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

Ethical issues in engineering design
In the operationalisation of safety, the engineers equated a safe trailer with a
structurally reliable trailer. Within the CLC there are ideas on good design
practice concerning structural reliability. These ideas are based on a shared
educational background and previous design experience within the CLC. It can be
concluded that there are norms about good design practice and that the engineers
used these norms in the trailer design. These norms were internal CLC norms.
These internal norms were not imposed by legislation or professional or technical
codes. The engineers reflected and thought about how these norms should be
used in the case design project. Discussions on whether or not to use ultimate
load in calculations could be regarded as discussions about the application of the
norms in this specific case. These discussions were also ethically relevant because
structural reliability poses limits for safe use. If a trailer collapses during use
because of metal fatigue or overloading this can cause injuries or fatalities.
Torsional stiffness has an important influence on how easily the trailer might roll
over. Trailers rolling over on highways cause a lot of traffic jams and accidents.
So choices covering structural reliability are ethically relevant.
During the operationalisation of a structurally reliable trailer, choices have to
be made between different available material properties. The engineers could, for
example, use material properties established by Lloyd’s register or properties
established by the CLC in co-operation with the CUR and the Rijkswaterstaat.
Material properties like allowable strain give upper limits for strain in a material.
This allowable strain should not be exceeded during normal use because this may
cause failure of the trailer.
Besides deciding on material properties choices had to be made on load
scenarios. The load scenarios are used to simulate the loads that a trailer will be
subjected to during use. If the strains remain below the allowable strain under
all load scenarios then the design suffices. If the allowable strain is exceeded
then other fibres should be used or more material should be added. Using finite
element modelling, the strains in the material of the trailer were calculated
under the load scenarios, one problem was that the load scenarios were not
known for this case. The engineers did not know what the loads on the trailer
would be when the trailer turned a corner or was braking when fully loaded with
sand. The load scenarios were not known and the proposed load scenarios were
adapted during the finite element modelling. So when it became obvious that the
allowable strain was exceeded drastically under a load scenario, the load scenario
was reduced and more fibres were added. In short, there was a lot of uncertainty
concerning the loads that the trailer would be subjected to during use.
Underestimating the load scenarios could lead to trailers that are not strong or
stiff enough in actual use and this can cause failure of a loaded trailer during
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