Based on conventional discrete element method, the idea and calculating method of dynamic discrete element (DDEM) was proposed, and a relevant program was developed. The application of the method is presented in rock ...Based on conventional discrete element method, the idea and calculating method of dynamic discrete element (DDEM) was proposed, and a relevant program was developed. The application of the method is presented in rock mechanics and engineering, which indicates that the method can be widely used in dynamic response and stability analysis of jointed rockmass under dynamic load. [展开更多
Discrete element method(DEM)-based simulations are crucial for bridging macro and micro research,particularly owing to the limitations of experimental methods.This paper reviews the simulation techniques used for part...Discrete element method(DEM)-based simulations are crucial for bridging macro and micro research,particularly owing to the limitations of experimental methods.This paper reviews the simulation techniques used for particle breakage in DEM,summarizes the research status,and discusses pertinent issues to outline future prospects for particle breakage simulation.Fragment replacement method(FRM)and bonded particle method(BPM)are widely used to simulate particle breakage based on DEM.In BPM models,sub-particle size selection,particle cluster generation mode,and bonding parameters are crucial considerations.Although BPM can simulate the breakage of particles with complex shapes,it cannot re-simulate them,posing difficulties in coordinating calculation load and simulation accuracy.For FRM,the fragment replacement mode and particle breakage criteria are critical.The number and size of replacement particles are difficult to match with actual conditions,and ensuring mass conservation is significantly challenging.Although the initial computational load in FRM is relatively low,it increases significantly as the simulation progresses.To address these issues,we propose a simulation method that integrates BPM and FRM,allowing sub-particle breakage in BPM to be realized by FRM.展开更多
针对内充气吹式排种器对圆形种子适应性差、排种效果不佳的问题,对内充气吹式排种器进行优化设计,为增强种子充填容积和气流压附力在型孔底部开设不同结构的槽孔。基于离散单元法理论建立玉米籽粒粘结颗粒模型,运用EDEM-CFD耦合分析方法...针对内充气吹式排种器对圆形种子适应性差、排种效果不佳的问题,对内充气吹式排种器进行优化设计,为增强种子充填容积和气流压附力在型孔底部开设不同结构的槽孔。基于离散单元法理论建立玉米籽粒粘结颗粒模型,运用EDEM-CFD耦合分析方法,以型孔内种子在排种盘转动过程中所受的曳力值为指标,在入口风速为30 m/s、前进速度为8 km/h的工作条件下对3种不同型孔结构排种盘进行圆粒种子排种效果的耦合仿真,分析排种过程中圆粒种子所受曳力的变化情况及清种和压种性能。仿真结果表明:同一排种盘中,因大圆粒种子迎风面积大于小圆粒种子,所受曳力均大于小圆粒,迎风面积大的颗粒更易被清出型孔;径向内开方孔盘型孔内气流对颗粒的曳力及压附力均较大,且增大了型孔对种子在径向方向的充填容积,该盘对圆粒种子及混合种子的工作效果均较好。为验证仿真结果进行台架试验,当前进速度为8 km/h时进行3种排种盘工作压强的单因素试验,结果表明,径向内开方孔盘合格率随工作压强的增大而增大,当工作压强大于5.5 k Pa时,合格率超过95%,明显优于其他2个排种盘;对径向内开方孔盘进行前进速度为4~12 km/h、工作压强为4~8 k Pa的双因素试验,结果表明,合格率随着前进速度和工作压强的增大而增大,针对不同前进速度,当工作压强高于6 k Pa时,合格率接近96%,漏播率低于1%。展开更多
在目前颚式破碎机的设计工作中,电机功率的选择主要以经验计算为主,常有计算功率较之需用功率偏大或偏小的现象发生。为分析破碎机在破碎物料过程中功率的变化规律,使用离散元软件EDEM(Engineering Discrete Element Method)建立物料及...在目前颚式破碎机的设计工作中,电机功率的选择主要以经验计算为主,常有计算功率较之需用功率偏大或偏小的现象发生。为分析破碎机在破碎物料过程中功率的变化规律,使用离散元软件EDEM(Engineering Discrete Element Method)建立物料及破碎机的离散元模型。对岩石试件进行点载荷试验,得到其抗拉强度,并在EDEM中模拟物料的压缩试验,对物料BPM(Bonded Particle model)模型参数进行标定,使物料的破碎行为与真实岩石保持一致。在实验室用颚式破碎机内进行岩石的破碎工作,并记录破碎机的功率变化规律,与模拟物料破碎得到的功率变化曲线进行对比,发现两者基本吻合,得到的功耗数据可为电机的合理选择提供一定的参考。展开更多
基金Project(49772167)supported by National Natural Science Foundation of Chinaproject supported by Open Research Fund of Geotechnical Lab of Ministry of Territorial Resources of Chinaproject supported by Beijing Science Star Foundation
文摘Based on conventional discrete element method, the idea and calculating method of dynamic discrete element (DDEM) was proposed, and a relevant program was developed. The application of the method is presented in rock mechanics and engineering, which indicates that the method can be widely used in dynamic response and stability analysis of jointed rockmass under dynamic load. [
基金financially supported by the National Natural Science Foundation of China (No.52104155)the China Postdoctoral Science Foundation (No.2023M733778)the Fundamental Research Funds for the Central Universities,China (No.2024ZKPYNY01)。
文摘Discrete element method(DEM)-based simulations are crucial for bridging macro and micro research,particularly owing to the limitations of experimental methods.This paper reviews the simulation techniques used for particle breakage in DEM,summarizes the research status,and discusses pertinent issues to outline future prospects for particle breakage simulation.Fragment replacement method(FRM)and bonded particle method(BPM)are widely used to simulate particle breakage based on DEM.In BPM models,sub-particle size selection,particle cluster generation mode,and bonding parameters are crucial considerations.Although BPM can simulate the breakage of particles with complex shapes,it cannot re-simulate them,posing difficulties in coordinating calculation load and simulation accuracy.For FRM,the fragment replacement mode and particle breakage criteria are critical.The number and size of replacement particles are difficult to match with actual conditions,and ensuring mass conservation is significantly challenging.Although the initial computational load in FRM is relatively low,it increases significantly as the simulation progresses.To address these issues,we propose a simulation method that integrates BPM and FRM,allowing sub-particle breakage in BPM to be realized by FRM.
文摘针对内充气吹式排种器对圆形种子适应性差、排种效果不佳的问题,对内充气吹式排种器进行优化设计,为增强种子充填容积和气流压附力在型孔底部开设不同结构的槽孔。基于离散单元法理论建立玉米籽粒粘结颗粒模型,运用EDEM-CFD耦合分析方法,以型孔内种子在排种盘转动过程中所受的曳力值为指标,在入口风速为30 m/s、前进速度为8 km/h的工作条件下对3种不同型孔结构排种盘进行圆粒种子排种效果的耦合仿真,分析排种过程中圆粒种子所受曳力的变化情况及清种和压种性能。仿真结果表明:同一排种盘中,因大圆粒种子迎风面积大于小圆粒种子,所受曳力均大于小圆粒,迎风面积大的颗粒更易被清出型孔;径向内开方孔盘型孔内气流对颗粒的曳力及压附力均较大,且增大了型孔对种子在径向方向的充填容积,该盘对圆粒种子及混合种子的工作效果均较好。为验证仿真结果进行台架试验,当前进速度为8 km/h时进行3种排种盘工作压强的单因素试验,结果表明,径向内开方孔盘合格率随工作压强的增大而增大,当工作压强大于5.5 k Pa时,合格率超过95%,明显优于其他2个排种盘;对径向内开方孔盘进行前进速度为4~12 km/h、工作压强为4~8 k Pa的双因素试验,结果表明,合格率随着前进速度和工作压强的增大而增大,针对不同前进速度,当工作压强高于6 k Pa时,合格率接近96%,漏播率低于1%。
