Investigation of the Interpretability of Three Function Structure Representations: A User Study

Function models are used during the conceptual design phase of the design process to model the intended use or objective of a product, independent of the products physical form. Function models also aid in guiding design activities such as generating concepts and allocating design team resources. Recent research effort have focused on the formalization of function models through a controlled vocabulary and archival of functional representations in computer-based repositories. However, the usefulness and interpretability of these function models has not fully been explored. This paper presents the results of a user study to ascertain the interpretability of functional representations at three levels of abstraction. In this interpretability is defined as the ability to identify the product based on a functional representation. These function models vary in abstraction in two dimensions: (1) the number of function within the model and (2) the specificity of the terms used within the functional models. Sixteen mechanical engineering graduate students are asked to identify the products from the functional models in these three abstraction levels. In addition to identifying the product, students are asked to record time and list any keywords in the functional model that help them to choose a product. Analysis of the results indicates that interpretability of a functional model increases substantially by using free language terms over a limited functional vocabulary and environmental context of the product. Additionally, the number of functions within the functional model correlates with the identification of similar products.