Research On Improvement Of Boundary Modeling Software Based On STL File

With the development of science and technology and the guidance of national strategy,over the years China's agricultural mechanization level has been improved steadily.In the large-scale development of agricultural mechanization,the loss caused by the grain harvesting process can not be ignored,so the importance of design and manufacture a highly efficient agricultural parts is self-evident.In the traditional mechanical design,design and manufacture of mechanical parts usually by hand,such as calculating or drawing by hand,with the guidance of existing experience.Although the design results in the strength and other aspects can meet the requirements,due to experience and blindness,not only the design and manufacture makes a longer cycle,but also the poor accuracy of the design can not achieve the best results.In modern mechanical design,computer-aided design reduces design effort,improves design speed and design quality,and use the computer simulation technology can simulate the design results,if it can't meet the expected results,you can quickly modify and then get the design drawing.Finally,you can process the accurate products by putting the satisfied product model into the NC processing equipment.In the simulation of agricultural machinery components,the interaction between particles and particles and the interaction between particles and mechanical parts is studied by using discrete element method under simulated parameter setting.According to the law of kinematics and dynamics,making the particles and mechanical parts move in the specified way to achieve the purpose of simulating the real situation.An important process before this is meshing for mechanical parts to establish its boundary model,the quality of the boundary model directly affects the accuracy of the subsequent simulation calculations.In order to carry out accurate boundary modeling of various complex agricultural machinery parts,at the same time in order to get rid of the dependence on specific CAD software in the secondary development to establish a general method for boundary modeling on different CAD platforms,our research group adopts the method to finish the boundary modeling based on STL file.This paper does some optimization for the boundary modeling software based on the preliminary work of the research group,and adds some user-friendly new features to make the whole boundary modeling software more perfect.The new software provides data fetching for two kinds of STL files,the program can automatically determine the type of file and read the contents of the file correctly.This paper provides a solution for multiple separate entities when building a topology,improves the ability to extract the boundaries of the program,and it also provides angle control to ensure the accuracy of meshing indirectly in the process of merging planes.For the needs of certaincircumstances,this paper increases generation of uniform grids in the meshing process.When the mesh of the solid model is finished,it is often necessary to add motion attributes or material properties for certain parts.The user can add attributes for the entire entity model boundary or a portion of its boundaries based on the plane's number when the planes are merged to provide a more realistic simulation effect.Although the improved STL file-based boundary modeling software can provide the correct boundary modeling for the solid model,there are some performance problems.The speed of meshing for complex solid models is too slow,that makes the user's waiting time at the interface is too long.For this problem,this paper has done two aspects of improvement: it starts a background worker thread to complete the entire modeling process,so that user can still operate the interface in the waiting process.Besides,it uses Open MP for multi-core parallel to complete the grid division,because it's the most time-consuming part.In this way,it shortens the time of meshing and improves the efficiency of the software boundary modeling.At the same time,with the growing demand for the functions of the software,this paper increases the export and import of boundaries.So the original boundaries and attributes can be used for the multiple simulation in the same entity model,it can eliminate the whole process of boundary modeling to provide users with a convenient.Meanwhile,it provides the function of displaying mode for the model boundary and the setting of the boundary's color and transparency using Open GL technology,it makes the simulation better and truly beautiful,and provides a good user experience.At last,after completing the improvement of the software,the work done in this paper has been tested and verified.The results shows the improved results and the newly added features all achieved the desired results.Therefore,this paper is effective for the improvement of STL file-based boundary modeling software.