Test and modeling on static ground pressure of rubber track conversion system

Abstract: Rubber track conversion system is typically fitted instead of tyres on vehicles, with the aim of decreasing ground pressure, improving the trafficability, and protecting the soil. It is important to accurately predict its ground pressure. The configuration of rubber track conversion system is generally triangle, and the integral structure, road wheels' arrangement and track size are different from integrated track system. In this paper, the ground pressure distribution under rubber track conversion system was analyzed, and a prediction model for ground pressure distribution was established based on the test data. Firstly, the ground pressure under rubber track conversion system on solid and soft ground was tested by using Tekscan pressure measurement system. The test results showed its ground pressure distribution had the characteristics of both tracked vehicles and wheeled vehicles, but was different from the two. When rubber track conversion system was on the solid ground, the distribution of ground pressure was similar to tracked vehicles in the longitudinal direction, showing a multi-peak discontinuous trend. The ground pressure of track between load wheels was almost 0, and the peak distribution was similar to wheeled vehicles, showing a bell-type trend. The greater the load, the more uniform the peak. In the lateral direction, the distribution was uniform and continuous under the track, also showing a bell-type trend. When rubber track conversion system was on the soft ground, the distribution of ground pressure was multi-peak and continuous in the longitudinal direction. The peak distribution also showed a bell-type trend. In the lateral direction, the distribution of ground pressure on the soft ground was similar to its distribution on the solid ground. Secondly, according to the test data, a mathematical model of the ground pressure under the rubber track conversion system was proposed. In the longitudinal direction, the ground pressure was expressed by the second cosine function, and in the lateral direction, the ground pressure was expressed by a linear function. Model input parameters included the load on the track, track width, track length, number of road wheels, road wheel diameter, and so on. The ground hardness parameter of model was used to represent various ground conditions. The more soft the ground, the greater the value of this parameter. Then, simulation results derived from the mathematical model and experimental data were compared and analyzed. When rubber track conversion system was on the solid ground, the model could predict the peak under road wheels and the distribution of the ground pressure at the middle and the edge of road wheels, while the model could not perfectly predict the ground pressure of track between road wheels. When rubber track conversion system was on the soft ground, the model could predict the distribution of ground pressure and the peak under road wheels; the smaller the load on the track, the greater the model error. Compared with other models, the hardness parameter which represents the various ground condition can avoid the plate sinkage and shearing test, improving the practicability of the model. Finally, based on the predict model, the calculation equations of static steering resistence moment for rubber track conversion system were deduced for solid and soft ground. By comparing the calculated value with the test data, the results showed that the maximum error of the simulation results and test data was about 4.71%, so the model can be applied to the analysis of the steering performance of the rubber track conversion system. The proposed predict model can provide realistic estimates of the ground pressure and can also be used for structural design and other performance studies of rubber track conversion system.