Aluminum foam integral armor: a new dimension in armor design

Closed-cell aluminum foam offers a unique combination of properties such as low density, high stiffness, strength and energy absorption that can be ta ilored through design of the microstructure. During ballistic impact, the f oam exhibits significant nonlinear deformation and stress wave attenuation. Composite structural armor panels containing closed-cell aluminum foam are impacted with 20-mm fragment-simulating projectiles (FSP). One-dimensional plane strain finite element analysis (FEA) of stress wave propagation is p erformed to understand the dynamic response and deformation mechanisms. The FEA results correlate well with the experimental observation that aluminum foam can delay and attenuate stress waves. It is identified that the alumi num foam transmits an insignificant amount of stress pulse before complete densification. The ballistic performance of aluminum foam-based composite i ntegral armor (CIA) is compared with the baseline integral armor of equival ent areal-density by impacting panels with 20-mm FSP. A comparative damage study reveals that the aluminum foam armor has finer ceramic fracture and l ess volumetric delamination of the composite backing plate as compared to t he baseline. The aluminum foam armors also showed less dynamic deflection o f the backing plate than the baseline. These attributes of the aluminum foa m in integral armor system add a new dimension in the design of lightweight armor for the future armored vehicles. (C) 2001 Elsevier Science Ltd. All rights reserved.