PETN Ignition Experiments and Models

Hobbs, Michael L.; Wente, William Baker; Kaneshige, Michael J.

doi:10.1021/jp1007329

Cited by 18 publications

(16 citation statements)

References 20 publications

(57 reference statements)

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“…The SITI experiments [2] have been modified to study the effects of ullage and confinement as shown schematically in figure 2. Figure 2a shows the TATB sample as two 2.54 cm diameter by 1.27 cm tall pressed pellets.…”

Section: Sandia's Instrumented Thermal Ignition Experiments (Siti)mentioning

confidence: 99%

“…Pressure was monitored with a transducer connected to the top of the apparatus through various lengths of tubing. More information regarding this modified SITI experiment can be found in reference [2]. Figure 3 shows an example of the measured temperature and pressure profiles for a low-density and high-density SITI experiment.…”

Section: Sandia's Instrumented Thermal Ignition Experiments (Siti)mentioning

confidence: 99%

“…The drop in temperature could be due to expansion cooling, reduced reaction rates, and energy dissipation. [2] and are only briefly discussed in this section. Thermal ignition is determined by solving the conductive energy equation using a volumetric source for the chemical reactions.…”

Section: Sandia's Instrumented Thermal Ignition Experiments (Siti)mentioning

confidence: 99%

“…The engineering model does not 1) track gas flow, 2) calculate separate gas and condensed temperatures, and 3) determine permeability due to reactions or strain. Figure 4 presents the four-step pressure dependent reaction mechanism used by Hobbs and Kaneshige [2]. The first step represents drying of the adsorbed water following the work of Glascoe et al [3].…”

Section: Sandia's Instrumented Thermal Ignition Experiments (Siti)mentioning

confidence: 99%

“…Cookoff of the IHE, triaminotrinitrobenzene (TATB) with a chlorotrifluoroethylene/vinylidine fluoride (Kel-F) binder, will be used as an example. In previous work [2], this plastic bonded explosive (PBX) was shown to be pressure dependent. Ignition times depend on the degree of confinement, the initial density of the PBX, and the amount of space in the confining apparatus not occupied by the PBX.…”

Section: Introductionmentioning

confidence: 96%

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Effect of confinement during cookoff of TATB

Hobbs

Kaneshige

2014

J. Phys.: Conf. Ser.

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Abstract. In practical scenarios, cookoff of explosives is a three-dimensional transient phenomenon where the rate limiting reactions may occur either in the condensed or gas phase. The effects of confinement are more dramatic when the rate-limiting reactions occur in the gas phase. Explosives can be self-confined, where the decomposing gases are contained within non-permeable regions of the explosive, or confined by a metal or composite container. In triaminotrinitrobenzene (TATB) based explosives, self-confinement is prevalent in plastic bonded explosives at full density. The time-to-ignition can be delayed by orders of magnitude if the reactive gases leave the confining apparatus. Delays in ignition can also occur when the confining apparatus has excess gas volume or ullage. Understanding the effects of confinement is required to accurately model explosive cookoff at various scales ranging from small laboratory experiments to large real systems. IntroductionPredicting the response of energetic material during an accident, such as a fire, is important for high consequence safety analysis, even for insensitive high explosives (IHE). The ignition time, the amount of decomposed gas, the thermo-mechanical sensitization of the degraded energetic material (EM) at ignition, burning of the degraded EM, the possible run-up to detonation and subsequent violence is needed for safety assessments. Even if the EM does not thermally ignite, degraded HE at elevated temperatures are more sensitive to shock initiation than pristine HE. For example, the shock sensitivity of the IHE triaminotrinitrobenzene (TATB) at elevated temperature was shown to be similar to room temperature 1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) [1]. Predictive models must be able to resolve phenomena across ten orders of magnitude in time from hours to sub-microseconds and six orders of magnitude in space from microns to meters. These models should include robust computational tools with solvers for numerically stiff sets of differential equations using adaptive gridding on massively parallel computers. Constitutive models for the EM should consider coupled thermal, mechanical, and chemical phenomena. Constitutive models for confining materials are also needed at elevated temperatures.In the early stages of a cookoff event, the mechanical response and decomposition gas velocities are slower than acoustic wave speeds and can be determined in a quasistatic manner. During this time, heat transfer, decomposition, and gas generation are coupled. Reaction rates are dependent on temperature and, in some cases, pressure. Disparity in thermal expansion between the confinement and the EM can change heat transfer paths as well as available gas volume. The pressurization rate and the degree of confinement influence the probability of deflagration-to-detonation transition (DDT) in the EM.

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Section: Sandia's Instrumented Thermal Ignition Experiments (Siti)mentioning

confidence: 99%

Section: Sandia's Instrumented Thermal Ignition Experiments (Siti)mentioning

confidence: 99%

Section: Sandia's Instrumented Thermal Ignition Experiments (Siti)mentioning

confidence: 99%

Section: Sandia's Instrumented Thermal Ignition Experiments (Siti)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Effect of confinement during cookoff of TATB

Hobbs

Kaneshige

2014

J. Phys.: Conf. Ser.

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X‐Band Microwave Properties and Ignition Predictions of Neat Explosives

Daily

Glover

Son

et al. 2013

Propellants Explo Pyrotec

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Microwave frequency electromagnetic properties are critical for understanding and predicting the heating and ignition behavior of explosives subjected to microwave irradiation. In this work we report relative complex permittivity measurements in the X‐band (8–12 GHz) for 13 neat explosives measured by the circular cavity technique. This data set was then used in conjunction with COMSOL 4.3 Multiphysics® finite element analysis software to design and simulate a low power (100 W), high electric field X‐band microwave applicator. The role of the sample holder on our ability to directly study the response of explosives to electromagnetic energy is examined and shown to be critical. Times to ignition were predicted for PETN, TATB, and HMX and indicate that for the proposed applicator and considered properties ignition may occur in less than one second exposure. These predictions show that explosives can be effectively heated in short time scales through direct microwave heating without absorptive binders or inclusions.

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Function of a PETN‐Based Exploding Bridgewire Detonator Post Melt

Manner

Yeager

Smilowitz

et al. 2020

Propellants Explo Pyrotec

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Exploding bridgewire (EBW) detonators are used for a variety of purposes and subjected to a wide range of conditions during transport and use, however, few studies have been conducted on stability at high temperatures. Many EBW's contain pentaerythritol tetranitrate (PETN) as the initiating explosive, which has been shown to exhibit a relatively low melt at 141°C, followed by an onset of decomposition of approximately 160°C. In the present work, we have evaluated the behavior of PETN with X-ray radiography in commercial RP-80 EBW detonators at temperatures just above the melt. These experiments show that PETN remains stable in the solid-state, but after reaching the melt temperature is vulnerable to mixing, followed by rapid evolution of gases and decomposition. Our results indicate that the orientation of the thermally treated detonator with respect to gravity is important after the PETN reaches the melted state: this shows for the first time why thermal tests on PETN-based detonators often result in varied outcomes.

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PETN Ignition Experiments and Models

Cited by 18 publications

References 20 publications

Effect of confinement during cookoff of TATB

Effect of confinement during cookoff of TATB

X‐Band Microwave Properties and Ignition Predictions of Neat Explosives

Function of a PETN‐Based Exploding Bridgewire Detonator Post Melt

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