Armor Technology

Blast | Ballistic | B2P

Armored vehicles require material capable of blast and ballistic protection that is also lightweight, strong, and environmentally rugged. One of the best ways to achieve weight reduction in an armor system is to combine the functions of a structural component while also protecting against ballistic fragments and mitigating blast damage. Microtruss™ periodic cellular materials offer this capability and allow improved protection without compromising vehicle weight.

Blast

Microtruss™ periodic cellular materials produced by CMI have the ability to absorb a larger amount of energy than solid material of equal mass. Therefore effective blast resistance can be provided by lighter weight designs. Additionally, our designs minimize backside deflection and, in turn, damage to vehicle and crew. Blasts generate pressure waves which exert an impulse force of short duration (milliseconds) on surrounding objects. During this process the structures that come in contact with the impulse force undergo severe plastic deformation at extremely high strain rates. The total energy absorbed by the structure taking the blast impulse determines the ability of the structure to sustain those blasts and protect the assets behind it. CMI's periodic cellular materials can achieve the combination of high strength and energy absorption necessary for effective performance under blast conditions.

The absorption mechanisms of a Microtruss™ sandwich panel under blast conditions is depicted in the above illustration. When a blast hits the face of the sandwich panel, the face plate will stretch and wrinkle followed by the propagation of the impulse force into the core. The core will then buckle and collapse, absorbing the maximum kinetic energy of the blast. Finally the back face plate takes the remaining blast pressure towards the end of the blast event where the intensity of the impulse force is considerably reduced. Thus, the periodic structure maximizes the absorption of the impulse energy created by the blast and distributes or diffuses the intensity of the force, leading to protection of the assets behind the sandwich structures. In a solid equivalent, the mechanism of impulse energy absorption is instantaneous and there is minimum dissipation of energy achieved. Therefore the blast impulse is more focused in smaller area of cross-section leading to early failure of the solid monolith. It is our strong belief that light weight Microtruss™ sandwich panels are ideal structures for energy mitigation from blast as well as ballistic impact.

CMI is also working with the automotive industry and utilizing CMI's cellular metal concepts for a variety of automobile components. CMI's Microtruss™ designs offer light weight and impact resistance capability which make them attractive products for the automotive industry.

Ballistic

Microtruss™ periodic cellular materials have exhibited excellent ballistic resistance when augmented by partially or fully filling the open-celled core with ballistic resistive materials. Initial research has been conducted on an integral armor concept. These concepts were tested against and able to withstand assault weapon rounds of specific threat levels. The face sheet/truss combination served to reduce the incoming kinetic energy of the projectile by plastic deformation. Upon contact with the ceramic, the projectile initiated a fracture cone which in turn eroded the projectile into smaller, slower fragments. This occurred due to a combination of the high hardness and fracture toughness. Individually, all of the components either diminished the incoming velocity or defeated the threat. Further, the synergy between the components allowed for a complete ballistic resistive material. For further details contact CMI.

B2P (Blast and Ballistic Protection)

Current research and testing on CMI's periodic cellular materials have shown promising results to mitigate blasts and prevent ballistic penetrations. Depicted in Figure 2 is an empty pyramidal truss lattice sandwich panel that has resisted a blast impulse

Figure 2. Side profile of a 304 SS empty pyramidal truss lattice after being subjected to an incident pressure wave.

Notice the minimal amount of deflection of the rear face sheet, as nearly all of the energy of the blast was dissipated by core member buckling, face sheet yielding and face sheet buckling. In the preliminary generations, the armor's ballistic resistance has shown equal promise. For details contact CMI.

This application of CMI's technology can also be extended to the aerospace industry as well as ground based structures such as "at risk building locations" including the gates and walls of secure entry points at sensitive locations. Virtually any need for ballistic and blast protection is likely a suitable candidate for CMI's technology.