PSI - Issue 56

Cristina Vălean et al. / Procedia Structural Integrity 56 (2024) 97– 104 Author name / Structural Integrity Procedia 00 (2023) 000 – 000

99

3

3D

three-dimensional

1. Materials and methods The materials used in study are commercially available filaments of pure PLA and PLA mixed with three types of fillers: short glass fibers, short carbon fibers and bronze particles, named in the article PLA+GF, PLA+CF and PLA+BP respectively. The PLA+GF is composed of a PLA matrix (85%) and glass fibers (15%), the PLA+CF is composed of a PLA matrix (85-90%) and carbon fibers (15-10%) and the PLA+BP has more than 80% metal particles [15]. The size of the fibers and bronze particles have a wide range, according to our own measurements: glass fibers 200-300 μ m, carbon fibers 100-300 μ m, bronze particles 5-30 μ m. All filaments were 1.75 mm in diameter, semicrystalline and possessed similar processing temperatures (below 230 °C), according to their manufacturers. The 3D printing was conducted on Makerbot Sketch printer using the following parameters: extruder temperature – 220 °C, build plate temperature – 50 °C, layer height – 0.1 mm, infill density – 95%, infill pattern – linear, nozzle diameter – 0.4 mm, printing velocity: – 35 mm/s. The microscopic images of the samples were obtained using Olympus BX51M microscope at 100  magnification. The images in the Figure 1 represent the surface morphology of each representative sample.

Fig. 1. Microscopic images 100  , of the printed structures: (a) pure PLA, (b) PLA+GF, (c) PLA+CF, (d) PLA+BP

The tensile and flexural tests of the samples were performed according to ISO 527-1:19 standard [16] for tensile tests and ASTM D 790:17 [17] for flexural, on 5 kN Zwick Roell testing machine. The tests were carried out at a loading velocity of 2 mm/min, in control of the displacement, at room temperature.