PSI - Issue 46

Adis J. Muminović et al. / Procedia Structural Integrity 46 (2023) 125 – 130 A.J. Muminovi ć et al. / Structural Integrity Procedia 00 (2021) 000–000

129

5

Tooth root fracture

Melting of a tooth surface.

Intensive wear of a gear tooth surface

Welded teeths

c)

b)

a)

Fig. 6. Gears failure: a) drive gear with 60% of infill, b) driven gear with 60% of infill, c) driven gear with 100% of infill

100000 150000 200000 250000 300000

Measurement manualy stopped after 15 000 s (300 000 rev)

3495 s (69995 rev)

1250 s (25000 rev)

400 s (8015 rev)

186,5 s (3710 rev)

0 50000

Revolutions until failure (rev)

"20%"

"40%"

"60%"

"80%"

"100%"

Infill volume percentage

Fig. 7. Summary results of fatigue life of gears made of PLA with infill

4. Conclusion The effect of the infill volume percentage of 3D printed PLA gears on fatigue life and failure types was investigated in this paper. As for gears with 20% infill volume, both the drive teeth and the gear body failed. At the driven gear, tooth root fracture and melting of the tooth surface were observed. The drive gear with 60% of the infill volume failed due to tooth root fracture and melting of the tooth surface. As for the driven gear, melting of some teeth was observed. Furthermore, it was found that parts of some drive gear teeth were welded to the driven gear teeth. Gears with 40% and 80% of the infill volume have failed, similar to gears with 60% of the infill volume. Gears with 100% infill volume did not fail even after 300 000 revolutions, although considerable wear of the teeth was observed. It has been shown that the life of gears made of PLA increases significantly with the increase in volume percentage. Acknowledgements This research is supported by the University of Sarajevo – Faculty of Mechanical Engineering through project: Modernization of Laboratory for Machine Testing.