Observation of Damage During Dynamic Compression of Production and Low-Defect HMX Crystals in Sylgard® Binder Using X-Ray Phase Contrast Imaging

Paulson, Shane; Roberts, Zane A.; Sorensen, Christian J.; Kerschen, Nicholas E.; Harr, Michael; Parab, Niranjan D.; Sun, Tao; Fezzaa, Kamel; Son, Steven F.; Chen, Wayne W.

doi:10.1007/s40870-019-00225-8

Cited by 6 publications

(4 citation statements)

References 41 publications

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“…Purdue maintains a 38.1 mm bore, single-stage, helium-powered, light gas gun there. The gun and experimental diagnostics details can be found in previous papers based on our work [13][14][15]. The upper velocity of the gun is limited because of the space requirements of sector 32B and tops out near 550 m/s.…”

Section: Experimental Configurationmentioning

confidence: 99%

Phase Contrast X‐Ray Imaging of the Collapse of an Engineered Void in Single‐Crystal HMX

Blum‐Sorensen

Duarte

Drake

et al. 2022

Propellants Explo Pyrotec

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Imaging the collapse of a single void that creates a hot spot initiation site in an otherwise defect‐free explosive is challenging given the spatial and temporal scales involved in explosive systems. This work presents our attempt to examine a single hot spot mode (void collapse) in single‐crystal octahydro‐l,3,5,7‐tetranitro‐l,3,5,7‐tetrazocine (HMX) embedded in Sylgard. The hot spot heating mechanisms involved with pore collapse include adiabatic heating, jetting, and viscoplastic dissipation. Quantifying the dynamics of a pore collapse is a crucial step to understanding which mechanisms dominate during ignition events. Our experiments were conducted with a single‐stage, light‐gas gun at Argonne National Laboratory's Advanced Photon Source, applying the phase contrast imaging technique while collecting high‐speed video. The details of HMX single crystal production, defect (pore) engineering, and sample construction, along with experimental results are presented here. These results demonstrate that detailed collapse dynamics can be obtained from homogeneous, single‐crystal explosives with this approach. Qualitative comparisons are made with simulation data which show good agreement in the transition between a quasi‐symmetric pore collapse and an asymmetric collapse with jetting across the pore as measured with normalized pore area and pore circularity.

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Section: Experimental Configurationmentioning

confidence: 99%

Phase Contrast X‐Ray Imaging of the Collapse of an Engineered Void in Single‐Crystal HMX

Blum‐Sorensen

Duarte

Drake

et al. 2022

Propellants Explo Pyrotec

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“…Nevertheless, the HMX crystal is crucial for providing detonation power, and more attention should be directed toward understanding the effect of cracks within HMX crystals on heat conduction. Recently, with the advancement of X-ray CT technology, some researchers have been able to the morphology of the surface and interior of HMX single crystals, as well as the crack initiation and extension of different types of crystals upon impact in a matrix or binder. − However, little research has addressed the differentiation between cracks generated by thermal expansion and phase transitions for HMX crystals, and there has been scarce investigation into the relationship between these different cracks and heat conduction.…”

Section: Introductionmentioning

confidence: 99%

Generation and Evolution Mechanism of Cracks in HMX Single Crystals around Phase Transition Temperature

Wang,

Liang,

Wang

et al. 2024

Crystal Growth & Design

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Thermal-induced cracks in explosive crystals could hinder heat conduction, generate hot spots, and ultimately induce detonation, posing safety hazards for the storage and transportation of explosives and impacting their performance. The thermotropic phase transition occurring below decomposition and detonation temperature complicate the evolution and mechanism of the cracks during heating for some explosives. In this work, the generation and evolution of cracks induced by the heating at both 180 and 185 °C above the phase transition temperature were investigated for the classical energetic crystal HMX. Three types of cracks, fast cracks, slow cracks, and small cracks, were observed and the corresponding formation mechanisms and distribution characteristics were systematically studied by optical microscopy, scanning electron microscopy, 3D X-ray computed tomography, X-ray diffraction, and Raman spectroscopy. The results indicate that fast cracks form due to thermal expansion, tending to be perpendicular to the lattice b-direction. Slow cracks arise from the (101) (or (1̅10)) plane slipping and exist only in the subsurface. Small cracks originate from the β–δ phase transition of HMX, are denser and more disordered, and mainly occur close to the heated surface. These findings provide further insight into the relationship between thermal damage and the heat conduction characteristics of HMX crystals.

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“…Considerable evidence suggests that microcrack evolution plays an important role in hotspot formation in lowvelocity-impact ignition [8,9]. Lu et al [10] and Chen et al [11] found that microcrack evolution is a very complex process that involves fracture inside explosive crystals and binders as well as debonding between the crystals and the binders.…”

Section: Introductionmentioning

confidence: 99%

“…Considerable evidence suggests that microcrack evolution plays an important role in hotspot formation in low‐velocity‐impact ignition [8, 9]. Lu et al .…”

Section: Introductionmentioning

confidence: 99%

Effect of Continuous Damage Accumulation on Ignition of HMX‐Based Polymer Bonded Explosives under Low‐Velocity Impact

Liu

Chen

Zhang

2020

Propellants Explo Pyrotec

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The ignition phenomena of polymer-bonded explosives (PBXs) due to hotspot formation from grit/friction, shear band formation, and friction between microcrack surfaces have not yet been clarified. Microcracks are known to play a critical role in PBX ignition under low-velocity impacts. Further, microcrack evolution determines whether or not a specimen ignites because of complex mechanicalthermal-chemical coupled processes. Although many studies have investigated the multiphysics processes of ignition under single impacts, few have investigated multiple-impact scenarios that are more likely in reality. The present study focuses on the influence of continuous damage accumulation during multiple impacts on the safety assessment of octahydro-1,3,5,7-Tetranitro-Tetrazocine (HMX)-based PBXs. The Visco-SCRAM model combined with restart technology is applied to conduct simulations with the standard confined Steven test. By controlling the first impact velocity, the damage accumulation could be designed. When the first impact velocity increases from 5 to 20 m/s, the second impact velocity threshold decreases from 34 to 22 m/s and specific mechanical energy decreases from 600 to 240 m 2 /s 2. Multiple impacts change the temperature distribution and ignition position. Further, different projectile shapes influence multiple impacts differently. Owing to continuous damage accumulation, the second impact velocity threshold decreases for flat and pin projectiles. Dimensionless analysis reveals that the trends of critical dimensionless parameters for flat and pin projectiles are similar, whereas oval projectiles show a different response.

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Observation of Damage During Dynamic Compression of Production and Low-Defect HMX Crystals in Sylgard® Binder Using X-Ray Phase Contrast Imaging

Cited by 6 publications

References 41 publications

Phase Contrast X‐Ray Imaging of the Collapse of an Engineered Void in Single‐Crystal HMX

Phase Contrast X‐Ray Imaging of the Collapse of an Engineered Void in Single‐Crystal HMX

Generation and Evolution Mechanism of Cracks in HMX Single Crystals around Phase Transition Temperature

Effect of Continuous Damage Accumulation on Ignition of HMX‐Based Polymer Bonded Explosives under Low‐Velocity Impact

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