Cracking the Code of Armor

ASEE Prism, Feb 2006 by Grose, Thomas K

SECURITY

IN THE SHELL of the abalone-a marine gastropod-nature has devised one of the best armors. The outside layer is very hard and can withstand strong impacts. The beautiful inside layer-which scientists call nacre, and jewelry aficionados call mother-ofpearl-can absorb energy if the outside layer does break. It's a material that's still little understood. However, two civil engineers at North Dakota State University, Kalpana Katti and Dinesh Katti, are using complex computer modeling and state-of-the-art measuring equipment (including an atomic force microscope and a spectrometer), and they've begun to crack the mysteries of the abalone shell. The Department of Defense sees nacre as a potential armor covering for aircraft. By studying nacre after it had been fractured, the Kattis discovered one key reason for its toughness: it is composed of interlocking platelets that resemble hexagonal bricks and mortar: a simple, yet effective design. The abalone is one of the most primitive of mollusks, but its shell may someday yield secrets for creating high-tech armor and protective coatings. -TG