PSI - Issue 56

Dan Ioan Stoia et al. / Procedia Structural Integrity 56 (2024) 90–96 Author name / Structural Integrity Procedia 00 (2019) 000–000

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1. Introduction 3D printing technology is an additive manufacturing process by which a digital model is transposed into a physical model. Fused Deposition Modeling (FDM) is one of the most used 3D printing technologies, by which a thermoplastic filament is melted, extruded and deposited in layers to build the geometry of the printed model [1, 2]. As much as it is used due to its multiple advantages such as low cost of the printers and the raw material respectively the good quality of the printed products, FDM is a highly accessed research topic. One of the subjects analyzed in many studies is the effect of the process parameters on the mechanical behavior of the printed parts. There are many parameters that influence the mechanical properties of the 3D printed parts, such as, [3]: extrusion temperature, print speed, infill pattern and density, build orientation, raster orientation and width, layer thickness and color, [4]. Due to the large numbers of parameters, which require a large volume of experiments, different experimental strategies have been developed such as full-factorial design [5], Taguchi method [6], ANOVA [7], path planning strategies [8], automated neural network search [9], and fuzzy logic [10]. These strategies lead to identification of the best combinations of parameters that improve the mechanical properties of the printed materials, with a reduced volume of experimental tests. A less studied subject, and which is the objective of this paper, is the mechanical behavior of the adhesion between the consecutive traces of the deposited material and also of the air extruded filament. So, the aim of the paper is to conduct tensile tests on the following extruded samples: air extruded, one trace deposited on the platform, two consecutive traces deposited on the platform and fourteen consecutive traces deposited on the platform and also for the raw filament (Figure 1). In addition, in order to establish the relation between the degree of the crystallinity of the polymer and the mechanical properties, differential scanning calorimetry tests were conducted.

Fig. 1. Block illustration of the study

Nomenclature Φ 1

diameter of the filament

diameter of the air extruded PLA thickness of the deposited trace

Φ 2

d

b 1 b 2 b 3

width of the deposited material (one trace) width of the deposited material (two traces) width of the deposited material (fourteen traces)