Review of the Wedge Test and Single Curve Initiation Principle Applied to Aluminized High Explosives

Elia, Thomas; Chuzeville, Vincent; Baudin, Gérard; Genetier, Marc; Lefrançois, Alexandre; Osmont, Antoine; Boulanger, R.

doi:10.1002/prep.201900300

Cited by 8 publications

(7 citation statements)

References 13 publications

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“…There is a downward step signal for low impedance explosives. (2) There is no additional chemical energy to sustain the steady structure of the reaction zone in the Teflon, and the rarefaction wave catches up with the leading shock, resulting in the Flatten VN' spike signal. Teflon can flatten the VN' spike, which affect the calibration of the reaction rate equation.…”

Section: Discussionmentioning

confidence: 99%

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Effects of encapsulation of manganin gauges on the pressure profiles from shock initiation experiments

Miao,

Jiang,

et al. 2023

Propellants Explo Pyrotec

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The Lagrangian test can measure the shock initiation process of explosives for different incident shock pressures. The manganin gauges record pressure histories for several DNAN‐based melt‐cast explosives. The encapsulation of the gauges results in three types of characteristic signals: (1) a step signal on the low‐pressure shock front, (2) a flatten Von Neuman's (VN's) spike on the high‐pressure shock front, and (3) a V‐shape signal behind the shock front. To reveal the mechanism underlying these characteristic signals, a one‐dimensional Lagrangian hydrocode, was used to simulate the propagation of a sustained shock in both ideal and non‐ideal systems. The simulation results show that the impedance mismatch between encapsulation material and explosives is the main reason for the three characteristic signals. The calibration of shock initiation model should take the encapsulation material into account so as to determine shock initiation model parameters accurately.

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Section: Discussionmentioning

confidence: 99%

“…The wedge test [2] is a useful method to study the process of shock initiation, and has been used for many explosives since 1961 [3]. In the wedge test, a known intensity plane shock is generated by a plane wave generator or high‐speed flyer impact.…”

Section: Introductionmentioning

confidence: 99%

Effects of encapsulation of manganin gauges on the pressure profiles from shock initiation experiments

Miao,

Jiang,

et al. 2023

Propellants Explo Pyrotec

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“…Jet penetration into explosives is a continuous process, and the attenuation of the penetration velocity is small. Referring to the pop curve of explosives [28], the logarithm of initiation depth of uncompressed explosive X u is assumed to be linearly related to the logarithm of the initial pressure s at the penetration interface when the jet begins to penetrate the explosive. Therefore,…”

Section: Detonation Threshold Of Covered Finite Thickness Explosivementioning

confidence: 99%

Critical Initiation Threshold of Covered Finite Thickness Explosive under Impact of Shaped Charge Jet

Chen

Jia

Xia

et al. 2021

Propellants Explo Pyrotec

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The compression depth of explosives is obtained on the basis of Lee penetration equation and the upper bound method to analyze the critical initiation threshold of finite thickness explosives. According to the pop curve, a theoretical model that reflects the relationship between critical initiation threshold and explosive thickness is established. Numerical simulation was carried out to simulate the initiation process and initiation threshold of explosives with different cover plate thicknesses. At the same time, we combine with the experimental data, to compare with the theoretical results. The calculations are in good agreement with data. Results show that the height of the bulge on the back of the cover plate and the compression depth of the explosive gradually increase with the thickness of the cover plate. When the cover plate reaches a certain thickness, there is no significant change on the final height of the bulge and the compression depth of the explosive. The decrease in explosive thickness increases the critical initiation threshold value, and the logarithm of the critical initiation threshold of the finite thickness explosive is approximately linearly related to the logarithm of the explosive thickness minus the compression depth. Therefore, this study can provide a reference for the initiation and simple calculation of the critical threshold of finite thickness explosives.

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“…We presented many results in 2020 [3] and discussed the limitations of the fibers made in silica. Depending of the pressure level, a silica CFBG is not sensitive over its entire length, especially in shock-to-detonation transition (SDT) experiments [4][5][6] or if a small amount of HE is used. The confinement of the CFBG plays also a role.…”

Section: Introductionmentioning

confidence: 99%

Polymer chirped fiber Bragg grating for more sensitive shock velocity measurements

Barbarin,

Thamié,

Hereil

et al. 2024

Optical Waveguide and Laser Sensors III

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The performances of a single-mode polymer chirped fiber Bragg grating (CFBG) made in a microstructured PMMA fiber is investigated to measure shock and detonation velocities. The polymer material makes the fiber sensor more sensitive at lower pressure values than with silica. The optical characterization of the microstructured polymer CFBG is discussed. The single-mode fiber offers a stable reflected optical spectrum over time and the manufacturing process used provides a constant chirp rate along the grating. The maximum reflectivity of the microstructured polymer CFBG provides enough signal for the photoreceiver without significantly increasing the optical source power. The actual limitations include the global shape of the reflected spectrum, which comprises many dips, and the optical losses that reduce sensor sensitivity towards the end of the grating. Anyhow, a first detonation experiment intended to measure shock and detonation velocities in a wedge test was completed. The X-T diagram showing the shock and detonation wave positions as a function of time presents two slopes corresponding to a shock velocity of 4695 m/s and a steady-state detonation velocity of 8392 m/s. These values are very similar to the ones obtained with 48 piezoelectric pins, but the uncertainties remain high (>2%) for this first experiment. Nevertheless, the experience proves that the PMMA material is suitable for detonation physics experiments. Technical solutions were identified to improve sensor performance. First, optical losses could be reduced within the grating and a more constant reflectivity level could be obtained. Sensitivity would be similar along the full length of the grating. The second point of focus will be to prevent any dips in the reflected optical spectrum. With these improvements, we should achieve uncertainties of less than ± 1% (at k=2) for shock and detonation velocity measurements.

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Review of the Wedge Test and Single Curve Initiation Principle Applied to Aluminized High Explosives

Cited by 8 publications

References 13 publications

Effects of encapsulation of manganin gauges on the pressure profiles from shock initiation experiments

Effects of encapsulation of manganin gauges on the pressure profiles from shock initiation experiments

Critical Initiation Threshold of Covered Finite Thickness Explosive under Impact of Shaped Charge Jet

Polymer chirped fiber Bragg grating for more sensitive shock velocity measurements

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