Thermally‐Driven Changes to Porosity in TATB‐Based High Explosives

Armstrong, Christopher; Mang, Joseph T.

doi:10.1002/prep.202100022

Cited by 10 publications

(8 citation statements)

References 30 publications

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“…The gas volume fraction shown in Figure 7(c,d) is continuous in both the impermeable and permeable explosive layers. The gas volume fraction is similar in magnitude to the gas volume fraction reported in [14].…”

Section: Resultssupporting

confidence: 80%

“…The gas volume frac- [7]. Predicted solid fraction at various times using the model in [14] coupled to the MMP model. tion shown in Figure 7(c,d) is continuous in both the impermeable and permeable explosive layers.…”

Section: Resultsmentioning

confidence: 99%

“…The condensed and gas volumes in Eqns. (14)(15)(16)(17) were used to determine the gas volume fraction which is given in Eq. ( 18).…”

Section: Gas State When Pore Radius Is At R = Rmentioning

confidence: 99%

“…(a) Measured (green solid lines) and predicted (black dashed lines) temperature for SITI experiment 280[7]. Predicted solid fraction at various times using the model in[14] coupled to the MMP model.…”

mentioning

confidence: 99%

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A Micromechanics Pressurization Model for Cookoff

Hobbs

Brown

Kaneshige

et al. 2021

Propellants Explo Pyrotec

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A micromechanics pressurization (MMP) model has been derived for explosive decomposition models that are pressure‐dependent. The model includes volumetric thermal strain and internal pressurization using well‐known solutions of elastic equations that include displacement of the condensed phase. The model is based on observations of a heated, high‐density, plastic bonded explosive (PBX) containing 95 wt% triaminotrinitrobenzene (TATB) with 5 wt% chlorotrifluoroethylene/vinylidene fluoride binder (Kel‐F). The model was developed for explosives that are either permeable or impermeable to decomposition gases. The MMP model is based on pore mechanics which describe reaction nucleation, decomposition chemistry, and elastic volumetric expansion. The model accounts for the expansion or swelling of the explosive into the surrounding gas‐filled ullage space. The pressurization model was used in conjunction with a simple decomposition model to determine ignition time and internal temperatures for the TATB‐based explosive at 1881 kg/m3. The MMP model was used to predict pressure, specific surface area, and gas volume fraction. A Latin hypercube sensitivity analysis showed that prediction of ignition time was most sensitive to the maximum pore pressure which defines the threshold between permeable and impermeable explosive layers. The MMP model coupled to a pressure‐dependent chemistry model can predict accurate ignition times for high‐density PBX's exposed to high temperatures and may be useful for more general application scenarios.

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Section: Resultssupporting

confidence: 80%

Section: Resultsmentioning

confidence: 99%

“…The condensed and gas volumes in Eqns. (14)(15)(16)(17) were used to determine the gas volume fraction which is given in Eq. ( 18).…”

Section: Gas State When Pore Radius Is At R = Rmentioning

confidence: 99%

mentioning

confidence: 99%

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A Micromechanics Pressurization Model for Cookoff

Hobbs

Brown

Kaneshige

et al. 2021

Propellants Explo Pyrotec

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show abstract

“…micron-sized) pores. Armstrong and Mang (2021) performed a similar study by small-angle neutron scattering on PBX 9502, and showed that micron-sized pores grow until 120 • C, and that new pores appear above this temperature. They found, additionally, some residual growth after cooling back to ambient.…”

Section: Introductionmentioning

confidence: 96%

The irreversible thermal expansion of an energetic material

Trumel¹,

Willot

Peyres³

et al. 2021

Journal of Theoretical, Computational and Applied Mechanics

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The works deals with a macroscopically isotropic energetic material based on triamino-trinitrobenzene (TATB) crystals bonded with a small volume fraction of a thermoplastic polymer. This material is shown experimentally to display an irreversible thermal expansion behavior characterized by dilatancy and variations of its thermal expansion coefficient when heated or cooled outside a narrow reversibility temperature range. The analysis of cooling results suggests the existence of residual stresses in the initial state, attributed to the manufacturing process. Microstructure-level FFT computations including the very strong anisotropic thermoelastic TATB crystal response and temperature-dependent binder plasticity, show that strong internal stresses develop in the disoriented crystals under thermal load, either heating or cooling. Upon cooling, binder plastic yielding in hindered, thus promoting essentially brittle microcracking, while it is favored upon heating. Despite its low volume fraction, the role of the binder is essential, its plastic yielding causing stress redistribution and residual stresses upon cooling back to ambient.

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Cookoff of Powdered and Pressed Explosives Using a Micromechanics Pressurization Model

Hobbs

Brown

Kaneshige

et al. 2021

Propellants Explo Pyrotec

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Cookoff experiments of powdered and pressed TATB‐based plastic bonded explosives (PBXs) have been modeled using a pressure‐dependent universal cookoff model (UCM) in combination with a micromechanics pressurization (MMP) model described in a companion paper. The MMP model is based on the accumulation of decomposition gases at nucleation sites that load the surrounding TATB crystals and binder. This is the first cookoff model to use an analytical mechanics solution for compressibility and thermal expansion to describe internal pressurization caused by both temperature and decomposition occurring within closed‐pore explosives. This approach produces more accurate predictions of ignition time and pressurization within high‐density explosives than simple equation‐of‐state models. The current paper gives details of the reaction chemistry, model parameters, predicted uncertainty, and validation using experiments from multiple laboratories with errors less than 6 %. The UCM/MMP model framework gives more accurate thermal ignition predictions for high density explosives that are initially impermeable to decomposition gases.

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Thermally‐Driven Changes to Porosity in TATB‐Based High Explosives

Cited by 10 publications

References 30 publications

A Micromechanics Pressurization Model for Cookoff

A Micromechanics Pressurization Model for Cookoff

The irreversible thermal expansion of an energetic material

Cookoff of Powdered and Pressed Explosives Using a Micromechanics Pressurization Model

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