| When the working parts of agricultural machinery works, it always follow the flow of agricultural material. For example, when seed-metering device meters, there is flow of seeds, fertilizer, soil of the time; while turning over and plowing the farmland, there is a movement of soil all the time; Agricultural product reaping, transporting, grading, processing and packing, are followed by relevant movement of agricultural particle material all the time too. The movement of agricultural particle material relates to not only one's own mechanics nature, but also has something to do with relevant agricultural machinery, especially the structure form and performance parameter of its working parts. A good agricultural machinery design should make agricultural particle material move according to the way that it is anticipated, such as the movement of seeds while seeding; it can reduce the unnecessary damage in the moving course, such as the seed is damaged while seeding; it can save mechanical motive force to consume, such as draw motive force to consume while ditching, plowing and turning over the soil; it must consider the interaction of working part of agricultural machinery particle material , including the dynamics characteristic at this moment.The nature of agricultural particle material lies between solid and fluid, though the particle is of simple structure, but it has complicated mechanics characteristics. Adopting the traditional mechanics method to study the interaction of agricultural particle material and working parts of agricultural machinery and dynamical problem, can only considers particle material colony as a whole, it is unable to analyzing interaction, movement course and influence of moving among particles which are in the granular colonies, and therefore it can't solve this problem well. While carrying on the agricultural machinery design at present, mostly depend on experience or testing method, it is time-consuming to get ideal result while being strenuous.The interaction between granular agricultural material and the related machinery working parts and the flow process of agricultural material are studied by discrete element method (DEM), which can be used to estimate the working performance of these agricultural machinery working parts. It is likely to set up an universal digital design and analyzing software for the related agricultural working parts if the parameter design CAD software and the discrete element method performance-estimating software are integrated. The previous universal digital design method and the related key technology are studied by using the seeding meters working parts including the precision seeding device and the granular agricultural material soybean as an example in this dissertation. The two dimension DEM model of soybean is established and the idea to establish the DEM analyzing model by the CAD model of the agricultural working part is carried out. The two dimension DEM precise seed-metering device analyzing software is developed, in which software the seed metering device DEM model is produced by its CAD model based on the redevelopment of AutoCAD, and the Visual C++ programming language and Object ARX are used. So this software can import design drawing from AutoCAD, and start computing after the relevant parameters are inputted, and simulate the working process of granular material and agricultural parts by the previous computed results.The clear seeds process of the precise seed-metering device is analyzed by this system, the results are: the starting angle and the end angle of clear seeds process increased with the angle velocity and the diameter and the friction coefficient of the seeds metering wheel increased, the end angle increased more quickly with the angle velocity of seed metering wheel increased and the friction coefficient is more significant for the starting angle of clear seeds process; The end angle and the difference between end angle and starting angle increased with the filling hole diameter increased but decreased for the star...
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