: This paper presents a systematic approach based on the axiomatic design theory to assess the inherent flexibility of the product family to generate the product variants for customers’ needs. Assuming a decoupled or un-couple product design, the inherent flexibility of a product family for meeting a customisation requirement is defined as the ratio between the effectively relative change and the required relevant changes due to cascade effects responding to the change of the corresponding functional requirement. The Flexibility Indices (FIs) of a base product with two specific conditions, the uncoupled design and modularised design are discussed. The variety generation equations are built, and the characteristics of Flexibility Index (FI) are observed. A simplification approach of comparing FIs is also proposed. To illustrate this concept, an example of FIs of a motorcycle product family is introduced and discussed.
Bin Dan, Mitchell M. Tseng