PSI - Issue 41

Cosmin-Florin Popa et al. / Procedia Structural Integrity 41 (2022) 557–563 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Keywords: Impact Strenght, Izod, PLA, PETG, FDM;

1. Introduction The additive manufacturing technique changed the prototyping process and reduced the cost of the product. The additive manufacturing allows to create objects with complex geometry, in a shorter time than with classical manufacturing methods. Fused Depositing Modeling (FDM) is the most used technology in additive manufacturing: low cost, no need for a controlled atmosphere and low residual material. These are a few advantages of FDM technology. The FDM technology presented a layer-by-layer staking process. The FDM presented an anisotropic thermal conductivity and interfacial thermal contact resistance and for building components has unique thermal properties Hardikkumar et al (2018), and the fill design parameter showed no significant influence on the surface roughness Mohd et al (2020). In Hadi (2019) study the result for fracture energy and the influence of surface roughness are shown which does not have a great influence. The orientation of printing has a higher influence, the worst cases are at 45 and 90 under quasi-static loading, Gtl et al (2021). Also, the layer thickness has a great influence; Subbarao et al. (2021) studied the thickness effect in case of storage and loss module value. He shown that it is better to have a 0.17 mm layer thickness. Szczepanik et al. (2020) and Srinivasan (2020) shown that all the effects of fill density and surface roughness for PLA material has a lower influence for the compressive strengths, yield and Ultimate Tensile Strength. Durgashyam et al. (2019) investigate the contribution of the layer thickness for PETG materials. The contribution for PETG of layer thickness for tensile strength was 57.82% and 41.87% for flexural strength respectively. An isotropic material model that captures the viscoplastic material behavior of FDM printed PLA parts subjected to the uniaxial loading was validated by Volgin et al. (2021). The materials build by 3D printing show different mechanical properties in different directions due to the inherent anisotropic features of the printing process Wang et al. (2020), Fu et al. (2021). Regarding material properties some work defines increasing the number of layers leads to decreasing of both the Young modulus and tensile strength Valean et al. (2020). Impact strength increases and tensile strength decreases due to increasing the layer thickness Tanveer et al. (2022). Valean et al. (2020) show that the notch insertion is more evidence in mode I of cracking for PLA. Impact testing has been developed to measure experimentally a product of materials to high speed loaded. Izod testing is used to measure the impact resistance of plastics. The test specimens are similar with Charpy V-notch but in case of Izod the specimens are tested in vertical position. The method is affected by several factors such as speed test, notch geometry, and temperature. The purpose of this study was to determine the impact energy and strength from PLA and PETG specimens, obtained through FDM technology. In the first part of the paper, the materials used, test method and the equipment’s are presented. Next, results of the tests are presented, followed by main the conclusions drawn. 2. Materials and methods The specimens were printed using Prusa MK3 printer equipped with an HFE300 extruder for printing parts with filaments of 2.85 mm diameter. The printer parameters was set used a 3D printing software, parameters such as head speed, extrusion temperature, raster angle and so on. The specimens dimension used were in according to ISO 180 and are presented in Fig. 1. The dimensions on the drawing are in millimeters. The longitudinal direction of the notch is always parallel to the thickness h. Two materials were used to build the specimens: polylactic acid (PLA) and polyethylene terephthalate glycol (PETG). In this paper four thicknesses were used for the specimens: 4mm, 6mm, 8mm and 10mm. Six specimens for each dimension were printed with a 100% infill density. The raster in-plane laying on the XY plane at an angle of 45˚ was defined for the infill. The layer thickness for printing was 0.15 mm. To ensure the quality of the printed specimens, the nozzle temperature and the built platform was controlled to be at around 60°C