The influence of corrosion on stress concentration factor at shaft to flange radius

Abstract

This paper describes the influence of corrosion on stress concentration factor and crack initiation at shaft-flange transition section. The real turbine shaft failure case study is used for research. This case study and numerical calculations show that the seal box solution led to constant leakage of river water in the zone of critical radius and resulted in corrosion fatigue cracks and turbine shaft failure. Thus, the Finite Element Analysis is performed to calculate the stress concentration factor increase as a result of corrosion occurrence. The corrosion at shaft-flange transition section is modelled in the zone with maximum stresses with a corrosion pit dimensioned to comply with real in situ dimension of pits. The presented research points new trends in stress concentration factor calculation. The obtained numerical results for maximum stress and stress concentration factor in critical zone confirmed failure analysis study outcome.