农机部件数字化设计软件平台AgriDEM开发

为解决农机产品开发周期长、工作量大和成本高等问题,研制了集设计和性能分析评价为一体的农机部件数字化设计软件平台AgriDEM(agricultural discrete element method)。该平台通过将CAD软件与自主研发的基于DEM-CFD-MBK(discrete element method,computational fluid dynamics,multi-body kinematics)耦合的分析软件集成,可在设计阶段由农机部件的CAD模型(CAD软件设计图),进行农机部件工作过程的动态仿真和工作性能的分析评价,由此实现农机部件结构方案和尺寸参数的优化。该文详细介绍了该平台的架构和关键技术实现方法,包括农机部件分析模型的建模方法、颗粒的建模方法、基于OpenMP的并行计算方法、基于DLL的模块封装及原型系统开发等,最后通过一个实例验证了该平台的可行性和有效性,可为农机部件的优化设计和数字化设计提供参考。

Development of digital design software platform AgriDEM for agricultural machinery parts

The traditional way to develop agricultural machinery parts, in which the test of feasibility of agricultural machinery parts is confirmed by manufacturing prototype machinery, is unable to meet the needs of agricultural production due to its shortcomings such as the long development cycle, the heavy workload and the low efficiency. Therefore, it's necessary to design and implement a digital design platform that combines mechanical analysis with computer simulation technology, and the design effect of agricultural machinery parts can be tested by using this platform instead of manufacturing prototype machinery. Therefore, a digital design software platform for agricultural machinery components i.e. AgriDEM (agricultural discrete element method) was designed and implemented through integrating CAD (computer aided design) with a self-developed analysis software based on the coupling of DEM-CFD-MBK (discrete element method, computational fluid dynamics, multi-body kinematics). The AgriDEM had 4 modules, i.e. boundary modeling, particle modeling, calculation, and visualization and analysis. Boundary modeling module could transform a CAD software design of agricultural machinery into an analysis model that could participate DEM calculation and DEM-CFD-MBK coupling calculation by the secondary development of CAD software or the read of the STL (standard template library) file. Particle modeling module was a software that could establish three-dimensional (3D) spherical particle models, 3D non-spherical particle models, 3D corn grain models, 3D soybean grain models, 3D wheat plant models, and so on. Non-spherical particle were filled with spherical particle. Calculation module was a software that could calculate the working process of agricultural machinery including the fluid process of particles and the contact conditions between the particles, separately with DEM or with the coupling of DEM-CFD-MBK. Visualization and analysis module was a software that could make calculation result visualized and analyze the performance of agricultural machinery. These 4 parts were coupled together by database or data file. During the development of the AgriDEM, C++ language was used to write code, and VS2010+MFC was chosen as the development platform. This platform could simulate, analyze and evaluate the working performance and working process of agricultural machinery in the design stage; by changing the CAD model of agricultural machinery parts, the working process with different principle, different structures and sizes of components and the work performance were evaluated and analyzed, so as to realize the optimization of agricultural machinery parts' structure and size parameters. The architecture of this platform was described in detail in this paper, and the implementation methods of the key technologies were introduced, including the modeling method of the boundaries model, the modeling method of the particles, the parallel computing method based on OpenMP, the module encapsulation method based on DLL (dynamic link library), and the development method of prototype system. Finally, the feasibility and the effectiveness of this platform were confirmed through testing instances. The new method in this study can provide the reference for the optimization design and digital design of agricultural machinery parts.