| A road surface model system platform of VPG technique was constructed based on the deep research on random road numerical simulation method and vehicle-road system dynamics. By using the platform, it was achieved to regenerate 1-D,2-D and 3-D numerical road available for virtue testing environment; then the dynamic response of vehicle to the excitation caused by road irregularities was analyzed by means of MSC.ADAMS, ANSYS/LS-DYNA, etc.; and furthermore, a comparative analysis was made to discuss the influence of road flexibility on vehicle dynamic response.According to the PSD function of random road irregularities, cross-spectral density function and coherence function, a 2-D PSD expression, auto-spectral density and coherence function were deduced. Afterwards, an introduction was given to the fundamental theories and methods of numerical expression of random road in time domain and some different numerical algorithms were analyzed, then a 1-D road model in time domain was established, and numerical simulation and verification of numerical road surface model were accomplished.On the basis of numerical simulation method of 1-D random road, an EFFT 2-D numerical simulation method based on PSD was deduced. Then by the use of FBM theory and wavelet transform method, a 2-D numerical simulation was carried out for random road surface. Moreover, by means of image processing and pattern recognition theory, an image database of random road surface of standard grade was set up, and then the 2-D numerical road surface regeneration method and system model were established based on road surface image matching.IFFT method was used to carry out superposition of deterministic event and stationary stochastic road surface, then a 2-D numerical model of typical testing intensified road surface was built, and a 2-D wavelet analysis was conducted to process the detail signals of simulated road surface model by means of wavelet analytical method.The regeneration algorithms of straight road, winding road, ramp road, intensified deterministic testing road, etc. in VPG environment were analyzed so as to regenerate a 3-D road surface model which was used in vehicle-road system simulation. After that, a typical dynamic model of testing vehicle was built with a regenerated random road surface of standard grade and an intensified deterministic testing road surface as its input excitation respectively, and the dynamic simulation was carried out for vehicle-road system, then the vibration response and PSD spectrum analytical curve were obtained. According to the postprocessing curve data, the vehicle's riding comfort was evaluated and the fatigue life of vehicle structure was analyzed and predicted.Based on the elastic layered space theory and finite element (FE) analysis method, a coupled dynamic model of flexible tyre-flexible road was established by means of ANSYS/LS-DYNA software. Through simulation and calculation, the dynamic responses of a vehicle running on the flexible roads of different irregularity grade were obtained and compared with those on the rigid roads, and then the influence of road flexibility and roughness on vehicle riding comfort performance was discussed.It was concluded that the flexible coupling of road surface and tire implemented a repressing on the vibration response of vehicles from the road excitation, and for high grading road the vibration rsponse of vehicles was mainly from the road surface flxibility, furtherly, with the decrease of the road grade, the excitation from road irregularities gradually became dominant in the contribution to the vehicle's vibration response.
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