【摘要】 提出可变动布尔运算 ,并用它实现了特征模型的构造与尺寸变动。可变动布尔运算是对传统布尔运算的改进 ,由它构造的特征模型的尺寸变动算法基于 B- Rep/CSG混合表示 ,通过直接操纵模型的 B- Rep来实现 ,同时支持约束特征的连锁驱动。所提方法可以方便地实现三维参数化特征设计 ,实时响应速度快 ,有重大的实用价值。更多还原

【Abstract】 A new variational Boolean operations and feature based models variation algorithm are developed. This algorithm is based on a hybrid scheme, which consists of extended B Rep, generalized CSG and feature relation graph. The extended B Rep and generalized CSG contains not only complete geometry information and construction information respectively but also bi directional pointer. The feature relation graph reflects adjacency relationships among features in a part model. The bi directional pointer between extended B Rep and generalized CSG ensures the variation algorithm quick addressing and jumping within the span of feature models. Boolean operations are implemented in local area by directly operating on extended B Rep model and overcomes many drawbacks of other traditional methods, most of which need to redo all of the previous work to implement dimension variation. The product information will not lose after dimension variation. Furthermore, chain reaction of constrained feature are also supported. Therefore, the variation of models has very high efficency. What we proposed in this paper can realize 3D parametric feature based design and modification conveniently, but it applies only to polyhedron model.更多还原