PSI - Issue 77

Martin Matušů et al. / Procedia Structural Integrity 77 (2026) 127 –134 Author name / Structural Integrity Procedia 00 (2025) 000 – 000

130

4

Table 2

Series description using color coding to distinguish heat treatment of the specimens.

Number of series with R =0.1

Number of series with R = -1

Tested geometry

ID-code

Heat Treatment

Color coding

Specimens were left as built without any additional heat treatment. A conventional heat treatment recommended by the supplier of the printing powder (GE), which also manufactures the used 3D printer. Specimens were heated to 240 °C and held for 6 hours, followed by cooling on air. Specimens were heated to 200 °C for 2 hours, followed by air-cooling to ambient temperature. Specimens were heated to 300 °C for 2 hours, followed by water-cooling.

Red

2

-

A

NoHT

T240

Blue

12

3

A-H

T200

Green

2

-

A

T300

Orange

3

-

A

2.2. Fatigue experiments The fatigue tests conducted in this study were terminated upon reaching any of the following criteria: • A decrease in testing frequency by more than 10 Hz, • A variation in load amplitude exceeding ±0.5 kN, • A shift in static load beyond ±0.5 kN, • Completion of 10⁷ cycles, at which point the specimen was classified as a run -out. Run-out specimens were subsequently subjected to an additional fatigue test with at least double the original load amplitude to further assess their behaviour.

Fig. 2 S-N curves of four series of specimens with geometry A and different heat treatments [2; 9]. Kohout- Věchet (K&V) model [8] was used to derive S-N trends. The model is described as follows: = [ ∙ + + ] . (1)