The deformation and fracture of β-HMX

Palmer, S. J. P.; Field, J. E.

doi:10.1098/rspa.1982.0137

Cited by 104 publications

(64 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Generally, fracture of energetic crystals is unlikely to produce a critical hot spot owing to the low fracture surface energy of the crystals (tens of mJ; Field et al 1982;Palmer & Field 1982); however, for pressed explosives, it can be important when tough grits are added, which tend to sensitize the system. Even polymer grits have this effect , so sensitization would be expected for PBXs with a brittle binder.…”

Section: (A ) Ignition Mechanisms In Pbxsmentioning

confidence: 99%

High strain rate properties of a polymer-bonded sugar: their dependence on applied and internal constraints

et al. 2008

View full text Add to dashboard Cite

This paper describes research performed on a polymer-bonded sugar (PBS) consisting of 66% caster sugar in a hydroxyl-terminated polybutadiene (HTPB) binder The mechanical response of the PBS and pure HTPB to applied loading at a strain rate of approximately 2000 s K1 at temperatures from K80 to C228C is presented. The materials were also characterized using dynamic mechanical analysis, X-ray tomography and quasi-static loading. These measurements are required for the development of intermediate strain rate constitutive models of polymer-bonded explosives, for which PBSs are a commonly used mechanical simulant.The current constitutive modelling suffers from a lack of experimental data on wellcharacterized composites and binders, especially at intermediate strain rates. This is particularly important for understanding the effects of mixing two materials. Applications of such modelling include explosive safety and fundamental understanding of the various deformation mechanisms. In this paper, the dependences of strength and deformation mechanism on temperature, and, in particular, the glass transition temperature of the binder, are shown. Physical damage plays an important role; X-ray tomography scans support debonding as the primary form of damage during roomtemperature deformation. These results are in agreement with previous investigations and are discussed in this context.

show abstract

Section: (A ) Ignition Mechanisms In Pbxsmentioning

confidence: 99%

High strain rate properties of a polymer-bonded sugar: their dependence on applied and internal constraints

et al. 2008

View full text Add to dashboard Cite

show abstract

“…Since the HMX is a brittle material, the critical stress governing fracture in this case is the maximum tensile stress. 8 In a diametral compression case as observed here, the maximum tensile stress occurs normal to the line joining the contact points; 37 hence, the crack developed in the direction that joined the two contact points. As the specimen was compressed further (t ¼ 115 ls), the previously cracked crystal was completely fragmented between the contacts.…”

mentioning

confidence: 88%

“…8 HMX crystals were observed to show an extensive twinning 8 and dislocation slip 9 behavior on the favorable crystal planes prior to fracture. However, the eventual cracking behavior was controlled by the resulting tensile stresses generated by the compressive loading.…”

mentioning

confidence: 99%

See 1 more Smart Citation

High speed X-ray phase contrast imaging of energetic composites under dynamic compression

Parab

Roberts

Harr

et al. 2016

Applied Physics Letters

View full text Add to dashboard Cite

Fracture of crystals and frictional heating are associated with the formation of “hot spots” (localized heating) in energetic composites such as polymer bonded explosives (PBXs). Traditional high speed optical imaging methods cannot be used to study the dynamic sub-surface deformation and the fracture behavior of such materials due to their opaque nature. In this study, high speed synchrotron X-ray experiments are conducted to visualize the in situ deformation and the fracture mechanisms in PBXs composed of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) crystals and hydroxyl-terminated polybutadiene binder doped with iron (III) oxide. A modified Kolsky bar apparatus was used to apply controlled dynamic compression on the PBX specimens, and a high speed synchrotron X-ray phase contrast imaging (PCI) setup was used to record the in situ deformation and failure in the specimens. The experiments show that synchrotron X-ray PCI provides a sufficient contrast between the HMX crystals and the doped binder, even at ultrafast recording rates. Under dynamic compression, most of the cracking in the crystals was observed to be due to the tensile stress generated by the diametral compression applied from the contacts between the crystals. Tensile stress driven cracking was also observed for some of the crystals due to the transverse deformation of the binder and superior bonding between the crystal and the binder. The obtained results are vital to develop improved understanding and to validate the macroscopic and mesoscopic numerical models for energetic composites so that eventually hot spot formation can be predicted.

show abstract

“…These hotspots in energetic materials form through mechanisms such as compression of voids, friction between crack surfaces inside the material, and localized shear deformation. [1][2][3][4][5] Heating due to each of these mechanisms depends on the histories of the states of local stress and rate of deformation in the material. Existing literature examines the behavior of energetic crystals and polymer-bonded explosives (PBXs) in two general forms: as single crystals with anisotropic material properties, [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] and as heterogeneous collections of energetic grains with isotropic material properties.…”

Section: Introductionmentioning

confidence: 99%

Analysis of thermomechanical response of polycrystalline HMX under impact loading through mesoscale simulations

Hardin¹,

Rimoli²,

Zhou³

2014

AIP Advances

View full text Add to dashboard Cite

We investigate the response of polycrystalline HMX 3,5,3,5, under impact loading through a 3-dimensional mesoscale model that explicitly accounts for anisotropic elasticity, crystalline plasticity, and heat conduction. This model is used to quantify the variability in temperature and stress fields due to random distributions of the orientations of crystalline grains in HMX under the loading scenarios considered. The simulations carried out concern the response of fully dense HMX polycrystalline ensembles under impact loading at imposed boundary velocities from 50 to 400 m/s. The polycrystalline ensemble studied consists of a geometrically arranged distribution of bi-modally sized and shaped grains. To quantify the effect of crystalline slip, two models with different numbers of available slip systems are used, reflecting differing characterizations of the slip systems of the HMX molecular crystal in the literature. The effects of microstructure and anisotropy on the distribution of heating and stress evolution are investigated. The results obtained indicate that crystalline response anisotropy at the microstructure level plays an important role in influencing both the overall response and the localization of stress and temperature. The overall longitudinal stress is up to 16% higher and the average temperature rise is only half in the material with fewer potential slip systems compared to those in the material with more available slip systems. Local stresses can be as high as twice the average stresses. The results show that crystalline anisotropy induces significant heterogeneities in both mechanical and thermal fields that previously have been neglected in the analyses of the behavior of HMX-based energetic materials. C 2014 Author(s)

show abstract

The deformation and fracture of β-HMX

Cited by 104 publications

References 8 publications

High strain rate properties of a polymer-bonded sugar: their dependence on applied and internal constraints

High strain rate properties of a polymer-bonded sugar: their dependence on applied and internal constraints

High speed X-ray phase contrast imaging of energetic composites under dynamic compression

Analysis of thermomechanical response of polycrystalline HMX under impact loading through mesoscale simulations

Contact Info

Product

Resources

About