Improvement Research Of Corn Ears Threshing Process Simulation Software Based On3D DEM

In the production process of corn ears, most of them use corn thresher to thresh. Due tothe work process of various mechanical components on the corn thresher is very complicated.Most research institutions at home and abroad use many methods to simulate the corn earthreshing process. However, it is quite different between the experimental the results and theactual. So the research group using DEM(Discrete Element Method) and computer simulationtechnology,and then separating the whole corn ear into a number of corn cobs and corngrains to study. Combined with the particle dynamics method, the research group finally hasthe simulation software of corn threshing process based on3D DEM.At present, we have achieved good results for the simulation software of corn earthreshing process. But the simulation calculation is still take a long time. Thus reducingsimulation time it takes has become an urgent requirement to improve this software. Inmodern computer applications, multi-core processors are becoming more and more popular.Therefore to apply the multi-core processors for parallel technology, are becoming the key forcorn ears threshing to reduce simulation time, and it can also give full play to the performanceof multi-core processors. At the same time, it is more and more serious for the duplication ofwork in the software development process. To do this, we can reduce costs to develop andmaintain this software. The use of dynamic link library technology is a simple and effectiveway to share library, and it can improve the value of codes. Dynamic link library technologycan make each module developed independently without affecting on other functions betweenapplications. In order to develop this simulation software, the research group decides to usethe dynamic link library technology. It can improve the quality of the developed softwareeffectively, reduce the duplication of development program code greatly, and savedevelopment time.The basic principle of discrete element method is explained first of all, and methods ofparallelization are analyzed, as well as the technology and classification of the dynamic linklibrary is introduced briefly. Then this paper introduces some functions commonly used ofOpenMP standard library in parallel algorithms. By introducing the software which using theserial algorithm, the research group put forward in a new software named corn ears threshingprocess simulation software, which using the parallel algorithm for multi-core andmulti-threading. Through this software, corn grains, corn cobs and corn ears are all combinedwith multi-ball particles. In this article, the research group also makes improved for thecontact detection algorithm of triangular patch boundaries. Because of the need and theactual contrast, the function analysis of corn ears has been modified. Then there is a briefintroduction for the dynamic link library in two ways between static and dynamic library, and their advantages and disadvantages are compared. According to the characteristics of software,the research group combines with the dynamic link library technology to realize the modulardesign of corn ears threshing simulation software. And at the same time, this paper also makesdeep improvements on the necessary conditions for the conversion of operating platformprocesses between32and64-bit in3D DEM and the algorithms of polygon virtualboundaries.For the above tasks, the research group makes some tests and example verifications.Practical tests indicate that, after making success in multi-core and multi-threading parallelalgorithms for this software, the software has the same general trend as the one which hasused the serial algorithm, but the simulation time has been shortened clearly. And when thecorn ears threshing simulation software has collision detections with the boundaries whichcontain triangular patch boundaries, the research group can get the calculation results muchaccurately, and be more in accordance with the actual trends. Combined with dynamic linklibrary technology and multi-core and multi-threading parallel algorithms, the research grouprealized the modular design of corn ears threshing process. So as to improve the simulationspeed and also when this module is modified, there is no influence on other modules. Bymodifying in using64-bit operating platform for3D DEM, the computing speed has beenimproved obviously. At the same time, this modification brings convenience for developingbetween32and64-bit operating platform on3D DEM. Finally, through revising the polygonvirtual boundaries, the research group achieves many simulations like the condition ofdifferent sizes in many mechanical components in real life.