Exploring the Synergistic Effects of Combined Infill Patterns in Fused Deposition Modeling (FDM) for Enhanced Mechanical Performance
Authors: Gill Nathan , Millard Max , Sparks Brennan , Ren Ping 
Published: August 2024

Abstract
Fused Deposition Modeling (FDM) 3D printing is a widely utilized additive manufacturing method that finds widespread application in diverse industrial sectors. The incorporation and arrangement of infill structures have a substantial impact on the mechanical characteristics of objects fabricated by FDM. A multitude of scholarly investigations have thoroughly examined the effects of various infill structures and infill ratios on structural properties. Nonetheless, there exists a noticeable gap in research regarding the consequences of incorporating many infill structures inside a singular constituent produced through 3D printing.
The aim of this study is to address the current research gap by investigating the impact of different combinations of infill structures on the mechanical properties of 3D-printed objects, with a particular focus on the commonly used Polylactic Acid (PLA) material. PLA is selected as a suitable material owing to its biodegradable nature, user-friendly characteristics, and extensive acceptance, rendering it a pertinent choice for a diverse array of applications.
This research focuses on evaluating ASTM Type VI dogbone-shaped samples featuring 25 unique infill structures. These structures result from various combinations of five prevalent infill patterns: lines, cubic, triangles, grids, and gyroid. Each combination is structured in a “sandwich” configuration, creating complex and diverse infill designs. Tensile testing of these samples provides critical data for assessing the mechanical properties of the combined infill pattern specimens. The findings have significant implications for localized reinforcement in additive manufacturing. To illustrate this, an S-type hook was fabricated using a combined infill pattern of Cubic and Gyroid. This hook was then compared to others made with singular infill patterns to demonstrate the effectiveness of combined infill strategies in enhancing mechanical performance.
The research outcomes provide significant insights into the mechanical characteristics of 3D-printed objects using infill structures. It has been demonstrated that the use of various infill structures can enhance structural performance in specific areas of the printed components. This approach offers targeted reinforcement and optimizes resource utilization, making it an attractive choice for industries reliant on FDM 3D printing. Moreover, this research lays the groundwork for future studies in this domain. In subsequent research endeavors, it’s possible to broaden the scope of this study by examining a more extensive range of infill structure combinations and exploring different ratios within the same category of infill structures. Additionally, predictive models derived from the findings of this study could assist engineers and designers in efficiently optimizing infill structures, leading to significant savings in material and time during the 3D printing process.
The significance of this study goes beyond its direct applications. This research enhances the overall understanding of improving infill structures in FDM 3D printing, thereby having significant implications for industries such as aerospace, automotive, and other relevant sectors. The ability to enhance the mechanical properties of 3D-printed components while maintaining cost-effectiveness can potentially drive advancements and improvements across various industries. This further solidifies FDM 3D printing as a versatile and reliable manufacturing method.