Formation of local hot spots during the fracture of thin layers under shock

Afanas'ev, G. T.; Bobolev, V. K.; Kazarova, Yu. A.; Karabanov, Yu. F.

doi:10.1007/bf00740454

Cited by 16 publications

(12 citation statements)

References 2 publications

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“…9 and 10 to be approximately 5.1 x 10~3 Btu/in. 2 Precise distribution of this heat energy requires a heat transfer analysis. However, for a preliminary estimate, assume that half of the heat energy goes to the drop weight and anvil and that the other half is evenly distributed throughout a 0.001-in.…”

Section: Frictional Energy Discussionmentioning

confidence: 99%

“…One of the earliest papers was by Bowden and Gurton 1 and showed in experimental work the formation of hot spots in solid explosives. Afanas'ev et al 2 proposed a mechanism of hot spot formation in solid explosives by the release of energy along slip surfaces formed at the onset of mechanical failure. Field, Heavens, and Winter 3 ' 4 observed the impact initiation of ignition in explosives and postulated that hot spots result from locally obstructed plastic flow.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic finite element analysis of solid propellant impact test

So¹,

Francis²

1991

Journal of Spacecraft and Rockets

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The objective of this dynamic finite element analysis (with the computer code DYNA) was to better understand the mechanism of the initiation of ignition in the drop weight impact test of rocket motor composite solid propellant. The analysis showed that the shear stresses in the solid propellant are concentrated at the upper and lower propellant surfaces just inside the edge of the propellant sample. These shear bands are caused by friction stresses at the sliding interfaces between the propellant, drop weight, and anvil. The friction stresses generate localized heat concentrations as the propellant extrudes radially. Thus, there is high concentration of heat energy at the shear-band locations where the compressive stresses are low. Three sources of energy contribute to the hot spots at these critical locations: 1) frictional energy, 2) distortional energy, and 3) ammonium perchlorate crystal fracture. Frictional energy alone is sufficient to ignite the solid propellant. Thes,e analytically predicted hot spots are in agreement with experimental results that show that ignition occurs in the high shear stress bands near the edge of the specimen and not in the high compressive stress region at the center of the specimen.

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Section: Frictional Energy Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamic finite element analysis of solid propellant impact test

So¹,

Francis²

1991

Journal of Spacecraft and Rockets

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“…The dynamic behavior of energetic single crystals features a crucial effect on ignition or initiation of polymer-bonded explosives (PBXs). Bowden and Yoffe proposed defect-based "hot spots" mechanisms to explain prompt initiation of PBX under dynamic loadings, such as the collapse of pores or voids [1][2][3], formation of adiabatic shear bands [4,5], avalanches of dislocation pile-ups [6][7][8], and friction of crack surfaces [9,10]. Headed by Jerry Dick, researchers in the Los Alamos National Laboratory have conducted a lot of work to better understand the relationship between dynamic mechanical behavior and impact sensitivity within energetic crystals.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Anisotropic Response of β‐HMX and α‐RDX Single Crystals Using Plate Impact Experiments at ∼1 GPa

Wang

Huang

et al. 2018

Propellants Explo Pyrotec

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Dynamic responses of several orientations of cyclotetramethylene tetranitramine (HMX) and cyclotrimethylene trinitramine (RDX) single crystals were investigated by using plate impact experiments. The orientations studied included (011), (010), (100), (−111), (01−1), and (11−1) planes of HMX single crystals and (210), (100), (11−1), (2−10), and (111) planes of RDX single crystals. Crystal/window interface particle velocity profiles, which were measured by using velocity interferometer system for any reflector, showed distinct elastic‐plastic double‐wave structures. Dynamic mechanical properties were obtained according to impedance matching method. Elastic‐plastic responses of HMX and RDX exhibited strong anisotropy, nonlinear elasticity, and pressure/strain‐rate dependency. Anisotropy was explained by analyzing the relationship between the impact plane and deformation systems. Results revealed insights into ignition mechanisms and impact sensitivity and provided multiple data for calibration of physical‐based constitutive models.

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“…These interactions may result in high pressures, temperatures, and deformation rates and eventually lead to molecular decomposition and detonation. A number of mechanisms, including the collapse of voids or pores, 2,6 localized adiabatic shear, 7,8 dislocation pile-up avalanches, 9,10 and friction 11,12 have been assessed as possible sources of hot spots ͑cf. Field, Swallowe, and Heavens 13 and Field et al 14 for overviews͒.…”

Section: Introductionmentioning

confidence: 99%

Shock-induced subgrain microstructures as possible homogenous sources of hot spots and initiation sites in energetic polycrystals

2010

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The purpose of this work is to assess the feasibility of a homogeneous-or defect-free-initiation mechanism for high energetic materials in which initiation is a direct consequence of the heterogeneity of crystal plasticity at the subgrain scale. In order to assess the feasibility of these mechanisms, we develop a multiscale model that explicitly accounts for three scales: ͑i͒ the polycrystalline structure at the macroscale, ͑ii͒ singlecrystal plasticity-including subgrain microstructure formation-at the mesoscale, and ͑iii͒ chemical kinetics at the molecular scale. An explicit construction gives the effective or macroscopic behavior of plastically deforming crystals with microstructure, and enables the reconstruction of optimal microstructures from the computed macroscopic averages. An intrinsic feature of the optimal deformation microstructures is the presence of highly localized regions of plastic deformation or slip lines. Temperatures, strain rates, and pressures in these slip lines rise well in excess of the average or macroscopic values. Slip lines thus provide a plentiful supply of likely initiation sites, or hotspots, in defect-free crystals. We have assessed this initiation mechanism by simulating a PETN plate impact experiment and comparing the resulting predictions with experimental pop-plot data. The computed characteristic exponents are in the ballpark of experimental observation.

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Formation of local hot spots during the fracture of thin layers under shock

Cited by 16 publications

References 2 publications

Dynamic finite element analysis of solid propellant impact test

Dynamic finite element analysis of solid propellant impact test

Dynamic Anisotropic Response of β‐HMX and α‐RDX Single Crystals Using Plate Impact Experiments at ∼1 GPa

Shock-induced subgrain microstructures as possible homogenous sources of hot spots and initiation sites in energetic polycrystals

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