Engine vibration analysis with coupling between piston-connecting-rod dynamics and crankshaft torsional vibration

This paper deals with computer-based simulation techniques on automobile engine vibrations. In the previous study, we developed an in-house software package called EVAS (Engine Vibration Analysis System) for predicting engine vibrations under running condition. EVAS is a flexible multibody dynamics solver that can comprehensively analyze the coupled phenomena by using its predefined body elements and several types of force elements which express mechanical joints such as journal bearings. In this paper, in order to calculate crankshaft torsional vibrations more accurately and efficiently, we propose a new force element of piston-connecting-rod sub-system considering the dynamic effects induced by the elastic deformation of the crankshaft. The new force element is applied to an in-line 4-cylinder engine model and its effectiveness is discussed compared with the experimental results. Then, using the element, we also investigate the vibration transmitting mechanism from the torsional and bending vibrations of the crankshaft to the elastic vibrations of cylinder-block through the bearing dynamics forces.