title: Uncovering high-strain rate protection mechanism in nacre.
abstract: Under high-strain-rate compression (strain rate approximately 10(3) s(-1)), nacre (mother-of-pearl) exhibits surprisingly high fracture strength vis-à-vis under quasi-static loading (strain rate 10(-3) s(-1)). Nevertheless, the underlying mechanism responsible for such sharply different behaviors in these two loading modes remains completely unknown. Here we report a new deformation mechanism, adopted by nacre, the best-ever natural armor material, to protect itself against predatory penetrating impacts. It involves the emission of partial dislocations and the onset of deformation twinning that operate in a well-concerted manner to contribute to the increased high-strain-rate fracture strength of nacre. Our findings unveil that Mother Nature delicately uses an ingenious strain-rate-dependent stiffening mechanism with a purpose to fight against foreign attacks. These findings should serve as critical design guidelines for developing engineered body armor materials.
authors.affiliation: Department of Mechanical Engineering, University of South Carolina, 300 Main Street, Columbia, South Carolina 29208, USA.
authors.forename: Zaiwang
authors.initials: Z
authors.lastname: Huang
authors.forename: Haoze
authors.initials: H
authors.lastname: Li
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Pan
authors.forename: Qiuming
authors.initials: Q
authors.lastname: Wei
authors.forename: Yuh J
authors.initials: YJ
authors.lastname: Chao
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Li