典型蓖麻蒴果碰撞恢复系数的测定及分析

为研究蓖麻蒴果在脱壳时与脱壳部件之间的碰撞模型,揭示恢复系数的影响规律,基于蓖麻蒴果碰撞动力学原理和运动学方程,分别建立蓖麻蒴果碰撞过程中恢复系数的理论模型和试验装置。1)采用L8(4×23)型混合正交试验方案研究碰撞材料、含水率、下落高度和品种对蓖麻蒴果恢复系数的影响,并对碰撞材料、下落高度和品种进行单因素试验分析。2)利用高速摄影捕捉哲蓖4号和通蓖17号蓖麻蒴果碰撞时的反弹轨迹,并对其进行遍历循环计算,得出了蓖麻蒴果碰撞恢复系数。3)采用龙格库塔算法对碰撞动力学模型进行数值计算,采用遗传算法改进的Lsqcurvefit算法对恢复系数模型进行参数估计,得出了下落高度对恢复系数影响的解析表达式。试验结果表明:蓖麻蒴果恢复系数(COR)为0.268 8～0.426 4,影响其碰撞恢复系数因素主次顺序为碰撞材料、下落高度、品种和含水率,且碰撞材料对蓖麻蒴果恢复系数影响极显著;随下落高度的增加,恢复系数依次减少,且理论解与试验值相近,改进后的算法在恢复系数求解精度上分别提高约3.25%和3.02%。

Determination and analysis of typical castor seed collision restitution coefficient

In order to study the collision model of castor fruit between shelling components and castor fruit during collision progress and reveal the effect law of collision coefficient of restitution, a theoretical model of the restitution coefficient and the collision test device were established based on the collision dynamic principle and kinematics equation of castor fruit. 1) The influence of the restitution coefficient which the L₈ (4×2³) mixed orthogonal test scheme was used to research the collision material, moisture content, drop height, and variety on the castor fruit. Furthermore, the single-factor test was analysised for the collision material, drop height, and variety. 2) In view of the state of movement for collision between ZheBi 4 and TongBi 17 castor fruit, the trajectory of movement of castor fruit was captured with high-speed projection equipment and then the coefficient of restitution was calculated to traversal cycle calculations. 3) Runge-Kutta algorithm was used to perform numerical calculation on the castor collision dynamics model and the improved Lsqcurvefit algorithm of genetic algorithm was used to estimate the restitution coefficient model parameters. An analytical model, to determine the coefficient of restitution at under the effect of drop height was obtained. The test results demonstrated that the restitution coefficient of castor fruit is between 0.268 8 to 0.426 4, the primary and secondary impact factors of the collision restitution coefficient of castor fruit were the collision material, drop height, variety and moisture content. The collision material showed extremely significant effect on the restitution coefficient of castor fruit. With the increasing of drop height, the coefficient of restitution decreases in turn. And the theoretical solutions of collision restitution coefficient were similar to the experimental values. The accuracy of the improved algorithm was improved by approximately 3.25% and 3.02%, respectively.