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TOWARDS MODELING DESIGN RATIONAL OF SUPPLEMENTARY FUNCTIONS IN CONCEPTUAL DESIGN

The importance of sharing designer’s intention (socalled design rationale, DR) is widely recognized. This paper focuses on modeling DR of supplementary functions which prevent undesirable states of a required function (e.g., malfunctions). Although they do not essentially contribute to the achievement of the required function, they play an important role in design and design improvement of artifacts. Nevertheless, their DRs, that is, “what undesirable phenomena is avoided by them” and “how they avoid those phenomena”, often remain implicit. We aim at establishing ontologies for capturing such designer’s knowledge systematically in order to share such knowledge among designers. In this article, a modeling framework to explicate the design rationales of supplementary functions is proposed. For this purpose, we articulate concepts concerning a process of undesirable states and how a supplementary function prevents the process. By using such concepts, functionality of components and undesirable phenomena are integrated into an extended functional model. This model can be used in multiple tasks such as design, redesign, design review and reliability assessment. Besides, we present classification of supplementary functions based on the model and four display modes of the model according to the demand of a designer.