PSI - Issue 54

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Martin Matušů et al. / Procedia Structural Integrity 54 (2024) 135 – 142 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

137

Table 1. Printing parameters for skin and core of the specimen used as default by the Concept Laser M2 printer. Skin Core Power [W] 200 370 Speed [mm/s] 800 1400 Hatch spacing [mm] 0.112 0.112 Spot size [µm] 140 190 Layer height [mm] 0.025 0.050

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Fig. 1. a) Printing platform with two different view angles. b) Fatigue test specimen

• Table 2. Series description using colour coding to distinguish heat treatment of the specimens.

ID-code

Heat Treatment

Colour coding

Heat treatment recommended by the supplier of the powder (GE), which also manufactures the used 3D printer. Specimens heated to 240 °C and held for 6 hours in the furnace, followed by cooling on air. Heated to 200 °C for 2 hours in the furnace, followed by air-cooling to ambient temperature.

Blue

T240

T200 T300

Green

Heated to 300 °C for 2 hours in the furnace, followed by water-cooling.

Orange

2.2. Fatigue strength analysis Fatigue experiments that were conducted in this campaign had the condition to end the experiment when any of these limits is exceeded: • Frequency drops by 10 Hz. • Load amplitude changes by ± 0.5 kN. • Static loads changes by ± 0.5 kN. • 10 7 cycles are reached. These specimens are classified as runouts. Such specimens were then subjected to another subsequent cyclic loading with two times higher load amplitude at least. The Kohout- Věchet [3] model is employed for fatigue regression, effectively capturing the transition from low-cycle fatigue (LCF) to high-cycle fatigue (HCF), as well as the transition to the domain of fatigue limit. This can be observed in the curves depicted in Figs. 2 and 3.