Test & Measurement

Lightweight, Composite Metal Foam Stops Bullet

Vehicle designers may soon be able to develop lighter military vehicles without sacrificing safety, thanks to research from North Carolina State University. The researchers demonstrated that vehicle armor using composite metal foam (CMF) can stop armor-piercing, .50 caliber rounds – even though it weighs less than half as much. CMF is a foam that consists of hollow, metallic spheres embedded in a matrix of metallic alloys. In the NC State study, the researchers used steel-steel CMF; both the spheres and the matrix were made of steel. For the study, the researchers manufactured a hard armor system consisting of a ceramic faceplate, a CMF core, and a thin back plate made of aluminum. The armor was tested using .50 caliber ball and armor-piercing rounds, and was able to absorb 72-75% of the kinetic energy of the ball rounds and 68-78% of the kinetic energy of the armor-piercing rounds.