中文摘要：

三维实体B—rep模型分解是B—rep表示转换为CSG表示的关键问题，并且对深入分析CAD模型的几何形状及其结构关系具有重要意义．文中提出一种基于面壳封闭的方法分解B—rep模型，该方法采用先分割后缝合的策略．首先识别模型中的所有切割环，然后通过切割环将B—rep模型分割成多个面壳，最后利用切割环在面上的收缩将面壳封闭成实体．经过上述3个步骤，可以将具有二次曲面的B—rep模型有效地分解为加体和减体的组合，同时实验表明该方法具有较高的计算效率．

英文摘要：

Decomposition of 3D solid models with B-rep format is a crucial problem in transforming the models to CSG format, and it also benefits shape and structure analysis of these models. Here, a face-shell shrinking approach for model decomposition is presented. First, cutting loops of a B-rep model are recognized through local shape analysis, then the B-rep model is decom- posed into multiple face shells along edges in the cutting loops, and finally, the face shells are transformed into solids by shrinking the cutting loops on the faces. With the above three steps, B-rep models with quadric surfaces can be effectively decomposed into the composition of positive and negative volumes. At the same time, the experimental results show that this approach is efficient.