Open Access

ARTICLE

Effect of the Strain Rate and Microstructure on Damage Growth in Aluminum

R. R. Valisetty¹, A.M. Dongare², A.M. Rajendran³, R. R. Namburu¹

1 Army Research Laboratory, Comp. & Info. Sciences Directorate, APG, MD 21005.
2 Department of Chem., Mat. & Biomol. Engg., Univer. Connecticut, Storrs, CT 06269.
3 Department of Mech. Engineering, University of Mississippi, University, MS 38677.
ramakrishna.r.valisetty.civ@mail.mil, dongare@uconn.edu

Computers, Materials & Continua 2013, 36(3), 231-255. https://doi.org/10.3970/cmc.2013.036.231

Abstract

Materials used in soldier protective structures, such as armor, vehicles and civil infrastructures, are being improved for performance in extreme dynamic environments. Nanocrystalline metals show significant promise in the design of these structures with superior strengths attributed to the dislocation-based and grain-boundary-based processes as compared to their polycrystalline counterparts. An optimization of these materials, however, requires a fundamental understanding of damage evolution at the atomic level. Accordingly, atomistic molecular dynamics simulations are performed using an embedded-atom method (EAM) potential on three nano-crystalline aluminum atom systems, one a Voronoi-based nano-crystalline system with an average grain size of 10 nm, and the other two single crystals. These simulations are performed under the condition of uniaxial expansion at several strain rates ranging from 10⁶s^-1 to 10¹⁰s^-1. Results for the effective stress are discussed with the aim of establishing the role of the strain rate and microstructure on the evolution of the plastic strain and void volume fraction and the eventual loss of stress carrying capability of the atom systems.

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