Sakerhetsutvardering av visirhjalmar: En jamforande studie med finite element-metoden for ansiktsskydd och hjarnskydd vid kollisioner

The main goal of the study is to compare different helmet geometries and evaluate their responses on face and brain protection upon facial impacts. With the aim to improve the safety of the user, visor helmets are evaluated and com- pared to a race helmet with goggles. The study was carried out by developing Finite Element (FE) Meshes of differ- ent helmets, such as a standard visor helmet, and a race helmet with goggles. The impact simulations were set up to study facial impacts with the Hybrid III 50th Dummy with different impact velocities (3 m/s, 5.42 m/s, and 6.8 m/s), and different impact locations on the face, such as forehead and nasal impacts. The resulting kinematics were obtained and used as input for the KTH Head Model to evaluate the intracranial response on the brain. The results for each helmet were compared against each other to obtain a comparison of injury risk, without considering absolute injury risks. The meshes of the helmets were validated with the EN960 headform, which was also compared to the Hybrid III Headform. The FE Simulation results on the forehead showed that the visor helmet at lower velocities (3 m/s) could provide slightly more protection than the helmet with goggles, but at higher speeds, the peak translational acceleration resulted much higher than when using goggles. In terms of brain strain, both helmets didn’t show significant differences, but higher risk probability was found when not using the visor or the goggles. As for the nasal impacts, significant interference with the Hybrid III nose was re- ported, giving unrealistic rotation to the head, thus the need to not consider those results as acceptable. The study shows that at lower velocities, the visor helmets could provide some protection regarding the translational acceleration, but in terms of concussion risk, no significant difference was found. Still, when not having a shield (e.g. visor or goggles), higher injury risk was found, indicating that having a face shield could provide some protection. Furthermore, it was found inaccuracies when working with the Hybrid III headform for localised impacts, specially in the nasal area. Thus, it shows the need to carry out further research on facial impacts, as well as further developing Finite Element Models of the face with the aim to achieve a high-biofidelity model to evaluate protective equipment.