Investigation of Torsional Vibration Characteristics of Marine Diesel Engine Crankshaft System

Evaluation of the torsional vibration characteristics of a crankshaft system is indispensable to the development of marine diesel engines. It influences the selection or decision about shafting components such as the flywheel, torsional damper, generator and even modification of the crankshaft itself. In this paper, experimental and analytical investigations of torsional vibration were carried out for a newly developed marine diesel engine. The measurements were performed on various system changes e.g. engine with and without torsional damper, tuning wheel and coupling of dynamometer or generator. Based on the measurement results, analytical models were tuned to achieve better reliability. Meanwhile the sensitivity of parameters–inertia, stiffness and damping on the free vibration and torsional response-were assessed quantitatively and qualitatively. Dynamic stresses in the highly stressed area of the crankshaft were also measured under actual operating conditions with telemetry equipment. The safety factor against fatigue was evaluated with the measured stresses and compared with the analyzed ones and showed good agreement with each other.