Vibration prediction of a multi-cylinder engine using multi-body dynamic simulation

This paper analyses the vibration behaviour of an in-line 4-cylinder, 4-strokes, internal combustion turbocharged direct injection gasoline engine. A detailed multi-body numerical model of the engine prototype was used to characterize the whole engine dynamic behaviour, in terms of forces and velocities. The cranktrain multi-body model was created starting from engine geometrical data, and the available combustion loads were employed for the Multi-Body Dynamic Simulation (MBDS). A combined usage of FEM and Multi-Body methodologies were adopted for the dynamic analysis: both crankshaft and cylinder block were considered as flexible bodies, whereas all the other components were considered rigid. The engine mounts were considered as flexible elements with given stiffness and damping. The hydrodynamic bearings were also modelled. The software LMS Virtual Lab (modules PDS and Motion) and ANSYS were used for the simulation.