Balistic Testing of the Kevlar.
A team of undergrads from the University of Maryland’s Department of Material Science and Engineering have improved the material design of Kevlar body armor. This improvement won the team the 2014 ASM International Undergraduate Design Competition.
By using carbon nanotubes, the improved material appears to have twice the resistance to ballistics as the benchmark product. This improvement allows for a decrease in armor thickness while increasing the overall strength of the new design.
Though Kevlar armor is often referred to as “soft body armor,” it will often reduce its flexibility due to the number of layers needed to protect the wearer. The goal of the Maryland team was to produce a lighter body armour and increase maneuverability without compromising the wearer’s safety.
Steven Lacey, Calisa Hymas, Kathleen Rohrbach, Samm Gillard, and Chris Berkey (Left to Right)
To achieve this goal Steven Lacey, Calisa Hymas, Kathleen Rohrbach, Samm Gillard and Chris Berkey aimed to improve the tensile strength of the Kevlar. This would allow for the number of layers to be reduced proportionally to the strength. As the resulting Kevlar is twice as resistant as the benchmark, the number of layers can be reduced from 30 to 15 layers.
To produce this result, the team modified Ballistic grade Kevlar 29 using a weave of carbon nanotubes (CNTs). The fabric was also treated using chemical processes for etching, soaking and curing. CNTs can be up to 100 times stronger than steel at just a sixth of the weight. This is remarkable considering that CNTs are only one thousandth the width of human hair. The undergraduate team predicted that CNTs might be the answer to reach their goals to improve Kevlar.
A vest prototype was produced and passed onto a US Army Research Lab for ballistic testing. The Lab fired small rounds into the sample as set out by the National Institute of Justice’s standards. The testing was able to detect the number of layers penetrated and the back-face deformation.
The results showed that the modified 15-layer Kevlar vest was able to stop the bullets on the second or third layer with a deformation of 14.23-20.2mm. This represents a ballistic resistance double the size of the benchmark and a tensile strength increase of 400 percent.
The students have been awarded $2000 and a travel grant to attend ASM’s Materials Science & Technology conference. At the conference they will receive an award for their efforts. However, we all know the true reward will be the lives this University of Maryland team will save.
Source University of Maryland.