Abstract
Microscopic defects such as voids and cracks in an energetic material significantly influence its shock sensitivity. So far, there is a lack of systematic and quantitative study of the effects of cracks both experimentally and computationally, although significant work has been done on voids. We present an approach for quantifying the effects of intragranular and interfacial cracks in polymer-bonded explosives (PBXs) via mesoscale simulations that explicitly account for such defects. Using this approach, the ignition thresholds corresponding to any given level of ignition probability and, conversely, the ignition probability corresponding to any loading condition (i.e., ignition probability maps) are predicted for PBX 9404 containing different levels of initial grain cracking or interfacial debonding. James relations are utilized to express the predicted thresholds and ignition probabilities. It is found that defects lower the ignition thresholds and cause the material to be more sensitive. This effect of defects on shock sensitivity diminishes as the shock load intensity increases. Furthermore, the sensitivity differences are rooted in energy dissipation and the consequent hotspot development. The spatial preference in hotspot distribution is studied and quantified using a parameter called the defect preference ratio (r p r e f). Analyses reveal that defects play an important role in the development of hotspots and thus have a strong influence on the ignition thresholds. The findings are in qualitative agreement with reported trends in experiments.
Original language | English |
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Article number | 165110 |
Journal | Journal of Applied Physics |
Volume | 124 |
Issue number | 16 |
DOIs | |
State | Published - Oct 28 2018 |
Funding
Air Force Office of Scientific Research (Dr. Martin Schmidt) under Grant No. FA9550-15-1-0499 and the Defense Threat Reduction Agency (DTRA) (Dr. Douglas Allen Dalton) under Grant No. HDTRA1-18-1- 0004 is gratefully acknowledged. Part of the calculations were performed using supercomputers at the ERDC and AFRL DSRCs of the U.S. DoD High Performance Computing Modernization Program. Funding from the Air Force Office of Scientific Research (Dr. Martin Schmidt) under Grant No. FA9550-15-1-0499 and the Defense Threat Reduction Agency (DTRA) (Dr. Douglas Allen Dalton) under Grant No. HDTRA1-18-1-0004 is gratefully acknowledged. Part of the calculations were performed using supercomputers at the ERDC and AFRL DSRCs of the U.S. DoD High Performance Computing Modernization Program.
Funders | Funder number |
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Defense Threat Reduction Agency | HDTRA1-18-1-0004 |
Air Force Office of Scientific Research | FA9550-15-1-0499 |
Defense Threat Reduction Agency |