Mechanical Damage Analysis And Experimental Research On Potato Harvester Elevator

After wheat,rice and corn,potato is the forth important food crop in the world.With the development of Potato Main Grain Strategy,potato planting has been paid more and more attention in China.The potato planting area of China ranks first in the world,but the potato quality still has a big gap with some advanced countries.The serious mechanical damage during potato harvesting is one of the important reasons leading to the low potato quality in China.The mechanical damage in potato harvesting will impact a lot on the subsequent potato storage and processing.At present,the research of potato mechanical damage at home and abroad is ma inly from the potato material characteristics and related potato harvesting machinery.The research on how to reduce the potato mechanical damage has become the key to improve potato quality aimed at the widely used elevating chain type potato harvester in China.Therefore,aiming at above problem,this study explored the mechanism of mechanical damage on the elevating chain type potato harvester,determined the positions where mechanical damage can easily occur in the process of potato harvesting.Kinemati cs analysis and collision mechanics analysis of mechanical damage process were carried out,finite element simulation analysis was carried out on the collision model of potato and lifting chain,According to the factors affecting mechanical damages,some corresponding experiments were designed.The main contents are as follows:(1)To the specific varieties of potatoes,some basic parameters,including basic physical parameters and basic mechanical parameters,was determined to potato physical dimension and the mechanical properties of potato peel and tuber.The basic physical parameters include the measurement of axial size,shape index and radius of curvature,the basic mechanical parameters include the compression properties of potato tubers and the tensi le properties of potato peels.(2)According to the operating characteristic of elevating chain typer potato harverter,the position where mechanical damage can easily occur were determined,which potatoes drop from the end of the first lift chain to the secondary lift chain,which potatoes are thrown up by the reciprocator then drop to the secondary lift chain,which potatoes fall to the field or container after lifting.The kinematic analysis and mechanical analysis during the collision process as the subject investigated were carried out to determine the influencing factors of potato mechanical damage.(3)Through the analysis of the motion characteristics and collision mechanics characteristics of potato damage process,establishment of finite element model of potato and lifting chain based on measured physical and mechanical parameters of potato.Taking the operation parameters of the conventional lift chain potato harvester as the initial condition,the finite element model was calculated by using Hyper Works and LS-DYNA,and the simulation results were analyzed.(4)Mechanical damage test table had been designed and the bench test was finished according to the standard of the foreign scholars for the determination of the mechanical damage.The forward speed of the implement,the linear speed of the lift chain,the inclination of the lift chain and the drop height were the test factors,the damage standard value of the damaged skin area and the damage standard value of the damage depth were taken as the test i ndexes,the quadratic regression combined experiment was performed,regression analysis of test results and optimization job parameters reduce the potato mechanical damage.The verification test based on the electronic potatoes was carried out,and the mechanical damage condition can be improved by verifying the combination of the working parameters.The results are as follows:(1)The results of measuring the basic parameters of potato were as follows: according to the axial dimension range of Eugene 885 potato variety,the length was 60~ 90 mm,the width was 55~ 68 mm,the thickness of potato was within 47~60mm,and the shape index was in the range of 0.75~0.89.The mean curvature radius corresponding to the top is 18.53 mm,the average curvature radius corresponding to the waist is 43.22 mm,and the mean curvature radius at the bottom is 19.41 mm.The elastic modulus of potato tuber of Eugene 885 was 5.13 MPa,Poisson's ratio was 0.47,ultimate pressure was 384.8N and ultimate compressive stress was 0.96 MPa and the elastic modulus of potato was 5.13 MPa,the Poisson's ratio was 0.47,the ultimate pressure was 384.8N and the ultimate compressive stress was 0.96 MPa.The ultimate tensile force of potato peel is 8.04 N and the ultimate tensile stress is 0.358 MPa.A follow-up study will be carried out on this basis.(2)Through the analysis of the motion characteristics of the possible mechanical damage position of potato harvesting and the mechanical analysis in the process of collision,the factors affecting the mechanical damage caused by elevating chain type potato harvester were determined,which is the advance speed of the machine,the inclination angle of the lifting chain,the falling height,the linear velocity of the lifting chain and the self-weight of the potato.Then a mechanical damage test device for the lifting chain potato harvester was designed according to the factors mentioned above.(3)The factors that affect the mechanical damage of the potato were verified by the bench test,and the related parameters of the optimized lifting chain type potato harvester can be obtained to reduce the mechanical damage of the potato.The best operation parameters were determined by the test bed test.When the advancing speed of the implement is 1.05m/ s,the linear speed of the lifting chain is 1.5 m/ s,the inclination angle of the lift chain is 14 degrees,the falling height is 180 mm,the standard value of the damage to the skin area of the potato is 95.4,the standard value of the damage depth damage is 0.34,The rationality of the research on the mechanism of the mechanical damage of the potato and the rationality of the optimization of the working parameters were verified.The combination of the optimized working parameters is obviously superior to the mechanical damage of the potatoes under the traditional working parameters,and it can meet the requirements of reducing the mechanical damage of the potatoes by optimizing the working parameters.The related research in this paper provides a new idea and method for the study of mechanical damage principle and the optimization of working parameters of the elevating chain type potato harvester,and it provides theoretical support and technical reference for the study of potato mechanical damage.