基于FEM-DEM弛张筛面和料群耦合系统动态特性研究
Study on dynamic characteristics of the coupling system of flip-flow screen panel and material group based on FEM-DEM
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摘要: 针对潮湿细粒矿物在大挠度弹性筛分过程中存在料群堆积及筛面受力较大的问题,提出多球激振联合弹性筛分技术,探究筛分过程中弛张筛面和料群耦合系统在激振球作用下的动态特性。基于有限元法建立空载条件下筛面的运动学仿真模型,分析筛面的运动学特性;利用有限元和离散元耦合技术,探究料群对筛面运动学特性的影响规律;提出激振球作用下筛面与料群耦合系统的仿真模型,分析不同激振球个数作用下筛面及料群的动态特性;设计4因素、4水平正交试验方案,利用极差分析和方差分析研究物料颗粒数量、振幅、频率、激振球个数对弹性筛面运动状态和力学特性影响的显著程度;确定重载条件下筛面各因素的最优组合,并验证其准确性。研究结果表明:筛上料群特性对筛面的振幅具有较大影响,当筛面振幅的降低到一定程度时,会导致筛上物料出现堆积现象;采用多球激振筛面的方法能够减小筛面的挠度变形,使筛面整体位移上升,两端受力减小,加载料群的筛面由类周期运动转变为非周期性混沌运动,且基频振幅组成更加复杂,有利于筛上物料运动的活跃性。正交试验及响应优化结果显示:激振球和物料质量为影响弹性筛面运动学和力学特性的显著性因素,且当激振振幅为4 mm,频率为8 Hz,激振球个数为3时,重载工况下的弛张筛面位移最大,受力最小。Abstract: Aiming at the problems of material group accumulation and large stress on the screen surface in the process of large deflection elastic screening of wet fine-grained minerals. Multi-ball excitation combined with elastic screening technology is proposed,exploring the dynamic characteristics of the coupling system of flip-flow screen panel and material group under the function of excitation ball in the screening process. The kinematic simulation model of screen panel under no-load condition is established based on the finite element method,and the kinematic characteristics of the screen panel is analyzed. The coupling technology of finite element and discrete element is used to explore the influence of material group on the kinematic characteristics of the screen panel. The simulation model of the coupling system between the screen panel and the material group under the function of the excitation ball is proposed,and the dynamic characteristics of the screen panel and the material group under the function of different excitation balls are analyzed. The orthogonal test scheme of four factors and four levels is designed,and the range analysis and variance analysis are used to study the significance of the influence of the number of material particles,amplitude, frequency and the number of exciting balls on the motion state and mechanical characteristics of the elastic screen panel. The optimal combination of the screen panel factors under heavy load conditions is determined,and its accuracy is verified. Results show that the characteristics of the material group on the screen panel have a great impact on the screen panel's amplitude,and the material on the screen will accumulate when the amplitude of the screen surface decreases to a certain extent. Using multi-ball excites screen panel,the overall displacement of the screen surface increases,the stress at both ends of the screen panel decreases,the screen panel with loaded material group changes from quasi-periodic motion to aperiodic chaotic motion, and the composition of fundamental frequency amplitude is more complex,which is conducive to the activity of material movement on the screen panel. The results of orthogonal test and response optimization show that the excitation ball and material mass are the significant factors affecting the kinematic and mechanical characteristics of the elastic screen panel,and when the amplitude of the screen surface is 4 mm,the frequency is 8 Hz,and the number of excitation balls is 3,the flip-flow screen panel in the screening process not only has a large displacement,but also receives a small force.