PSI - Issue 41

Mohammad Reza Khosravani et al. / Procedia Structural Integrity 41 (2022) 664–669 Mohammad Reza Khosravani et al. / Procedia Structural Integrity 00 (2022) 000–000

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et al, 2022), mechanical properties of components fabricated by FDM technique depend on the printing parameters, and here printing parameters such as layer thickness, fill density, and feed rate were kept constant in preparing all specimens. In Fig. 2, a schematic of 3D-printed open-hole specimen is illustrated.

Raster width

Raster angle

Contour width

Air gap

Contour to contour air gap

Fig. 2. A schematic of fabricated specimens and FDM printing parameters.

After fabrication, we measured hole diameter and specimen thickness using a digital caliper and dimensional ac curacy of 3D-printed parts was confirmed. Since manufacturing defect can be occurred during 3D printing process (Khosravani and Reinicke, 2021b), defining quality requirement of 3D-printed components in the context of interna tional standard is a necessity.

3.2. Tensile tests

The improvement of manufacturing processes and development of new material depend on profound knowledge of material behavior. In this context, experimental practices play a crucial role in production e ffi ciency and product quality. Therefore, designing and conducting an appropriate experiment can provide reliable data and prove ideas for real world environment. Here, the test coupons have been examined using a hydraulic tensile test machine equipped with a 15 kN load cell. The machine has cross-head speed range of 0.01 mm / s to 30 mm / s. In order to avoid the likely e ff ect of the displacement rate, all tests were performed under displacement control condition with a constant rate of 1 mm / min. We used an appropriate tensile grips in order to keep the specimen perfectly aligned in the vertical direction. A preload of 5 N was applied to specimen prior to test start to take up slack from gripping apparatus. Fig. 3 shows a specimen under tensile test conditions and a fractured specimen. In this study, at least nine specimens for each hole diameter were fabricated and examined.

Fig. 3. The test set-up (left), and a fractured specimens (hole diameter: 6 mm) (right).

According to ASTM D5766 (ASTM D5766, 2018), failures that do not occur at the hole are not acceptable failure modes and failure which occur at the hole are acceptable. In this context, various mode of failures can be found on