PSI - Issue 18

Goran Vukelic et al. / Procedia Structural Integrity 18 (2019) 406–412 Author name / Structural Integrity Procedia 00 (2019) 000–000

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corrosion and scaling at elevated temperatures. Measured yield and maximum tensile strength are in line with expected for steel 28NiCrMoV8-5. Optical and scanning electron microscopy images revealed damage to the teeth surface. Damage evolving around teeth can clearly be tracked, from the introduction point to the end of contact. The origin of the damage can be tracked to the point where the sum of all applied and misapplied stresses intersect the net strength of the gear. Spalling originated below the surface, near the case/core transition surface, leading to final failure of the gear shaft. Comprehensive data of the research performed include adequate images of fractured surface at suitable magnification with details of damage growth and advancement. Numerical analysis indicated localized high contact stresses and TVMS reduction for damaged gear teeth. In order to reduce the contact stress and the effects of high contact stress, material of pinion should be case hardened steel and positive profile shift on the pinion should be performed in manufacturing. Obtained results can be used in understanding the damage, wear and failure behavior of spiral bevel gears in heavy duty gearboxes and further improvements of gear design, manufacturing, finishing and assembly could be made based on this analysis. Acknowledgements This work has been supported by the University of Rijeka within the project uniri-technic-18-200 “Failure analysis of materials in marine environment”. References [1] R. Ma, Y.S. Chen, Q.J. Cao, Research on dynamics and fault mechanism of spur gear pair with spalling defect, J. Sound Vib. 331 (2012) 2097–2109. [2] J.R. Davis, Gear Materials, Properties, and Manufacture, American Society for Materials, Materials Park, 2005. [3] W. Ost, P. De Baets, J. Quintelier, Investigation of a failed axle of a reduction gearbox, 14 (2007) 1194–1203. doi:10.1016/j.engfailanal.2006.11.030. [4] O. Asi, Fatigue failure of a helical gear in a gearbox, 13 (2006) 1116–1125. doi:10.1016/j.engfailanal.2005.07.020. [5] V. Rajinikanth, M.K. Soni, B. Mahato, M.A. Rao, Study of microstructural degradation of a failed pinion gear at a cement plant, Eng. Fail. Anal. 95 (2019) 117–126. doi:10.1016/j.engfailanal.2018.08.031. [6] Deutsche Norm DIN 3991, Teil 1-4 [7] C.G. Cooley, C. Liu, X. Dai, R.G. Parker, Gear tooth mesh stiffness : A comparison of calculation approaches, MAMT. 105 (2016) 540–553. doi:10.1016/j.mechmachtheory.2016.07.021. [8] Y. Luoa, N. Baddoura, G. Hanb, F. Jiangc, M. Lianga, Evaluation of the time-varying mesh stiffness for gears with tooth spalls with curved bottom features. Eng. Fail. Anal. 92 (2018) 430–442. doi: 10.1016/j.engfailanal.2018.06.010.

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