2 1. INTRODUCTION TO RELIABILITY IN MECHANICAL DESIGN
e most important aspect of engineering design is that engineering design is a process.
Why is it a process? Engineering design is a process not because it consists of several steps and
might take a long time to complete it, but mainly because the final approval of the design is
not by theoretical calculations or numerical simulations, but by the actual testing on the pro-
totype. For example, when we do a complicated math problem, which might need a few hours
or a few days, we know the obtained solution is right or not after we finish it because we can
plug them in the equations to check the solution. For an engineering design project, even the
accurate theoretical calculation and complicated numerical simulation results suggest that the
design should be safe and could satisfy the design requirements, the design product cannot be
released to mass-production and customers. Engineering design experience has approved that
design product without throughout testing on the prototypes might cause significant problems
for customers and company.
According to the last few hundred years of engineering successful and unsuccessful experi-
ence, lots of different theory about the design process have been proposed for guiding engineers
to conduct the engineering design. e five-phase engineering design process proposed by Ger-
ard Voland is one of these good theories. e five-phase engineering design process includes:
(1) Phase One: Needs Assessment; (2) Phase Two: Design Specifications; (3) Phase ree: Con-
ceptual Designs; (4) Phase Four: Detailed Design; and (5) Phase Five: Implementation. e
detailed information about the five-phase design theory can be found in the book Engineering
by Design, authored by Gerard Voland [
1]. We will provide brief descriptions of the five-phase
engineering design process as follows [2].
1.1.1 PHASE ONE: NEEDS ASSESSMENT
e main task in Phase One is to check whether needs are real and feasible or not. e “needs”
is a current problem or current unsatisfactory status. e needs can come from personal expe-
rience, customers, or society. However, some claiming demands might not be a real need and
might fade quickly. Some needs might not be feasible for the project team because it might not
be technically feasible or financially viable. For example, many people wish that they could have
a device which could directly import the knowledge of books into their brains. is device might
be feasible in the future. However, it is certainly not technically feasible now. For another ex-
ample, constructing a more advanced airplane is always a real need, but it will not be financially
viable for a small company because it has limited human resources and funding.
e outcomes of Phase One are as follows. (1) e need is not a real need. No further
action is needed. (2) e need is a real need, but it is not technically nor financially feasible
for the project team. e need might be stored for future use. No immediate action is needed.
(3) e need is a real and feasible need for the project team. Only if the need assessment passes
Phase One, will it proceed to Phase Two: Design Specifications. However, the design project
or the project team is not still officially established or formed.
..................Content has been hidden....................
You can't read the all page of ebook, please click here login for view all page.