Fractographic Study of Marine Diesel Engine Connecting Rod Stud Bolt Crack

Failures of marine diesel engine components can lead to serious consequences for a vessel, cargo and the people on board a ship. These consequences can be financial losses, delay in delivery time or a threat to safety of the people on board. This is why it is necessary to learn about connecting rod bolt failures in order to prevent worst-case scenarios.

This paper aims at determining the origin, velocity and the duration of fatigue crack development of a diesel alternator engine which suffered a significant failure of one of its mains, not long after a major overhaul had been completed and with less than 1000 running hours having elapsed.

It was verified with fatigue rupture of one of the four connecting rod stud bolts. Tensile tests were performed in the remaining connecting rod bolts. During this procedure, another fatigue crack in an adjacent bolt was identified. The probable root case of damage, and at the end some final remarks are presented.