Development of a Dynamic Model for Predicting the Rigid and Flexible Motions of the Crank Slider Mechanism

Abstract

A continuous model is developed to predict the rigid and flexible motions of the piston assembly/connecting rod/crankshaft mechanism for a single cylinder engine. The model accounts for the torsional vibration and the out-of-plane transverse deformation of the crankshaft along with the out-of-plane transverse deformation of the connecting rod. The eigenvalue problem of the crankshaft, including the counterweights, the flywheel, and the crank gear, is solved to obtain the analytical expressions for the elastic modes of the crankshaft. The resulting mode shapes are then used in the assumed modes method to approximate the structural flexibility terms. The differential-algebraic equations of motion are obtained by implementing the Lagrange principle. The digital simulation results illustrate the role played by the topological nonlinearities inherent in the system and reveal the relationships with which the rigid and flexible motions of the crank-slider mechanism would interact.