Analysis And Research Of Vibration Characteristics Of Coach

Vibration of vehicle would be generated when it is driving or idle due to road roughness, speed changes, imbalance between wheels, engine and transmission system and other external and internal excitation. Taking a coach as the research object, this paper researched vibration theory and methods of vibration analysis through studying the analysis method of vehicle vibration characteristics and vibration diagnosis techniques external and internal.Firstly, dynamic characteristic of the coach is analyzed based on finite element method and the engine vibration excitation on the coach vibration is researched. The finite element model for the coach is established, the free-state modal analysis of the coach and the modal analysis for sub-construction of the under-frame are both carried out. Harmonic response analysis is carried out based on the modal analysis considering separately the vertical and horizontal excitation of two engine operating conditions. The vibration of various parts of the coach is studied though displacement response of the body caused by the harmonic power of engine.Secondly, a half-car model with four degrees of freedom is established with the road spectrum according to random vibration theory. Analysis of response of coach-body under random excitation is carried out though simulating the kinetic equation. The impact of suspension's stiffness and the speed on the passenger riding comfort is reached.Finally, multi-state vibration testing of complete vehicle is carried out, auto-power spectrum of different speed of engine are got. The reason of abnormal vibration is that the engine under particular speed resonates with vehicle body frame and the rear frame.