Proceedings of DETC’00 2000 ASME Design Engineering Technical Conferences September 10-13, 2000, Baltimore, Maryland, USA DETC00/DTM-14562 QUANTITATIVE MEASURES FOR DESIGN BY ANALOGY Daniel A. McAdams Department of Mechanical and Aerospace Engineering and Engineering Mechanics University of Missouri-Rolla Rolla, Missouri 65409-0050 Email: dmcadams@umr.edu Kristin L.Wood Manufacturing and Design Research Laboratory Department of Mechanical Engineering University of Texas Austin, Texas 78712-1063 Email: wood@mail.utexas.edu ABSTRACT In this paper a quantitative measure for design-by-analogy is developed. This measure is based on the functional similarity of products. By using this product similarity measure, designers are able to formalize and quantify design-by-analogy techniques during concept and layout design. The similarity measure and its application is clarified and validated through a case study. The case study is the original design of a pickup winder. KEYWORDS: Design-by-Analogy, Product Similarity, Functional Analysis, Customer Needs, Novel Product Design 1 Introduction During the design and development of new products, design engineers use many techniques to generate and define new and “good” concepts. Inherent in this search of solutions is the con- scious and unconscious reliance on prior experience and knowl- edge. Numerous attempts have been made to organize, qualify, and make accessible the critical design experience and knowl- edge needed to solve particular problems. Some of these tech- niques take the form of knowledge based design, expert design systems, and design rules or design guidelines. In this paper, quantitative measures are developed that allow designers to iden- tify products which are similar in a manner critical to the suc- cess of a design. This focused identification allows these similar products to be reviewed in context of the design problem at hand for configuration, concept, and embodiment information. These measures allow formalized design-by-analogy efforts by identi- fying products that have design-critical similarity. The paper is organized in the following way. First, the no- tion of similarity as used here is clarified. Toward the goal of finding the important product similarities, ground work is devel- oped to make comparisons between products. In the remainder Address all correspondence to this author (573-341-4494). of this paper, these notions of product similarity in the search for analogies are explored. Also, a procedure for applying these techniques to a design problem is presented. Lastly, an exam- ple application of the design-by-analogy techniques is applied to an original design case study. The paper concludes with a brief discussion of the contributions of the work presented here. 2 Relevant Analogies The notions of similarity, and analogies based on similarity, are broad. From Moody charts to the Periodic Table, organizing schemes based on similarities and differences is a critical tool in engineering and science. In the field of fluid mechanics, the com- parison of different objects based on similarities in the Reynolds number, the Biot number, or other meaningful metrics for com- parison, is not only common place, but critical to the fundamen- tal understanding of the relevant physics that affect the systems. Before developing a design tool based on analogy, the basis for making the comparison is necessary. For example, based on a color comparison, a car and a watch may be similar. In fact, they also may share the similarity of manufacturing country of ori- gin. Reviewing a watch as an exercise to find alternative ways to mix fuel and air in the car is likely a fruitless exercise. Before searching for design information in existing and similar designs, the notion of similarity needs to be understood in the context of design. A fundamental philosophy of this paper is that customer needs drive the product function. In turn, the resulting required functions have a key impact on the resulting form. Design philosophies such as this have been proven valid and effective in the literature (Pahl and Beitz, 1996; Ullman, 1997; Ulrich and Eppinger, 1995; Hubka and Eder, 1988). Based on this philos- ophy, the similarity notion of interest here is at a customer in- fluenced level. In other words, if two products have a function in common, such as store energy, and this function is related to 1 Copyright  2000 by ASME