Development of a dual sideway-share subsurface tillage implement: Part 2. Effect of tool geometry on tillage forces and soil disturbance characteristics

Simulation of tillage tool-soil interactions provides opportunities to accelerate new equipment design and evaluate its performance. The dual bent blade subsurface tillage implement which its performance has been evaluated in the field, is a new conservation tillage tool deserving its soil cutting efficiency to be improved by optimizing its geometry using discrete element method (DEM) modeling. In order to achieve this objective, the effect of share size (5.9, 7.6, 11.3, 16.8, 22.6 and 28.2 cm), rake angle (7.5 degrees, 15 degrees, 25 degrees, 30 degrees, 35 degrees and 40 degrees), tilt angle (10 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees and 40 degrees), and shank rake angle (45 degrees, 60 degrees, 75 degrees, 90 degrees and 97.5 degrees) of the tool plowing at 150 mm depth, on soil cutting forces and soil disturbance characteristics were investigated using the validated DEM model developed in part 1 of this study. Results showed that the draft and vertical forces increased with increasing share size, while the specific resistance (SR) decreased. With increasing share rake angle, the draft force, SR, upward vertical force and the degree of soil pulverization increased. The minimum SR of the tool was at the tilt angle of 20 degrees. But at this tilt angle, the uniformity of the cutting-depth for a long share-size was low, due to greater lateral bending of the share. As the rake angle of the shank decreased, the draft and vertical upward forces decreased. DEM simulation results showed that an efficient non-inversion tillage implement design can be achieved by developing a dual sideway-share subsurface tillage tool having a total cutting width of 53 cm with the rake and tilt angles of 15 degrees and 10 degrees, respectively, and attached to a 75 degrees-rake-angle shank and plowing 150 mm deep in a sandy clay loam soil.