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Title: Explosive-induced shock damage in copper and recompression of the damaged region

Here, we have studied the dynamic spall process for copper samples in contact with detonating low-performance explosives. When a triangular shaped shock wave from detonation moves through a sample and reflects from the free surface, tension develops immediately, one or more damaged layers can form, and a spall scab can separate from the sample and move ahead of the remaining target material. For dynamic experiments, we used time-resolved velocimetry and x-ray radiography. Soft-recovered samples were analyzed using optical imaging and microscopy. Computer simulations were used to guide experiment design. We observe that for some target thicknesses the spall scab continues to run ahead of the rest of the sample, but for thinner samples, the detonation product gases accelerate the sample enough for it to impact the spall scab several microseconds or more after the initial damage formation. Our data also show signatures in the form of a late-time reshock in the time-resolved data, which support this computational prediction. A primary goal of this research was to study the wave interactions and damage processes for explosives-loaded copper and to look for evidence of this postulated recompression event. We found both experimentally and computationally that we could tailor the magnitude of themore » initial and recompression shocks by varying the explosive drive and the copper sample thickness; thin samples had a large recompression after spall, whereas thick samples did not recompress at all. Samples that did not recompress had spall scabs that completely separated from the sample, whereas samples with recompression remained intact. This suggests that the hypothesized recompression process closes voids in the damage layer or otherwise halts the spall formation process. This is a somewhat surprising and, in some ways controversial, result, and the one that warrants further research in the shock compression community.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [1] ;  [5] ;  [4] ;  [6] ; ORCiD logo [7]
  1. National Security Technologies, LLC, Santa Barbara, CA (United States)
  2. National Security Technologies, LLC, Los Alamos, NM (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. National Security Technologies, LLC, North Las Vegas, NV (United States)
  5. Univ. of California, San Diego, La Jolla, CA (United States)
  6. Washington State Univ., Pullman, WA (United States)
  7. National Security Technologies, LLC, Santa Barbara, CA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-16-22919
Journal ID: ISSN 0021-8979; TRN: US1701675
Grant/Contract Number:
AC52-06NA25396; AC52-06NA25946
Type:
Published Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 120; Journal Issue: 8; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Programs (DP) (NA-10)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1313245
Alternate Identifier(s):
OSTI ID: 1340966