Abstraction of mid-surfaces from solid models of thin-walled parts: A divide-and-conquer approach

• Identification of and discussion on general issues on the existing methods for mid-surface abstraction.
• Adoption of the divide-and-conquer paradigm to address the issues on the mid-surface abstraction.
• Providing a general algorithm to abstract more complete mid-surfaces for complex solid models.

Abstraction of mid-surfaces from solid models of thin-walled parts is becoming a useful function for idealizing the solid models for engineering analysis. Various abstraction techniques have been developed and adapted to commercial CAD systems. However, they are generally lacking in completeness and robustness. That is, for some complex solid models, valid mid-surfaces are not created and mid-surfaces which are created may not be valid or of little use in practice. Existing techniques utilize rules and heuristics in detecting appropriate face-pairs and generating mid-surface patches, but these rules and heuristics often do not apply to complex solid models. To address this problem, a divide-and-conquer approach to mid-surface abstraction is proposed in this paper. A solid model is decomposed into simple volumes, and mid-surfaces of the simple volumes are abstracted. The mid-surfaces of the simple volumes are then composed into the mid-surfaces of the original solid model. The proposed method has been implemented and tested with practical examples. The results of case studies have been presented to attest to the usefulness of the proposed method. Some general issues on mid-surface abstraction are also discussed.