Authors

Abstract

In order to better use the discrete element method (DEM) to study the cutting and throwing process of King grass (KG) stalk in mechanical harvesting, the DEM model and contact parameters of KG stalk were studied in this paper. By using the Multi-sphere method, the DEM model of KG stalk was established in EDEM software; Through the impact bounce test and slope sliding test, the stalk-steel coefficient of static friction, stalk-steel coefficient of restitution and stalk-stalk coefficient of restitution were calibrated as 0.372, 0.656 and 0.523, respectively; Based on the stacking test, using the response surface methodology, the optimal values of stalk-stalk coefficient of static friction, stalk-stalk coefficient of rolling friction, stalk-steel coefficient of rolling friction were calibrated as 0.393, 0.072 and 0.144, respectively. The throwing test bench of stalk was designed, and the actual and simulation throwing test were carried out. The relative error of throwing distance in bench test and simulation test under four throwing speeds was 1.15%, 7.76%, 8.88% and 10.46%, respectively. The throwing trajectory curve of the simulation test is consistent with that of the actual test, which verifies the accuracy of the DEM model and contact parameters of KG stalk.

Abstract in Chinese

为更好的应用离散元法研究王草茎秆与收获机械的作用机理，寻求王草茎秆离散元模型的最优接触参数组合。论文对王草茎秆的物理参数进行测量，并基于多球粘结颗粒模型在EDEM软件中建立了王草茎秆的离散元模型；采用台架试验和仿真试验相结合的方式，通过碰撞弹跳试验和斜面滑动试验，得到茎秆-钢板静摩擦因数、王草茎秆-钢板碰撞恢复系数和茎秆-茎秆碰撞恢复系数依次为0.372、0.656和0.523；基于堆积试验，利用响应面优化方法，以EDEM仿真堆积角与实际堆积角的相对误差为指标，确定茎秆-茎秆静摩擦因数、茎秆-茎秆滚动摩擦因数以及茎秆-钢板滚动摩擦因数的最优数值分别为0.393、0.072和0.144；进行王草茎秆实际抛送试验和CFD-DEM气固耦合仿真抛送试验，得到不同抛送板转速（400、500、600和700 r·min-1）条件下，台架试验和仿真试验抛送距离的相对误差分别为1.15%、7.76%、8.88%和10.46%，仿真试验的茎秆抛送轨迹曲线与台架试验抛送轨迹曲线相吻合，验证了王草茎秆离散元模型和接触参数的准确性。