Stress Calculation and Fatigue Strength Evaluation for Grooved Defect Caused on Crank Shaft of 2700kW Main Diesel Engine

Abstract

A grooved defect of 0.43mm depth x 7mm width x 370mm length = 1/3 circle caused on crank shaft of 2700kW main diesel engine was found during CMS inspection of special survey dock. At first permanent repair by machining the crank pin to remove 1.0mm depth all around with fitting oversized crank pin metal have been discussed. However it is expected for 3 months at least to make up oversize crank pin metal. So, the vessel was sailed out after removing notches from the defect carefully with confirming safety condition by stress calculation with fatigue strength evaluation of the crank shaft contained the defect and checking lubricating flow condition. This time, its summary is shown in this paper.