Title: Response and representation of ductile damage under varying shock loading conditions in tantalum

Abstract

The response of polycrystalline metals, which possess adequate mechanisms for plastic deformation under extreme loading conditions, is often accompanied by the formation of pores within the structure of the material. This large deformation process is broadly identified as progressive with nucleation, growth, coalescence, and failure the physical path taken over very short periods of time. These are well known to be complex processes strongly influenced by microstructure, loading path, and the loading profile, which remains a significant challenge to represent and predict numerically. In the current study, the influence of loading path on the damage evolution in high-purity tantalum is presented. Tantalum samples were shock loaded to three different peak shock stresses using both symmetric impact, and two different composite flyer plate configurations such that upon unloading the three samples displayed nearly identical “pull-back” signals as measured via rear-surface velocimetry. While the “pull-back” signals observed were found to be similar in magnitude, the sample loaded to the highest peak stress nucleated a connected field of ductile fracture which resulted in complete separation, while the two lower peak stresses resulted in incipient damage. The damage evolution in the “soft” recovered tantalum samples was quantified using optical metallography, electron-back-scatter diffraction, and tomography.more » These experiments are examined numerically through the use of a model for shock-induced porosity evolution during damage. The model is shown to describe the response of the tantalum reasonably well under strongly loaded conditions but less well in the nucleation dominated regime. As a result, numerical results are also presented as a function of computational mesh density and discussed in the context of improved representation of the influence of material structure upon macro-scale models of ductile damage.« less

Authors:

Bronkhorst, C. A. ^[1]; Gray, III, G. T.  ^[1];

• Search DOE PAGES for author "Gray, III, G. T."
• Search DOE PAGES for ORCID "0000-0002-4540-7061"

Addessio, F. L. ^[1]; Livescu, V. ^[1]; Bourne, N. K.  ^[2];

• Search DOE PAGES for author "Bourne, N. K."
• Search DOE PAGES for ORCID "0000-0002-8883-1196"

MacDonald, S. A. ^[2]; Withers, P. J. ^[2]

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+ Show Author Affiliations

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Univ. of Manchester, Manchester (United Kingdom)

Publication Date:

Thu Feb 25 00:00:00 EST 2016

Research Org.:

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

Sponsoring Org.:

USDOE

OSTI Identifier:

1239566

Report Number(s):

LA-UR-15-27463
Journal ID: ISSN 0021-8979; JAPIAU

Grant/Contract Number:  

AC52-06NA25396

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Applied Physics

Additional Journal Information:

Journal Volume: 119; Journal Issue: 8; Journal ID: ISSN 0021-8979

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 97 MATHEMATICS AND COMPUTING