全膜双垄沟起垄覆膜机镇压作业过程仿真分析与试验

为深入研究全膜双垄沟起垄覆膜机镇压作业过程中不同工作参数对机具运行及种床构建质量的影响,该文利用ABAQUS软件建立镇压装置轮组与种床土壤互作的三维有限元模型,模拟镇压作业过程中触土部件与土壤相互作用的动态过程。采用三因素三水平Box-Behnken试验设计方法,建立载荷、机具前进速度、土壤含水率与垄面沉陷量、水平牵引阻力及渗水孔偏移量之间的数学模型,寻求覆膜机镇压轮组的最优作业参数组合。仿真试验中采用基于ALE算法的自适应网格划分技术解决网格畸变导致的仿真中断问题。仿真结果确定了3种不同土壤条件下较优的作业参数组合,并进行田间验证试验。结果表明,土壤含水率为15%条件下,机具前进速度为1.01m/s,施加载荷为100N时镇压轮组所受水平牵引阻力均值为44.15 N,大垄垄面平均沉陷量为11.82 mm,渗水孔平均偏移量为8.25 mm,试验结果满足全膜双垄沟种床构建质量要求。本文建立的三维有限元模型可用于预测镇压装置工作过程中的作业情况,可为机械化双垄沟种床构建作业方式及起垄覆膜机镇压装置的设计提供参考。

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.