Figure 5:

The representative time-histories of the transmitted force for six different drop heights (h) from 0.61 m (2 ft) to 1.93 m (6.34 ft) around the first impacts. (A) h = 0.61 m. (B) h = 1.52 m. (C) h = 1.63 m. (D) h = 1.73 m. (E) h = 1.83 m. (F) h = 1.93 m. The red solid lines and black dashed lines represent the results of the off-the-shelf helmets and the helmets with air bubble cushioning liner, respectively. The failure of the native helmets starts between h = 1.73 m (D) and h = 1.83 m (E), where a narrow, sharp force impulse appears on the top of the base force impulse. The helmets with air bubble cushioning liner do not show any sign of failure for the entire drop height range.