筛分作业中颗粒同筛面间碰撞过程的数值研究

引入离散元法的弹性-阻尼-滑动接触模型,建立了描述颗粒同筛面之间的碰撞的数学模型,编制了模拟筛面上单颗粒运动的计算机程序并进行了数值试验,发现碰撞过程的接触时间主要取决于颗粒同筛面之间的接触刚度,而同筛分机的转速无关。为考察筛分机处理难筛分物料的能力定义了瞬时透筛系数这一指标,研究结果农明:增大筛面振幄较增大振频对瞬时透筛系数的增大更为有效,从而验证了潮湿细粒物料的低频大振幅筛分理论。

Numerical study on collision process between particles and screen plate

The collision between particle and the screen plate is the basic behavior of screen. Based on the spring-dashpot-slide contact model of DEM(Discrete Element Method), a mathematical model describing this behavior was built and a corresponding program which could simulate the single particle motion was developed by VC .Net. Numerical tests show that the contact time of collision process depends on mainly the contact stiffness between particle and the screen plate, having nothing to do with the screen rotational speed. To evaluate the screen ability for sieving difficult screen material, a new index named the instantaneous penetrating factor is put forward. Research result indicates that the screen amplitude has a much more effect on the instantaneous penetrating factor than the screen vibration frequency thus verifying the low frequency and large amplitude theory for moist fine materials.