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Introduction 13
Decomposition:
Synthesis:
Composition:
Simulation:
Confirmation:
the authors as ‘mapping the design space’ – producing
guidance for those who wish to make design decisions
based on wider considerations and who wish to comprehend
the consequences of their decisions. The most
cost-effective activity at this stage is accurately recalling
and comprehending what has gone before.
Once the analytical stage is complete, it is time for
design decisions to be made. The whole entity must be
decomposed into its constituent parts, each of which has
design goals associated with it – cost, performance,
weight, etc. It is at this time the first real design decisions
are made that shape the product. Those decisions
are to be made in the light of the preceding analysis.
Once the design is decomposed into manageable portions,
the task of synthesizing (creating) the design begins.
During this phase, analytical tools are used to support
individual activities and verify the conformance of the
proposed design with the intended design goals. An
example of this might be the use of kinematic simulation
to verify that the suspension geometry characteristics
are those required. Discerning the requirement itself
is the function of the earlier decomposition phase.
The reassembly of the separate portions of the design,
each of which by now has a high level of confidence at
reaching its individual design goals.
Might also be referred to as ‘virtual prototyping’. High
fidelity models that have been a long time in preparation
are used to assess predictively, in some detail, the
behaviour of the whole design. Models prepared during
the synthesis activity are taken and reused. It is in this
arena that great strides have been made in terms of processing
power, model reuse and interpackage integration
over the last decade. Unfortunately, in the minds of
some, these super elaborate models are all that is possible
and anything less is simply worthless, passé and
old fashioned. These are valuable models and have a
crucial part to play in the process, but without a wellshaped
concept design they are unwieldy white elephants.
Also included in the simulation activity should be prototype
vehicles, produced from non-representative tools
and/or processes, that are physical simulations instead
of mathematical ones. The increasing use of ‘virtual’
prototyping obviates these physical prototypes except
for those where an understanding of the man/machine
interaction is necessary. One of several arenas where
this remains true is the dynamics task.
Sign-off testing is to be carried out on real vehicles. This
stage should reveal no surprises, as changes at this stage
are expensive.