Trauma plate


A trauma plate, also known as a ballistic plate or ballistic panel, is a protective plate that is an add-on component or insert to a ballistic vest. Its primary purpose is to absorb the ballistic impact of projectiles received and reduce ballistic trauma and blunt trauma transferred to the wearer of the vest. As such, trauma plates supplement the ballistic protection of the section of the vest that they are positioned in.

Trauma plates are most commonly found in the front, rear, and side pockets of a ballistic vest or plate carrier and positioned around the chest, back, and sides of the abdomen respectively. Vests like Dragon Skin do not contain traditional trauma plates, and may use a different form of protection like miniature trauma plates akin to scale armor.

Shapes and sizes

Trauma plates can be found in a variety of sizes and shapes. The most common shapes are rectangle, rounded rectangle, and irregular hexagon, as well as cuts widely known as SAPI, which bear visual similarities to the SAPI plate.
In concealed vests, the trauma plates are most commonly 5″ × 8″, with variants including 5″ × 7″, 5″ × 9″, 6″ × 8″, and 6″ × 9″. Thickness varies based on material and application but rarely exceed 1/4″.
In tactical vests, worn as outerwear, the trauma plates are most commonly 10″ × 12″ with some variation depending on the vest. Thickness varies, depending on material and application, but rarely approaches 1/2". For larger plates intended to cover the torso, cuts can reach 15x16".
In specialized/military-grade vests, a considerable portion of the vest is made up of rigid, trauma-plate like inserts. Since they are an essential part of the vest, they are NOT typically considered the same as trauma plates or pads and are typically referred to as inserts, much like the aramid ballistic inserts found in concealed, duty, and tactical vests. SAPI vests are an example of this type of vest. In most SAPI based vests/carriers, the outer vest is made out of and lined with aramid material made to carry multiple ballistic inserts, typically made out of ceramics. These inserts are shaped to fit the carrier and have sizes that vary depending on the size and shape of the vest.

Materials

Most trauma plates or pads are made of a combination of materials. The following categories denote the primary material used in different plate packages.

Ceramic

plates or ceramic armor, typically composed of boron carbide or similar material, are common place in military applications. The advantages of ceramic armor is that they are not only lighter than metals, but much harder as well, which enables them to deform most penetrators.
Ceramic material defeats projectiles by shattering it into pieces, decreasing the penetration ability of projectile. Compared to steel or titanium, ceramic plates have inferior multi-hit resistance due to its somewhat brittle nature, although there are workarounds. As such, they are vulnerable to projectiles which hit in a tight grouping, as these create a stress concentration on the plate and shatter the section of plate targeted.

Metal

Most metal trauma plates are made primarily of steel or titanium, although aluminum and various alloys also exist. Metal trauma plates can be used for reducing blunt trauma due to the conductive traits of the material. Unfortunately, due to its lack of deformation, shock is still transmitted through the plate, more so than ceramic.
Given the nature of the material used, there is a risk for ricochet and spall. To address this, metal plates are oftentimes encased in anti-spall lining designed to trap projectile fragments and spalling. Additionally, plate carriers and bullet resistant vests assist in trapping these fragments.
Munitions above 3100 fps have been known to penetrate NIJ Level III steel armors, most notably the 5.56 M193 round.

Fabric

Often called soft trauma plates, these are flexible plates that typically do little to reduce trauma. They are typically composed of layers of aramid fabrics, similar to, if not the same as the material found in the vest. They may also include thin sheets of metal or ultra high molecular weight polyethylene to add stiffness and some trauma protection.

Plastic

Multi-layered sheets/plates of ultra high molecular weight polyethylene can provide an added ballistic enhancement equal to or even greater than metal plates with less weight. With these, there is the cost of less trauma reduction and the improbable but possible risk of fracture. The layered sheets that exist in each plate, are sometimes separated by high density foam, which provides some compression to aid in dissipating the kinetic energy of an impact. Though this is more often found in cheap polycarbonate plates that provide some trauma reduction, but no ballistic value.
Polymer
Several companies have created viscoelastic polymer compounds capable of a very high degree of energy/force dissipation as a result of shock, vibration, or g-force side loading. The material, and padding made from it, derives its superior energy adsorbing behavior from the unique physical properties of the viscoelastic compound.  The bulk of the compound is composed of a high molecular weight, highly viscous, highly elastic polymer fluid.  The fluid is then compounded with rheological modifiers and other fillers to control the physical and rheological properties of the finished padding compound.  Zoombang is one example of a polymer compound trauma pad.

Nanomaterials

As a potential material for future trauma plates and anti-ballistic fabrics, carbon nanotube and nanocomposite materials offer strength to weight ratios that are potentially superior to other materials. For further information on these materials as applied to ballistics, please visit the section on ballistic vest nanomaterials in ballistics. There are plates made of nanomaterials currently available in commercial products.

Special threat plates

Special threat plates, also known as multi-threat, special purpose, rifle, and special application plates, are plates that have a notably higher ballistic rating than the vest. There is no standard for materials or ballistics for these plates, though most meet the NIJ Standard for armor type III. Some plates are made of a combination of materials, like ceramic on plastic, plastic on metal, etc.
Some manufacturers may use these labels as marketing rather than enhanced protection.
Common special threats are NIJ Level III+, NIJ Level IIIA+/NIJ Level IIIB. NIJ Level III+ is especially noted for its use by steel body armor manufacturers Level III+ usually in this context indicates resistance/protection against high velocity threats of 3,100 feet per second or higher, as steel armor is notoriously vulnerable to faster threats. NIJ Level IIIA+ indicates a defensive capacity exceeding Level IIIA.
Much lesser known threat defenses like NIJ Level IV A, the A indicating Aramid in the NIJ system, were made against threats such as the THV munition.