A nonlinear 3D finite element analysis of the soil forces acting on a disk plow

This study aimed to compare predicted soil forces on a disk plow with measured forces within the tillage depth of clay (90 g kg^(-1) sand, 210 g kg^(-1) silt, 700 g kg^(-1) clay) and sandy loam (770 g kg^(-1) sand, 40 g kg^(-1) silt, 190 g kg^(-1) clay) soils. The model assumed the effects of both tilt angle and plowing speed. Two plowing speeds (4 and 10 km/h) at three tilt angles (15(degree), 20(degree)and 25(degree)) were compared and the draft, vertical, and side forces determined. A 3D nonlinear finite element model was used to predict the soil forces while a dynamometer was used to measure them on a disk plow in the field. An incremental method was used to deal with material nonlinearity and the Trapezoidal rule method was used to analyze the dynamic response of soil during tillage. Field tillage experiments were conducted to verify the results of the finite element model. It was found that increasing the tilt angle of the plow increased the draft and vertical forces and decreased the side force. Increasing plowing speed increased the draft and side forces and decreased the vertical force. Generally, the results from the finite element model were found to be compatible with the experimental results in clay soil, while in sandy loam the differences between predicted and measured data were probably due to problems of measuring soil mechanical characteristics in the triaxial test.