Ethical issues in engineering design - 3TU.Centre for Ethics and ...

Ethical issues in engineering design
Vincenti’s divisions of the design hierarchy are more fine grained at the lower
levels. Component design is not the lowest level but middle level. Disco et al. add
the systems level at the highest level.
According to Vincenti, the degree of external constraint is larger if the design
process is lower in the design hierarchy. The higher levels of the design process
pose external constraints for the lower levels. Examples of these constraints are,
amongst others, dimensional constraints, a part needs to fit in the whole product,
but also constraints concerning the function of the part.
The ideas of Vincenti and Disco et al. about design hierarchy seem to
resemble the phases in the design process presented in section 2.2.1, but there is
a difference. The difference between design hierarchy and the phase of the design
process is that a design process is done for every product, subassembly or part.
This means that at every level of the hierarchy all phases of the design process are
gone through. One could think for example of the generation of concepts design
phase of a part of a product. This would be the generation of concepts design
phase of a middle level design. The relative importance of design phases can
differ in the design hierarchy, for example in high level design the phase of the
design process in which detailed drawings are made can be relatively
unimportant compared with the generation of concepts.
Type of design
Besides the notion of design hierarchy Vincenti also introduced the notion of
design type ranging from normal to radical design. Vincenti uses the terms
“operational principle” and “normal configuration” to indicate what normal
design as opposed to radical design is [Vincenti, 1990]. “Operational principle” is
a term introduced by Polanyi [Polanyi, 1962]. It refers to how a device works. The
normal configuration is described by Vincenti as:
‘….. the general shape and arrangement that are commonly agreed to
best embody the operational principle.’ [Vincenti, 1990, 209]
Examples of different working principles of car engines are a combustion engine
and a fuel cell electrical engine. Both engines power cars but they have different
working principles. In a combustion engine fuel and air are let into a cylinder
and ignited. The expanding volume of the ignited gases is used to get a rotational
movement. In fuel cell cars an electrochemical reaction between hydrogen and
oxygen produces electricity. This electricity is used to drive the car. So although
both engines power the car they do so in a different way. In normal design, both
operational principle and normal configuration are kept the same as in previous
designs. In radical design, the operational principle and/or normal configuration
are unknown or it is decided that the conventional operational principle and
normal configuration will not be used in the design.
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