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Title: Fracture Effects on Explosive Response (FEER); FY2018 Report

Abstract

It is known that the violence of explosive response is affected by inertial and mechanical confinement. In a mechanical insult, the impact location creates a contact pressure that can act as confinement surrounding the ignition location, as has been observed in the Skid Test experiment. Under certain conditions — the details of which have not been well characterized — the ignition can produce cracking in the explosive, down which flames are observed to propagate. Cracks serve to simultaneously provide additional surface area for accelerating the reaction, as well as vent paths for quenching the reaction. These are competing behaviors, and the factors which govern the outcome are poorly described. A new experiment was devised to examine the effect of a controlled pre-load pressure on the explosive response. Sixteen experiments were performed on 1-inch thick discs of PBX 9501, with diameters of 1 in ch, 4.25 in ch, and 5 in ch. The explosive was compressed to a known pre-load between two clear windows and ignited at the center of the bottom surface with a focused laser impinging on a graphite inclusion. The ensuing reaction was imaged through the windows used to compress the sample, and from the side. A specklemore » pattern was applied to some samples for performing DIC (digital image correlation) for the purpose of quantifying the strain field and tracking crack growth. A threshold behavior was observed, in which higher-pressure pre-load resulted in cracks forming, while lower-pressure pre-load vented across the face of the explosive. This report presents the preliminary results, discusses the observations, enumerates hypotheses regarding the observed behavior, identifies lessons learned, and outlines a path forward for the next round of testing. Proof testing was only recently concluded and considerable additional analysis is required. These data will be valuable for the ongoing development of a constitutive mechanical and cracking failure model that will aid in predicting explosive response in mechanical impact scenarios.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1477627
Report Number(s):
LA-UR-18-29694
DOE Contract Number:  
AC52-06NA25396
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
FEER; fracture; explosives; response

Citation Formats

Holmes, Matthew David, Parker, Jr., Gary Robert, Broilo, Robert M., Heatwole, Eric Mann, Feagin, Trevor Alexander, Lopez-Pulliam, Ian Daniel, Vaughan, Larry Dean, Erickson, Michael Andrew Englert, and Schulze, Peter Andreas. Fracture Effects on Explosive Response (FEER); FY2018 Report. United States: N. p., 2018. Web. doi:10.2172/1477627.
Holmes, Matthew David, Parker, Jr., Gary Robert, Broilo, Robert M., Heatwole, Eric Mann, Feagin, Trevor Alexander, Lopez-Pulliam, Ian Daniel, Vaughan, Larry Dean, Erickson, Michael Andrew Englert, & Schulze, Peter Andreas. Fracture Effects on Explosive Response (FEER); FY2018 Report. United States. doi:10.2172/1477627.
Holmes, Matthew David, Parker, Jr., Gary Robert, Broilo, Robert M., Heatwole, Eric Mann, Feagin, Trevor Alexander, Lopez-Pulliam, Ian Daniel, Vaughan, Larry Dean, Erickson, Michael Andrew Englert, and Schulze, Peter Andreas. Thu . "Fracture Effects on Explosive Response (FEER); FY2018 Report". United States. doi:10.2172/1477627. https://www.osti.gov/servlets/purl/1477627.
@article{osti_1477627,
title = {Fracture Effects on Explosive Response (FEER); FY2018 Report},
author = {Holmes, Matthew David and Parker, Jr., Gary Robert and Broilo, Robert M. and Heatwole, Eric Mann and Feagin, Trevor Alexander and Lopez-Pulliam, Ian Daniel and Vaughan, Larry Dean and Erickson, Michael Andrew Englert and Schulze, Peter Andreas},
abstractNote = {It is known that the violence of explosive response is affected by inertial and mechanical confinement. In a mechanical insult, the impact location creates a contact pressure that can act as confinement surrounding the ignition location, as has been observed in the Skid Test experiment. Under certain conditions — the details of which have not been well characterized — the ignition can produce cracking in the explosive, down which flames are observed to propagate. Cracks serve to simultaneously provide additional surface area for accelerating the reaction, as well as vent paths for quenching the reaction. These are competing behaviors, and the factors which govern the outcome are poorly described. A new experiment was devised to examine the effect of a controlled pre-load pressure on the explosive response. Sixteen experiments were performed on 1-inch thick discs of PBX 9501, with diameters of 1 in ch, 4.25 in ch, and 5 in ch. The explosive was compressed to a known pre-load between two clear windows and ignited at the center of the bottom surface with a focused laser impinging on a graphite inclusion. The ensuing reaction was imaged through the windows used to compress the sample, and from the side. A speckle pattern was applied to some samples for performing DIC (digital image correlation) for the purpose of quantifying the strain field and tracking crack growth. A threshold behavior was observed, in which higher-pressure pre-load resulted in cracks forming, while lower-pressure pre-load vented across the face of the explosive. This report presents the preliminary results, discusses the observations, enumerates hypotheses regarding the observed behavior, identifies lessons learned, and outlines a path forward for the next round of testing. Proof testing was only recently concluded and considerable additional analysis is required. These data will be valuable for the ongoing development of a constitutive mechanical and cracking failure model that will aid in predicting explosive response in mechanical impact scenarios.},
doi = {10.2172/1477627},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {10}
}

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