Fig. 3

Example, identifying helmet damage. a Visible cracks can be seen on the outer surface of the fibreglass shell. One area of damage can be seen. b Visible delamination of the fibreglass shell can be seen in two distinct locations. Top and bottom of photo. The damaged area at the bottom of the photo corresponds to the external damage. c Visible crush of the EPS liner. d A section was cut through the centre of the damaged area and the liner thickness was measured at its thinnest point. It measured 13.2 mm. e Reviewing the CT images showed clear crushing of the EPS liner. At its thinnest point, the crushed region measured 13 mm in this case