Kevlar KM2

Kevlar KM2 is a synthetic para-aramid fiber produced by DuPont. The fiber is an evolution of the original Kevlar fiber, that first became available between 1992-1998.^[1] The following quotes summarize Kevlar KM2's properties.

"DuPont created Kevlar KM2 to achieve the performance goals defined by casualty reduction testing for the United States Department of Defense. Today it is used extensively for fragmentation protection in the U.S. military. Helmets and vests made with Kevlar KM2 provide enhanced bullet and fragmentation resistance while remaining comfortable and breathable in the most inhospitable climates.

Excellent thermal stability at temperature extremes, water repellency, chemical stability and resistance to petroleum products have made Kevlar KM2 an indispensable asset to the military personnel who use it every day."^[2]

"Kevlar KM2 fiber is a transversely isotropic material. Its tensile stress–strain response in the axial direction is linear and elastic until failure. However, the overall deformation in the transverse directions is nonlinear and nonelastic, although it can be treated linearly and elastically in infinitesimal strain range. For a linear, elastic, and transversely isotropic material, five material constants are needed to describe its stress–strain response."^[3]

After 2007, the clear and present information on KM2 from the DuPont website, was removed. The weight, denier, weave, and thickness: was all detailed there.^[4] The website also had a PDF detailing tests that proved that KM2 was "drier", "cooler", and "more flexible" than the Kevlar used in "PASGT" (Kevlar 29).^[5]

Kevlar KM2 is described as being for "Bullets/Fragments" and is marketed towards military use, while Kevlar Protera is for "Bullets / Blunt Trauma" and law enforcement use.^[6] This indicates that KM2 is about as advanced as Protera, but has different mechanical properties.

Dupont reports that testing shows that KM2 can provide the same protection as earlier systems for 35% less weight.^[6]

Applications / Usage

According to Dupont, the Ranger Vest first produced in 1992 used KM2 fiber.^[7] The Interceptor Vest, also used KM2.^[8]

In a V50 test using a "0.22 caliber, Type 2, 17-grain fragment-simulating projectile; MIL-STD-662E", the PASGT Vest has a rating of 1650 feet per second, but the Ranger Vest has a rating of 2100 feet per second. This is extremely close to the "25%' improvement reported on the Dupont website.^[7]