Digital Twins for Life Prediction of Wind Turbine Pitch Bearings

Research projects

Project Description:

The Project

Modern large-scale wind turbines are equipped with individual pitch controllers to allow the blades to rotate under different wind speeds. The rotation of the blades is necessary to change the angle of attack as to control power production and loads acting on a wind turbine. Accurate positioning of blades of a wind turbine is essential to maximise energy production and ensure its operational safety therefore pitch bearings are critical components of a wind turbine.

As a wind turbine operates under variable wind speed conditions, this means that the blade pitch bearings can be constantly subjected to oscillating movements of small amplitudes and variable frequencies. Under these conditions, two critical wear damage modes of the pitch bearing raceways, false Brinelling and fretting corrosion, have been identified from wind turbine field operation [1].  For bearings operating under small oscillations, such as pitch bearings, currently there is no established international design standard to calculate their service life accurately. To address these issues, the current industrial solution is to design the full-scale pitch bearing test rig and to perform full-scale bearing life testing. These extremely costly full-scale tests are to identify key operating conditions on damage development and to test the service life of pitch bearings therefore to extend the bearing life as long as possible. This is because replacement and maintenance of pitch bearings of large-scale wind turbines are extremely expensive in offshore wind farms.

The aim of this project is to develop a digital twin life prediction method for pitch bearings of the large-scale wind turbines with individual blade pitch controllers. The project will develop a bespoke medium-scale laboratory tribometer and multi-scale numerical damage simulation models of roller-raceway surface contact for pitch bearings, with consideration of operation conditions by analysing the SCADA data of filed operating wind turbines. The project will seek answers to research questions if the wear coefficient derived from the experiment tests using the bespoke medium-scale laboratory tribometer, under the actual pitch bearing motion and loading profiles, could be used in numerical damage simulation to predict the service life of pitch bearings of various scales. The developed digital twin life prediction method could have potentials to replace the costly full-scale pitch bearing tests employed in the industry.

The project has two main themes and four areas of activities to develop physical and virtual twins of the damage development of pitch bearings to support the bearing life prediction. The development of the physical twin includes (1) a data analysis model for creating pitch bearing motion and loading profiles from the wind turbine SCADA data, and (2) a medium-scale laboratory test method of roller-on-surface contact to evaluate frictional behaviour and wear damage accumulation. The development of the virtual twin includes (3) a finite element wear simulation model of roller-on-surface contact of the medium-scale laboratory test and the roller-on-raceway surface contact of the pitch bearing of a large-scale wind turbine; and (4) a calculation method for pitch bearing life prediction based on simulation of wear damage accumulation under actual pitching bearing operation conditions.

The successful applicant will join the Department of Mechanical Engineering, working with researchers in Structural Integrity, Dynamics and Tribology Research Groups.  More information about the department research can be found at


Training and Skills

The student will receive training in use of relevant finite element software via the University of Sheffield and online courses. Extensive guidance will also be given through technical training in the University of Sheffield on experimental procedures for material wear damage test and measurement.

The student will be in a position to continue in academia or to move to a job in the wind energy industry.



[1] Schaeffler.

[2] Extend wind turbine life with pitch bearing upgrades.

[3] E. Hurtado and H. Long. Damage and Failure in Wind Turbine Pitch Bearings, Industrial Project Report, sponsored by the Powertrain Research Hub, the UK Offshore Renewable Energy Catapult, 2019-2020.

[4] T. Harris, J. H. Rumbarger, and C. P. Butterfield, Wind Turbine Design Guideline DG03: Yaw and Pitch Rolling Bearing Life, NREL, no. December, p. 63, 2009.

[5] F. Schwack, M. Stammler, G. Poll, and A. Reuter, Comparison of Life Calculations for Oscillating Bearings Considering Individual Pitch Control in Wind Turbines, Journal of Physics: Conference Series, vol. 753, no. 11, 2016.

[6] A. Sevinc, M. Rosemeier, M. Bätge, R. Braun, F. Meng, M. Shan, D. Horte, C. Balzani, and A. Reuter, IWES Wind Turbine IWT-7.5-164, no. June, p. 62, 2014.

[7] Powering Offshore Renewable Energy Research: Powertrain Research Hub.

[8] H. Long. Wind Turbine Pitch Bearings – Enhanced Test Strategy for a Large-scale Test Rig, sponsored by the EPSRC Impact Acceleration Award and the UK Offshore Renewable Energy Catapult, 2022-2023.

[9] E. Hurtado. False Brinelling and Fretting Wear in Wind Turbine Pitch Bearings. PhD Thesis, The University of Sheffield, 2022.

[10] M. Stammler, A. Reuter, and G. Poll, Cycle counting of roller bearing oscillations – case study of wind turbine individual pitching system, Renewable Energy Focus, vol. 25, no. June, pp. 40–47, 2018

[11] M. H. Zhu and Z. R. Zhou. On the mechanisms of various fretting wear modes, Tribology International, vol. 44, no. 11, pp. 1378–1388, 2011.

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