Dynamic Simulation Analysis And Test Study Of Commercial Vehicle Cab Suspension System

Cargo by road has become an extremely important means of transportation in China because of perfection of its road networks, and heavy duty trucks are always taken as the major tool for road transportation over long distance. Cab suspension systems can effectively attenuate vibration between cab and chassis, which largely determine the level of comfort experienced by drivers of trucks, if vibration of a truck's cab exceeds the limit of legal requirements, then tiredness, nausea and other sense of discomfort occur in the drivers, so it is necessary to do more specific research into cab suspension systems to improve cab ride comfort.Design of cab suspension systems in China has been typically empirical and also with reference to foreign prototype sample, but the same situation doesn't occur abroad now. Carmakers overseas develop cab suspension systems primarily by adopting the platform of virtual prototype technology; the method not only greatly shortens products'development cycle and improves products'quality, but also are extremely good value for money. By making use of this method, the dissertation has done some research into a three-axle heavy duty truck through processes of vehicle dynamic modeling, simulation analysis and cab suspension systems'parameter optimization, aiming at bettering drivers'ride comfort. To be more specific, it can be summarized as follows.Firstly, the dissertation gave a short description of cab suspension systems'vibration absorption principal, function and classification, including common mount components'structure and application. Then, the dissertation briefed cab suspension systems'research approach and current study in China and abroad based on a large amount of reading, which gave inspiration to my work and pointed out the direction of my endeavor. The first section of this dissertation also explained some ground-level knowledge of multi-body system dynamics and optimization theory, especially the procedures to model and optimize vehicle dynamics in the software of ADAMS.Secondly, after real structure of the truck was simplified aiming at solving the problem of its structural complexity, a full vehicle dynamic model was built and simulated in software of ADAMS. The model includes cab suspension system, front suspension, balanced suspension, steering, powertrain, chassis and some other assemblies or parts. According to the triangular waveform superimposing method, a virtual road needed for simulation was created in the software of MATLAB. The model was validated by comparing simulation results and test data derived from the same measuring points. Parameter optimization of cab suspension system was conducted on basis of the verified model; the results of optimization indicated that reasonable choice of variable parameters such as stiffness and damping coefficients had a significant importance in isolating vibration passed to the cab. At last, some certain tests were carried to study the structural dynamic characteristics of the cab suspension system.This study provides a guide to design cab suspension system. Virtual prototype technology applied in the research is so helpful, which is strongly believed to have a more wonderful future in development of vehicle design in China.