网格化复杂曲面延拓算法研究

Study on Extension Algorithm of Complex Mesh Surface

曲面延拓在航空复材零件的模具设计领域有着广泛的应用,针对CAD造型软件无法对复杂曲面进行直接延拓的问题,将曲面细分为三角网格,并对STL(STero-Lithography)格式的文件进行拓扑重建,利用网格线面间的几何关系检测出曲面内部孔洞及外边界,在边界网格处生成延拓面片。为了避免缝隙和自交的产生,对曲面的凹凸角点进行检测并分别处理。为了提高延拓质量,避免产生狭长网格,提出了分步延拓算法,并给出步长计算方法。最后通过CATIA的逆向工程模块对数据进行重建,针对存在内部孔洞和不连续边界的复杂曲面以及拼接曲面,验证了本算法的有效性。

Surface extension has a wide application of the composite materials mold design in the aviation industry.A novel method is proposed for complex surfaces which cannot be directly extended by using CAD software.Complex surfaces are discretized into triangular meshes and expressed in STL files.The topological relationships among the patches are used to reconstruct STL files so as to detect the inner holes and outer boundaries of the surface,and then the meshes are generated alongside the boundaries.In order to avoid the generation of gap and intersection,the concave and convex angular points of the surface are detected and processed separately.In order to improve the quality of extension and avoid unexpected grids,a step-by-step extension algorithm is adopted and appropriate step length is calculated.Finally,the data is reconstructed by using CATIA's reverse engineering module so as to verify the effectiveness of the algorithm.