Search

Your search keyword '"Eakins, Daniel E."' showing total 2 results
Start Over Author "Eakins, Daniel E." Topic aluminum
2 results on '"Eakins, Daniel E."'

1. MECHANISTIC ASPECTS OF SHOCK-INDUCED REACTIONS IN NI+AL POWDER MIXTURES.

Author

Eakins, Daniel E. and Thadhani, Naresh. N.

Subjects
*MECHANICAL shock, *HIGH pressure (Science), *CONDENSED matter, *SHOCK waves, *CONTINUUM mechanics
Abstract

A combination of parallel-plate impact experiments utilizing stress measurements and mesoscale numerical simulations are used to investigate the effect of particle morphology on the mechanical and chemical response of Ni+Al powder mixtures. The instrumented gas-gun impact experiments were performed at pressures up to 6 GPa. Based on measured shock velocity increases and shock compressibility changes consistent with the Ballotechnic model, the flake-based powder mixture was found to exhibit shock-induced reaction. The particle-level mechanistic details of deformation, mass-flow, and mixing, were explored through discrete particle continuum simulations, validated against the experimental results. The micron-scale spherical and flake mixtures were found to display widely varying configurational changes at several length scales, which give insight into why the flake-Ni morphology is more susceptible to shock-induced reactions under the imposed conditions. [ABSTRACT FROM AUTHOR]

Published
2007
Full Text
View/download PDF

2. Attenuation of the Dynamic Yield Point of Shocked Aluminum Using Elastodynamic Simulations of Dislocation Dynamics.

Author

Gurratxaga-Lerma, Beñat, Balint, Daniel S., Dini, Daniele, Eakins, Daniel E., and Sutton, Adrian P.

Subjects
*YIELD strength (Engineering), *ALUMINUM, *SHOCK waves, *ELASTODYNAMICS, *DISLOCATIONS in metals, *LASER peening
Abstract

When a metal is subjected to extremely rapid compression, a shock wave is launched that generates dislocations as it propagates. The shock wave evolves into a characteristic two-wave structure, with an elastic wave preceding a plastic front. It has been known for more than six decades that the amplitude of the elastic wave decays the farther it travels into the metal: this is known as "the decay of the elastic precursor." The amplitude of the elastic precursor is a dynamic yield point because it marks the transition from elastic to plastic behavior. In this Letter we provide a full explanation of this attenuation using the first method of dislocation dynamics to treat the time dependence of the elastic fields of dislocations explicitly. We show that the decay of the elastic precursor is a result of the interference of the elastic shock wave with elastic waves emanating from dislocations nucleated in the shock front. Our simulations reproduce quantitatively recent experiments on the decay of the elastic precursor in aluminum and its dependence on strain rate. [ABSTRACT FROM AUTHOR]

Published
2015
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results