Blast and Impact Mechanics

There has been much work done on the mechanics of blasts and their relationship to the optimization of blast-resistant structures. Less work has been done on tailoring material architectures for armor to be used as external protection for delicate structures, such as the brain in a skull. This provides the focus of the current work, in which the mechanics for the mitigation of blast and impact by armor is developed, and then used as the basis for a proposed design for multi-use armor incorporating viscoelastic materials. One high-profile application of this work is the sports helmet. Current helmets used in sports such as football, hockey, and lacrosse do a very good job of reducing the force that is transmitted through the helmet to the skull. This prevents skull fracture and, to a certain extent, it reduces the acceleration of the brain, providing some brain injury protection. However, these helmets do very little to mitigate the impulse transmitted to the brain. That is, most of the kinetic energy associated with the impact event is not dissipated by the helmet (or the skull), and the impulse is delivered to the brain causing brain motion relative to the skull and therefore, brain injury. We have developed a design strategy for structures that must dissipate energy over and over and over again using elastic and viscoelastic materials. These impact-resistant structures may be used in helmets, body armor, and padding (shoulder pads and shin guards), to better protect wearers from soft tissue injuries, including traumatic brain injury. They may also be used to protect delicate behind-armor objects in a wide variety of applications such as electronic packaging, vehicles, and playground surfaces.