PSI - Issue 47

Mohammad Reza Khosravani et al. / Procedia Structural Integrity 47 (2023) 454–459

455

2

Author name / Structural Integrity Procedia 00 (2023) 000–000

manufacturing (Prakash et al., 2018). 3D printing is a group of modern manufacturing technologies that are generally similar to each other in that they add and bond materials in a layered fashion to form the final product. Di ff erent 3D printing techniques can be used in fabrication utilizing various materials such as polymers, metals and ceramic pow der. Although lots of advances have been achieved in the field of 3D printing, there are of course several challenges, barriers, and unanswered questions in this domain. For example, geometric accuracy, consistency of short-term and long-term structural performance, cost of construction, and quality assurance need further investigation. 3D printing has attracted much attention over the past ten years due to its immanent advantages. It has been used in di ff erent fields, such as medicine (Higgins et al., 2022), aerospace (Dagkolu et al., 2021), education (FordMinshall, 2019), automotive industry (Nascimento et al., 2022), construction (Khosravani and Haghighi, 2022), and food industry (Mantihal et al., 2020). According to ASTM 2792-12 (ASTM F2792, 2012), the current 3D printing processes are classified into seven techniques of which material extrusion is considered in the present study. Since 3D printing techniques have been used in a various fields, di ff erent engineering issues have been investigated in this domain (Khosravani and Reinicke, 2020; Montgomery et al., 2021; Zhang et al., 2021; Nasiri and Khosravani, 2021; Lee and Yun, 2022). For instance, in (Khosravani et al., 2021) influence of a post-processing on the mechanical properties of 3D-printed parts was investigated. In this context, original and treated specimens were subjected to a se ries of tensile loads, three-point bending tests, and water absorption test. The experimental tests indicated fracture load in untreated specimen was decreased after surface treatment. At the same time, in (Polyzos et al., 2021) delamination in 3D-printed fiber reinforced products was investigated. In this context, the delamination test was performed nylon 3D-printed parts reinforced with carbon fibers. Analytical methods and numerical models were used by researchers to determine the fracture toughness of the 3D-printed parts. The results indicated that the polynomial chaos expansion technique is accurate for explaining the mechanical behavior of the reinforced 3D-printed composites. Later, influence of printing parameters on the crack path direction on 3D-printed parts was investigated in (Milovanovic et al., 2022). To this aim, polylactic acid (PLA) material was used to prepare the specimens using fused deposition modeling (FDM) process which is one of the cheapest and most widely used 3D printing methods. In detail, Single edge notched bend ing (SENB) specimen batches with di ff erent infill density were printed for fracture toughness test. A series of tests was conducted and documented results showed that the infill density has a significant impact on fracture toughness of 3D-printed PLA parts. Although 3D printing was introduced for fabrication of prototypes and small-scale production, currently it has been used for fabrication of functional end-use products. Therefore, the mechanical strength and behavior of 3D printed components have become of significant importance. In this context, fatigue and fracture behavior of 3D printed parts have been investigated in several research works (Allum et al., 2020; Santonocito, 2020; Yavas et al., 2021; Khosravani et al., 2022). In a study (Jia and Wang, 2019), architected specimens for compact tension (CT) fracture test were designed and based on the experimental tests the fracture toughness was determined. In this respect, J integral was calculated by adding the elastic part and the plastic part. Although this method was originally developed to determine the fracture toughness of homogeneous metallic materials, in many study this approach it has been adopted to evaluate the fracture toughness of heterogeneous materials. The experimental findings indicated that the material microstructure (heterogeneity) have a crucial role in toughening composites. Later, tensile, flexural, and fatigue behavior of 3D printed woven and nonwoven continuous carbon fiber reinforced polymer composites were studied (Ekoi et al., 2020). It was observed that fiber orientation influenced the failure mechanism of composites during tensile testing. In a recent study (Qu and Li, 2023), the influence of 3D printing residual stress and external load on stress intensity factor at initial crack front was investigated. In detail, the impeller was printed and finite element method was used to simulate 3D printing process of the impeller. The obtained results confirmed that the crack initiation position is a ff ected by the maximum residual stress of the printed impeller after heat treatment. The present study aims to investigate e ff ects of printing parameters on the fracture behavior of 3D-printed parts. To this aim, PLA material is utilized to fabricate the specimens. Particularly, the specimens were printed with 45 ◦ / - 45 ◦ and 0 ◦ / 90 ◦ filament orientations at printing speed of 20 mm / s and 80mm / s. A series of CT tests was conducted and linear elastic fracture mechanics approach was used to determine the fracture toughness values for each group of examined specimens. This work is structured as follows: Section 2 presents experimental setup and procedure. In this context, details of specimen preparation and experimental tests are explained. In Section 3, experimental observations and the obtained results are presented and discussed. Finally, a short summary in Section 4 concludes the paper.