Dynamic fracture and hot-spot modeling in energetic composites

Grilli, Nicolò; Duarte, Camilo A.; Koslowski, Marisol

doi:10.1063/1.5009297

Cited by 51 publications

(27 citation statements)

References 52 publications

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“…Notice that this computational phenomenon (unstoppable "thickening" of damage around crack lines) can be observed in many phase-field simulations of dynamic brittle fracture published in the literature (e.g. [90,91], see Fig. 18) even if the topic has not been paid the attention it probably deserves.…”

Section: Time Of Crack Branchingmentioning

confidence: 88%

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Comparison of peridynamic and phase-field models for dynamic brittle fracture in glassy materials

Mehrmashhadi¹,

Bahadori²,

Bobaru³

2020

Preprint

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We report computational results obtained with three different models for dynamic brittle fracture. The results are compared against recent experimental tests on dynamic fracture/crack branching in glass induced by impact. Two peridynamic models (one using the meshfree discretization, the other being the LS-DYNA’s discontinuous-Galerkin implementation) and a phase-field model lead to interesting and important differences in terms of reproducing the experimentally observed fracture behavior and crack paths. We monitor the crack branching location, the angle of crack branching, the crack propagation speed, and some particular features seen in the experimental crack paths: small twists/kinks near the far edge of the sample. We discuss the models’ performance and provide possible reasons behind the failure of some of the models to correctly predict the observed behavior.

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Section: Time Of Crack Branchingmentioning

confidence: 88%

“…In (a): time evolution of damage field ( from[90]) with white regions in the damage field represent values with ϕ > 0.97. In (b): increasing expansion of damage in the direction perpendicular to the crack growth direction, with time (from[91]) .…”

mentioning

confidence: 99%

Comparison of peridynamic and phase-field models for dynamic brittle fracture in glassy materials

Mehrmashhadi¹,

Bahadori²,

Bobaru³

2020

Preprint

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“…For opened cracks κ = 5−ν, while for closed cracks κ = 3. The relation between a' and β e is a = (2G β e ) 1/3 (17) The deviatoric constitutive law of PBX1314 is obtained by the combination of Equations (2), (14), (16) and expressed as .…”

Section: Dynamic Damage Modelmentioning

confidence: 99%

“…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 ]. The calculations reveal that the localized damage at the particle-binder interface contributes to the formation of hot spots.…”

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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“…The role of friction is also addressed by a third approach based on a damage phase field to describe the appearance and evolution of cracks [13,15,16,27,28]. This method allows (1) to replicate the damage observed during impacts on single crystals [18,28] and (2) to reproduce the initiation threshold of the β-HMX single crystal observed at 445 m/s [16,29].…”

Section: Introductionmentioning

confidence: 99%

Plastic Dissipation and Hot‐Spot Formation in HMX‐Based PBXs Subjected to Low Velocity Impact

Drouet

Picart

Bailly

et al. 2020

Propellants Explo Pyrotec

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Low-velocity, shock-free impact is one of the accidental loads that can lead to a thermal explosion, the latter being the consequence of a chain of mechanisms depending on the microstructure of the material. To investigate the causes, the predictive capability of numerical tools depends on the physics embedded in the models. While a consensus has developed around the concept of hot spots, the exact nature of the thermo-mechanical heat-generating processes that preceded them remains to be clarified. We are studying a composition similar to the PBX 9501. HMX crystals are mixed with a few percent of a polymer binder. Recent experiments (reverse edge-on impact test) have revealed the influence of the plasticity of HMX grains even at low strain rates and low confinement. The heat released by the plastic dissipation has been identified as a potential candidate for the formation of hot spots. In this study, a numerical representation based on a polycrystalline β-HMX material subjected to intense shear is presented. Due to the high pressure generated by the impact, the intergranular slip is ignored. Emphasis is placed on the heterogeneity resulting from the micro-structural characteristics and the interaction between the anisotropic single crystals. The behavior of the binder and the influence of other heterogeneities such as friction or micro cracks are set aside. Finally, the mechanical dissipation is calculated in the models and the maximum temperature is deduced.

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Dynamic fracture and hot-spot modeling in energetic composites

Cited by 51 publications

References 52 publications

Comparison of peridynamic and phase-field models for dynamic brittle fracture in glassy materials

Comparison of peridynamic and phase-field models for dynamic brittle fracture in glassy materials

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

Plastic Dissipation and Hot‐Spot Formation in HMX‐Based PBXs Subjected to Low Velocity Impact

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