Study the effect of tool geometry and operational conditions on mouldboard plough forces and energy requirement: Part 2. Experimental validation with soil bin test

Forces acting on tillage tools directly affect vehicle fuel consumption of tillage operations. Both tool forces and soil disturbance are a function of tillage tool type, tool geometry, and operational conditions. A soil bin experiment in a sandy loam soil was conducted to validate the results obtained from the finite element method (FEM) simulation of the interaction between soil and a mouldboard plough, carried out in part 1 of this study. An octagonal load cell was used to measure the draught and vertical forces. A special support was manufactured to modify the cutting angle (alpha) and the lifting angle (beta). Tillage forces and soil disturbance were measured for different speed (0.5, 1, 1.5, and 2 m/s), depth (100, 150, 200, and 250 mm), cutting (30°, 45°, 60°, and 75°), and lifting (25°, 40°, and 55°) angles, and were presented for the same soil conditions of those considered in the FEM. The soil disturbance including the width and surface area of the cut soil, and the height, width, and the surface area of the soil inversion were measured with a laser scanner. Results showed that both the FEM calculations and the soil bin measurement presented the same tendency for the variation of draught and vertical forces with speed, depth, cutting, and lifting angles. The maximum error recorded between the measured and the FEM results was 33.8%. It was found that the draught and vertical forces increased linearly with speed, whereas a second order polynomial and linear relationships were established with depth, respectively. Draught increased linearly with both the cutting and lifting angles, whereas, the vertical force decreased linearly with these angles. The study of the soil disturbance showed that the operating conditions (speed, depth, and cutting angles) of the mouldboard plough had an important effect on the quality of the tillage (soil loosening and inversion). Both the FEM and the soil bin tests showed that at a working speed of 1 m/s and a depth of 150 mm with lower lifting and cutting angles of 25° and 45°, respectively, provide the best combination for lowering energy consumption. The soil bin tests showed that these settings provide a good soil disturbance.