CHARACTERIZATION OF BLASTS FROM LABORATORY-SCALE COMPOSITE EXPLOSIVE CHARGES
Open Access
- Author:
- Biss, Matthew Michael
- Graduate Program:
- Mechanical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- November 16, 2009
- Committee Members:
- Gary Stuart Settles, Dissertation Advisor/Co-Advisor
Gary Stuart Settles, Committee Chair/Co-Chair
Richard A Yetter, Committee Member
Panagiotis Michaleris, Committee Member
Daniel Linzell, Committee Member
Michael J Hargather, Committee Member - Keywords:
- Laboratory-scale
Booster charge
Composite explosive charges
Shadowgraph visualization
TNT equivalent - Abstract:
- Though multitudes of experiments have been conducted on explosive material characterization, none have properly addressed the effects of a booster charge, which is used to surpass the high-energy threshold required for detonation of an insensitive explosive material. The added pressure effects produced by the booster have long been disregarded. To fill this gap, the present research addresses the booster charge effects when employed in a composite-charge arrangement at the laboratory scale, i.e. with explosive charges in the gram-range. The composite charge consists of a well-characterized spherical booster charge surrounded by a concentric, spherical “candidate material” shell charge. By way of composite-charge explosive characterization, the radial-TNT equivalent of the candidate explosive material is determined through the removal of the known booster effects. Laboratory-scale air-blast explosive tests are conducted using digital high-speed shadowgraph visualization to measure the radial propagation of the explosively-driven shock wave as a function of time. An ultra-high-speed digital camera is also incorporated to measure the radial propagation rate in close proximity to the explosive charge itself. Profiles of peak shock wave pressure vs. shock wave radius are determined from the temporal history of the shock wave propagation. Initial experiments are performed with both booster and shell charges made of characterized pentaerythritol tetranitrate (PETN), in order to determine the booster relationship within a composite-charge arrangement. Using peak shock wave pressure vs. shock wave radius profiles, a procedure is developed to remove the booster effects from the composite-charge signature, yielding the sole effects of the shell material, as if it were detonated alone. Method verification is performed by comparing results to previous homogeneous explosive material characterization. A second booster removal procedure is developed based upon the explosive impulse rather than peak shock wave pressure. Temporal pressure histories of the shock wave pressure decay are measured using piezoelectric pressure transducers. Explosive impulse is calculated from these pressure histories through knowledge of the peak shock wave pressure, the positive pressure duration, and the waveform parameter describing the pressure decay. Composite explosive charges are numerically modeled to verify the proposed peak shock wave pressure and explosive impulse booster removal procedures. Finally, this composite-charge characterization procedure is extended to the characterization of smokeless powder (SP), cyclotrimethylene trinitramine (RDX), and cyclotetramethylene tetranitramine (HMX). The results demonstrate the ability to successfully test and characterize insensitive explosive materials, requiring a booster charge for detonation, at the laboratory scale by way of composite charges.