| When the working parts of agricultural machinery works, it always follows the flow of agricultural materiel. For example, when seed metering device meters, there is flow of seeds, fertilizer, soil all the time; While turning over and ploughing 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 materiel all the time too.The nature of agricultural particle materiel 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 materiel and working part of agricultural machinery and dynamical problem, can only considers particle materiel colony as a whole, it is unable to analyze interaction, movement course and influence of moving among particles which are in scattered 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.In the 1970s, Cundall, etc. proposed Discrete Element Method (DEM); it can analyze the mechanics behaviors of particle colony. In the 1990s, some scholars began to adopt this method to study the dynamical problem of agricultural particle materiel and agricultural machinery working part. But till now, research of this respect only focuses on the interaction of supplies with specific target (such as supplies storehouse) and its simulation analyze, and has not come to consider the question from the standing of setting up a kind of design method and software in common use yet; And most research concentrates on such simple solid of material storehouse, for those agricultural machinery working parts which have complicated structure, such as seed metering device, ditching device, ploughing device ,has not appeared in the newspapers yet.This text is on the basis of the studying the current situation and existing problem of this respect to analyze both at home and abroad, presents a thought to establish the oneself analyzing model of the DEM based on the CAD model of agricultural machine's working parts, and then implements the integration between CAD software and the DEM analyzing software, thus develops an analysis and design system of precision seed metering devices.This system mainly consists on before-treatment dealing sub-system, DEM calculating sub-system, after-treatment dealing sub-system. It uses Visual C++6.0, ObjectARX and AutoCAD as the development tools. In order to be more convenient to expand the systematic function further, every sub-system is developed based on orient-object method. Among them dealing sub-system and DEM calculating sub-system relied on the database to transmit the data, and DEM calculating sub-system and after-treatment sub-system's integrating are realized by writing and reading the same datum file.The before-treatment dealing sub-system is a re-development utilizing ObjectARX2000 to carry on under the environment of AutoCAD2000. The main purpose is to distill the drawing which the designer designed with AutoCAD, and sets up the movement way in the course of calculating in emulation of every figure element (such as a line segment, a section of arcs), set up the emulation models of " the element of the figure plus movement way ", and store the model in the database, support DEM calculating that sub-system is used.The DEM calculating sub-system calculates receiving- strength situation and sport situation of agricultural machinery part with agricultural particle materiel, particle materiel with particle materiel. Users can choose the analysis model which is wanted to calculate in the figure database, and then according to the characteristic of supplies choose different mechanics model and input the relevant parameter, utilize DEM algorithm to calculate out dispersed sport orbit, receiving-stre...
|
PDF Full Text Request