The Research Of Structural Simulation Of Wood Chips Unloading System Based On EDEM

The huge demand for wood chips in China has led to the development of related industries,but the following problem is that the operation efficiency of wood chips unloading equipment can not meet the needs of efficient development,and the structural optimization of the unloading system is becoming increasingly urgent..Compared with other bulk cargo materials,wood chips have the characteristics of large water content and poor fluidity.The most serious problem in the process of discharging wood chips is that they are difficult to grab and easy to clog and agglomerate.Considering the actual situation of the port,this paper takes the gantry crane with bucket in Rizhao Port as the reference standard,uses SolidWorks to establish the model of each part of the unloading system,and uses the method of combining theoretical calculation and EDEM simulation analysis to carry out the structural optimization simulation research of the wood chips unloading system.The main research contents are as follows:(1)The effects of the basic properties of wood chips such as particle size,density,humidity and stacking angle on their fluidity were analyzed.The simulation model of wood chips was established based on Hertz-Mindlin with JKR contact model principle.By means of "virtual calibration" and experimental measurements,the required parameters for the discrete element simulation of wood chips unloading process were obtained,which filled a blank in the material types in the discrete element analysis.(2)The advantages and disadvantages of all kinds of grabs when grabbing wood chips are analyzed,and the simulation model of multi-jaw plate grab which is most suitable for grabbing wood chips is established by using SolidWorks software.By analyzing the trajectory of grab excavation,the complex motion is decomposed into uniform linear lifting and uniform rotation around the hinge point.The above conditions realize the EDEM simulation of grab excavation process.The force of grab in the process of grabbing is analyzed.The cut-in resistance,push resistance and friction resistance are calculated respectively.The finite element analysis is carried out in Ansys Workbench,which provides a basis for structural optimization of grab.(3)Funnels with different structures was built by using SolidWorks and introduced into EDEM to simulate the process of discharging wood chips in funnels and observe their flow state.According to the physical characteristics of wood chips,simulation analysis is carried out from the aspects of funnel wall angle,funnel grid size and funnel grid shape,from which the optimal design scheme is selected to achieve a reasonable,reliable and efficient system.(4)The belt unloader is the most suitable device for unloading wood chips from funnel based on the characteristics of wood chips,the combination with the whole unloading system and the economic point of view.The belt unloader itself is efficient enough,so it will not become the "short board" of the whole system.The key to the research is to cooperate with other parts of the system.Through EDEM simulation research,it is proved that using belt unloader to unload funnel is feasible and effective.The force of conveyor belt is analyzed by using post-processing function.At the same time,the working condition of belt unloader is simulated when the funnel may have accumulated material,which provides theoretical guidance for equipment management of belt unloader.