基于离散元的设施农业就地翻土犁的研究与试验

Experimental study on in-situ tilling plow in facility agriculture based on discrete element method

针对设施农业空间狭小,土壤病虫害严重,无法使用铧式犁深翻的问题,提出一种就地翻土解决办法。根据逆向工程得到就地翻土犁犁体逆向曲面,通过现有犁体成型原理,参照铧式犁犁体耕宽、耕深、犁体安装角、切土角、导曲线提升角、开度、犁体长度等参数,创设就地翻土犁犁体正向曲面;实测设施农业土壤相对湿度为34.57%、土壤堆积角为39°,通过EDEM软件中的接触参数数据库GEMM得到接触参数范围,标定土壤颗粒间表面能为4.19 J/m^(2)、碰撞恢复系数为0.282、动摩擦因数为0.051、静摩擦因数为0.629,创设试验土槽;引入原沟落土率概念;构建原沟落土率与曲面参数间的相互作用模型,得到最佳原沟落土率曲面参数;利用Design-Expert软件进行分析,以原沟落土率为响应指标,使用Plackett-Burman试验设计方法开展多因素两水平显著性筛选试验,得到影响原沟落土率耕宽、犁铧安装角、切土角3个显著性因素;对3因素进行Box-Behnken试验设计,得到278.392 mm耕宽、40.522°犁铧安装角、23.211°切土角最佳设计参数。针对优化结果进行试验,得到试验结果与预测结果误差为3.13%,试验结果表明,所研究就地翻土犁可以达到就地翻垡的目的,并为解决设施农业内土壤深翻问题提供参考。

In view of the problem that the arable plough could not be used for deep ploughing due to the narrow space of facility agriculture and the serious soil diseases and insect pests,a method of turning soil on the spot was put forward.Based on the reverse engineering,the reverse surface of the plough body of the local soil turning plough was obtained.Based on the existing forming principle of the plough body,the forward surface of the plough body of the share plough body was established by referring to the ploughing width,ploughing depth,installation angle of the plough body,soil cutting angle,guiding curve lifting angle,opening and length of the plough body.The soil relative humidity was 34.57%and the soil accumulation angle was 39°.The contact parameter range was obtained by GEMM,the contact parameter database of EDEM software.The surface energy between soil particles was 4.19 J/m^(2),the collision recovery coefficient was 0.282,the dynamic friction coefficient was 0.051,and the static friction coefficient was 0.629.The concept of soil fall rate in original gully was introduced.The interaction model between soil fall rate and surface parameters was established,and the optimal surface parameters of soil fall rate were obtained.Using Design-Expert software,plackett-Burman experimental design method was used to carry out multi-factor and two-level significance screening test with soil fall rate as the response index.Three significant factors affecting soil fall rate of the original ditch were obtained,namely,plow width,plowshare installation angle and soil cutting angle.Box-Behnken experimental design was carried out for the three factors,and the optimal design parameters of 278.392 mm plow width,40.522°plow share installation angle and 23.211°soil cutting angle were obtained.Based on the optimized results,the error between the experimental results and the predicted results is 3.13%.The experimental results show that the tilling plow can achieve the aim of tilling in situ,and provide a reference for solving the problem of soil deep tilling in facility agriculture.