The selection. Figure 6.10 shows the strength—density chart. Values of M1
correspond to a grid of lines of slope 1. One such is plotted as a diagonal line
at the value M1¼200 kJ/kg. Candidate materials with high values of M1 lie in
the search region towards the top left. The best choices are unexpected ones:
composites, particularly CFRP, high strength titanium alloys and some
ceramics, but these are ruled out by their low toughness.
But what of the lead flywheels of children’s toys? There could hardly be
two more different materials than CFRP and lead: the one, strong and light