Crankshaft Alignment Reasoning Method of 2-Stroke Diesel Engine Using Genetic Algorithm

We propose a new reasoning method of crankshaft alignment in 2-stroke diesel engine for installing an engine on a vessel and for maintain the engine in good condition. The crankshaft alignment has not been reasoned qualitatively with practical measurement methods in 2-stroke diesel engine. In this study, a crankshaft alignment reasoning method is considered by using a measurement method, crankshaft deflection measurement method. Firstly, a model of a crankshaft and bearing support system of diesel engine is developed to calculate crankshaft deflection under assumed uneven crankshaft alignment. The model is solved by using transfer matrix method. Secondly, for the purpose of to calculate the crankshaft alignment by a measured crankshaft deflection result, it is necessary to solve the inverse problem. Therefore, genetic algorithm is applied for this solution. In this solution, each bearing height is changed until to fit the calculated crankshaft deflection under the assumed alignment for measured crankshaft deflection result. Finally, the developed algorithm is evaluated with actual measurement results in an engine. As a result, the developed algorithm is good correspondence with the difference height between adjacent bearings and also with the engine bedplate sag curves in several vessel conditions.