ACAM8 full paper Deshpande Smith Randall submitted
Condition monitoring of planetary gearboxes: modelling mesh stiffness in the presence of planet gear tooth root cracks
Lav G. Deshpande1, Wade A. Smith1* and Robert B. Randall1
1 School of Mechanical and Manufacturing Engineering, University of New South Wales, Australia
*Corresponding author. Email: wade.smith@unsw.edu.au
Abstract: This paper describes the dynamic model of a planetary gear system to simulate vibrations in the presence of a tooth crack in the planet gear. Planetary gearboxes present a unique challenge to the condition monitoring community due to the rotating axes of the planet gears and the time-varying transmission path of the vibration signals depending on the location of the fault. The planet gear meshes simultaneously with the ring and the sun gears and the contact occurs on the opposite flanks of the planet gear tooth, which causes the crack (modelled here as a slot) to open in one of the meshing tooth pairs and close in the other, with slightly different mesh stiffness values. A simplified finite element based approach was used to predict the gearmesh stiffness curves in the crack opening and closing scenario, which were then incorporated in the simulation model. The simulated vibration signals showed good correlation with the measured signals and improved spectral matching was observed over earlier results which ignored the differences between crack opening and closing, and the variation in single tooth pair stiffness with rotation angle.
Keywords: gear fault, gearmesh stiffness, kurtosis, planetary gearbox, simulation, vibration signal processing.
1 Introduction
Planetary gears are widely used to transmit power in many applications such as automotive, aircraft, marine and wind turbines. Some of the advantages of planetary transmissions are compactness due to co-axial shaft arrangement, large torque-to-weight ratio due to load sharing by multiple sun and ring gearmeshes and high power efficiency. However, similar to parallel shaft spur
Lav G. Deshpande1, Wade A. Smith1* and Robert B. Randall1
1 School of Mechanical and Manufacturing Engineering, University of New South Wales, Australia
*Corresponding author. Email: wade.smith@unsw.edu.au
Abstract: This paper describes the dynamic model of a planetary gear system to simulate vibrations in the presence of a tooth crack in the planet gear. Planetary gearboxes present a unique challenge to the condition monitoring community due to the rotating axes of the planet gears and the time-varying transmission path of the vibration signals depending on the location of the fault. The planet gear meshes simultaneously with the ring and the sun gears and the contact occurs on the opposite flanks of the planet gear tooth, which causes the crack (modelled here as a slot) to open in one of the meshing tooth pairs and close in the other, with slightly different mesh stiffness values. A simplified finite element based approach was used to predict the gearmesh stiffness curves in the crack opening and closing scenario, which were then incorporated in the simulation model. The simulated vibration signals showed good correlation with the measured signals and improved spectral matching was observed over earlier results which ignored the differences between crack opening and closing, and the variation in single tooth pair stiffness with rotation angle.
Keywords: gear fault, gearmesh stiffness, kurtosis, planetary gearbox, simulation, vibration signal processing.
1 Introduction
Planetary gears are widely used to transmit power in many applications such as automotive, aircraft, marine and wind turbines. Some of the advantages of planetary transmissions are compactness due to co-axial shaft arrangement, large torque-to-weight ratio due to load sharing by multiple sun and ring gearmeshes and high power efficiency. However, similar to parallel shaft spur
References: [1] L. Deshpande, R. Randall, and W. Smith, "Diagnostics of planet gear faults from the effects of meshing with the ring and sun gears," in The 21st International Congress on Sound and Vibration (ICSV21), Beijing, China, 2014. [2] L. G. Deshpande, "Simulation of vibrations caused by faults in bearings and gears," PhD Dissertation, School of Mechanical & Manufacturing Engineering, Faculty of Engineering, University of New South Wales, Sydney, Australia, 2014. [3] H. Endo, "Simulation of gear faults and its application to the development of differential diagnostic technique " PhD Dissertation, Mechanical & Manufacturing Engineering, Faculty of Engineering, University of New South Wales, Sydney, Australia, 2005. [4] Z. Chen and Y. Shao, "Dynamic simulation of planetary gear with tooth root crack in ring gear," Engineering Failure Analysis, vol. 31, pp. 8-18, 2013. [5] I. Howard, S. Jia, and J. Wang, "The dynamic modelling of a spur gear in mesh including friction and a crack," Mechanical Systems and Signal Processing, vol. 15, pp. 831-853, 2001. [6] A. Bligh, "‘Design, Manufacture and Testing of a Planetary Gearbox For the Purpose of Internal Vibration Based Condition Monitoring’," BE Thesis, UNSW, 2012. [7] W. Smith, L. Deshpande, R. Randall, and H. Li, "Gear diagnostics in a planetary gearbox: a study using internal and external vibration signals," International Journal of Condition Monitoring, vol. 3, pp. 36-41(6), 2013. [8] A. Kahraman, "Load sharing characteristics of planetary transmissions," Mechanism and Machine Theory, vol. 29, pp. 1151-1165, 1994. [9] M. Inalpolat and A. Kahraman, "A theoretical and experimental investigation of modulation sidebands of planetary gear sets," Journal of Sound and Vibration, vol. 323, pp. 677-696, 2009. [10] D. Forrester and D. Blunt, "Analysis of epicyclic gearbox vibration," presented at the HUMS 2003 Conference, 2003. [11] P. D. McFadden, "A technique for calculating the time domain averages of the vibration of the individual planet gears and the sun gear in an epicyclic gearbox," Journal of Sound and Vibration, vol. 144, pp. 163-172, 1991.