Abstract: In recent years, history-based, constraint-based and feature-based CAD systems (often gathered under the generic name of parametrics), appeared as a major progress both to express and to capture conceptual designs and design intents. This deployment raise two major issues. The first one is to define a data model that provides for exchange capabilities between heterogeneous CAD systems and for archiving. The second one is the well known "topological naming" problem.
The goal of this paper is to propose an unified modeling framework for parametric data, that addresses these two issues. This framework, defined in the object-flavored EXPRESS data specification language, involves a three layers architecture. Gathering the complete definition of a parametric object in the same data model permits both to simplify the data-management, and to define a neutral description of parametrics, enabling exchange between heterogeneous CAD systems.
Keywords: CAD/CAM, geometric modeling, parametrics, constraint-based model, formal specification
Classification (MSC2000): 68U07
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