Fatigue Failure of Steam Turbine Disks—A Centenary Tribute to Wilfred Campbell

Abstract

The year 2024 marks one hundred years since Wilfred Campbell published his landmark work on vibrational analysis of rotating disk following a series of disk failures in steam turbines. Despite the absence of advanced engineering analytical tools, Campbell came up with an elegant method to visually demonstrate and capture the mode shapes in rotating disks. The first part of this paper reviews Campbell's life and analytical and experimental work in this area. Regardless of the current advanced engineering capabilities to predict nodal shapes in turbine disks, turbine disks still experience failures related to vibration. The second part of the paper discusses a recent case study where a turbine disk failure occurred as a result of vibration. The discussion includes metallurgical root cause failure analysis and engineering analysis to predict the vibrational characteristics. Metallurgical failure analysis confirmed that the primary mode of failure was fatigue and did not have any issues with the disk material or its mechanical properties. Finite element modeling and analysis were used for the engineering analysis to predict the natural frequencies of the bladed-disk. The engineering analysis showed the evidence of potential resonance, and the failure was related to nodal vibration issues.