Simulation And Experimental Investigation Of Potato Digging Shovel Working Resistance Based On Discrete Element Method

Digging parts as one of the core components of potato digging shovel,it is a component which is directly related to potato tuber root and soil,its performance directly affects the performance of the whole machine.At present,the study of the interaction between the shovel and the soil is limited to the finite element static analysis and the dynamic analysis based on the continuum theory.However,it is actually affected by tuber and root,there is a relatively large degree of soil dispersion around tubers and roots,soil particle dispersion is greater during the excavation process.Discrete element method as a general method for the study of discontinuous media,it is more suitable for the study of tuber harvest soil mechanics.This paper relies on the National Natural Science Foundation of China "Dynamic repture property of the aggregate of soil-potato tuber-root system and it's coupling mechanism with digging shovel(51505305)",the method of combining field experiment with discrete element method is used,contrast potato digging shovel working process and the force situation,on the one hand,it verifies the feasibility of the experimental discrete element model and the other is the basis for the optimal design of the subsequent excavation.At the same time,it can also be used for the harvested soil dynamics analysis of other tuber crops.This paper is mainly including the following aspects:(1)Identification of soil discreteness and parametric measurement.?In Jianping County,Chaoyang City,planting potato field 3 acres,the soil firmness was tested every 10 days from tuber to harvest,to analyze the effect of tuber enlargement on soil dispersion.?The basic physical characteristic parameters of soil around the potato tubers of potato harvest time were determined by experiment,including soil texture,moisture content,density and firmness,which provides the data basis for the establishment of discrete element simulation model.(2)Simulation of potato digging shovel working process and the force situation by discrete element method.?Establish a discrete element model corresponding to the actual working condition of digging shovel-soil.Mainly include the choice of contact model(Hertz-Mindlin with Bonding Contact Model)?establishment of three-dimensional model of potato digging shovel(Using SolidWorks software)?production of soil particle plant(the parameter selection is determined by the experimental determination and the later repeated debugging)and the establishment of simulation boundary.?Using the discrete element software EDEM to simulate the movement process of the digging shovel,obtain the the force of the digging shovel.(3)Field test.Establishment of field test system,including the overall design and connection of the test system;selection and calibration of the force measuring frame,the tension sensor and the angle sensor.?Single factor field tests,to ensure that other operating parameters remain unchanged,only change the operating speed,get the potato digging shovel working process variation,analysis the effect of operating speed on working resistance of potato digging shovel.(4)Comparative analysis of test results and simulation results.The simulation of potato digging shovel by the horizontal force and vertical force of the change trend with increasing speed are basically the same with the change in field experiment with increasing speed:The horizontal resistance of potato digging shovel increases with increasing speed,minimum at 0.25m/s;the vertical resistance decreases first and then increases with increasing speed,it is the smallest when the working speed is 0.38m/s,horizontal resistance is always bigger than vertical resistance.The results show that it is feasible to simulate the working resistance of potato digging shovel by discrete element method.