Numerical Analysis of Stake Mark Induced Failure of a Rotor Shaft

In this paper, the stake mark induced failure of a generator rotor forging is analysed using finite element analyses in combination with a Cockroft & Latham failure model. Evidence is found from damage analysis that the rotor failed due to micro cracks and residual stresses induced by a double stake mark, which was located at a position subject to concentrated rotating-bending stress amplitudes and torsional mean stress. The analysis presented here verifies the results of the damage analysis by showing that the stake mark configuration of the failed rotor was the most detrimental among a number of similar configurations. According to the finite element analysis, this stake mark configuration combines a high probability of inducing propagating sub-surface micro-cracks with considerable tensile residual stresses.