Improvement Research And Functional Addition On The Visualization Module Of The 3D DEM-Based Simulation Analysis Software

The simulation work of agriculture production process is quite complex, it not only includes dynamic simulations of various agricultural machinery assemblies with different motion modes and of numerous granular materials in the production process, but also includes the real-time mechanical analysis of interaction condition between particles and particles as well as between particles and machinery boundaries. Based on the real situation in the process of agriculture production, it is reasonable to adopt the discrete element method in order to study the agricultural simulation system. When the discrete element method is used to analyze the models under research, a discrete group is decomposed into numbers of independent individual units, which overcomes the limitations of continuity assumption in continuum mechanics. The discrete element method concretely analyzes every particle, which makes it possible to simulate the motion morphology and motion state of the whole system. However, dealing with such a great number of particles is bound to produce a huge amount of data information, so a high-efficient way to process the calculation results is in urgent need. The visualization technique in simulation domain can well meet the demand of real-time result analysis; also it is more intuitional and pictorial. Therefore, it is imperative to visualize the processing results in the process of system simulation.The 3D DEM-based simulation analysis software which developed by our research group uses Open GL and MFC(basic class libraries of Visual C++) to realize functions related to visualization module, and this module aims to complete two tasks: one is to collect geometrical data; the other is to render 3D models. At present, the visualization module is applied in two aspects: one is to get geometric information of machinery assemblies by inquiring database in order to statically display the selected boundary model; the other is to get geometric information of particles and boundaries by reading results file in order to dynamically display the calculation results. During the implementation process of dynamic display, there is data interaction between calculation module and visualization module, which involves large numbers of read-write operations on result files. Therefore, the display effect greatly depends on data volume, which leads to display problems such as image flicker, unsmooth render etc. during large-scale playing of particle files. To solve these problems, firstly, the visualization implementation approach of the 3D DEM-based simulation analysis software is studied in this paper; then the particle file access procedure is simplified in order to optimize the massive animation playing quality to some extent; finally double-buffer mechanism which is supported by Open GL is enabled in order to reduce the chance of playback flicker.Now, the 3D DEM-based simulation analysis software can be successfully applied in granule modeling、machinery modeling and calculation file playback, and decent display effect is achieved. As the continuous improvement of the software, simulation and analysis functions are extended constantly by our research group; growing amounts of information need to be displayed on the screen; and more and more complicated visual effects need to be realized. Therefore, the function expansion to the visualization module of the 3D DEM-based simulation analysis software is necessary. In this paper, Open GL functions such as geometric modeling、transformation matrix、matrix stack、color and lighting process、color blending、tessellation technique etc. are adopted to fulfill the functional addition to the visualization module. Firstly, oxyz coordinate is added to show the deflexion direction of machinery boundaries; during file playback, the display of simulation time and play duration is realized; these two functions aim to make the visualization module more user-friendly. Then the function of particle color setting is accomplished in order to visualize more particle properties on the screen and enrich the particle display effect. Finally, the functions of boundary color setting and boundary transparency setting are added, which make the boundary display effect more vivid、artistic and multiple. These newly added functions well extend the now available visualization module; therefore, better observation effect and better visual experience can be provided to users.In our research group, one of the significant development purposes of TDEM is to simulate contact and collision processes between granule materials with complex shapes and agricultural machinery components. In order to rid the particle modeling of dependency on Pro/E, a 3D non-spherical particle modeling software based on sphere filling is developed by our research group. This modeling software can not only automatically modeling the non-spherical particle by filling spheres according to geometric information of particle vertexes or triangle meshes, but also accurately read and play DXF scan files. On this basis, the article extends the file handling function to make STL scan files with different two formats can also be read and played by the 3D non-spherical particle modeling software; at the same time, the manual modeling method based on sphere filling is added to the modeling module, and obviously this modeling approach is more direct. Through these functional additions, the existing modeling software has become more adaptive, and the interactivity between users and software system has been enhanced.Finally, the research work is tested in this article. Through the testing instances, it can be verified that the aforementioned improvements on the visualization module of the 3D DEM-based simulation analysis software has optimized the dynamic display effect of the large-scale data playback; also the validities and the feasibilities of these newly added functions have been verified.