Bicycle helmet modelling and validation under linear and tangential impacts

In the context of head protection against traumatic brain injuries, this work attempts to understand the degree of protection offered by a commercial bicycle helmet under both linear and oblique impact conditions. In accordance with EN 1078 standard, an experimental program has been carried out on an existing helmet by performing 90 normative impacts. In parallel, a finite element model (FEM) of this helmet has been developed and implemented under the LS-DYNA (R) crash code to numerically reproduce the 90 experimental standard impact tests. Experimental oblique impacts on this commercial helmet have also been performed in order to validate it and to be able to assess its protection capability in case of tangential impact. Finally, the bicycle helmet FEM has been coupled to a Hybrid III dummy head FEM and oblique impacts have been reproduced numerically leading to a realistic behaviour of the helmet model in terms of rotational accelerations.