The recent successes of British cyclists, in the Tour de France and Olympic Games, have resulted in an unprecedented increase in children taking up cycling in the UK. An increase in bicycle accident related head injury is inevitable and the focus will predictably turn to whether helmets optimally prevent injury. Many studies indicate that overall, head injury rates can be significantly reduced by their use. However, concerns remain that whilst preventing translational acceleration related head injury, bicycle helmets may actually increase the risk of angular acceleration related injury, due to their pronounced geometry. A 3D biofidelic-child-head form and two market-leading bicycle helmets were created in MSC ADAMS™, to investigate the potential effects of helmet geometry on head impact induced loading. Helmet safety standards for angular acceleration exposure do not currently exist, therefore, three oblique impact tests were established, representing the three anatomicalaxes. Peak impact angular and linear accelerations were compared between un-helmeted and helmeted head forms. Bicycle helmets reduced linear and angular accelerations by an average 54 g and 3295 rad/s 2 , respectively. The overall reduction in angular acceleration was, however, modest. Thus, it is recommended that International test standards be urgently revised to include measures to encourage a further reduction in exposure.
Keywords: biomechanical, bicycle helmet, head injury, children
MOJ Sports Medicine
Research ArticleOpen Access
Biomechanical engineering investigation of the risk of children wearing a bicycle helmet suffering an angular acceleration induced head injury 110Copyright: ©2017 Khalid et al. using Solidworks™, which was modified to conform to required dimensions:-overall curvature and shape of an established EN960 head form. 13 A number of previous studies. 14,15 were utilised to ensure the head form was suitably biofidelic, data to describe the head mass distribution was then derived from the most comparable head, 12 that is, 3.66kg compared with 3.67 kg.
Citation14,15 Additional verification was sought by comparison to the head mass of the 'Small Female' (that is, 5 th percentile) Hybrid III dummy, 16 which is identical to that of the Hybrid III 10-year-old. For consistency, centre of mass values were utilized from the above Hybrid III head form. Inertial parameters were used from the heads between 3.6 and 3.7kg.14 Whilst the skull stiffness varies across the head surface, with the temporal region recognised as being one of the weakest areas, 17 a lack of literature meant it was impossible to quantify a child's skull stiffness. Instead, an average value of 583.4 N/mm was calculated, based upon the minimum and maximum values reported from lateral, side and frontal loading of adult heads.18,19 A 0.75 scaling factor was then applied to this data, to calculate the skull stiffness at 7 years of age, 20−22 In the knowledge that full skull stiffness is achieved at 20 years, interpolation was used to calculate a 10-year-old...