PSI - Issue 56

Cosmin Florin POPA et al. / Procedia Structural Integrity 56 (2024) 176–183 Popa Cosmin-Florin/ Structural Integrity Procedia 00 (2019) 000–000

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1. Introductions Additive manufacturing is the process that can build complex parts layer by layer without wasting material and having a fast building speed. The 3-D printing employs an additive manufacturing process whereby products are built on a layer-by-layer basis, through a series of cross-sectional slices, Barry (2012). On the other hand, the only material waste is a few rows of material, the contour of the printed specimens. The AM technology is used for complex parts without any other operations, Zhang et al. (2018). AM technology is used in different fields, such as mechanical Henriques et al. (2018), biomechanical Malik et al. (2015), Mulford et al. (2016), aeronautical engineering Ahmed et al (2013), Kroll et al (2011)), and so on. The first 3D printer based on Fused Deposing Modelling was made in the USA in the 1980s; this technology is used much more than other technologies, Dudek et al. (2013). To use the FDM technology, it is necessary to define a 3D model and import it into a 3D printer software to establish the parameters and export it into a G-code file. The parameters that can be established in the software are printing speed, layer thickness, bed temperature, and nozzle temperature. FDM is an additive manufacturing method and is the most widely used because of its ease of use. Materials used in the FDM method are thermoplastic polymers. Although some experts in the field would restrict 3-D printing to units with inkjet-based print heads that create an object on a layer-by-layer basis, others would apply this term to office or consumer versions of rapid prototyping machines that are relatively low-cost and easy to use Casey (2009). The filament is heated until the material is melted and can be deposited on the other layer. The specimens were made according to the ASTM B 831-5 standard, which is used for thin sheet metal specimens to characterize the mechanical properties in shear specimens. For printed specimens, there is no specific standard for in-plane shear properties. Valean et al. (2020) and Marsavina et al. (2022) investigated the influence of manufacturing parameters on the tensile properties, respectively fracture toughness of FDM specimens made of PLA. Ziemian et al. (2012) studied the dependence of the mechanical properties of ABS parts produced by FDM on raster orientation and the conclusion of the paper is mechanical properties display anisotropic behavior with the orientation of raster and the directionality of polymeric molecules. In order to identify additional material parameters, Rauch et al. (1992) made many studies of the constitutive behavior during shear deformation, especially for the examination of large strains. Bouvier et al. (2006) analyzed the homogeneity of the shear zones depending on the geometric ratio of the shear gauge. The in-plane simple shear with a single shear zone is a very efficient technique for evaluating the shear properties and for analyzing the in-plane plastic anisotropy of metals Rauch et al. (1998) For those types of specimens which are in-plane loaded is easy to use digital image correlation DIC to measure the strains during the test, Liew et al. (2018). DIC is a non-contact optical digital method to measure specimen deformation Casey et al (2009). The method was used instead of the extensometer, which can influence the fracture zone. DIC uses 2 cameras positioned at 700 mm by the specimen and an angle of 60 degrees, so it is not necessary to touch the specimen. The DIC accuracy is very high, and the computational efficiency has been improved. Song et al. (2017) found that polylactic acid (PLA) specimens had three different strengths in three directions, and the strength along the build direction had the smallest value. Popa et al. (2022) investigated the influence of thickness under the Izod impact test and observed that PETG specimens have better accuracy in results and a brittle fracture. The objective of this study was to investigate the difference in shear behavior between specimens with and without contour. For this investigation, specimens adhering to ASTM 831-5 specifications, utilized polyethylene terephthalate glycol (PETG). 2. Material and methods The specimens were made from blue PETG, the color has a characteristic that has been shown to have an impact on the material's behavior. Shear specimens were 3D printed using a Prusa MK3 printer with a 2 mm nozzle and 1.75 mm filament diameter. Printing parameters included a nozzle temperature of 230°C and a bed temperature of 85°C, adhering to ASTM 831-5 specifications for shear specimen geometry. Simultaneously, blue PETG was characterized using tensile specimens, which were manufactured and subjected to experimental investigation. Post-testing, Young's modulus and ultimate strength were determined.