Characteristics of axial vibration of marine diesel engine crankshafts

박용디이젤기관의 크랭크축계 종진동특성에 관한 연구

In former papers which were published already, authors had derived calculation formulae for the axial stiffness and the radial force conversion factor of crankshaft. In this paper, crankthrow axial stiffness and radial force conversion factors of actual engines are calculated by these theoretical formulae and then their characteristics are investigated. As the results, the axial stiffness and the radial force conversion factor of the latest super-long stroke engine are smaller than those of old-type engines. The influence of the former brings down the resonance speed of engine and the latter reduces the exciting force of axial vibration, but as the harmonic component of axial vibration force becomes rather strong, its effect of reducing is considerably canceled. In conclusion, as the latest super-long stroke engine is seemed to be liable to axial vibration of crankshafat, it is recommend that, in the design stage of propulsion shaft, its axial vibration condition must be more carefully checked.