Soil failure associated with crack propagation for an agricultural tillage tool

Tillage loosens soil to depths of 75-150 rum (3-6 in.). As the soil is tilled, the failure path precedes the motion of the tillage tool. Previous studies have examined soil forces acting on a tine by predicting different soil failure patterns. This paper quantifies the rate and the path of the cracks associated with soil failure front. The propagation of the soil failure path by observing the temporal profile of the leading edge of the failure crack with respect to the tool motion was examined. Crack propagations were analysed for sweep operating at 4 km h(-1) speed, and two operating depths of 75 and 100 mm using high-speed digital videography. Higher depth of operation showed distinct phases for crack development and propagation. Short and intermittent soil crack propagation with lower propagation growth rates was observed for shallow depth of operation. Crack growth rate has been observed to have a sinusoidal relation with time. (C) 2005 Elsevier B.V. All rights reserved.