PSI - Issue 10

K.G. Raptis et al. / Procedia Structural Integrity 10 (2018) 33–40 K.G. Raptis and A.A. Savaidis / Structural Integrity Procedia 00 (2018) 000 – 000

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formed on the surface of the tooth. It is easy for a lubricant of low viscosity to penetrate into those cracks and cause them to open (pitting) and grow. Thus, it is important to check the gears under surface pressure.

Table 5. Comparison between experimental and FE stress

Total Load at HPSTC P (N)

FE Max Stress (MPa)

Experimental Max Stress (MPa)

Normalized Experimental Max Stress

Deviation %

Test Number

Normalized FE Max Stress

Gear 1

Gear 2

- 0.6 - 1.9 + 1.2 - 3.8

1 2 3 4

18N 28N 22N 28N

28N 18N 28N 22N

192.381 205.63 202.408 212.269

3.048 3.048 3.048 3.048

3.066 3.108 3.012 3.167

2.931 2.742 2.786 2.656

2.948 2.796 2.753 2.760

4. Conclusions

As far as the comparison between experimental and numerical results is concerned, it has been found that the deviations between measured and predicted maximum stress were in a range of [-3.8% - +1.20%]. These deviations were independent of the applied power (random or maximum) and the corresponding tangential force, for equal geometrical and material parameters. As far as the global stress distribution in the tooth area is concerned, it is expected that application of the load in a larger region instead of a point would lead to better correlation between predicted and experimentally observed values.

Fig. 15. Comparison between theoretical and experimental stress at the toe of the spur gears having z 1 = 18, 22 and 28

The deviation increases with teeth number of the cooperating gear, while keeping the pinion teeth number constant. As the teeth number increases the value of the maximum stress is decreasing. The deviation decreases as the ratio z 2 /z 1 tends to one. References Abdullah, M.Q., Abood, A.N., Abbas, E.N., 2017. Experimental and numerical studies to the contact stresses in asymmetric spur gears, 1st International Conference on Recent Trends of Engineering Sciences and Sustainability, Iraq, 978-1-5386-0802-9 IEEE, College of Engineering/ University of Baghdad, Iraq. Colbourne, J., 1987. The Geometry of Involute Gears. Springer-Verlag, ISBN: 0-387-96522-X, p. 253. Costopoulos, N.T., Spitas, V.A., 1994. Analytical mechanics of spur gears, Proceedings of the 4th National Congress of Mechanics 1, 187-194, Xanthi, Greece.