Torsional vibration analysis of a multi-body single cylinder internal combustion engine model

Abstract

This paper presents a detailed multi-body numerical nonlinear dynamic model of a single cylinder internal combustion engine. The model comprises all rigid body inertial members, support bearings, joints, couplers, and connections between the various engine components, as well as means of vibration damping. The detailed model is parameterised, thus enabling virtual prototype testing of various engine designs, as well as allowing the engine designer to carry out a comprehensive noise, vibration, and harshness (NVH) investigation of engine performance. This new approach in engine design reduces the conceptual design-to-development cycle time and removes the need for extensive engine testing, which accounts for a considerable cost in engine design and development process. The model incorporates the simultaneous solution of large displacement dynamics of engine components, infinitesimal vibrations of support bearings, and the trapped air-fuel cylinder transient pressures. The results obtained provide time histories of the dynamic response of all inertial members, such as the piston, the flywheel, and the connecting rod. The torsional vibrations of the crankshaft and both synchronous and asynchronous whirl of journal bearings are also obtained. The simultaneous solution of nonlinear inertial rigid body dynamics, the combustion process, and nonlinear vibrations of the crankshaft main journal bearing supports brings about a new approach in the numerical analysis of complex nonlinear multi-body dynamic problems. Frequency domain analysis of the results shows agreement with generally known experimental spectra. The numerical results also agree with a closed-form analytical solution reported by various authors.