Foam based materials were originally incorporated into helmets in the 1970’s, providing an effective method of absorbing impact energy and so protecting against severe head injury. Similar materials still exist in the majority of protective helmets today, indicating a need for an innovative approach that will achieve a step change in energy absorption performance. This paper focusses on tailoring the Miura Ori (MO), origami derived geometry, as a method to achieve a material structure tailored to maximise impact energy absorption, whilst complying with existing product design constraints. This ambitious concept was then realised using an elastomeric, additive manufacturing powder, before being tested against foam derived from a commercially available American football helmet. MO pads demonstrated comparable performance versus foam at relatively low impact velocities, though recorded a peak acceleration 15% less than foam at the highest impact velocity. This difference increased once the respective samples were exposed to their third impact, demonstrating the superior performance of MO over multiple impacts. The MO material demonstrated encouraging energy impact absorbing behaviour, with scope remaining to further optimise the geometry in order to further enhance performance. Furthermore, opportunities exist for achieving superior shear energy performance than contemporary materials and, ultimately, for harnessing the benefits of additive manufacturing to fabricate person specific headwear optimised for a given impact environment.
Keywords:
additive manufacture, cellular structures, impact, helmet, personal protection