Design of an Advanced System for Motorbike Helmets Able to Dissipate Rotational Accelerations Caused by Tangential Impacts

A novel device based on non-Newtonian fluids for the attenuation of tangential impacts energy in helmets has been designed and tested. Non-newtonian shear-thickening fluids have provided the best energy attenuation in tangential impacts model tests. The system is made of a series of pads with a case containing the fluid in which is immersed a rigid pin, able to move in all direction. This movement permits to absorb tangential impact energy during its movement. A series of seven pads have been used to modify a motorcycle helmet made of two concentrical liners made of polystyrene. The liners have been only connected by pads and therefore are free to rotate. Oblique impacts tests on the helmet have shows a 14% reduction of the brain injury criterion. Moreover, the maximum of the rotational acceleration is moved to longer times, indicating a retard of the acceleration of the head due to the effect of the pads. The novel system can be applied with minimal modifications in most sport and motorbike helmets.