Effect of Nozzle Diameter on Tensile and Fracture Behavior of 3DPrinted FDM-PLA Samples S. S. Hosseini1, A. Nabavi-Kivi1, M. R. Ayatollahi1,∗, M. Petru2 1 Fatigue and Fracture Research Laboratory, Center of Excellence in Experimental Solid Mechanics and Dynamics, School of Mechanical Engineering, Iran University of Science and Technology, Narmak 16846, Tehran, Iran 2 Faculty of Mechanical Engineering, Technical University of Liberec, Studentsk´a 2, 461 17, Liberec, Czech Republic ∗ m.ayat@iust.ac.ir Keywords: Fused Deposition Modeling (FDM), Nozzle diameter, Fracture resistance The Fused Deposition Modeling (FDM) technique is a subcategory of 3D printing processes that works by extruding a fine polymeric filament through a nozzle on the heated platform. Polylactic Acid (PLA) is among the mostly used materials in the FDM technique with good applicability in the medical industry [1]. In recent years, researchers have tried to figure out how the manufacturing processes in the FDM technique can influence the mechanical performance including the basic mechanical properties [2] as well as the fatigue and fracture behavior [3]. Most of the studied manufacturing parameters were raster angle, layer orientation and printing speed [4]. Meanwhile, little information about the effects of nozzle diameter on the mechanical properties of 3D printed polymers is available. Therefore, the current paper surveys the influence of nozzle diameter on the mechanical properties and mode I fracture behavior of FDM-PLA specimens. Four different nozzle diameters of 0.4, 0.6, 0.8, and 1 mm with two raster configurations of 0/90◦ and 45/-45◦ were considered. Dog-bone and Semi-Circular Bending (SCB) samples were designed and printed for tensile and fracture tests, respectively. Also, to evaluate the fracture resistance of FDM-PLA pre-cracked samples, the critical value of J-integral (Jc) was used and calculated through finite element analysis. The experimental results indicated that 1 mm nozzle diameter with the raster angle of 45/-45◦ could provide higher mechanical properties compared to other cases. This was also true for the fracture experiments where the SCB samples printed through the 1 mm nozzle diameter and 45/-45◦ raster orientation had the highest value of Jc (10400 J/m2). Besides, the paths of crack extension were monitored and discussed comprehensively. References [1] Ramesh, M and Panneerselvam, K. (2021). "Mechanical investigation and optimization of parameter selection for Nylon material processed by FDM," Mater. Today Proc., 46, 9303-9307. [2] Liu, J., Naeem, M. A., Al Kouzbary, M., Al Kouzbary, H., Shasmin, H. N., Arifin, N., ... & Abu Osman, N. A. (2023). Effect of Infill Parameters on the Compressive Strength of 3D-Printed Nylon-Based Material. Polymers, 15(2), 255. [3] Azadi, M., Dadashi, A., Dezianian, S., Kianifar, M., Torkaman, S., & Chiyani, M. (2021). 19
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