The Dynamic Simulation And Analysis Of Tracked Vehicle Walking System And Soft Ground

The walking system is the most fundamental system in tracked vehicles and plays a key role in the process of enhancing tracked vehicles’ performances, such as maneuverability, all-road passing ability and light-weight attribute. Recently as the generalization and application of multi-body dynamics softwares, more and more research priorities have been put on the dynamic behaviors of tracked vehicles’ walking system. The walking system of a tracked vehicle and soft ground dynamic model has been built based on LMS Virtual.lab Motion. The model’s obstacle performance in special conditions and adhesive characters on soft ground are simulated in computer.When modeling the walking system, most papers emphasis on the post-processing like analyzing vehicles’ performances instead of the pre-procession like modeling the vehicle and rarely documents have discussed the computing procedures of contact and soil forces inside the software. As it is the contact of ground and track shoes that ensures the walking system to work normally, the definition of contacts will influence the rightness of the model and the analysis of the performances directly. Therefore, the contact forces’ mechanism of action in the software is mainly illuminated theoretically and practically in this paper.Firstly, this paper introduces the mathematic model of contact and friction forces, the computation methods of normal and shear forces of the soil as well as the searching courses of contact points as solving contact and collision problems in LMS Virtual.lab Motion, a multi-body software. Then, the definitions of contacts between the sprockets, the road wheels, the soil and track shoes are instructed emphatically. Finally, the influence on contact forces from three parameters, the max penetration depth, the restitution coefficient and the transition velocity, in the definition of contact is analyzed.In aspect of simulation and analysis of driving systems, how the tracked vehicle passes precipices is simulated and analyzed with the dynamic model built. A method for transit the precipice is concluded that the vehicle approaches with a low speed and passes in speed of3m/s. The influence on ride comfort from filter effects of the track is studied by using different sinusoidal road surfaces as the stimulation whose wavelengths are as differenttimes as the segments intercept.In aspect of modeling the soft soil, as neither the contact style between the sprockets,the road wheels, the soil and track shoes nor the parameters of the soil like the humidity has been studied specifically in papers before, a new method for simulating sprockets and track shoes when defining the contact between driving system and soft soils is demonstrated in this paper while testing the parameters of the soil through experiments. Parameters of sandy soils and clay are obtained through platen experiments and shearing experiments.In aspect of vehicle simulation on soft ground, a scheme for testing the adhesion coefficient of the ground is designed to shorten the simulation time and the method is applied to test the adhesion coefficient of sandy soils and clay.