63
C H A P T E R 9
e Engineering Design
Process
9.1 TRADITIONAL ENGINEERING DESIGN
What separates engineers from scientists? It has been said that scientists study what is while en-
gineers create what has never been [86]. Creating what has never been requires a process and the
engineering design process is the embodiment of this creative design process. e engineering
design process was developed for usage in the late 1960s as a way to improve the teaching of
the engineering design process. As design courses were introduced into the first and final year’s
undergraduate engineering curricula, a need to codify and formalize the teaching of design was
needed. Recognizing that traditional engineering design is a messy process that does not trans-
late well into teaching, a simplified more formal process was needed that could be taught to
undergraduate engineering students in beginning engineering courses offered during the first
year’s curriculum.
e output from the design process is usually the complete specifications for an artifact
or sometimes a process and represents the final design stage. Where the process begins is an-
other question. Traditionally, the first step or phase in the design process is labeled “Identify the
Need or Problem.” A primary question here is who does this identification or problem defini-
tion. Downey [87] suggests that traditionally the engineer is handed the problem definition or
need and becomes the “problem solver.” Many engineers and engineering educators primarily
define themselves as problem solvers and this characterization is widespread among engineering
students, i.e., to be a good engineer requires being a good problem solver, thus the heavy em-
phasis by high school advisors on being an excellent student of mathematics and sciences as a
prerequisite for studying engineering in college. We, along with Downey, believe that engineers
must become far more involved in the design definition or needs assessment before design can
commence. As we will discuss later, engineers must not only do the design right, they must also
do the right design.
In order to suggest changes to the engineering design process as discussed in the preceding
chapters, we must define what we mean by the engineering design process. ere are many
design models [88–90] commonly used but for simplicity we shall chose a model that has been
used by the one of the authors for many years in teaching first-year engineering design courses.
Figure 9.1 presents the steps or phases of this engineering design process. In this approach to
design, a design is reached that meets the established criteria for success. If such a design is not
64 9. THE ENGINEERING DESIGN PROCESS
achieved then either the process is terminated or restarted based upon what was learned during
the first attempt at design. It should be noted that traditionally a client provides the first step
by identifying a need or problem to be addressed through the design process and presents this
information to an engineering design team. More recently, in a more entrepreneurially driven
society, the client and the design team may be the same, that is, the design team identifies the
need or problem to be considered. Examples of this by social entrepreneurs in designs for use
in developing countries to address challenges such as sanitation, clean water, and energy needs
abound.
e description below is not meant to be inclusive of all aspects of the design process but
rather just to illustrate the basic ideas of the process to provide the reader with the necessary
background to understand later modifications to this described process. For example, the mem-
ber composition of a design team is extremely important in a successful design process. ere are
many excellent books (e.g., [89]) devoted entirely to the engineering design process that discuss
topics such as team composition in much greater detail than the present work.
(1)
Identify the
Need
(5)
Select the Best
Solution
(8)
Select the
Best Solution
(2)
Problem
Definition
(6)
Prototype
(4)
Develop
Possible Solutions
(7)
Evaluate the
Prototype
(3)
Research
Figure 9.1: Steps in the engineering design process.
9.1. TRADITIONAL ENGINEERING DESIGN 65
Let’s examine the process as shown in Figure 9.1. Step 1 is to identify the need or prob-
lem. In this phase, if engineers are not involved they should be included. However, care must
be exercised here for there is a serious problem with including engineers at this early stage.
As engineers are the technical experts they tend to jump to technical solutions too rapidly—
specialization of people results in specialized approaches [60]. Previous chapters have developed
questions to push things away from the world of specialization earlier in the design process.
Step 2 is the problem definition. is phase is primarily devoted to clarifying the objectives
set out by the client and gathering information needed to develop an engineering statement of
what the client wants. In addition, this is where the users’ requirements are established and it is
extremely important that users be included in this phase of the design process. is is the first
place where all three constituents come together as a team: client, design team and members of
the user community. is is also where constraints are identified. e entire purpose of this step
is to develop a revised problem statement, including constraints that the client, design team and
users agree on.
Once a revised problem statement is agreed upon, the process enters Step 3 which consists
of the research phase. e design team needs to thoroughly understand the problem or need
before any possible designs can be outlined. ere are many ways to conduct this research. A
thorough review of the literature for similar problem statements will usually provide information
on the so-called state-of-the-art and prior work in the area. For some problem examples, the
reverse engineering of similar products can be extremely useful. One of the authors likes to
advise that the design team identify the hardest parts of the problem in order to focus attention
on these rather than the parts of the problem where solutions may be more obvious. e reason
for early identification of the difficult parts is to try and keep the design cycle short if such
problems cannot be resolved. If hard parts of the problem are left to later stages, the costs of
the design phase are significantly higher than if the design process gets terminated at an earlier
stage because additional research is required to attack difficult problem areas. is is also the
point where the criteria for meeting the design objectives are defined. In other words, how do
we know that we have an acceptable design?
Once a library of research materials is developed and the criteria for evaluation are de-
veloped, then possible designs may be explicated. is constitutes Step 4 as shown. In many
other design process models this phase is defined as the conceptual design stage. is is where
the majority of engineering tools are used. For example, finite element modeling or fluid flow
analyses. Some costing analysis may be developed or other issues such as construction, mainte-
nance, disposal, etc., are considered. is is also where the critical step is taken that the design
will be technical in nature. We shall modify this step based on the questions of just technology
and sustainability in a later section.
Based on criteria developed in Step 3, possible design(s) (sometimes referred to as con-
ceptual designs) are enumerated for further development. It is possible that multiple designs
are carried forth to the next phase although in most cases a single design is more usual. Step 5
66 9. THE ENGINEERING DESIGN PROCESS
represents the selection of the best possible design(s) (sometimes referred to as the preliminary
design).
If an artifact is to be developed, a prototype is constructed in the next step (Step 6). In
many cases, problems will develop during this phase that may require taking one or more steps
back in the design process. As well, features may cause the prototype to be modified to achieve
a better solution. From this step forward in the design process, iteration of the design process
may arise. For large design projects, constructing a prototype may not be possible. In such cases,
simulation becomes a common form of design development and improvement.
Step 7 is the test and evaluation of the prototype. is phase is carried out based on the
evaluation criteria developed in Step 3. Again, additional tests may become obvious once this
phase begins. When a simulation model has been developed instead of a physical prototype, the
computer model is used for the evaluation phase by simulating various operating conditions in a
way that is convincing to the design team that the model is representative of a prototype’s actual
behavior. Assuming that all works out as anticipated, the design moves into its final phase.
Step 8 is the documentation of the design solution (the detail design). All plans and de-
sign documents must be finished in this phase and should include costing analysis, materials
acquisition plans, fabrication or assembly operations, resource and energy analyses, maintenance
documents, disassembly, reuse, recycling, and disposal plans.
9.1.1 JUST TECHNOLOGY DESIGN
We now want to illustrate how our concept of Just Technology can be melded with the traditional
engineering design process described above. Figure 9.2 is a schematic diagram that has our four
Just Technology questions shown in the middle of the traditional design process. e questions are
placed in the middle to signify that they play a central role throughout the design process—they
are not meant to be secondary issues to be considered on an ad hoc basis.
9.1.2 PROBLEM FORMULATION
e first three steps in the design process—identifying a need; defining the problem; and
research—are all required to develop a full understanding of the challenge or issue being ad-
dressed. ese early stage steps are where our Just Technology questions are extremely critical to
the goal of developing more just approaches to these challenges. We stated above that we believe
that engineers should be involved in the initial phase of identifying the need. is recommenda-
tion did come with a warning: don’t jump to conclusions (for engineers: technological decisions)
too early. To counteract this concern we insert Question 1: Is there a real lasting, serious, issue
that we know with a reasonable level of certainty. See how the role of engineers involvement
at this stage goes from considering solutions to refining the identification of the real challenge
at hand! is provides a natural role for engineers to contribute early in the process. At this
stage the focus can now be on the nature of the challenge being considered, not just whether a
challenge appears to exist.
9.1. TRADITIONAL ENGINEERING DESIGN 67
To properly address the first Just Technology question, it must also be considered through-
out the next two design steps: problem definition; and research. Efforts at defining the problem
should be framed by the metrics of how lasting and serious the challenges are, along with an
understanding of how certain we are of our knowledge concerning the challenge.
e third and final step before moving onto potential designs is to research both the chal-
lenge and previous approaches implemented on similar challenges. is is the step that bridges
the definition phase and the further design phases. By the end of this step, research should
complete the task of answering the first justice question. Research related to the problem being
identified and defined must be broadened to include the considerations of Justice.
9.1.3 SOLUTION GENERATION
“I learned from this to always hold back, to make sure that even when I think I have the
answer, to generate a short list of alternatives.” ([91, p. 66])
e next two steps in the design process comprise developing preliminary designs and then
choosing a “best” design. Here the second Just Technology question should play a critical role.
Typically, at this stage the only designs being considered are technological in nature. For Just
Technology to happen, non-technological or low tech designs need to be considered. is begs
the question if engineers are qualified to consider these non-traditional solutions. e answer is
probably not! So it is important at this stage that other areas of expertise are included. is marks
a big change from traditional engineering design, as when the design process has preceded this
far it has usually become a purely technology-based discussion—other types of designs are not
considered.
e second step in this phase results in a choice being made as to the best design. Our
push for Just Technology does not mean that by considering non-technological solutions the best
choice is non-technical. Instead, it has only made sure that other alternatives have been properly
considered in the decision process.
9.1.4 PROTOTYPES
Our third phase in design again includes two steps: develop; and evaluate a prototype. Now the
third
Just Technology
question comes into play—are we confident our solution will work. Again,
our focus must shift from a purely technological functional question to the broader question
of will the design work for the bigger challenge being addressed. It is one thing to say that a
technology performs to functional standards but quite another to believe it addresses the problem
at hand.
9.1.5 IMPLEMENTATION
Finally, the decision to commit to a particular design must incorporate our fourth Just Technology
question: does it cause greater harm than the challenge itself? For example, if we are talking
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