Finite Element Analysis of Helmeted Impacts and Head Injury Evaluation with a Commercial Road Helmet

This research was conducted to assess the safety performance of a commercial motorcycle helmet, homologated by the most relevant current standards and currently available in the market. The evaluation was based on accurate reproduction of translational impacts specified by the ECE R22.05 standard to assess motorcycle helmets. The Finite Element numerical framework was validated against two different sets of experimental results. The first addressed the constitutive model of the expanded polystyrene, the material responsible for energy absorption during impact; the second related to the headform's centre of mass acceleration after the impacts defined in the ECE R22.05 standard. Both were successfully validated. Once a functioning and validated numerical motorcycle helmet model was created, the Strasbourg Finite Element Head Model was employed to evaluate in more detail the severity of sustained injuries after impacts in one of the four specified points of ECE R22.05 instead of employing a rigid headform. From this analysis, it was concluded that brain injuries such as concussion and diffuse axonal injury may occur even with a helmet that complied with the majority of existing motorcycle helmet standards. The need for improving current test procedures and head injury criteria is strongly recommended to reduce the exposure to these types of head injury.