Research And Implementation Of ACIS Interface For ZW3D CAD

The data exchange between3D-CAD systems is an important component of CAD system, at the same time, difficulty. The data exchange concerns the data share and interchange among different CAD systems. It makes the important significance and practical value to a CAD system spread. However, choosing the different way to exchange the CAD data would affect the data stability, usability and the performance of the data interface. In this paper, the special data interface was chose combining with the needs of the actual project research. Therefore, a special data interface based on B-Rep is proposed in this paper, and then several key issues of the technique are studied.Under study of the project, the special interface of ZW3D was developed, which possesses the independent intellectual property rights facing the ACIS. In this paper the following key issues were researched and solved:1. Aim at solving the topological structure difference between the two CAD systems, the separation method between the geometry and topology were adopted in this paper. Topology reconstruction is needed and topology consistency must be maintained under the contrast of these CAD systems. According to the relationship between the two systems, topology is established corresponding one to one to reconstruct the topology. The model’s topology is reconstructed exactly by adding extra topology nodes properly.2. Order to solving the geometry inconsistency, the popularity and the oneness of the NURBS are used. The geometry data exchange was accomplished based on the NURBS in the post processor of the data interface, which guarantees the integrality of the data. However, we would use the NURBS fitting method in the preprocessor of the CAD data interface.3. On the basis of the research on the geometric invariant principle of the parameters curve, the method on the reconstruction of the parameter domain was used to solve the parametric domain inconsistence issue with geometry’s topology. In this paper, the curve and surface being the inconsistence problem were cut and regularized to the [01] space finally to maintain the geometry and topology consistency.4. After studying the different solutions to deal with the problem of singularity point happening with some special models, and sorting out the differences between the quadrilateral domain and the non-quadrilateral domain, we filtered the invalid information and maintain the useful data in the preprocessor. In the post processor, we would add the extra edges to the loop properly, and then, connect the geometry and topology of those extra edges.On the basis of the above research, the special interface facing the ACIS was achieved successful with the support of the project named "The key technology research and industrialization development of a new generation of CAD support platform"(2008B090500264). The special interface makes a great practical progress in the ZW3D2012.