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Different notions of function: results from an experiment on the analysis of an existing product

The paper argues that designers in practice struggle to express functions in a coherent way, because they have fluid notions of function and none of the approaches to functional modelling proposed by academic research have become became widely accepted or commonly used in practice. As the literature on functional modelling did not engage with the practical usability of the models beyond illustrative examples, this result is not surprising. The research reported in this paper argues for the first time why this is the case, based on an experiment and interviews in companies. The experiment was carried out at Karlsruhe Institute of Technology in 2009 by Eckert (as visiting researcher), with twenty engineers, who were asked to identify the functions of a hydraulic pump that is widely used in off- road vehicles; its subsystems, components and fluid flows. In order to account for differences introduced by particular product representations, half the participants used a physical pump and the other half used maintenance drawings. The range and completeness of descriptions varied considerably; from the intentional and goal directed to extensional and structural descriptions of the product. The paper complements theoretical work by authors including Vermaas (TUDelft) and Crilly (Cambridge), providing new momentum to an ongoing discussion on functions in a series of workshops including the Design Computing and Cognition conferences. This research on the nature and application of functional modelling in engineering design processes has been consolidated by Eckert in subsequent papers and collaborations, especially with Vermaas in a coedited special issue of Artificial Intelligence for Engineering Design, Analysis and Manufacturing AIEDAM vol 27(3), 2013, with an important editorial frame by Vermaas and Eckert on ‘My functional description is better!’ and a paper by Eckert on ‘ That which is not form: The practical challenges in using functional concepts in design’.