Analytical Investigation On Vibration Prediction And Reduction Of Motorcycle Based On A Virtual Model

The vibration problem of motorcycle is the most important factor affecting the ride comfort, manipulation stability and driving safety. The research of motorcycle vibration belongs to the field of motorcycle dynamic research, and this is just the direction of modern motorcycle technology development.This dissertation is a component of a project of vibration analysis and reduction of a 200cc motorcycle. Through the research of this dissertation, the author try to explore a method of building the motorcycle FE model and predicting and reducing vibration of motorcycle by analysis through this model.Firstly, as the key point of virtual analysis of motorcycle vibration, a correct virtual model of motorcycle will be built. By studying on the contemporary production of this field, the author takes the finite element method to build the motorcycle model. In order to assure the validity of this model, the author analyzes the key parts of the motorcycle thoroughly during the model building, and make some experiments to prove the model.Secondly, engine is the main vibration source of the motorcycle. This dissertation study on the motorcycle engine dynamic property, and give the principle of the engine excitation. The author describes the balance method of inertial force of engine. By installing balance shaft in the engine, the engine vibration is reduced. Through the experiment of vibration force test, the author gets the date to apply on the finite element model as the load.Thirdly, from the finite element method model analysis and experimental model impact, the nature frequencies and model shapes of the motorcycle is got; The harmonic analysis give the vibration transfer property; By applying engine excitation on the model, the vibration of some parts critical to the ride comfort is predicted.Fourthly, in order to reduce the vibration of the motorcycle, some revision is made to the model, including engine elastic suspension, motorcycle structure revision. Through the analysis based on the model, the best method to reduce the vibration of this motorcycle is brought forward. By vibration experiment on the real motorcycle after revision, the validity and feasibility of the revision is proved.Fifthly, the road surface irregularity excitation is applied to the motorcycle model, and the ride comfort is analyzed through the PSD analysis.