The Physical And Mechanical Property Analysis Of Com Ears And Simulation Research On Com Threshing Progress

Corn is a multipurpose and high yield crop. After years of development, it hasbecomethe largest food crop in China. Corn threshing is one of the key aspects in theprocess of cornharvesting, and corn threshers are widely used in our country.Therefore, it is very important toimprove the corn thresher’s performance for ensuringthe quality of corn grain and increasing farmers’income.In this paper, the physical and mechanical property of corn ears is researched,and the discrete element method (DEM) is adopted to simulated analyse the cornthreshing process. There is a review of the research status of corn threshers, thephysical and mechanical property of corn ears and the application of DEM in the fieldof particle breakage. We selected two varieties of corn ears and one drum–type cornthresher as the research object, tested the physical properties and threshingmechanical properties of the corn ears. At the same time, the fracture factors of corncob were researched. At last, we carried out a bench test and simulated the cornthreshing progress using three-dimensional DEM analysis software which isresearched independently by our group. The main work and results of this paper are asfollows.(1) The characterization parametersof the corn ears ofhengda988and xianyu335were tested and analyzed, including length of corn ear, number of rows and kernels,diameter of corn ear and corn cob, angle of corn ear edge, ratio of corn ear section.The correlationof corn ear length, number of rows, diameter of corn ear and diameterof corn cob was analyzed. The relationship of corn ear length, number of kernels perrow was also studied.(2)A spiked thresher was selected as experimental platform, in order to study theeffect factors of corn cobs cracking in threshingprocess, including moisture of corn,length of ear, speed and length of the thresher drum. The threshing process issimulated and analyzed by self-developed software.Conclusionsare as follows.①The majority of the cracking section of corn cob were flat.②The higher The threshingroller rotary speed, the greater the number of corncobsections.When the threshing roller rotary speed reaches at600r/min,the number of corn cob sectionswould grow at a more subdued pace.The length of threshing rollerand the corn varietieshave little effect on the number of corn cob sections within acertain range. The corn cob moisture content has great influence onthe number of corncob sections. The moisture content is lower, the higher the number of corn cobsections.The longer the length of corn ear, the greater the number of corn cobsections.The distributions of cracking ratio of corn cobs are normal distribution withdifferent test factors.(3)A bench test of the threshing process is carried out. The test factors includethe rotary speeds of threshing roller, the lengths of threshing roller, the corn varieties,the corn ear feeding, the lengths ofcorn ear and the corn moisture. The performanceindicators include thegrain threshed rate, the grain crushed rate, thegrain impurityrate.Conclusions are as follows.①The threshing roller rotary speed is higher, the higher the threshed rate ofsimulation. All of threshed rate of simulation is higher than the bench test.The higherthreshing roller rotary speed, the more similarthe threshed ratesbetween the bench testresults and the simulation results, and the maximum relative error is only1.86%. Thelength of threshing roller rotaryis longer, the higher the threshed rate of simulation.The relative error of grain threshed ratesof xianyu335is larger than hengda998.②The threshing roller rotary speed is higher, the higher the grain crushed rateofsimulation.The length of threshing roller rotaryis longer, the higher the graincrushed rate of simulation.Thegrain crushed rate test results the threshing roller rotaryspeed is higher, the higher the threshed rate, but when the threshing roller rotary speedreaches a certain value the threshed rate is stabilized.When the length of threshingroller rotary is900mm, the maximum relative errorbetween the bench test results andthe simulation results is0.54%.The relative error of grain crushed ratesof xianyu335is larger than hengda998.