Topological Optimization of 3D Printed Nylon: Influence of Infill on Fatigue, UTS, and Porosity

ABSTRACT In this study, the fatigue behavior of Nylon PA66 manufactured by 3D printing was evaluated using three commercial standard infill patterns (hexagonal, concentric, and linear) and two proprietary topological design patterns (hexagonal–concentric and hexagonal–linear) developed in CAD. All samples maintained a constant 80% infill and the same weight. Two designs of experiments (DOE) and ANOVA analysis were applied to optimize the tensile strength, minimize the porosity, and design optimized geometries by combining single patterns. Increasing the nozzle temperature from 260°C to 280°C improved the UTS by 33%. In terms of fatigue performance, both topological patterns exceeded one million cycles at 5 Hz when the applied load did not exceed 60% of the UTS, demonstrating a remarkable improvement in the behavior of the material. These results underline the influence of internal topological infill design on the mechanical strength of Nylon PA66 under static and dynamic loads but considering a statistical reliability approach.