| Abstract: | A set of soil-track interaction relations was made developed for the morbility simulation of tracked or crawler system vehicles on dry, loose sand. These interaction relations were developed specifically for multibody mobility codes in which the soil-vehicle interaction is represented solely by soil-track interaction forces. By employing plate penetration and shear tests, an average pressure-sinkage relation, a shear force-slippage relation, and a sinkage-slippage relation were measured. These plate test data were sufficient only to describe the soil-track interaction on hard ground. On soft ground, however, it was found that intermittent sinkages induced by each passage of the road wheels become important. This dynamic contribution is called “agitation sinkage.” Based on this observation, the sinkage rate (velocity) was decomposed into elastic and plastic rates; the plastic part consists of normal force-induced, slip-induced, and agitation-induced components. Whereas the elastic and the first two components of the plastic sinkage rate were characterized by the conventional plate penetration and plate shear tests, the last term, agitation sinkage, required a new dynamic test in which the sinkage of the track after successive passages of moving road wheels was measured. It is recommended that this new field measurement technique be adopted to characterize the agitation sinkage for various terrains. |
