Abstract
Imprecision in the values of design parameters is an inherent character of the analysis stage of engineering design when the ideas have not yet converted to precise values and some of the design parameters remain flexible. The goal of this paper is to illustrate the application of the concepts of fuzzy set theory to represent this imprecision in design after a basic analytical model of the part being evaluated is developed. The idea is to help the designer efficiently study the effect of changing the values of certain parameters so that the number of iterations required to reach a final design can be reduced. The concepts of fuzzy set theory are used to represent design variables and the vertex method is utilized to calculate the fuzzy outputs in an interactive manner through an existing constraint manager (Design Shell) developed at The Ohio State University.