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

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body, while at the driven gear, the damage occurred only on the teeth, as shown in Fig. 5b. The two failure types in driven gear were identified: the first was tooth root fracture, and the second was tooth surface melting. As for a drive gear with 60% of the infill volume, the tooth root failure and melting of the tooth surface were observed as shown in Fig 6a. Furthermore, at the driven gear, the melting of the teeth was observed, as well as the presence of drive gear parts welded to their tooth flanks (Fig. 6b). Gears with 40% and 80% of infill volume have failed similarly to gears with 60% of infill volume. Although there was significant wear on the teeth of gears with 100% infill volume (Fig. 6c), it had no effect on their functionality. A summary of fatigue life results, expressed in the number of revolutions until failure, for the tested gears is shown in Fig. 7. As the volume percentage of infill grows, the fatigue life, indicated by the number of revolutions until failure, increases significantly. The effect of outer shell thickness, different infill patterns, as well as applied torque and speed on the integrity and fatigue life of gears can be further studied. The life of the gears could be extended by reducing the torque and speed. In the future tests, the accelerated fatigue life testing methods such as the Locati method (Locati 1955, Braut et al. 2021) or Nicholas method (Nicholas 2002; Baragetti, S. et al. 2018, 2019, 2020; Arcieri et al. 2020) should be considered.

3.00

2.00

Total failure point: after 3710 rev. 186,5 s

20% of infill volume

1.00

0.00 Torque [Nm]

‐1.00

Number of revolutions

0 0,0

800 40,0

1600 80,0

2400 120,0

3200 160,0

4000 200,0

Time [s]

Fig. 4. Measured torque during test until failure of gear with 20% of infill volume

Total destruction of a gear body

Tooth root fracture

Melting of a tooth surface.

b) Driven gear

a) Drive gear

Fig. 5. Failure of gears with 20% of infill volume