What Composite Materials Are Used in Body Armor?

Category: TECHNICAL TEXTILES

Country: United States

By Taha Khan
12th February, 2024.

Body armor is protective clothing that can absorb or deflect weapons and projectiles to protect the wearer from any injury. This article discusses composite materials used in body armor, their structural makeup, properties, and recent relevant studies.

A Brief Background to Body Armor
Throughout human history, many conflicts have resulted in battles and wars. Body armor has been of central importance in order to make combatants as safe as possible against a variety of weapons. Historically, many different kinds of body armor are found in different cultures and societies, each with unique advantages and drawbacks. For instance, full metal body armor was very effective in terms of blocking any sword or arrow attack, but at the cost of mobility as compared to full leather body armor that allowed mobility and protection against minor cuts but made the wearer vulnerable to heavy blows.

With advancements in technologies used in warfare, as weapons have evolved, so has body armor, making old technologies almost obsolete. The weapons used in modern warfare are deadlier and more varied than those used by their predecessors and require even more advanced protection against them.

Modern Body Armor
Modern body armors are usually made by focusing on properties like strength-to-weight ratio, resistance against impact, and durability. Conventional materials like steel alone fail to provide all the properties necessary for modern body armor. Therefore, modern armors use composite materials that are engineered by combining two or more materials with distinct properties, creating superior performance characteristics. The structural makeup of these composites plays a crucial role in determining their effectiveness in protecting the wearer.

Soft Body Armor Composites
Generally, for soft armor applications, Ultra-High Molecular Weight Polyethylene (UHMWPE) such as Dyneema and Spectra or aramid fibers like Kevlar and Twaron are used. These fibers are woven together and embedded in a resin matrix to form a composite structure offering great durability, lightweightness, and flexibility due to their high tensile strength, which makes them effective in absorbing and dispersing impact energy. The structural makeup of these composites consists of multiple layers of woven or laminated sheets oriented in different directions, creating a crisscross pattern that enhances the material's overall strength, whereas the resin matrix binds the fibers together, providing additional structural stability.

Hard Body Armor Composites
Ceramic matrix composites consist of ceramic tiles embedded in a polymer or aramid fiber matrix and are usually used in hard armor plates. These ceramic tiles are usually made of alumina or silicon carbide,  arranged in a mosaic-like pattern, which enhances the material's ability to absorb and disperse impact energy, preventing penetration by projectiles, whereas the surrounding matrix holds the ceramic tiles in place, providing additional strength.

Similarly, in recent years, hybrid composites like a combination of aramid fibers and UHMWPE in a single composite structure have been introduced in body armor applications. The structural makeup of hybrid composites is carefully engineered to optimize the benefits of each component by incorporating them into specific regions of the body armor based on the expected threats.

Recent Developments

KFRP Composite Impact Enhancement
In a 2018 study, researchers focused on enhancing the impact response of Kevlar Fiber Reinforced Polymer (KFRP) composites for body armor applications. The study investigated the effect of different matrix combinations, specifically the addition of rubber, on ballistic impact behavior. Composite samples were prepared with epoxy and varying percentages of rubber, then tested against 9mm Full Metal Jacketed (FMJ) bullets.

The results revealed a positive impact of adding rubber, showing improved energy absorption, reduced back face signature (blunt trauma), and enhanced ballistic resistance. Among the samples, the composition with 12.5% rubber demonstrated optimal results, providing better impact resistance with lower blunt trauma. The study emphasizes the importance of composite design in mitigating internal injuries caused by ballistic impacts, showcasing potential advancements in body armor technology.

Natural Fiber Composite for Ballistic Armor
In a 2020 study, researchers explored using natural-fiber-reinforced polymer composites as an alternative material for ballistic armor. The study compared the ballistic performance of a commonly used UHMWPE composite, Dyneema, with an epoxy composite reinforced with 30 vol % natural fibers extracted from pineapple leaves (PALF). The objective was to enhance the protection of level IIIA ballistic armor vests by introducing the PALF composite plate, effectively upgrading the armor to level III.

The results showed that the PALF/epoxy composite, when combined with a ceramic front layer, met the National Institute of Justice's (NIJ) international standard for level III protection. This composite exhibited comparable ballistic performance to Dyneema, with weight reduction and cost advantages, making it a promising alternative for body armor applications.

Conclusion
In conclusion, body armors are very important in the modern defence industry, providing significant protection to the wearers against bullets and other dangerous projectiles and creating a real impact by saving lives and reducing casualties, especially in battlegrounds. New materials, such as the enhanced KFRP composites with rubber additives and the PALF/epoxy alternative to Dyneema, highlight the crucial role of composite design in mitigating injuries and providing durability, lightweight, flexibility, and impact resistance, which are essential for modern body armor.

References and Further Reading
Benzait, Z., & Trabzon, L. (2018). A review of recent research on materials used in polymer–matrix composites for body armor application.
Journal of Composite Materials.

Ebuka Precious Anaso (2020) The Evolution of Body Armor. Body armor spanning from Ancient to Modern times.

Liu, W., Chen, Z., Cheng, X., Wang, Y., Amankwa, A. R., & Xu, J. (2016). Design and ballistic penetration of the ceramic composite armor.
Composites Part B: Engineering.

Luz, F. S. D., Garcia Filho, F. D. C., Oliveira, M. S., Nascimento, L. F. C., & Monteiro, S. N. (2020). 
Composites with natural fibers and conventional materials applied in a hard armor: A comparison. Polymers.

Okhawilai, M., Parnklang, T., Mora, P., Hiziroglu, S., & Rimdusit, S. (2019). The energy absorption enhancement in aramid fiber-reinforced poly (benzoxazine-co-urethane) composite armors under ballistic impacts.
Journal of Reinforced Plastics and Composites.

Pasha, R. A., Khan, H. H., Nasir, M. A., Anjum, N. A., & Sardar, H. W. (2018). Effect of Rubber particles on Kevlar Fiber Reinforced Polymer composite against High Velocity Impact
Technical Journal of University of Engineering & Technology Taxila.

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