基于离散元法的三七仿生挖掘铲设计与试验

为减小三七收获过程中的挖掘阻力，以三七根茎及种植土壤为研究对象，测定本征物理参数，设置Bonding键参数建立三七根茎的离散元模型，分析根土粘结机理，利用Hertz-Mindlin with JKR建立三七根茎-种植土壤离散元复合模型；建立并分析挖掘铲的理论力学模型，确定仿生挖掘铲设计尺寸(长×宽×厚)为：360 mm×150 mm×8 mm、入土角30°、铲尖半角60°;采集野猪头三维模型的点云数据，确定仿生铲的结构曲线方程，建立仿生挖掘铲的三维模型；开展仿生挖掘铲与平面挖掘铲的仿真对比试验，追踪颗粒位移流向得平均位移以及平均挖掘阻力，分析颗粒的速度矢量明晰了挖掘铲面的减阻机理，得仿生挖掘铲的仿真试验减阻率为19.15%;利用高速摄影和阻力采集设备开展土槽试验，结果表明土壤颗粒流向与仿真趋势一致，仿生挖掘铲和平面挖掘铲的平均挖掘阻力为1 207.23、1 594.49 N,仿生挖掘铲减阻率为24.29%,与仿真试验减阻率十分接近，验证了离散元模型准确可靠、挖掘铲力学模型构建准确，仿生结构设计合理。

Design and Experiment of Panax notoginseng Bionic Excavating Shovel Based on EDEM

In order to reduce the digging resistance during Panax notoginseng harvesting, the roots and planting soil of Panax notoginseng were taken as the research object, the intrinsic physical parameters were measured, Bonding parameters were set to establish the discrete element model of roots and stems of Panax notoginseng , and the root and soil bonding mechanism was analyzed. The Hertz-Mindlin with JKR was used to establish the discrete element composite model of roots and stems and planting soil of Panax notoginseng. The theoretical mechanical model of the digging shovel was established and analyzed, and the design model size of the bionic digging shovel was determined as follows: 360mm×150mm×8mm, entry angle of 30°, half angle of the shovel tip of 60°. The point cloud data of the three-dimensional boar head model were collected, the structural curve equation of the bionic shovel was determined, and the three-dimensional model of the bionic excavator shovel was established. The simulation comparison test of bionic excavator shovel and plane excavator shovel was carried out, the average displacement and average excavation resistance were obtained by tracking the particle displacement flow direction, and the drag reduction mechanism of excavation shovel surface was defined by analyzing the particle velocity vector. The drag reduction rate of the bionic excavator was 19.15% in the simulation test. The soil groove test was carried out with high-speed photography equipment and resistance acquisition equipment. The results showed that the flow direction of soil particles was consistent with the simulation trend. The average digging resistance of the bionic excavator and the surface excavator was 1207.23N and 1594.49N, and the drag reduction rate of the bionic excavator was 24.29%, which was very close to the drag reduction rate of the simulation test. It was verified that the discrete element model was accurate and reliable, the mechanical model of excavation shovel was constructed accurately, and the bionic structure design was reasonable.