Modeling, Simulation And Experiment Study On Ride Performance Of Light-Duty Trucks

The light-duty trucks account for a large proportion in auto industry that is one of the most important industries in China. And the development of light-duty trucks also plays important role in the development of auto industry. The ride comfort is required more and more strictly with the improvement of standard of life. It has become an important performance index by which the vehicle gaining advantage in the competition. It can influence both passengers and the vehicles directly. To the passengers, ride performance directly influence their comfort, working efficiency and health, response to the psychological situation and accurate response of the driver when they have been exposed to complicated driving and working environment. It will influence the stability of the 'road-human-vehicle' system; play a very important role in keeping driving safety. a comfortable vibration environment is also important to the passengers in guaranteeing their healthy and excellent psychological situation when arrival. To the vehicle, ride performance influences the working space of suspensions and the dynamic loads of tyres. The dynamic loads caused by vehicle vibration will accelerate the wear and tear of vehicle assemblies and parts, which leads to too early fatigue failure of the assemblies and parts. When the dynamic loads work on the road surface through tyres, the road surface inclined to fatigue damage and macroscopic damage. Dynamic tyre loads would also lead to the destruction of vehicles if the amplitude of its responses is out of range.In order to analyze and optimize the ride performance of light-duty trucks, a seven degree of freedom ride performance model is established with the Lagrange's equation method. The motion differential equations of the ride performance model are derived, the measurement methods of mass, moment of inertia, stiffness, damp, distances of the mass centers and road roughness inputs in the ride performance model and the are discussed subsequently.After that, the dynamics natural characteristics, frequency characteristics and dynamic response analysis are carried out to get the calculation methods of natural characteristics and the ride performance evaluation criterion (the root mean square value of vertical acceleration on the driver's seat). Modal experiments, indoor racing experiments and outdoor running experiments are carried out then to validate the ride performance model and analyze the abnormal vibration causes of WL light-duty truck.Because of the large influence of the different matchup of the vertical stiffness of the suspensions and the damp of shock absorbers, Optimal design model that uses the root mean square value of vertical acceleration on the driver's seat as the objective function, uses the vertical stiffness of the suspensions and the damp of shock absorbers as infection variables is established to analyze the influence of infection variables to the ride performance of light-duty truck. Several optimization schemes are proposed based on the analysis, and root mean square values of vertical acceleration on the driver's seat under different schemes are obtained and compared to validate the effect of optimization.