Simulation analysis and test on suppression operation process of ridging and film covering machine with full-film double-furrow

Raised bed cropping coupled with full film mulching is a cultivation method for arid and semi-arid regions to improve water use efficiency, which is usually constructed mechanically using machine. The purpose of this paper is to analyze how different combinations of working parameters of the machine affect such seedbeds constructed with a double-furrow ridge. The interaction between the soil-compact component in the machine and the soil surface was simulated using a three-dimensional finite element model in the ABAQUS software. Based on the three-factor and three-level Box-Behnken design, a mathematical model was proposed to describe how the applied load, forward speed of the machine and soil moisture content combined to affect compression of the ridge, horizontal traction resistance and offset of the infiltrating hole in attempts to find the optimal operating parameters. An adaptive meshing method based on the ALE algorithm was used to alleviate a possible mesh distortion caused by soil compression in the finite element simulation. In the analysis, the vertical displacement of the suppression wheels in the machine was used as a reference to quantify the seedbed subsidence. The reference horizontal traction was calculated assuming that the machine moved forward, and the offset of the infiltrating hole was used as a reference for the extent to which the plastic film was torn. The optimal working parameters under different soil conditions were determined by comparing the three references, and they were then verified against field experiments. The results showed that the average horizontal traction to the soil-compact wheels was 44.15 N, the average subsidence of the wider ridge was 11.82 mm, and the average offset of the infiltrating hole was 8.25 mm. These met the requirements for raised seedbed with double- furrow and full film mulching, and proved that the three-dimensional finite element model was able to predict operation of the machine. It was also found that the size of the ridge did not change significantly and the film tearing was in acceptable range. The suppression wheels ran smoothly and only moderately compacted the soil. The methods and the results presented in this paper provide references for designing and developing machines for mechanically constructing raised seedbed with double-furrow and full film mulching.