基于离散元法的平仓机驱动轮与玉米颗粒的相互作用研究

Study on the interaction between the rigid wheel and corn of a flat grain machine based on discrete element method

为研究不同的驱动轮结构与粮食表面的相互作用规律,基于PFC^(3D)软件建立驱动轮在粮面上行走模型,针对PFC^(3D)中建立的玉米模型参数缺乏准确的问题,依托玉米直剪试验采用中心组合设计试验方法对线性接触模型下的玉米离散元参数进行标定,利用标定后的参数进一步研究驱动轮在粮食表面的驱动性能。结果表明,对内摩擦角影响显著的3个参数分别是弹性模量为385 MPa、阻尼系数为0.62、种间摩擦系数为0.051;在伺服控制每个驱动轮的垂直向负载受力平均为248.79 N得到:挂钩牵引力均值119.92 N,驱动轮扭矩均值27.26 N·m,沉陷量在35 mm以上,与粮库试验沉降量存在误差0.2 mm。更改驱动轮的相关参数重复试验分析得出,随轮齿高度、驱动轮直径和转速的增加挂钩牵引力都在增加。

In order to study the interaction law between different driving wheel structures and grain surface,the driving wheel walking model on grain surface was established based on PFC^(3D) software.Aiming at the problem that the parameters of the corn model established in PFC^(3D) were not accurate,based on the direct shear test of corn,the discrete element parameters of corn under the linear contact model were calibrated by the central combination design test method,and the driving performance of the driving wheel on the grain surface was further studied by using the calibrated parameters.The three parameters that had significant influence on the internal friction angle were elastic modulus of 385 MPa,damping coefficient of 0.62 and interspecific friction coefficient of 0.051.Under the servo control,the average vertical load force of each driving wheel is 248.79 N,and the following results are obtained:the average hook traction is 119.92 N,the average torque of driving wheel is 27.26 N·m,and the amount of subsidence is more than 35 mm,and there is an error of 0.2 mm with the settlement amount of grain granary test.Modifying the relevant parameters of the driving wheel,the repeated test analysis showed that the hook traction increased with the increase of tooth height,diameter of the driving wheel and the speed.