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Introduction to Mechanical Engineering Design 11
from first principles, textbooks, or handbooks relating the known and unknown
parameters; experimentally or numerically based charts; specific computational tools
as discussed in Sec. 1–4; etc.
• State all assumptions and decisions. Real design problems generally do not have
unique, ideal, closed-form solutions. Selections, such as the choice of materials, and
heat treatments, require decisions. Analyses require assumptions related to the
modeling of the real components or system. All assumptions and decisions should be
identified and recorded.
• Analyze the problem. Using your solution strategy in conjunction with your decisions
and assumptions, execute the analysis of the problem. Reference the sources of all
equations, tables, charts, software results, etc. Check the credibility of your results.
Check the order of magnitude, dimensionality, trends, signs, etc.
• Evaluate your solution. Evaluate each step in the solution, noting how changes in strat-
egy, decisions, assumptions, and execution might change the results, in positive or neg-
ative ways. Whenever possible, incorporate the positive changes in your final solution.
• Present your solution. Here is where your communication skills are important. At
this point, you are selling yourself and your technical abilities. If you cannot skill-
fully explain what you have done, some or all of your work may be misunderstood
and unaccepted. Know your audience.
As stated earlier, all design processes are interactive and iterative. Thus, it may be nec-
essary to repeat some or all of the above steps more than once if less than satisfactory
results are obtained.
In order to be effective, all professionals must keep current in their fields of
endeavor. The design engineer can satisfy this in a number of ways by: being an active
member of a professional society such as the American Society of Mechanical
Engineers (ASME), the Society of Automotive Engineers (SAE), and the Society of
Manufacturing Engineers (SME); attending meetings, conferences, and seminars of
societies, manufacturers, universities, etc.; taking specific graduate courses or programs
at universities; regularly reading technical and professional journals; etc. An engineer’s
education does not end at graduation.
The design engineer’s professional obligations include conducting activities in an
ethical manner. Reproduced here is the Engineers’ Creed from the National Society of
5
Professional Engineers (NSPE) :
As a Professional Engineer I dedicate my professional knowledge and skill to the
advancement and betterment of human welfare.
I pledge:
To give the utmost of performance;
To participate in none but honest enterprise;
To live and work according to the laws of man and the highest standards of pro-
fessional conduct;
To place service before profit, the honor and standing of the profession before
personal advantage, and the public welfare above all other considerations.
In humility and with need for Divine Guidance, I make this pledge.

5 Adopted by the National Society of Professional Engineers, June 1954. “The Engineer’s Creed.” Reprinted
by permission of the National Society of Professional Engineers. NSPE also publishes a much more extensive
Code of Ethics for Engineers with rules of practice and professional obligations. For the current revision,
July 2007 (at the time of this book’s printing), see the website www.nspe.org/Ethics/CodeofEthics/index.html.