Experimental Study of the Trafficability of Agricultural Vehicles (II)

Measurement of Contact Pressure

Abstract

The ultimate objective in designing tractive device for agricultural vehicles is to provide the required tractive efforts with minimum detrimental efforts on soil structure. A step toward determing the method necessary for this design is the measurements of stress distribution in soil under various sizes of tire. In this paper, the change of contact pressure and contact length with the number of passes of model rigid wheel and the influence of rigid wheel sizes on the soil compaction were investigated. The results may be summarized as follows.
Nominal contact length decreases and maximum of dynamic contact pressure increases with the number of passes of wheel in drier soil condition. But in wetter condition, the contact length increases due to remoulded soil with number of passes of wheel.
The ratio (Pdy/Pave) increases in wetter soil condition.
The results that deeper sinkage, greater contact pressure and higher dry density would be gained in smaller wheel as the result of travelling test using three wheels were illustrated.