At present, shafting alignment calculation is commonly performed as a continuous beam subject to weight of the propeller and the shaft itself. In many cases, main engines have been regarded as rigid, and bending behavior of the crankshafts was not carefully examined. In most cases of shafting alignment calculation, therefore, crankshafts were simply replaced with a round bar having a diameter equal to that of the journal. However investigation into recent damage of several main bearings showed the need for more accurate crankshaft alignment calculations. For this purpose, the crankshaft should be replaced with a round bar having equivalent bending stiffness. This report presents the numerical analysis results regarding determination of the diameter of an equivalent round bar..
Residual stresses and welding deformation caused by arc welding sometimes lower the strength of a welded joint and spoil its appearance. This paper presents an experimental method proposed for evaluation of welding deformations using an indirect displacement measuring system. We examined how the base metal deforms during the welding operation and how the final deformation pattern is affected by such factors as plate thickness and welding speed. A bead-on-plate weld is treated here. The experiments showed that a simple V-shaped deformation is observed in the case of a thick base metal, whereas a thin base metal deforms in a complex manner with its central portion being deformed downward.
Marine diesel fuel oil will be more widely used for marine diesel engines in the future because its low sulphur content helps in meeting regulations concerning exhaust gas emissions. Even if the properties of marine diesel fuel oil remain within those specifications, however, cases have been reported of poor combustion in marine diesel engines for generators. This paper reports the relationship between combustion characteristics and carbonaceous bonds as well as the possibility of evaluating combustion characteristics by identifying carbonaceous bonds in fuel oil.