Analysis of internal stress and anelasticity in the shock-compressed state from unloading wave data

Journal Article · Sat Nov 30 23:00:00 EST 1991 · Acta Metallurgica; (United States)

DOI:https://doi.org/10.1016/0956-7151(91)90034-X· OSTI ID:6918337

Johnson, J N; Lomdahl, P S; Wills, J M ^[1]

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1. Los Alamos National Lab., NM (United States)

This paper reports on time resolved shock-wave measurements have often been used to infer microstructural behavior in crystalline solids. The authors apply this approach to an interpretation of the release-wave response of an aluminum alloy (6061-T6) as it is dynamically unloaded from a shock-compressed state of 20.7 GPa. The anelastic behavior in the initial portion of the unloading wave is attributed to the accumulation of internal stresses created by the shock process. Specific internal-stress models which are investigated are the double pile-up, the single pile-up, and single dislocation loops between pinning points. It is found that the essential characteristics of double and single pile-ups can be represented by a single dislocation between two pinned dislocations of like sing. Calculations of anelastic wave speeds at constant unloading strain rate are then compared with experimental data. The results suggest that the residual internal stress is due to pinned loops of density 10[sup 15]M[sup [minus] 2], and the viscous drag coefficient in the shock-compressed state is on the order of 10[sup [minus] 7] MPa s (approximately two orders of magnitude greater than expected under ambient conditions).

• OSTI ID: 6918337
• Journal Information: Acta Metallurgica; (United States), Journal Name: Acta Metallurgica; (United States) Vol. 39:12; ISSN 0001-6160; ISSN AMETAR
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
664100 -- Theory of Electronic Structure of Atoms & Molecules-- (1992-)
664400 -- Experimentally Derived Information on Atomic & Molecular Properties-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ALLOYS
ALUMINIUM ALLOYS
CALCULATION METHODS
CRYSTAL STRUCTURE
DATA
DISLOCATION PINNING
DRAG
EXPERIMENTAL DATA
FRICTION
INFORMATION
INTERACTIONS
INTERNAL FRICTION
MICROSTRUCTURE
NUMERICAL DATA
SHOCK WAVES
SOLIDS
STRESS ANALYSIS