What is Engineering Design Process? Why are there so many design process models?
The research trend on the engineering design process has changed depending on the perspective of engineering. In the middle of the 20th century, research on engineering design process conducted in terms of applied science. Since the 1980s, some researchers viewed engineering as a problem-solving process. In recent years, many researchers agreed that engineering design processes are complex and amorphous; as a result, some researchers adopted an ethnographic approach to describe details of the engineering design process within the specific engineering contexts. In order to understand the engineering design process, we will review the discussions and arguments in the development of design theories.
1 Engineering Design as Applied Science
In the 1950s and 1960s, U.S. engineering education was science-oriented in its approach (Bousbaci, 2008). Since the Second World War, a number of theory-oriented European engineers—nuclear engineers and space engineers, in particular—moved to the United States (Seely, 1999). The science-oriented engineering research of the time influenced the U.S. engineering education curriculum, which primarily focused on theory-based science learning (Grinter, 1955). Moreover, the U.S. military supported this trend by providing science-oriented research funding (Bix, 2002). This context coincided with an engineering perspective called applied science (Howell, 2002; Pahl & Beitz, 2013; Simon, 1975). Fletcher and Shoup (1978) viewed engineering as
“an applied science which deals with the planning, design, construction, testing, management or operation of facilities, machine, structures, and other devices used by all segments of society” (Flether & Shoup, 1978, p. 2).
The applied science approach attempted to define the design process based on logical, systematic, and rationalist views. Herbart Simon (1973) argued that a design problem can be defined as a well-defined problem. He stated that a well-defined problem has the following properties:
- a definite criterion
- at least one problem space
- definable state changes, and
- representable states.
According to this approach, all problems are solvable if the problem solver decomposes the problem. On the other hand, if a problem is not solvable, its proponents believed, it is because the problem solver were not able to define the problem. Design science theorists believed that design processes could also be illustrated via step-by-step models that divided design processes into distinct phases, including problem definition, analysis, ideation, and evaluation (Simon, 1973). One representative model of this approach is Hubka’s systematic design process model (1983). Hubka presented the design process in comparison with the technical process, which depicted the design process as a wire drawing. For example, a design project is a technical process where space and time variables apply. Once the design project is initiated, the effects of human actions and technical systems lead the design process, which in turn influences the project output. The model attempted to define the basic elements of the design process and identify a unified design process model applicable to a variety of design tasks.
A Design Model through Technical Process Model (Hubka, 1983, p. 9). The model can be accessed through https://www.daaam.info/Downloads/Pdfs/proceedings/proceedings_2014/074.pdf
However, the applied science approach has failed to represent the dynamic characteristics of design processes (Sheppard, Macatangay, Colby, & Sullivan, 2008). Rittel and Weber (1973) argued that design problems cannot be defined by definite rules and operations. He labeled this characteristic of design problems as wicked problems that lack definitive formulation, stopping roles, operations, and definitive solutions. Accordingly, Dorst (2004) argued that most design problems have the following three characteristics: 1) design problems are partly determined by explicit needs and constraints; 2) a major part of design problems is underdetermined; and 3) most parts of design problems can be considered undetermined. The applied science approach has contributed to the foundation of design process research, but is limited in its capacity to represent complex, intertwined design processes.
2 Engineering Design as Problem-Solving
An alternative approach to study the design process focused on problem-solving activities (Clarkson & Eckert, 2004; Cross, 2000; Lawson & Dorst, 2013). This approach emphasized engineers’ problem-solving activities: generating ideas, exploring the consequences, and evaluating the results. The underlying idea of this approach is that problem-solving plays as a fundamental operation in human activities. Similar to the applied science approach, this idea views the full design process as smaller sub-processes, such as conceptual design, prototyping, and product manufacturing (Ball, Evans, Dennis, & Ormerod, 1997). The problem-solving approach considers problem-solving as a sub-process of the design process. This approach led to the development of design process phase models that solved engineering problems step by step (Lawson & Dorst, 2013). The phase models allow engineers to easily generate a comparable solution by treating the engineering design task as problem-solving.
Many researchers have investigated how engineers generate the best solution via problem-solving approach. Lawson (1979) compared the problem-solving styles of architectural engineers and scientists and concluded that architectural engineers tended to use solution-oriented strategies, while scientists preferred to use problem-focused strategies. Lu (2015) studied the relationship between problem-solving types and design quality. Lu compared four problem-solving style types: problem-driven, information-driven, solution-driven, and knowledge-driven. Lu’s study concluded that the solution-driven strategies yielded more creative design outcomes than the other types. Dorst and Cross (2001) examined the design process in terms of creativity and confirmed that iterations between problem-space and solution-space are key to the generation of creative ideas.
Some critics have claimed that problem-solving process models do not explain all aspects of the design process. Bucciarelli (2003) argued that design process models depicted by shapes and arrows can only reflect a narrow view of the design process. Engineers often experience frustration when they try to solve a certain engineering problem according to a design process model because the model does not work as described.
3 Engineering Design as Ethnography
The multifaceted nature of engineering has led many researchers to adopt an ethnographical approach as a research methodology (Bucciarelli, 2003; Latour & Woolgar, 1986; Vinck, 2009). This ethnographical research method provides a realistic description of engineering tasks within the specific engineering contexts. Vinck (2009) used this approach to illustrate engineers’ day-to-day lives. Vinck visited engineers’ plants, design offices, and laboratories to observe what real engineers do. Using the ethnographical approach, Vinck presented the natural characteristics of engineering as: socio-technical complexity, negotiation and optimization, and comprehensive job practices (from designing to presenting the design solution). One advantage of this approach is that it does not simply claim that engineering is complex; it also identifies how the complexity occurred and was managed. The ethnographical approach can describe the engineering design process with realistic and authentic illustrations.