Abstract EN:

An improved adaptive triangle and tetrahedral adaptive mesh generator has been developed. The interfaces of B-Rep which is used to smooth over the differences in various CAD systems and the mesh data structures based on topology and relation matrix are also introduced. For 3D combined surfaces, an extended Advancing Front Technique (AFT) is extended to overcome the meh quality-worsening problem in closed surface mesh generation due to introducing virtual boundaries into 2D open parametric domains in resulting generate high-quality meshes and guarantee convergence in both open and closed surfaces. Ffor the shifting-AFT, it's not necessary to introduce virtual boundaries manually and automatically while meshing a closed surface, better-shaped triangles will be generate. Comparing with direct methods, the shifting-AFT avoids carrying out costly and unstable 3D geometrical computations in real space. During rolling back of tetrahedral meshing the advancing path is changed by changing front's preferential factor, the times of rolling back is decreased significantly. Moreover, node inserting based on linear programming technique improves the convergence of the algorithm. At the end, a robust backward search method based on walk-through algorithm is proposed to deal with the searching problems in non-convex fields and to avoid the problems of infinite loop