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The Constrained Object (COB) Representation for Engineering Analysis Integration


Wilson, M. W.(2000) The Constrained Object (COB) Representation for Engineering Analysis Integration, Masters Thesis, Georgia Institute of Technology, Atlanta.


The wide variety of design and analysis contexts in engineering practice makes the generalized integration of computer-aided design and engineering (CAD/CAE) a challenging proposition. Transforming a detailed product design into an idealized analysis model can be a time-consuming and complicated process, which typically does not explicitly capture related idealization and simplification knowledge. Recent research has introduced the multi-representation architecture (MRA) and analyzable product models (APMs) to bridge the CAD-CAE gap with stepping stone representations that support design-analysis diversity. This thesis generalizes the underlying techniques to form the constrained object (COB) representation.

The COB representation is based on object and constraint concepts to gain their modularity and multi-directional capabilities. Object-flavored techniques provide a semantically rich way to organize and reuse the complex mathematical relations and properties that naturally underlie engineering models. Representing relations as constraints makes COBs flexible because constraints can generally accept any combination of I/O information flows. This multi-directionality enables design sizing and design verification using the same COB-based analysis model. Engineers perform such activities through out the design process, with the former being characteristic of early design stages and vice versa.

The COB representation has generalized and extended techniques from the APM representation. Enhancements include a more efficient constraint processing algorithm, support for external solvers as white-box relations, and improved lexical forms. With these enhancements, COBs can represent additional types of MRA concepts beyond just APMs, namely analysis building blocks (for design-independent analytical engineering concepts) and context-based analysis models (for explicit associativity between design and analysis models).

To validate the COB representation, this thesis presents electronic packaging and aerospace test cases implemented in a prototype toolkit called XaiTools™. In all, the test cases utilize some 340 different types of COBs with some 370 relations, including automated solving using commercial math and finite element analysis tools. Results show that the COB representation gives the MRA a more capable foundation, thus enhancing physical behavior modeling for a wide variety of design models, analysis models, and engineering computing environments.