Applying Micro-Mechanics to Finite Element Simulations of Split Hopkinson Pressure Bar Experiments on High Explosives

Mas, E. M.; Clements, B. E.; Blumenthal, Brennan T.; Cady, Carl M.; Gray, G. T.

doi:10.1063/1.1483596

Cited by 4 publications

(4 citation statements)

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“…For PBX1314 the RDX crystals are treateda se lastic in this model. The shear and bulk moduli weret aken to be 5.4 GPa and 12.5 GPa respectively [38,39].G MM parameters for polymer binder are giveni nT able 1. According to the principle of correspondence, the relationship between the Young's modulus E,p oisson's ratio n,b ulk modulus k,a nd shear modulus m are obtainedb yt he elasticm echanics in the laplace transform domain (Equation ( 28)).…”

Section: Numerical Results and Comparisonswith Experimentsmentioning

confidence: 99%

Dynamic Mechanical Behavior of PBX

Xiao

Sun

et al. 2016

Propellants Explo Pyrotec

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1IntroductionPolymer bonded explosives (PBXs) [1][2][3][4] have usually been considered as ap articulate composite material containing the energetic materials hexahydro-1,3,5-trinitro-1,3,5-s-triazine (RDX) embedded in av iscoelastic polymer binder. PBXs are widely used in av ariety of conventional engineering and aerospace fields. As ah ighly-filled composite material, PBX exhibits complex physical and mechanical properties that are dependent on an umber of variables, such as temperature, strain rate, grains weight, and size distribution of grains, etc. [5,6].The Los Alamos National Laboratory (LANL) performed al ot of research on dynamic mechanical properties of PBXs. These results suggested that dynamic mechanical properties of PBX are strongly influenced by strain rate and temperature [7][8][9][10].A lso, the compressive strength is enhanced when increasing strain rate or decreasing temperature. PBX9501i sw idely researched at present,a nd the result illustrated that PBX9501 duringh igh-rate loading continue straining after the maximum flows tress have been achieved. Figure 1s hows the published compressive stress-strain data on PBX9501 currently known to the authors. When the peak strengths of PBX9501 are achieved, the flow strength beginst od ecline sharply because of damage accumulation. Graye tal. [11] revealed that at high-rate PBX 9501 fails via predominantly transgranular cleavage through the HMX crystals. Strains to failure remain almost constant throughout,a talevel of approximately 1-3 %. In fact, these damagep rocesses give rise to the enhanced sensitivity of PBX9501 followinga ni mpact.In the presented work, the micromechanical modelh as profited greatly from the theoretical analysis of Weng and co-workers [12-17] and considerable referencet ot heir work is madet hroughout this article. Their work is based on Eshelby's celebrateds olution of the stressa nd strain fields arising from the presence of an ellipsoidal inhomogeneity in an elastic matrix and Mori and Ta naka'se ffective medium theory,w hich was used to extendE shelby's analysis to larger valueso ff iller concentration [18,19].C lements and Mas have put forth am ethod that is ah ybrid of two Abstract:T he dynamic mechanical properties of PBX1314 and its binder are systematicallyi nvestigated. Based on split-Hopkinson pressure bar technique, the experimental results of PBX1314 and its binder are obtainedu nder high strain rate. Ac onstitutive theory is developed for modeling the mechanical response of dynamically loaded PBX1314 binder.T oa ccomplish this aim, the PBX1314 binderi sa ssayed by relaxation tests at different temperatures, in order to apply the time-temperature superposition principle (TTSP) and raise the masterc urves, based on WLF equation.The rate dependence of mechanical response of the polymer binder is accounted for by ag eneralized Maxwell viscoelasticity model. The basis for this work is Mori and Ta naka's effectivem ediumt heory.T he grains in this analysis are assumed to be spherical and uniformly distributed in the b...

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Section: Numerical Results and Comparisonswith Experimentsmentioning

confidence: 99%

Dynamic Mechanical Behavior of PBX

Xiao

Sun

et al. 2016

Propellants Explo Pyrotec

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“…Lastly, an in-depth study of the microstructural behavior of such granular materials has to be made. From an experimental point of view, this means being able to observe the local failure mechanisms and the sliding mechanisms at the granular scale with particular attention to their dependence on the strain rate [38][39]. …”

Section: Resultsmentioning

confidence: 99%

Dynamic behavior of an aggregate material at simultaneous high pressure and strain rate: SHPB triaxial tests

Bailly

Delvare

Vial

et al. 2011

International Journal of Impact Engineering

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International audienceLow velocity impacts on energetic materials induce plastic deformations and sliding friction which can lead to ignition. If some ignition criteria have been proposed, the remaining difficulty is to characterize the mechanical behavior of the material when submitted to the corresponding solicitations (high pressure and high strain rate). Thus, a technique based on the Split Hopkinson Pressure Bars system is proposed to carry out a triaxial compression test. A cylindrical specimen is placed into a confining ring and is compressed by the system of bars. The ring prevents the radial extension of the specimen and creates a lateral confining pressure. The material and dimensions chosen for the ring maintain a constant radial pressure during the test. Some tests were carried out on an inert aggregate material and proved the validity of this experimental device. The experimental data processing shows the influence of both the pressure and the strain rate. The shear stresses, which contribute to thermal dissipation and then to the ignition threshold, increase according to the pressure

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“…Most energetic materials are used as part of a composite system, with energetic crystals embedded in either an inert or energetic binder, creating PBXs. As a consequence, whilst a body of work has been performed to probe their mechanical response at quasistatic and intermediate strain-rates (see references [8][9][10]) and under conditions of Taylor impact [11], equivalent studies under one-dimensional shock loading is much less prevalent. The inert response (in terms of particle velocity -u p and shock velocity -U S ) has been studied either as part of a wider study on the equation of state [12][13][14][15], or in terms of their purely inert response [16,17].…”

Section: Introductionmentioning

confidence: 99%

The Strength of Two HMX Based Plastic Bonded Explosives During One Dimensional Shock Loading

Millett

Taylor

Roberts

et al. 2017

J. dynamic behavior mater.

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Keywords -plate impact; EDC32; EDC37; shear strength.A series of experiments have been performed to probe the mechanical response of two HMX based plastic bonded explosives to one dimensional shock loading. Manganin stress gauges in longitudinal and lateral orientation to the loading axis have been used as the diagnostic. Results indicate that despite major differences in the binder phase and smaller differences in the HMX crystal loading and morphology, the Hugoniot and shear strengths behind the shock front are near identical. We have proposed that this is due to the HMX crystals forming a network that supports the bulk of the applied stress.

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Applying Micro-Mechanics to Finite Element Simulations of Split Hopkinson Pressure Bar Experiments on High Explosives

Cited by 4 publications

References 1 publication

Dynamic Mechanical Behavior of PBX

Dynamic Mechanical Behavior of PBX

Dynamic behavior of an aggregate material at simultaneous high pressure and strain rate: SHPB triaxial tests

The Strength of Two HMX Based Plastic Bonded Explosives During One Dimensional Shock Loading

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