Research And Improvement On The Architecture Of The 3D DEM-based Simulation Software AgriDEM

In modern society,CAE software has been used more and more in the digital design and manufacture of mechanical products.CAE(Computer Aided Engineering)which is used to simulate,evaluate and optimize the design,production and operation of various mechanical products can overcome the shortcomings of traditional mechanical product testing method that is based on the prototype production such as cycle is long and efficiency is low.DEM(Discrete Element Method)is a numerical simulation method which is often used in CAE software.DEM combines many discrete particles and boundaries into a system,in which particles are in contact with other particles and boundaries.Then,the force between particles and boundaries are calculated according to the selected mechanical model.In this way,DEM can be used to simulate and analyze the contact between particulate materials and agricultural machinery and the flow process of particulate materials.After studying architectures of many DEM-based CAE softwares,this paper designes an architecture that can meet the needs of modern design concepts and requirements for the 3D DEM-based Simulation Software Agri DEM.There are four parts in the architecture: boundary modeling,particle modeling,calculation as well as visualization and analysis,and the four parts are coupled together through database and data files.Among them,boundary modeling whose function is to convert a CAD model into a boundary model that can be used for DEM calculation is mainly a further-developed CAD software.Particle modeling whose function is to convert the various shapes of non-spherical particles into particle models that can be used for DEM calculation is mainly a 3D non-spherical particle modeling software.Calculation is the core of the Agri DEM.The function of this part is to read boundary model,particle model and calculation parameters set by the user,and to calculate in the solver under the commands ordered by users.The result of the calculation is stored in the calculation result file.The function of visualization and analysis is to extract the corresponding information from the calculation result file and to use this information to do visualization and analysis work.The results of visualization and analysis could provide the basis for modifying the CAD model of agricultural machinery,thus the design of agricultural machinery could be optimized.The user interface of the Agri DEM in this paper is designed for the purpose of making the software look simple and layered.As a result,the rich functionality of the software is fully presented to users and the software is user-friendly.Two distinctive functions in the Agri DEM is establishment of primitive boundary and performance analysis.Establishment of primitive boundary means theDEM analysis model of the agricultural machinery is created by adding the primitive boundary directly to the calculation area instead of creating its CAD model when only a small amount of surfaces in the agricultural machinery are in contact with the particulate materials.Performance analysis means the performance of mechanical components is analyzed and evaluated according to the result of calculation,and this function includes individual particle analysis,boundary force analysis and particles flow statistic and other sub-functions.This paper also uses the memory-mapped file method,the point sprite method and the VBO method to optimize the performance of the visualization of the calculation results.Among them,the memory-mapped file method increases the speed.The point sprite method increases the speed of drawing particles.The VBO method increases the speed of sending triangular information from CPU memory to GPU memory.Through these three performance optimization methods,the fluency of simulation animation and simulation demonstration are improved.After the above work,the 3D DEM-based Simulation Software Agri DEM is tested in this paper.Through testing,the stability of the architecture,the simplicity and completeness of the user interface,the correctness and availability of all functions are confirmed.At the same time,the optimization of the performance of the visualization makes a difference.