Simulation of a multi-cylinder engine vibrational behaviour

This work analyses the vibrational behaviour of an in-line 4-cylinder, 4-stroke, internal combustion turbocharged direct injection gasoline engine. A multi-body numerical model of the engine is implemented, to simulate its dynamic response when running in a bench test. The cranktrain multi-body model is created using geometrical data extracted from engine CAD, using as excitation forces the experimentally measured in-cylinder pressure values. A flexible multi-body approach leverages on FEM modelling of crankshaft, cylinder block and head for the dynamic analysis, with remaining parts modelled as rigid. The engine mounts are modelled by flexible elements with given stiffness and damping. The importance of the explicit modelling of the rods connecting the engine with mounts is highlighted. The software Siemens-LMS Virtual Lab and ANSYS are used for the assessment.