| Tire is one of the great important subassembly of a vehicle. Every other forces and moments, besides air force and gravity, that influence the vehicle movement come from the interaction between the tire and road.In recent years, with the raised driving speed and people's attention on vehicle riding comfort, vehicle compliance becomes increasingly important, thus it requires us continuous research on the tire characteristics. As impact from the road is the main source of vehicle vibration, as well as tire and road is immediate contact, it requires us deeply research on the contact relation between them. Research of vehicle dynamics tire model experienced developments from level road to macro non-level road, and grated well achievement. But either vehicle dynamics tire model on level road or vehicle dynamics tire model on non-level road is both based on macro 2D road model, therefore the relative microcosmic changes can not express in the model when a vehicle elapse the uneven road in a small range. In fact, tire and road is contact in a process of complex 3D curved surface, and tire is envelope of road. And also during the actual driving process, it will encounter with various kinds of roads such as crown, pit, decelerating block. Therefore, in order to simulate the property of driving on the micro uneven road, it is necessary to build a more accurate 3D tire road contact model during the vehicle dynamics modeling.Based on inheritance and innovation of previous tire modeling theories and thoughts, this paper extends the tire and road contact model to the micro 3D uneven road, and explores a calculation method that effectively describes the tire and road contact. Thus it is more accurately to simulate the process of tire and road contact after inputting the road information into the tire model. The main content of this paper is organized in the following three aspects:Firstly, adopted the ring model form, the tire is simplified into two parts, the hub and tire-road contact footprint block. Tire-road contact footprint block is extended from one to several blocks, thus these tire-road contact footprint blocks are envelope of road when a vehicle elapse the micro uneven road, and the 3D contact process is simulated. Besides, the tire model is divided into four parts, they are force characteristic module, kinematics module, rotary dynamics module and road inputting module, thus the theoretical foundation for tire-road contact model is built up.Secondly, road model based on micro 3D uneven road is established. Road is segmented into a series of triangle mesh. The interval in X or Y direction is a certified value, road elevation and road friction coefficient are storied in the Z direction. Then three kind uneven roads in a small range such as crown, pit and cosine are built up, and the road data is storied for the tire-road contact calculation.Thirdly, according to the simple illumination model in the computer graphics, this paper explores a calculation method that effectively describes the tire and road contact. Firstly it judges the location of the tire-road contact point in the OXY plane and reads the relative road data, then it makes bilinear interpolation, at last it obtains the road elevation and unit normal vector as the road inputting information for tire model.Furthermore, the mathematical models are converted to computer programs, and verification and analysis is carried out. Validation results indicate that the vehicle dynamics tire-road contact model in this paper is not only suitable for level road and macro non-level road, but also fit for 3D uneven road in a small range. And it has high precision and efficiency too. The exploratory research in this paper has got stage achievements, and lays a foundation for the further research on the tire-road contact modeling based on micro 3D uneven road. |
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