Issue 50

N. Chatzidai et alii, Frattura ed Integrità Strutturale, 50 (2019) 407-413; DOI: 10.3221/IGF-ESIS.50.34 409 necessary since the temperature on the building platform was 20-25°C below the one that was setup initially, causing the detachment of the specimen. Once this raft was completed, deposition of the ABS material was started. Initially, at each layer, two shells that delimit the specimen were built, and thereafter the internal raster-by-raster material deposition was initiated. The building process continued until the plane at which the thermocouple had to be integrated was reached. At that point, the building process was paused temporally, to integrate the thermocouple, and then continued until the com- pletion of the specimen fabrication. In the case that two thermocouples were integrated in different layers, the building process was paused twice. Images of the specimens are shown in Fig.1. (a) (b) Figure 1 : Specimen with thermocouple in the (a) 21 st layer and (b) 1 st and 21 st layer. As shown in Table 1, specimens were built with two different building speeds (35 sec/layer and 65 sec/layer) and building orientations (0° and 90°). The orientation of the building process is prescribed according to the specimen’s physical coor- dinate system, as shown in Fig. 2. Specimen Building orientation Building speed (sec/layer) Layer of the embedded thermocouple 1 0° 35 1 2 0° 35 21 3 0° 35 1 and 21 4 0° 65 21 5 90° 65 21 Table 1 : Specimens and their building parameters. Figure 2 : Physical coordinate system of the rectangular specimen. For all the specimens, the infill density was set up to 0.9 for greater adhesion. The liquefier temperature of the extruded material was set up at 230°C, since higher temperatures caused burning of the material. Additionally, it deemed necessary to measure the envelope temperature, since it can't be controlled automatically by the 3D printer software. The temperature was found to be 85°C.