香蕉秸秆离散元仿真粘结模型参数标定与试验

为提高离散元法对指导香蕉秸秆粉碎还田装备设计与优化的准确性与可靠性,本文利用Hertz-Mindlin with bonding接触模型建立香蕉秸秆离散元粘结模型并进行参数标定。运用高速摄影技术开展碰撞恢复试验、静摩擦及滚动摩擦台架试验,确定了香蕉秸秆碰撞恢复系数、静摩擦因数和滚动摩擦因数等基本离散元模型接触参数。开展香蕉秸秆物理与仿真剪切试验,获得破坏香蕉秸秆外皮的力学特征曲线,确定物理最大剪切力为122.41N;通过中心组合设计（Central composite design, CCD）响应面法确定香蕉秸秆粘结模型的法向接触刚度、切向接触刚度、临界法向应力与临界切向应力的最佳参数组合为5.89×107N/m、2.49×106N/m、1.39×105Pa、1.34×105Pa。以参数标定结果进行仿真验证,结果表明,仿真剪切力结果与物理剪切力相对误差仅为2.34%,验证了该粘结参数标定方法的可行性,可为香蕉秸秆粉碎还田机设计与研究提供理论参考。

Calibration and Verification of Bonding Parameters of Banana Straw Simulation Model Based on Discrete Element Method

In order to improve the accuracy and reliability of using the discrete element method to guide the design and optimization of banana straw crushing and returning equipment, Hertz-Mindlin with bonding contact model was used to establish the discrete element bonding model of banana straw and carry out parameter calibration. The impact recovery test, static friction test, and rolling friction test were carried out by high-speed photography technology, and the basic discrete element model contact parameters such as impact recovery coefficient, static friction factor, and rolling friction factor of banana straw were determined. Physical and simulated shear tests of banana straw were carried out to obtain the mechanical characteristic curve of destroying banana straw outer skin, and the maximum physical shear force was determined to be 122.41N. The optimal parameter combinations of normal contact stiffness, tangential contact stiffness, critical normal stress, and critical tangential stress of the banana straw bonding model were determined by central composite design (CCD) response surface method. The simulation results showed that the relative error between the simulated shear force results and the physical shear force was only 2.34%, which verified the reliability and accuracy of the bond parameter calibration method, and provided a theoretical reference for the design and research of the banana straw crushing and return machine.