Local Deformation and Failure Mechanisms of Polymer Bonded Energetic Materials Subjected to High Strain Rate Loading

Ravindran, Suraj; Tessema, Addis; Kidane, Addis

doi:10.1007/s40870-016-0051-9

Cited by 44 publications

(13 citation statements)

References 31 publications

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“…This observation is very similar to the previously documented data on various polymeric foam specimens [39,40] and attributes to the critical strain rate hypothesis proposed for cellular structures [41]. with details provided in [42] was employed. Smaller cubic specimens of 14×14×14 mm 3 were used in SHPB tests to enforce more uniform deformation.…”

Section: Identification Of Inelastic Constitutive Responsesupporting

confidence: 86%

Effect of specimen size, compressibility and inertia on the response of rigid polymer foams subjected to high velocity direct impact loading

Koohbor

Kidane

2016

International Journal of Impact Engineering

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The influences of specimen length-to-diameter ratio, material compressibility, and inertia on direct impact response of high density closed-cell polymeric foam are investigated. High speed photography and stereovision digital image correlation are conducted to measure the full-field deformation response of the material subjected to direct impact. Inertia stress developed in the specimen is calculated from the acceleration distribution obtained from fullfield measurements. Total axial stress magnitude along the axis of the specimen is then reconstructed from inertia and boundary-measured stresses. It is clearly shown that there is an appreciable degree of spatial variability in strains, strain rates and stresses developed in the impacted foam specimens, whereas the degree of such axial variability is more significant at higher length-to-diameter ratios. The study is further extended to take advantage of such spatial variability to identify the rate sensitivity of the examined material over a wide range of strain rates from 1000 s-1 to 5000 s-1. The approach proposed here is shown to facilitate the identification of viscoplastic constitutive response of low impedance materials using a minimum number of tests.

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Section: Identification Of Inelastic Constitutive Responsesupporting

confidence: 86%

Effect of specimen size, compressibility and inertia on the response of rigid polymer foams subjected to high velocity direct impact loading

Koohbor

Kidane

2016

International Journal of Impact Engineering

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“…These observations are contrary to what was observed previously under quasi-static compression and transverse tensile (Brazilian) loading in which the HMX crystals were observed to de-bond from the estane and rubber binders before they cracked under the transverse tensile stresses. 21,22 This work confirms mesoscale digital image correlation (DIC) measurements and observations, 39 which describe the deformation mechanisms in polymer bonded sugar simulant as crystal fracture from force chains in the material and the rotation/sliding of crystals. These mechanisms are dependent on the volume fraction of crystals of the specific composite system.…”

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confidence: 81%

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

Parab

Roberts

Harr

et al. 2016

Applied Physics Letters

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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.

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“…Hopkinson pressure bar with in situ strain measurement using high-speed digital image correlation [33,34]. The conventional one-dimensional wave analysis is applied to calculate the shearing force [35].…”

Section: Two-stage Loading Of the Sample: Anisotropic Responsementioning

confidence: 99%

Strength of magnesium at high pressures and strain rates

Ravindran

Lovinger

Gandhi

et al. 2020

Extreme Mechanics Letters

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Local Deformation and Failure Mechanisms of Polymer Bonded Energetic Materials Subjected to High Strain Rate Loading

Cited by 44 publications

References 31 publications

Effect of specimen size, compressibility and inertia on the response of rigid polymer foams subjected to high velocity direct impact loading

Effect of specimen size, compressibility and inertia on the response of rigid polymer foams subjected to high velocity direct impact loading

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

Strength of magnesium at high pressures and strain rates

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