
Selection criteria 423
per unit creep zinc is the clear optimum choice. However, on cost per unit
fatigue strength then ABS is comparable and on cost per unit impact strength a
number of polymers are comparable.
20.5 Case studies: merit ratings
The following case studies on the selection of materials for gas turbine blades,
tool materials, bearing materials and plastic bottles for fizzy drinks illustrate
the use of merit ratings to reduce the list of materials to be considered.
Gas turbine blades
Gas turbine engines are used for the propulsion of vehicles such as warships
and aircraft, in electric generators and in pumping stations along oi ...