Physical Quantity Vocabulary for Functional Representation

The importance of functional representation cannot be overstated. In current practice, especially in the very early design stages, functional requirements are often randomly proposed and loosely represented, largely by means of human language. This paper presents a new function representation method, which aims to improve the consistence and accuracy of functional representation. The core component of the method is a functional vocabulary, which is composed of a set of carefully selected physical quantities. Traditionally, physical quantity is often used to measure the property of a physical object. Relatively few efforts have been devoted to employing physical quantity to represent functional requirement. Furthermore, we prescribe the designer to follow the IDEF0 modeling method to organize a pair of two physical quantities in the format of “input (design range) → output (design range)”. Lastly, we propose to leverage the new method to support Axiomatic Design's zigzagging process, the decomposition operation in particular. Multiple practical examples and a case study are presented in order to showcase how to use the proposed new method to solve real-world design problems.