Dynamic fracture and local failure mechanisms in heterogeneous RDX-Estane energetic aggregates

LaBarbera, D. A.; Zikry, M. A.

doi:10.1007/s10853-015-9102-1

Cited by 13 publications

(7 citation statements)

References 42 publications

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Section: Introductionmentioning

confidence: 99%

“…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.…”

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confidence: 99%

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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: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Dynamic Mechanical Behavior of PBX

Xiao

Sun

et al. 2016

Propellants Explo Pyrotec

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“…where G (n) and τ (n) are the shear modulus and relaxation time of the n-th component in the general Maxwell model. The deviatoric constitutive law of the N-component Maxwell model is obtained by Equations (12) and (13) .…”

Section: Dynamic Damage Modelmentioning

confidence: 99%

“…A criterion has been developed to distinguish whether the sets of hotspots are potential initiation sites [ 9 ]. In consideration of the microstructure, crystal physical property and binder viscoelasticity, investigations of hotspot formation in granular explosive and PBX indicate that heat localization is related to crystal anisotropy, microstructural heterogeneity [ 10 , 11 , 12 ], crystal sliding, and localized plastic deformation [ 13 , 14 ]. A phase field damage model is constructed to study the mechanical and thermal response of an HMX particle, which is embedded in the binder matrix [ 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Mechanical Damage and Non-Shock initiation of a New Polymer Bonded Explosive during Penetration

2020

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Complexities of heating mechanisms make it difficult to investigate the safety of a polymer bonded explosive (PBX) charge of earth-penetrating-weapons (EPWs) during penetration. In this paper, the dynamic damage and non-shock initiation of PBX1314 (60 wt % hexahydro-1, 3, 5-trinitro-1, 3, 5-s-triazine (RDX), 16 wt % aluminum, 24 wt % hydroxy-terminated polybutadiene (HTPB)) during penetration is investigated through experiments and simulations. In the experiments, steel projectiles filled with PBX1314 are launched to penetrate concrete targets. In the results, non-shock initiations occur on the tail surface of PBX1314 along with mechanical damage of the tail and middle part of PBX1314. A dynamic damage and initiation model is proposed to characterize the effects of microcracks on the mechanical and thermal responses of PBX1314. Investigation based on the model suggests that microcrack interfacial friction plays significant roles in damage, heat generation and localization in PBX1314. A non-shock initiation criterion is developed based on macroscale variables in PBX1314. Numerical simulations of the penetration experiments are performed by using the proposed model and criterion. The mechanical damage and non-shock initiation of PBX1314 in the experiments are successfully predicted. The simulation results indicate that the tail of PBX1314 impacts the projectile repeatedly during penetration. Finally, the initiation criterion is satisfied because of frictional heat localization near microcrack surfaces and initiation is activated in the tail of PBX1314.

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“…2,[9][10][11][12] Early work on RDX demonstrated that its chemical sensitivity depends strongly on the temporal evolution of lattice defects. 13,14 Ductile 15,16 and brittle 17,18 responses in RDX have been predicted and observed when chemistry is activated under different conditions. Different chemical mechanisms have been observed for decomposition activated at different strain rates.…”

Section: Introductionmentioning

confidence: 99%

Pressure-Thresholded Response in Cylindrically Shocked Cyclotrimethylene Trinitramine (RDX)

et al. 2020

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We demonstrate a strongly thresholded response in cyclotrimethylene trinitramine (RDX) when it is cylindrically shocked using a novel waveguide geometry. Using ultrafast single-shot multi-frame imaging, we demonstrate that <100-μm diameter single crystals of RDX embedded in a polymer host deform along preferential planes for >100 ns after the shock first arrives in the crystal. We use in-situ imaging and time-resolved photoemission to demonstrate that short-lived chemistry is linked to high-energy deformation planes. Using scanning electron microscopy and ultrasmall-angle X-ray scattering, we demonstrate that the shock-induced dynamics leave behind sintered crystals, with pore shapes and sizes that change significantly with shock energy. A threshold pressure of ~ 12 GPa at the center of convergence separated the single-mode planar crystal deformations from the chemistry-coupled multi-plane dynamics at higher pressures. Our observations indicate preferential deformation mechanics in our cylindrically shocked system, despite the applied stress along many different crystallographic planes. AUTHOR INFORMATIONCorresponding Author: Leora E. Dresselhaus-Cooper, dresselhausc1@llnl.gov † Present address: Author ContributionsThe project was directed by KAN. Shock experiments were carried out by LEDC. Samples were prepared by LEDC and DJM. USAXS experiments were performed with LEDC, FZ, JI and DJM. The orientation of the crystal in Fig. 6 was measured by LEDC, CT, SYGW and YSC.Analysis of the results were carried out by LEDC and KAN. The manuscript was written by LEDC, with supporting contributions from all authors.

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Dynamic fracture and local failure mechanisms in heterogeneous RDX-Estane energetic aggregates

Cited by 13 publications

References 42 publications

Dynamic Mechanical Behavior of PBX

Dynamic Mechanical Behavior of PBX

Dynamic Mechanical Damage and Non-Shock initiation of a New Polymer Bonded Explosive during Penetration

Pressure-Thresholded Response in Cylindrically Shocked Cyclotrimethylene Trinitramine (RDX)

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