PSI - Issue 68

Ibrahim T. Teke et al. / Procedia Structural Integrity 68 (2025) 365–371 I. T. Teke & A. H. Ertas/ Structural Integrity Procedia 00 (2025) 000–000

366

2

1. Main text Current research on the fatigue behavior of plastic components produced via 3D additive manufacturing is primarily centered on optimizing structural performance and refining key manufacturing parameters. These parameters include infill pattern, toolpath, nozzle temperature, bed temperature, and extrusion speed, all of which are crucial for enhancing production quality and achieving process standardization. Such advancements hold significant importance across various industries—ranging from mechanical and industrial sectors to automotive and biomedical fields—where the use of standardized fatigue specimens with simple geometries is essential for ensuring reliable and reproducible results. Advancements in surgical procedures and implant technologies also require a comprehensive understanding of tissue fatigue properties, which can be assessed through cyclic testing. Consequently, numerous studies have been conducted to investigate these properties, aiming to improve the long-term performance and reliability of biomedical implants. For instance, a novel 3D-printed clamp design has successfully standardized tendon fatigue tests, offering valuable insights into tendon behavior and enhancing surgical outcomes, which is achieved by Scholze et al. (2022). Additionally, Wang et al. (2023) 3D printing is extensively utilized in creating bone scaffolds for tissue engineering, where the fatigue behavior of scaffolds—shaped by their material properties, porosity, and interconnectivity—plays a pivotal role in their durability under cyclic loads. Bakhtiari et al. (2024) explored the mechanical and fatigue performance of 3D-printed PLA scaffolds, discovering that the Gyroid design offers superior compressive and fatigue strength, while the Voronoi design exhibits enhanced fatigue resistance at lower strengths. Ezeh and Susmel (2019) investigated the fatigue strength of PLA parts produced by fused filament fabrication (FFF), noting that the manufacturing direction has minimal impact on fatigue behavior. They concluded that PLA could be treated as a homogeneous material in fatigue design, with superimposed static stresses effectively assessed by the maximum stress in the cycle. Further research is suggested to explore the impact of infill levels and other key 3D printing variables on the fatigue strength of PLA components. Dolzyk and Jung (2019) examined the tensile and fatigue behavior of PETG parts made using FFF, finding that PETG exhibits competitive mechanical properties and reduced anisotropy across different build orientations, with longitudinally oriented specimens displaying the highest tensile strength and fatigue life. Akhoundi and Ouzah (2023) analyzed the effects of layer height, nozzle temperature, infill percentage, and bed temperature on the fatigue life of PLA parts made using extrusion-based 3D printing. They identified optimal settings—0.3 mm layer height, 220°C nozzle temperature, 100% infill, and 60°C bed temperature—that significantly influence fatigue life, as supported by both experimental results and finite element simulations. Prabakaran et al. (2023) assessed the fatigue behavior of Acrylonitrile Styrene Acrylate (ASA) parts manufactured using FFF, concluding that fatigue life improves with higher infill density, with a 100% infill density and line infill pattern providing the best performance. Cerda-Avila and Medellin-Castillo (2023) explored the impact of infill percentage and build orientation on the fatigue behavior of PLA parts produced using FFF. They found that higher infill percentages enhance fatigue strength, while upright build orientations lead to weaker fatigue properties. A new predictive model was developed to estimate the stress-life performance of PLA-FFF components based on process parameters, aiding in the design of 3D printed parts with improved fatigue resistance. Gomez-Gras et al. (2018) focused on the effects of fill density, nozzle diameter, layer height, and printing speed on the fatigue performance of PLA parts made using FFF. They concluded that fill density had the most significant impact on fatigue life, followed by nozzle diameter and layer height, with the honeycomb in-fill pattern extending the lifespan of printed parts. Alaghabed et al. (2024) examined the tensile and fatigue performance of Tough PLA components produced via FFF, emphasizing the influence of infill pattern, infill density, and localized reinforcement. They found that higher infill density significantly enhances tensile strength and Young’s modulus, with the grid infill pattern without modifiers offering the best fatigue life. Frascio et al. (2018) explored the fatigue behavior of ABS components produced using fused deposition modeling (FDM), noting that stress ratio significantly impacts fatigue strength, though deposition direction has a less pronounced effect. Despite typical additive manufacturing defects, the scatter in fatigue data was within reasonable limits. Jimenez-Martinez et al. (2023) aimed to enhance the understanding of fatigue behavior in 3D-printed PLA components, identifying that a 45° raster angle provides optimal fatigue performance under specific load conditions. They also observed that fatigue cracks can originate from the 3D-printed bed, even with 100% infill, due to internal voids. Singla et al. (2023) examined the effect