Soil bin

Just as wind tunnels are used to design airplanes, trains, automobiles, and model basins are used to design ship s hulls, soil bins are used to test off-road vehicles, lunar roving vehicles, caterpillar tractors, and military tanks. 

Consider the caterpillar vehicle shown in Fig. 7.1. The draw bar force ( )) required to drive a unit of fixed track design (length, width, and tread arrangement) at uniform speed (V) over sand of a given composition, particle size and moisture content will be a function of the following variables  

W = vehicle weight, [F] p = sand density, FL T s = sand particle size, [Z] 

After dimensional analysis, taking d, p, and V as the dimensionally independent quantities  

If a one tenth scale model is to be tested using sand of the same density as that on which the protot5 e will operate, and under the same acceleration due to gravity (g ), the following relations pertain  

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Figure 7.1. Model of tracked vehicle operating in a soil bin with soil particles of mean diameter (s).

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