Armoring light combat vehicles has always been a compromise, as the weight allowed for the armor could never provide adequate protection against all threats. The massive U.S. mine-resistant ambush-protected (MRAP) vehicle program was only an episode in the evolution of armored mobility. Future combat vehicles need to maintain a good balance between mobility, protection, size and weight—and all that at an affordable cost.

Armed forces have learned a lot in the past 20 years. Operational tempos have been high, and the types of conflict varied: some involving high-intensity warfare, others hybrid engagements employing anything from makeshift improvised roadside explosives (IEDs) and advanced anti-armor missiles, to massive suicidal attacks delivering truckloads of standard explosives. Through an evolutionary process, combat vehicles have adopted measures protecting their occupants from these threats.

But protection is not merely the armor plating, keeping one away from the hail of shrapnel and debris. It includes pre-empting attacks from rocket propelled grenades (RPGs), by disrupting their ability to deliver their lethal injection of plasma jet to penetrate the outer armor. Protection also addresses the tremendous blast propagated by the explosion. The shockwave transferred through the vehicle's structure has devastating effect on passengers' skeletons, smashing the soft brain tissue against the skull, causing severe internal injury and often death.

The new breed of armored vehicles reflects a balanced protection approach, providing shielding sufficient to defeat small arms and IEDs as part of the basic armor. Their structures are fitted with attachments designed to mount additional protection modules, known as B-kits, to meet higher threat levels, and applique, or C-kits, designed to address specific threats such as RPGs and explosively formed projectiles.

Structural elements made of armor-grade materials are often used in modern vehicles, underpinning the vehicle's frame. Traditionally, vehicle armor has been manufactured of high-hardness steel (HHS), which has recently improved with the introduction of the ATI-500-MIL standard. While offering a reasonable protection level and multi-hit resilience, HHS is also the heaviest solution and an all-steel solution is impractical for light vehicles.

Researchers are seeking alternative materials for ballistic protection that will match the ballistic properties of steel with considerably lower weight. Lower-density ceramic materials were the first step that enabled designers to achieve lighter protection. The latest composites—particularly, recently introduced nano-composites—offer new opportunities to increase ballistic protection while reducing weight, meeting design goals at affordable cost.

According to German armor manufacturer IBD Deisenroth Engineering, adding nano-ceramic backplates to an add-on armor module reduces the module's weight by 47%. According to IBD, a nano-composite ballistic protection module meeting Standard Agreement (Stanag) 34569 Level 3 threat would weigh only 32 kg (70 lb.), compared to 160 kg for a steel module with the same performance level. The company designed a complete nano-material-based protection suite for the MPV 4X4 vehicle from Iveco, reflecting an optimization process balancing protection level, weight and costs. The MPV system comprises nano-ceramic doors, nano-steel side armor and nano-composite curved counter-IED elements fabricated from advanced “flexible nano-composites.”

Holland-based Dyneema recently introduced HB, a new formulation of its high-strength fiber material. The company claims the composite structures fabricated of this material are 40% lighter than aramid (Kevlar), one of the lighter ballistic protection compounds. The result is thinner, lighter plates allowing for more flexibility in armor configurations and construction. The company also offers HB2, which can be pressed into complex shapes, and combined with steel or ceramics as a backing material.

TekShield, developed by Lockheed Martin Missiles and Fire Control, is a hybrid array, using wedge-like ceramic elements combined into a plate offering increased ballistic protection properties, compared to ceramic slabs of the same weight. The hybrid structure combines the toughness of ceramics, with the impact-absorbing properties of composites. It has been tested against a variety of threats, ranging from hand grenades to bomb blasts.

A different approach is HybridTech —Metal Matrix Composite (MMC) armor. According to the developer, CPS Technologies, this aluminum-encapsulated matrix offers lightweight, multi-hit capability, and cost-competitive alternatives to conventional steel, aluminum and ceramic-based armor systems. Under the development program, supported by the U.S. Army Research Lab (ARL), CPS has already delivered HybridTech Armor modules for ballistic testing.

Other promising technologies are carbon nanotubes (CNT), which have demonstrated excellent mechanical, electrical and magnetic properties. Fibers produced of CNT can be woven like cloth into composite layers to deliver structures several times stronger, tougher and stiffer than those currently in use, experimenting against ballistic impact.

Reducing the weight of transparent armor is a major challenge. Traditional transparent armors are made of layers of laminate composed of transparent materials such as silicon carbide (SiC), boron carbide (B4C), or alumina. These traditional armors are expensive to repair, as the entire armor surface must be replaced. To reduce costs, researchers at the U.S. Lawrence Livermore National Laboratory (LLNL) have developed Mosaic Transparent Armor (MTA). This material comprises small transparent tiles, made from traditional transparent armor materials and held together by an adhesive with the same refractive index as the tiles. This mosaic composition is likely to restrict the damage from a ballistic impact to a portion of the armor surface. Therefore, only the damaged tiles will be replaced. MTA also has lower specific weight and is easier to fabricate than conventional transparent armor. A prototype MTA window is under development at LLNL, which has patented the invention.

Exotic new materials and innovative processing methods currently developed in labs are likely to deliver armor materials with even higher performance, as well as being lighter and more affordable. To reach such high levels the U.S. Defense Advanced Research Programs Agency (Darpa) Extended Solids program is seeking to develop manufacturing processes that enable stabilization and production of high-pressure phase materials, without the limitations of scale introduced by current high-pressure processes, that exhibit properties far superior to those currently available for Pentagon applications.

Darpa has also developed lightweight materials that can absorb energy without failing, or breaking. A recent test demonstrated a nickel microtruss structure that achieved a 40% strain level without collapsing; in fact it fully recovers its form after the pressure dissipates. Such materials would make an important contribution in energy absorption.

But until revolutionary future materials are ready, troops must be protected today, and the type of protection most needed is an efficient countermeasure against simple, but highly lethal, advanced RPGs. Light armored vehicles are particularly vulnerable to these weapons. While simple bar armor provides reasonable statistical protection, the added weight is usually beyond the permissible weight for light vehicles.

Lightweight and efficient, the Q-Net design patented by Qinetiq consists of a net with embedded metal nodes supported on a lightweight frame that envelops the outside of the vehicle. The system defeats RPG threats by preventing detonation, with the nodes disrupting the fusing of the warhead. It can provide multi-hit capability protection from all angles, including overhead if specified. Q-Net has been deployed in large numbers protecting U.S. and coalition MRAPs and other vehicles against RPG threats. Last month Qinetiq introduced an upgraded, lighter version offering higher probability of defeat of RPGs. The system is now on operational service with the U.S., French and Polish forces in Afghanistan.

A different method of RPG protection recently introduced by Israel's Plasan is FlexFence. Applied as a “soft skin” applique, FlexFence increases the probability of defeat of RPGs to greater than 80%. Plasan claims that FlexFence defeats RPGs with higher probability than any other statistical armor. The new version has recently undergone live firing tests where it repeatedly demonstrated multi-hit capability (stopping several RPGs aimed at the same module). FlexFence is applied over the existing armor, without changing the vehicle's width or silhouette, maintaining the vehicle's ballistic protection. An advantage over slat or net armor is that it is less likely to be fouled by tree branches or debris.

An active protection system (APS), although more expensive, would provide the ultimate countermeasure against all types of shaped charge threats, including the most advanced tandem-warhead weapons, claims Rafael, the developer of the Trophy, the first (and only) operational APS. Rafael has recently come up with a Trophy variant optimized for light armored vehicles. The system is currently undergoing field testing in a variety of operational scenarios. Unlike the original Trophy, which fires multi-EFPs at the incoming threat, Trophy LV fires the countermeasure down at the RPG at very close range, smashing its warhead without initiating the lethal plasma jet. The system provides 360-deg. protection to the vehicle, including windows and doors, while minimizing the risk of collateral damage.

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