PSI - Issue 51

Daniel Ivaničić et al. / Procedia Structural Integrity 51 (2023) 199 – 205 D. Ivani č i ć et al. / Structural Integrity Procedia 00 (2019) 000–000

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Holding and loading assembly had to ensure quality and reliable clamping of the sample so a custom holding and loading device assembly is designed and manufactured, consisting of a load-bearing frame, L-profile 40x40x4, clamping plate, hexagonal socket M6 bolts and corresponding washers and nuts. An existing 10 mm thick steel plate served as a base for the device mounting. A shackle was placed through the hole on the free end of the sample which enabled the loading of the sample with existing 5 kg weight. The whole assembly is shown in Fig. 2 (Ivaničić (2020)).

Fig. 2. Custom holding and loading assembly.

2.2. Young's modulus determination In order to perform reliable FE analysis, Young’s modulus ought to be determined. The Young's modulus E of polymer material depends on manufacturing method, humidity, loading duration and other factors which is why different literature sources provide different values of Young's moduli E of ABS and PET-G, materials that will be used for 3D printing of optimized samples. The Young’s modulus can be determined by tensile or compressive loading of the sample, as well as by loading the sample by pure bending. For the purpose of Young’s moduli determination, a simple pure bending device was used. The schematic representation of the pure bending device is shown in Fig. 3.

Fig. 3. Schematic representation of pure bending device, Lovrin (2001).

Young’s modulus can be calculated using the following expression: 2 e 2 e e e 3 2   ⋅ ⋅ = −   ′ ⋅ ⋅ ⋅   Q L L E ν b δ w b .

(1)

For this purpose, beam elements with rectangle cross-section ( b e = 10 mm, δ e = 20 mm) have been 3D printed using Prusa i3 MK3 FDM 3D printer. Printed samples from both ABS and PET-G filament were loaded with 5 kg weights placed at the distance L from the supports. Deflection was measured in 3 points for each sample, both for unloaded and loaded condition to compensate printing imperfections. Using measured values of deflection in each point,