A functional approach to redesign

This paper describes a methodology to assist in the identification of possible conceptual design variants during redesign. The approach is based on functional reasoning and involves: (1) the structural and functional analysis of an existing design; (2) the production of abstract representations of functions and design entities using conceptual graphs; and (3) design interrogation based on a functional tree approach. The research reported in this paper also focuses on the definition and the representation of elementary mechanical functions. Extended Backus-Naur Form (EBNF) notations are used to structure in a computable form, the relevant information (or design knowledge) conceptualised in either the conceptual graphs or the functional trees. EBNF syntax is also used to formulate rules which aid the partial automation of the reasoning process. The EBNF notations can be mapped to any programming language. A diaphragm valve is used as a case study to demonstrate the approach.