Multifunctional auxetic graphene-metal structures for smart helmets
Abstract
Approved for Public ReleaseThe primary goal of a combat helmet is to protect the warfighters head from external threats during crit,ical missions. To be effective, combat helmets and their materials/structures must provide mechanical protection against ballistic,,blunt, and blast impacts while maintaining their minimum weight. The development of such protective materials/structures will dramat,ically increase operational endurance of military personnel without compromising their mobility and effectiveness, particularly cons,idering that combatants wear helmets up to 18 hours a day during training and engagement. Lightweight and strong helmet materials/st,ructures are also required to support the emerging technology of a smart helmet. For example, reducing helmet weight without comprom,ising protective functionality by developing innovative materials/structures with a large strength to weight ratio is crucial for th,e integration of a helmet with motion sensors, thermal imaging, night vision, and a heads-up display. Such an integrated smart helme,t will enable quicker, more informed decision-making during military operations owing to new sensing and communication capabilities., In addition to the mechanical properties of helmet materials/structures, their thermal and electrical functionality is being increa,singly emphasized due to a need for effective cooling of the head and its isolation from external electro-magnetic fields. Auxetic s,tructures are well known for their attractive characteristics, including high energy absorption, high fracture resistance, and low d,ensity. Our main working hypothesis is that the proposed multifunctional auxetic graphene-metal composites will offer significantly,improved material responses due to the integration of superior mechanical, thermal, and electrical properties of graphene tubes with, the advantages of auxetic structures. The mechanical strength of the proposed carbon-metal composite structures will be enhanced by, three mechanisms: 1) direct reinforcement from ultra-strong graphene tubes, 2) the size dependent strength (i.e., the thinner, the,stronger) of metal layers in individual ligaments, and 3) graphene-metal interplay that inhibits dislocation nucleation/annihilation,. It is worth noting that the ultimate strength of high-quality carbon materials is three orders of magnitude greater than stainless, steel. In addition to mechanical enhancement, the proposed structure will integrate the thermo-electrical advantages of carbon cons,tituents, namely excellent current density limit, electron mobility, and thermal conductivity with metals. The enhanced thermal and,electrical conductivities will improve thermal dissipation for effective cooling and isolation of the head from electromagnetic fiel,ds for protective and sensing applications. It is important to emphasize that unfavorable thermal sensation or thermal discomfort ar,e the most common reasons for not wearing head protective gear and, as a result, effective cooling is important for practical reason,s in addition to prevention of heatstroke.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 05, 2022
- Source ID
- N000142212146
Entities
People
- Wonmo Kang
Organizations
- Arizona State University
- Office of Naval Research
- United States Navy