AXIOMATIC DESIGN IN SOFTWARE DESIGN FOR SIX SIGMA (DFSS) - Software Design for Six-Sigma: A Roadmap for Excellence - page 329

has spread from Germany to most industrialized nations around the world. To date,
most research in engineering design theory has focused on design methods. As a
result, Several design methods now are being taught and practiced in both industry
and academia. However, most of these methods overlook the need to integrate quality
methods in the concept stage. Therefore, the assurance that only healthy concepts are
conceived, optimized, and validated with no (or minimal) vulnerabilities cannot be
guaranteed.
Axiomatic design is a design theory that constitutes basic and fundamental design
elements knowledge. In this context, a scientific theory is defined as a theory com-
prising fundamental knowledge areas in the form of perceptions and understandings
of different entities and the relationship between these fundamental areas. These
perceptions and relations are combined by the theorist to produce consequences that
can be, but are not necessarily, predictions of observations. Fundamental knowledge
areas include mathematical expressions, categorizations of phenomena or objects,
models, and so on. and are more abstract than observations of real-world data. Such
knowledge and relations between knowledge elements constitute a theoretical system.
A theoretical system may be one of two types—axioms or hypotheses—depending
on how the fundamental knowledge areas are treated. Fundamental knowledge that
are generally accepted as true, yet cannot be tested, is treated as an axiom. If the
fundamental knowledge areas are being tested, then they are treated as hypotheses
(Nordlund et al., 1996). In this regard, axiomatic design is a scientific design method,
however, with the premise of a theoretic system based on two axioms.
Motivated by the absence of scientific design principles, Suh (1984, 1990, 1995,
1996, 1997, 2001) proposed the use of axioms as the pursued scientific foundations
of design. The following are two axioms that a design needs to satisfy:
Axiom 1: The Independence Axiom
Maintain the independence of the functional requirements
Axiom 2: The Information Axiom
Minimize the information content in a design
In the context of this topic, the independence axiom will be used to address
the conceptual vulnerabilities, whereas the information axiom will be tasked with
the operational type of design vulnerabilities. Operational vulnerability is usually
minimized and cannot be totally eliminated. Reducing the variability of the design
functional requirements and adjusting their mean performance to desired targets are
two steps to achieve such minimization. Such activities also results in reducing design
information content, a measure of design complexity per axiom 2. Information content
is related to the probability of successfully manufacturing the design as intended by
the customer. The design process involves three mappings among four domains
(Figure 13.1). The first mapping involves the mapping between customer attributes
(CAs) and the functional requirements (FRs). This mapping is very important as
it yields the definition of the high-level minimum set of functional requirements
needed to accomplish the design intent. This definition can be accomplished by the