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Torsional and lateral bending vibrations of cylinder block have a large effect on engine noise. Cylinder block vibration not only causes noise to radiate from the cylinder block itself but it is also the major exciting force to the oil pan and timing belt cover. In order to reduce engine noise, it is important to completely understand the mechanism of cylinder block vibrations. An analysis is conducted using FEM and BEM to compute the influence of crankshaft torsional vibrations on cylinder block vibrations. A crankshaft system for a four cylinder automobile engine was used for analysis. Finite Element model of crankshaft is created using parametric modelling software developed based on ANSYS FEA software. Finite Element model of cylinder block, bearing cap, oil sump is also created using another parametric software developed based on ANSYS FEA software.

Modal Analysis is a well established technique which defines the inherent dynamic properties of the structure. At the same time the experimental harmonic analysis by shaker method is also a very important tool in solving some of the engine induced vibration problems in the automotive structure. Computer simulation technique using finite element methodology has been very effective tool in simulating the problem. However the right combination of these techniques has been a tricky situation. The paper describes the methodology of using right combination of these techniques to reduce the motorcycle chassis vibration which are induced by engine and drive-line excitation in minimum time. The method involves the Finite Element Modelling with shell elements, experimental harmonic analysis with frequency sweep upto 600 Hz, validation of the FE model, animation techniques and find out correct modification to fine tune the structure to eliminate the engine induced vibrations in the frame.

The problem of torsional vibration of the crankshaft of high speed diesel engine has become critical with increase in exciting forces due to high combustion pressures. This results in high torsional vibration amplitudes and hence high stresses. In such a case use of the damper pulley to control the torsional vibration amplitudes and stresses is one of the desired solution. In this paper torsional vibration analysis is carried out in case of six cylinder diesel engine using standard general purpose finite element package ANSYS and a method is developed to find out torsional vibration stresses leading to the selection of damper.