面向大型复杂焊接结构仿真的组合式自适应四面体网格生成算法

Combined Adaptive Tetrahedral Mesh Generation Algorithm for Simulation of Large and Complex Welded Structures

目的研究高质量、高效率的网格生成技术以实现大型复杂结构的焊接工艺仿真优化。方法提出一种组合式的自适应四面体网格划分算法,即在高效生成各个零部件四面体网格的基础上,根据焊缝中心面的几何信息自动对焊缝附近网格进行细分,再缝合成高质量的大型复杂焊接结构的整体四面体网格,并集成到自主可控的商用网格划分软件Vision Mesh中。提出了摄动几何边界的方法,解决了大型复杂结构STL几何体在存在几何错误时网格难以生成的问题。提出了基于BVH树结构表达的背景网格表达方法,解决了多条焊缝同时高效、自动细分的难题,并通过“四面体分割–四面体合并–四面体翻转–点平滑优化”方法,实现了四面体网格的高质量优化。结果算法网格效率可以达到200万个/h,生成的四面体99%以上均接近正四面体。可以由多个零部件一步组合生成大型结构的整体网格,并可对焊缝区域进行自动细分,大幅度简化了划分流程。将生成的网格导入国产焊接仿真软件InteWeld中进行测试,验证算法可用于大型复杂焊接结构整体应力变形的计算中。结论实现了大型复杂焊接结构的高质量自适应四面体网格划分,使用简便操作得到了高质量网格,为焊接结构件工艺仿真优化提供了前提。

The work aims to study a high-quality and high-efficiency mesh generation technology to realize the simulation optimization of welding process for large and complex structures.A combined adaptive tetrahedral meshing algorithm was proposed.On the basis of efficiently generating tetrahedral meshes for each component,the meshes near the weld were automatically subdivided according to the geometric information of the center plane of the weld,and then merged into high-quality overall tetrahedral meshes of large and complex welded structures,and finally integrated into Vision Mesh,an autonomous and controllable commercial meshing software.In this algorithm,the method of perturbing the geometric boundary was proposed,which solved the problem that the geometric errors often existed in large and complex STL geometries and mesh was difficult to be generated.The background mesh expression method based on the BVH tree structure expression was put forward,which solved the difficulty of efficient and automatic subdivision of multiple welds at the same time.Through the method of“tetrahedral division-tetrahedral merging-tetrahedral flipping-vertices smoothing optimization”,high-quality optimization of tetrahedral meshes was realized.The proposed algorithm could achieve a mesh efficiency of 2 million tetrahedrons/hour,and more than 99%of the generated tetrahedrons were close to regular tetrahedrons.Parts and components could be combined in one step to generate the overall mesh of large structures,and the weld area could be automatically subdivided,which greatly simplified the meshing process.The generated mesh was imported into China's welding simulation software InteWeld for testing,and the verification algorithm could be used for large-scale Global stress and deformation calculations of complex welded structures.This algorithm can realize high-quality adaptive tetrahedral meshing of large and complex welded structures,and obtain high-quality meshes with simple operations,which provides a prerequisite for process simulation optimization of welded structural parts.