Coupling Dynamic Characteristic Research For Wheels-track-terrain System Of High-speed Tracked Vehicles

The vehicle suffered strong random and impact excitation due to the interaction between road wheels, track and terrain, when driving in high speed. Different speed, different pre-tensioning and different terrain lead to big difference in excitation characteristic. Based on the background of national major fundamental research project, this thesis mainly focus on the dynamic characteristics of the drive system, the problems of the complex dynamic coupling to the road wheels-track-terrain.The roughness of four typical kinds of roads that the tracked vehicle driving were measured and also the road power spectral density are obtained by double track the shape parameter of roads. Piecewise fitting parameters were obtained by fitting the low frequency and high frequency of the roads then the input excitation was got for the calculating of the tracked vehicle suspension system dynamics simulation model and road simulation vehicle bench testing. By analyzing the mechanical properties of road soil of the soft terrain the soil mechanics parameters which providing the foundation for establishing the soft terrain simulation model and the road wheels-track-terrain coupling system excitation characteristic simulation model were obtained.The coupling interactions between the road wheels, track and terrain were analyzed in details. The connection properties of track is obtained that is the rounding for drive sprocket, idler, road wheel and the performance of the envelope surface characteristics. The four relative position relations of the road wheels, track and terrain was researched: the track contact with neither the road wheel nor the terrain contact; the track contact with the road wheel but not with the terrain; the track contact with the terrain but not the road wheel; the track contact with both the road wheel and the terrain. The following topics were also studied: the tension distribution of the track; the interaction between track and road wheel; the interaction between track and sprocket, the interaction between track and idler, the interaction between track and terrain.Base on the study four kinds of the typical roads and the coupling interaction relationship of the road wheels, track and terrain of tracked vehicle, the vibration characteristics of the dynamic model of tracked vehicle suspension system is studied by theoretical analysis, simulation calculation and experiment method.. Regard the four kinds of typical road roughness that considering the track’s affection and the vehicle speed as input, dynamic model of tracked vehicle suspension system was established. Then the vibration characteristic of the vehicle body and the road wheel were studied by Runge-Kutta method. The dynamics simulation model of tracked vehicle suspension system is got by multi-body dynamics simulation software. The vibration characteristics of vehicle body and the road wheel are studied when the tracked vehicle driving with different speeds on the four typical surface road. By doing vehicle bench testing, the dynamics theory model and multi-body dynamics simulation model of tracked vehicle suspension system was verified and calculation precision were got.Based on the four terrain mold and dynamic simulation mold of tracked vehicle suspension system, model of tracked vehicle road wheels-track-terrain coupling system excitation characteristic which includes terrain model, dynamic simulation mold of tracked vehicle suspension system and track mold is built. The influence of track pre-tensioning, vehicle speed, terrain landscape and mechanical properties of terrain on the excitation characteristic of the coupling system were analyzed. Using orthogonal analysis evaluated the significance of factors affecting the coupling characteristics. The results indicated that surface morphology is the most significant factors, vehicle speed followed and then pre tensioning force. Tracked vehicle suspension system dynamic theory model, simulation model and the road wheels-track-terrain coupling system excitation characteristic simulation model provided technical supporting for vehicle road simulation system which can put directly displacement excitation on the wheel.Based on the previous research, Track filtering effect was studied at different speed in four kinds of typical road surfaces. Under the same conditions dynamic displacement of the road wheel was studied by model of tracked vehicle suspension system and road wheels-track-terrain coupling system excitation characteristic simulation model. The power spectrums of road wheel dynamic displacement are compared by two models. The filter coefficients are obtained and fitting analysis was carried out on the track structure. Filtering function was established taking the vehicle speeds on four kinds of typical road into account and four kinds of typical road surface is filtered. After that the road surface amplitude elevation decreased, the high frequency component also reduced. The track filter has more influence on the high frequency components of road surface spectrum. The filtering function of road spectrum provide theoretical basis for loading excitation on road wheels of vehicle road simulation system.