Simulation of Energy Absorbing Materials in Blast Loaded Structures

Energy absorbing materials such as foam or honeycomb are of interest in blast protection because of their ability to absorb energy through plastic deformation. After reaching their yield stress, these materials exhibit a region of constant stress for increasing strain until the material is completely compacted. The energy needed to crush the material is proportional to the area under the stress-strain curve. Because foams and honeycombs have this “plateau” region, they absorb a considerable amount of energy relative to their low density. These materials are investigated to determine if their energy absorbing abilities can be used to mitigate the load and shock transferred to a vehicle structure subject to blast loading. Ballistic pendulum experiments show that energy absorbing materials increase the imparted impulse from a blast. This behavior was contrary to expected results so computational models were created in LS-DYNA to understand the phenomenon that causes an increase in imparted impulse. ConWep and Arbitrary-Lagrangian- Eulerian (ALE) techniques were used in simulations to demonstrate their efficiency and accuracy. An additional ConWep aluminum foam model was created to directly compare simulations against ballistic pendulum experiments found in the literature.