Testing and introduction of new materials - Orthopaedic Biomaterials in Research and Practice - page 377

Table 15.2 hypothetical design concepts: new thr material

Initial list Final list

Tusk
Modified wood
Cloned tree with new properties
Petrified wood
Coral
Metal impregnated coral
Woven ceramic fiber/resin impregnated
Carbon fiber/graphite
Carbon/silicon carbide powder composite
Carbon/polyethylene powder composite
Hydroxyapatite/polyethylene powder composite
Metal fiber-reinforced silicone nitride
Alumina/polymer composite
Woven sapphire fiber/metal impregnated
Sapphire beads with spring connectors
Whisker-reinforced polymer
New titanium alloy
Titanium/polymer power composite

Modified natural material
Fiber-reinforced composite
Powder composite
Modified titanium alloy

the most two approaches are seen to be clearly better than the rest. When
this selection is made, the process moves on to step 6.

Step 6: Complete design Completing the design of the approaches
selected in step 5 is the final pure design step of the design cycle. Not
much needs to be said in that it involves traditional engineering pro-
cesses of analysis, calculation, and simulation and may even require
some pilot experiments to verify design and manufacturing concepts.
Parametric studies, in which the effects of varying controllable indepen-
dent variables are tested, are of great value in later considerations.
When alternative approaches were selected (step 5), design comple-
tion usually results either in their being ranked in a pragmatic order of
preference or in the elimination of one or more owing to inability to
realize a complete design.

Step 7: Evaluate design Design evaluation is a simple process of com-
paring the attributes of the final design to the specified values developed
in step 3 and determining how well they are met. If no design confer-
ences have been held since the one at the end of step 3, now is the ideal
time to do so. Ideally, all high and most medium goals should be met,
through satisfaction of the dependent specifications, for the design to be
said to be acceptable and for it to advance to the next cycle of the overall
design process.
If, in the opinion of the reviewers, the design is not acceptable, there
are several options. They include reviewing the design concepts to see
whether additional ones may be developed, reviewing the specifications