Automatic Mesh Generation Technology Based On Virtual Geometry

With widely use of CAE technology in the engineering analysis, finite element mesh generation technique, as one of the core technology of CAE, has been paid more and more extensive attention. Due to various disciplines between different software systems, geometry models generated by CAD packages are often unsuitable for analysis softwares. Among the problems requiring editing are: Incomplete and inconsistent geometry descriptions, irrelevant minor details which severely complicate the meshing and complex models that need decomposition into parts. Therefore, before the effective meshing can proceed, there is the necessity to edit CAD models, to be suitable both for the analysis objectives and the available meshing algorithms.This paper gives a detailed study on automatic mesh generation technology, mainly including:1. It presents an in-depth discussion of automatic mesh generation algorithms, focusing on analysis and comparison of classical hexahedral meshing algorithms, and summarizes advantages and disadvantages of various methods and their applications.2. It introduces a virtual geometry based thesis, which provides a mechanism to adjust the model topology for optimal meshing, while leaving the original geometric descriptions unchanged. It gives definitions of virtual entities, along with a set of operators used to perform the editing operations commonly required for topology modifications, then it illustrates applications of virtual topology in model editing, including model correction, simplification and decomposition.3. Based on Open CasCade geometric modeling system, it proposes an innovative way of capturing topological relationships in the model, which has been implemented using a directed acyclic graph (DAG) that is independent of actual object, also it studies the constitution, modification, and removal of virtual topology. Finally, this paper designs an object-oriented software package called the Virtual Geometry Interface (VGI), comprising the architecture of VGI, responsibilities of detailed classes, and main class hierarchies.In the basis of theoretical support of virtual geometry and implementations of programming interfaces, virtual topology can be successfully employed in automatic meshing process. Mesh generation examples prove that, the virtual geometry based mesh generation technique is simply-operated, system compatible, and easy programming.