Study on Stress Intensity Factor of the Pit-Crack Model for Portal Crane Girders

In shipbuilding gantry cranes in long-term service the coastal humid salt-spray environment, main beam is affected many places by corrosion fatigue-formed pits, affecting structural strength of beam. This paper focuses on impact corrosion-generated pits under conditions crack nucleation. Corrosion fatigue nucleation a local damage evolution process and stress intensity factor criterion one critical to discern whether sprouts at pit. establishes pit-crack model based overall finite element portal crane, uses ANSYS software simulate complex boundary conditions. The results show that different sizes depth-to-diameter ratio greatly affect value concentration phenomenon may be causing emergence cracks; change size not obvious, but with increase significantly increased. According hypothesis semi-ellipsoidal pitting, relationship between pit proposed, its calculation are within 5% error compared method, it found effect etch positively correlated factor; depth–diameter ratio, budding location changes location, more likely generated from shoulder when exceeds 1.