Failure analysis of shaft for turbo air blower

In this study, the failure analysis of shaft for turbo air blower after 5months of service was performed. In order to scrutinize the fractured shaft and failure mechanism, the chemical compositions, microstructures and the mechanical properties of shaft material were examined. In addition, stress analysis was carried out by FEM (Finite Element Method). The causes for failure of a shaft would be indentified from tested results. The results showed that the shaft was failed by fatigue(especially, Very High Cycle Fatigue(VHCF)). Micro striations on the fractured surface were observed. Fatigue crack initiation started at the highest stress concentration region from FEM analysis results. Relatively small area of final fast fractured surface indicated that the shaft was under a low stress level at the time of failure. It is concluded that the shaft was failed by fatigue crack which initiated at the high stress concentration region of the shaft.