 7.12%. XRD results show that the partial crystallinity of the PLA material is degraded under the simulated seawater condition. The friction coefficients at the top and the bottom surface are 0.158 and 0.56. The surface wear deformation is progressed with surface roughness. The calculated values at the top and the bottom surface are 3.3 × 10-6 mm3/N-m and 6.5 × 10-6 mm3/N-m. The propeller blade's design has given an insightful understanding of wear degradation at the surface in the simulated seawater environment. Mainly, the salt content from the seawater has initiated surface degradation, which appeared as tiny pits. However, the degradation is in controlled mode, and the study is practically useful in the marine industry for contact/non-contact applications.