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It is the purpose of this paper to make clear the effect of typical torsional viscous-friction damper on the reduction of the axial, torsional and two directions of lateral vibrations from the analytical and experimental points of view. At first, a typical type of the torsional viscous-friction damper is fitted to a high-speed diesel engine and the axial, torsional and two directions of lateral vibration displacements at the pulley end are measured in order to investigate the effect of the damper on the reduction of these vibrations in the three dimensional space of the engine shaftings from the experimental point of view. Next, the characteristics of the axial, torsional and two directions of lateral vibrations of the engine shaftings are investigated by three dimensional analysis of forced vibration by the transfer matrix method, which has been developed by the authors.

This paper refers to a numerical computation for vibration displacements and stresses of a crankshaft with a shear type rubber torsional damper by the three dimensional transfer matrix method. The accuracy of this computation method is confirmed by comparing computed results with measured ones. Especially, in this work, the numerical computation method is proposed to compute the vibration displacements and stresses by means of replacing the rubber part of rubber torsional damper with a spring-dashpot model. Then dynamic characteristics are estimated by the complex torsional stiffness derived from a three-element Maxwell model. As a result the torsional vibration stress and bending vibration stress and vibration displacements (angular and lateral displacements) can be computed with an adequate accuracy. This computation method is applicable to predicting the conditions of vibration displacements and stresses, and will contribute to optimum design of the crankshaft.

A numerical simulation method by transfer matrix method is proposed to compute the vibration stress waveforms of a V-type, 8 cylinder diesel engine crankshaft in this work. This method will be able to predict the conditions of vibration stresses and be useful to design a crankshaft. The accuracy of this numerical method is confirmed by comparing the simulation results of the computation with the measured data. As a result of the comparisons with the measured data, it has been assured that the vibration stress waveforms can be computed with adequate accuracy by considering from 0.5-th to either 10-th or 12-th order per 0.5-th order harmonic components of exciting forces for a 4-cycle engine.