Importance of the Bicycle Helmet Design and Material for the Outcome in Bicycle Accidents

In Sweden the most common traffic group that needs to be hospitalized due to injury is cyclists where head injuries are the most common severe injuries. According to current standards, the performance of a helmet is only tested against radial impact which is not commonly seen in real accidents. Some studies about helmet design have been published but those helmets have been tested for only a few loading conditions. Therefore, the purpose of this study was to use finite element models to evaluate the effect of the helmet’s design on the head in some more loading conditions. A detailed head model was used to evaluate three different helmet designs as well as non-helmet situations. The first helmet (Baseline Helmet) was an ordinary helmet available on the market. The two other helmet designs were a modification of the Baseline helmet with either a lower density of the EPS liner (Helmet 1) or a sliding layer between the scalp and the EPS liner (Helmet 2). Four different impact locations combined with four different impact directions were tested. The study showed that using a helmet can reduce the peak linear acceleration (85%), peak angular acceleration (87%), peak angular velocity (77%) and peak strain in the brain tissue (77%). The reduction of the strain level was dependent on the loading conditions. Moreover, in thirteen of the sixteen loading conditions Helmet 2 gave lowest peak strain. The alteration of the helmet design showed that more can be done to improve the protective effect of the helmet. This study highlighted the need of a modification of current helmet standard test which can lead to helmets with even better protective properties as well as some challenges in implementing new test standards.