Cookoff

Asay, B. W.

doi:10.1007/978-3-540-87953-4_7

Cited by 3 publications

(2 citation statements)

References 41 publications

(59 reference statements)

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“…Based on the phase change and material transport that occurs during the cook-off of JEO explosives, a multiphase flow material-transport model was established for the time before ignition of the JEO explosives. The equation of energy conservation between different substances is [18]: where 1 is the density in kg • m À 3 , C p is the specific heat capacity in J…”

Section: Multiphase Flow Material-transport Modelmentioning

confidence: 99%

Cook‐Off Characteristics of NTO/HMX‐Based Plastic‐Bonded Explosives in a Shaped Charge

Wang

Fang

2023

Propellants Explo Pyrotec

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In this paper, the cook-off characteristics of NTO/ HMX-based plastic-bonded explosives, here after referred to as JEO, with confined and pressure-relief structures are investigated. Firstly, a pre-ignition thermal decomposition model and a post-ignition combustion model of the explosives were established. The chemical reaction kinetics and combustion reaction parameters in the numerical model were calibrated according to a small closed-bomb experiment. The cook-off process of the explosives was then studied by numerical simulation, determining the influence of different structures on the ignition time, ignition position, and reaction intensity of a JEO charge. The cook-off of NTO/HMX-based plastic-bonded explosives with different structures was then experimentally studied, obtaining the temperature curve of each explosive, the deformation of the shell and liner, the macro-reaction phenomena when the charge was ignited and the residue state after the reaction, which verified the validity of the numerical simulation.

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Section: Multiphase Flow Material-transport Modelmentioning

confidence: 99%

Cook‐Off Characteristics of NTO/HMX‐Based Plastic‐Bonded Explosives in a Shaped Charge

Wang

Fang

2023

Propellants Explo Pyrotec

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“…A number of different mechanisms have been suggested and studied regarding initiation and hotspot formation such as adiabatic compression of trapped gases, viscous or plastic heating, frictional effects between damaged surfaces, heating at crack tip etc that can be induced as a result of shock and low velocity impact loading conditions [9][10][11][12][13]. In addition, low magnitude mechanical insults during storage, handling or transportation can lead to microscale damage which can then influence the aforementioned hotspot mechanisms and thus have influence on operational reliability and accidental initiation [14][15][16][17]. As a result, several studies have indicated that energetic materials may react violently for relatively mild stimuli [18][19][20].…”

Section: Introduction Motivation and Backgroundmentioning

confidence: 99%

Mesoscale strain and damage sensing in nanocomposite bonded energetic materials under low velocity impact with frictional heating via peridynamics

Talamadupula

Povolny

Prakash

et al. 2020

Modelling Simul. Mater. Sci. Eng.

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The formation of hotspots within polymer bonded explosives can lead to the thermal decomposition and initiation of energetic materials. A frictional heating model is applied at the mesoscale in this study to assess the potential for the formation of hotspots under low velocity impact loadings. The frictional heating mechanism predominantly depends on the formation and growth of microstructural damage within the energetic material. Monitoring of the formation and growth of damage at the mesoscale is considered through the inclusion of piezoresistive carbon nanotube network within the energetic binder providing embedded strain and damage sensing. A coupled multiphysics thermo-electro-mechanical peridynamics framework is developed to perform computational simulations on an energetic material microstructure subject to low velocity impact loads. The coupled framework allows for the assessment of traveling compressive waves caused by impact with piezoresistive sensing, growth of damage with damage sensing and the possible formation of hotspots. The sensing mechanism has been shown to capture the presence of the compressive mechanical wave at different locations within the microstructure before large damage growth. It is observed that the development of hotspots is highly dependent on the impact energy. Higher impact energy leads to larger amounts of microstructural damage providing more damaged surfaces for friction to take place. The higher impact energy also yields larger relative velocities of sliding damage surfaces resulting in more frictional heating. With increase in impact energy, the model also predicts larger amounts of sensing and damage thereby supporting the use of carbon nanotubes to assess damage growth and subsequent formation of hotspots.

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Gas Transport in the Insensitive High Explosive PBX 9502

Englert‐Erickson

Holmes

Parker

et al. 2020

Propellants Explo Pyrotec

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Small-scale laboratory experiments were performed to analyze gas transport mechanics in PBX 9502, an insensitive high explosive (IHE) composition. Two independent investigations are reported here. First, gas permeametry and dynamic pycnometry techniques were used to measure the molecular flow (Knudsen) coefficient and the internally interconnected void fraction of pristine and thermally damaged samples in two uniaxial pressing orientations. The permeability of PBX 9502 was found to be unmeasurably low (of the same order of magnitude as PTFE) with gas transport being diffusion-dominated. Secondly, a pressure vessel experiment was developed to measure quasi-static and dynamic gas generation as the explosive was heated to self-ignition (cookoff). The gas generation results and the permeability/diffusivity findings provide evidence that PBX 9502 remains impermeable until seconds prior to self-ignition. At ignition, internal void-pressure drives macro-scale cracking and the sample becomes uniformly incorporated in the following deconsolidating deflagration. These results are discussed within the context of previous observations of pressure-dependent cookoff behavior of PBX 9502 and provide a more complete description of thermal damage evolution in this explosive composition.

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Cookoff

Cited by 3 publications

References 41 publications

Cook‐Off Characteristics of NTO/HMX‐Based Plastic‐Bonded Explosives in a Shaped Charge

Cook‐Off Characteristics of NTO/HMX‐Based Plastic‐Bonded Explosives in a Shaped Charge

Mesoscale strain and damage sensing in nanocomposite bonded energetic materials under low velocity impact with frictional heating via peridynamics

Gas Transport in the Insensitive High Explosive PBX 9502

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