The application and development of aramid materials in bulletproof helmets

Abstract

Bulletproof helmets are an indispensable and important piece of protective equipment in individual combat. Their protective performance mainly depends on the selection of materials and structural design. In recent years, aramid materials, as a type of high-performance fiber, have become the core material for bulletproof helmets due to their excellent strength, lightweight and energy absorption capabilities.

Our article summarizes the research on the materials and structural design of bulletproof helmets at home and abroad, and discusses the advantages of aramid materials in bulletproof helmets and their future development direction.

1. Introduction

As the military situation in the 21st century becomes more complex, warfare is gradually developing in the direction of high technology, informatization and localization. As the core force of modern warfare, individual combat has placed higher demands on protective equipment. As a barrier to protect the lives of soldiers, bullet-proof helmets can effectively resist bullets, fragments and other threats, reducing impact damage. According to statistics, in the Vietnam War, 12% to 14% of soldiers died from brain damage, while in the Iraq and Afghanistan wars, the prevalence of traumatic brain injury among US soldiers was as high as 19.5%. Therefore, the performance of bullet-proof helmets is directly related to the survivability and combat effectiveness of soldiers.

The development of modern bulletproof helmets has evolved from steel helmets to composite material shells. In the 1970s, the American company DuPont developed aramid fibers (Kevlar?), which pioneered the application of high-performance fiber materials in bulletproof helmets. China has also successively developed the QGF series of bulletproof helmets based on aramid, which significantly improves the protective performance and tactical adaptability of the helmet.

2. Design of ballistic helmet materials

2.1 Characteristics and applications of aramid materials

Para-aramid is a high-performance organic fiber synthesized from terephthaloyl chloride and p-phenylenediamine. It has the following excellent characteristics:

• High strength and high modulus: Para-aramid is five times stronger than steel, with a modulus of up to 124GPa, which can effectively absorb and disperse the impact energy of the projectile.
• Lightweight: Aramid fiber has a density of only 1.44 g/cm3, which significantly reduces the weight of the helmet and improves the soldier's mobility and comfort.
• Excellent energy absorption: When impacted, aramid fibers can quickly disperse stress, reduce backface deformation (BFD), and reduce non-penetrating injuries.
• Heat and corrosion resistance: Aramid is stable at high temperatures up to 300°C and has good resistance to chemical corrosion.

The Kevlar? series of aramid fibers developed by DuPont in the United States is widely used in bulletproof helmets, and Kevlar? K129 fiber-reinforced composites are used in the manufacture of advanced combat helmets (ACH). China has also achieved the industrialization of aramid fibers, and enterprises such as Yantai Taihe New Materials and China Bluestar Chengrand have launched domestically produced aramid products with stable performance.

2.2 Research on the modification of aramid materials

Despite its excellent properties, aramid is sensitive to ultraviolet light, and long-term exposure can lead to a decrease in mechanical properties. For this reason, researchers have modified aramid through nano-fillers to further enhance its protective properties. For example

• nano-carbon tube reinforcement: adding multi-walled carbon nanotubes (MWCNT) to aramid/epoxy resin composites, with an optimal filler content of 0.5%, can significantly improve impact resistance.
• Fabric structure optimization: By changing the interweaving geometry and fabric arrangement of aramid fibers, the energy absorption efficiency and protective performance can be further improved.

3. Structural design of ballistic helmets

In addition to material properties, the protective capability of ballistic helmets also depends on a reasonable structural design, including the shape of the shell, the lining system, and the fastening device.

3.1 Helmet design

The helmet shell is the main body of the ballistic helmet, and its shape and curvature design directly affect the ballistic performance and wearing comfort. The aramid composite helmet shell is usually designed in a hemispherical shape, which can effectively disperse the impact force and reduce the risk of penetration. At the same time, a reasonable curvature design helps to optimize the material performance and avoid the impact on the protective effect due to the reduction of structural integrity during the processing.

For example, the US PASGT helmet uses a laminate structure of 19 layers of aramid fibers to withstand fragment impacts at speeds of up to 663 m/s. Its improved version, the MICH helmet, has a beveled peak to reduce weight and increase ear room, making it easier for soldiers to use communication equipment.

3.2 Liner and shock absorption system

The liner system is an important part of the ballistic helmet that absorbs impact energy. The traditional mesh band structure is gradually being replaced by a foam-filled structure, which is made of polyethylene foam or polyurethane foam and can significantly reduce the impact force to protect the head.

Studies have shown that the peak intracranial pressure of a helmet with a foam liner can be reduced by more than 20% compared to a traditional mesh band structure. In addition, the new honeycomb energy-absorbing structure also exhibits good shock absorption performance and is expected to further improve the impact mitigation capability of the helmet.

3.3 Fastening device design

The fastening device is used to fix the helmet in place on the head, and its design needs to take both stability and comfort into account. At present, the four-point fastening method is widely used, but the traditional design requires holes to be drilled in the helmet shell, which may affect its structural integrity. For this reason, new helmets such as the IHPS use a locking mechanism on the inside of the helmet shell to reduce damage to the shell.

4. Development trends of ballistic helmets

With the complexity of the battlefield environment and the diversification of soldier needs, the future development of ballistic helmets will show the following trends:

1. Lightweight and high protection performance are equally important: By developing higher-performance aramid fibers and optimizing the fabric structure, the protection capability can be further improved while reducing weight.
2. Intelligent function integration: Integrate intelligent equipment such as night vision devices, communication equipment, and tactical cameras into the helmet to achieve integrated operations.
3. Multifunctional composite material applications: Explore the composite technology of aramid and materials such as ultra-high molecular weight polyethylene (UHMWPE) and ceramic fibers to develop more efficient ballistic composite materials.

5. Summary

The introduction of aramid materials has promoted the leapfrog development of ballistic helmet performance. Its high strength, lightweight and excellent energy absorption capabilities make it the core material of modern ballistic helmets. However, with the ever-changing battlefield needs, future ballistic helmets will need to further combine advanced materials and intelligent designs to meet the diverse needs of complex combat environments. Through continuous material research and structural optimization, ballistic helmets will surely play an even more important role in soldier protection.

Sinofibra specializes in providing high-performance materials for bulletproof helmets, including:

• aramid fibers
• aramid UD fabrics
• aramid woven fabrics

We are committed to providing customers with high-quality, reliable products to meet all types of protective material needs. Welcome to inquire or request a quote!