Numerical investigation on torsional stress concentration factor at the semi elliptical corrosion pit

Under torsion, stress distribution at semi elliptical corrosion pits, secondary pit nucleated at the bottom of semi elliptical base pits and also orientation of the semi elliptical primary pits have been investigated by conducting a series of three-dimensional pits models to predict stress concentration factor, systematically. Based on the finite element analyses, aspect ratio is the main parameter affecting SCF. Pits, having higher aspect ratio, are the most dangerous form and can cause significant reduction in the load carrying capacity. When a premature pit nucleates at the bottom of primary pit, SCF increases sharply within the secondary pit region.

► Crack readily nucleates at the pit having the maximum stress concentration value.
► Aspect ratio is the main parameter affecting on stress concentration factor.
► When a secondary pit nucleates at the bottom of primary pit, stress concentration factor increases sharply.
► If the size of the pit is known, reduction of load carrying capacity can be decided.