Researchers at North Carolina State University have demonstrated a new composite metal foam (CMF) material that can stop armour-piercing .50-cal rounds from piercing armoured vehicles as effectively as steel, while having the advantage of weighing half as much.
The discovery will allow military vehicles designers to develop much lighter armoured vehicles to the same safety standard as those using conventional steel.
North Carolina State University professor of mechanical and aerospace engineering Afsaneh Rabiei, who invented the material, said: “The CMF armour was less than half the weight of the rolled homogeneous steel armour needed to achieve the same level of protection. In other words, we were able to achieve significant weight savings – which benefits vehicle performance and fuel efficiency – without sacrificing protection.”
CMF is a foam made of hollow metallic spheres, usually steel or titanium, embedded within a larger metallic matrix, which can be made from steel, titanium, aluminium, or a mix of other metallic alloys. In this instance, the research team used a steel-steel CMF.
To test the material, the researchers developed a full armour system comprising of a ceramic faceplate and a thin aluminum back plate, with the hard CMF sandwiched in between.The armour was then fired at using .50-cal ball and armour-piercing rounds at velocities of between 500 m/s per second and 885 m/s. The CMF layer absorbed 72%-75% of kinetic energy of the ball rounds and 68%-78% of the armour-piercing rounds’ kinetic energy.