An experimental study on shock wave mitigation capability of polyurea and shear thickening fluid based suspension pads

The present experimental study investigates shock wave mitigation capability of potentially new personal protective equipment (PPE) suspension pads made from polyurea and shear thickening fluid (STF). The shock tube test results show that when placed behind Twaron fabric systems with thickness ranging from 2 mm to 18 mm, the replacement of conventional flexible foam pad with STF and STF-infused foam pads with the same thickness of 20 mm greatly reduces the normalized peak pressure (by about 72% for each pad). However, this benefit is partially offset by a large increase in the normalized impulse (by about 78% for the STF pad and 131% for the STF-infused foam pad) which may cause the shock wave mitigation performance of these two pads to become less effective. Interestingly, the use of 4 mm thick polyurea pad can greatly reduce the normalized peak pressure and impulse as well (by about 74% and 49%, respectively). These results reveal that among the potentially new suspension pads tested, the polyurea pad displays the best shock wave mitigation performance. Therefore, polyurea has potential for use as a suspension pad in personal protective equipment requiring shock wave mitigation capability such as fabric ballistic vests, bomb suits and combat helmets.