Flexural Properties Evaluation of Additively Manufactured Components with Various Infill Patterns

Abstract

Mohd Azhar Harimon, Department of Engineering Mechanics, Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia (UTHM), Batu Pahat, Johor, Malaysia. Email: mazhar@uthm.edu.my In additive manufacturing technology, especially by Fused Filament Fabrication (FFF) based 3D printing, infill pattern is one of the key parameters that must be considered in improving the mechanical properties of the fabricated components. Since the finished products not only may undergo tensile or torsional but also bending forces, it is important to understand how such implementation of infill pattern could affect its flexural characteristics. In this study, such investigations of flexural characteristics were conducted not only on commonly used infill patterns such as honeycomb, rectilinear, Hilbert curve, and concentric but also on rarely examined ones such as octagram spiral and Archimedean chord infill patterns. Following the ASTM D970 standard, ten specimens for each infill patterns and additional ten solid specimens, with a total of 70 specimens, were used in the three-point flexural testing. The measured values of load and deflection were used to determine the flexural stress-strain curve for each infill pattern. Then, the flexural strength, flexural strain at break, flexural modulus of elasticity, and flexural modulus od toughness were obtained. In terms of flexural strength, it was found that the highest and lowest values were provided by concentric and Archimedean chord infill patterns, respectively. Furthermore, honeycomb and octagram spiral were found to be the infill patterns that had the highest and lowest value of flexural strain at break, respectively. Interestingly, from the investigation on the elasticity and toughness moduli of all infill patterns, it had become apparent that the optimum infill patterns to be applied for additively manufactured components were honeycomb and concentric infill patterns, owing to its ability to withstand a relatively higher load and deformation before fracture. Nevertheless, generally, the implementation of infill patterns decreased the flexural strength and strain at break by 50% at minimum and 40% at maximum, respectively, in comparison to that of solid. It can be concluded that the effect of infill patterns, especially those that were rarely explored ones, had been investigated.