There have been several attempts over a period of 20 years to simulate bone fracture by incorporating breakable components in crash test dummies. None has come into regular use. This report considers attempts to develop dummy motorcyclists with breakable legs. Material characteristics are discussed and the variation in the scatter fracture load of different materials is compared using the Weibull modulus. The materials used in the different dummy legs have been calibrated statically and uni-axially, whereas in crash tests multiaxial dynamic loads are sustained. The Independent Action criterion is used to show that compressive and torsion loads have only a small effect on bending and that differences in results from different laboratories is the result of scatter in the material characteristics.

The effect that leg fracture has on dummy trajectory is described using previously published experimental pedestrian impacts, motorcycle crash tests and pedestrian and car occupant computer simulation studies. Head trajectory is shown to be largely unaffected by leg fracture.