Dynamic response of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>Cu</mml:mtext></mml:mrow><mml:mrow><mml:mn>46</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mtext>Zr</mml:mtext></mml:mrow><mml:mrow><mml:mn>54</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>metallic glass to high-strain-rate shock loading: Plasticity, spall, and atomic-level structures

Arman, Bedri; Luo, Sheng‐Nian; Germann, Timothy C.; Çağın, Tahir

doi:10.1103/physrevb.81.144201

Cited by 94 publications

(27 citation statements)

References 66 publications

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“…4͑b͒ and 4͑c͔͒, similar to a shocked metallic glass. 31 The elastic precursor is not definitely identified in our simulations, similar to experiments. 1,3 The shock front ͓Fig.…”

Section: -supporting

confidence: 46%

“…3 In metallic glass simulations, this rounding is related to plastic deformation. 31 However, such rounding in phenolic resin occurs even at u p = 0.25 km s −1 ͑elastic shock; see below͒, likely due to viscoelastic behavior. 3 ͑Both viscoelasticity and rate-dependent plasticity play a role at higher shock strengths.͒ Since there is no crystalline order in phenolic resin, there are no definitive structure features related to its plasticity as dislocations to crystal plasticity.…”

Section: -mentioning

confidence: 99%

“…109, 013503 ͑2011͒ the order of H, O, and C, and such differences may give rise to localized shear deformation, similar to the observation on a metallic glass. 31 The backbone of a polymeric chain is composed of C atoms, and the stiffness of the backbone may enhance the slip resistance of C atoms. At longer range, the orientation of a segment in a chain may also affect its deformation.…”

Section: -4mentioning

confidence: 99%

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Dynamic response of phenolic resin and its carbon-nanotube composites to shock wave loading

Arman

Luo

et al. 2011

Journal of Applied Physics

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We investigate with nonreactive molecular dynamics simulations the dynamic response of phenolic resin and its carbon-nanotube ͑CNT͒ composites to shock wave compression. For phenolic resin, our simulations yield shock states in agreement with experiments on similar polymers except the "phase change" observed in experiments, indicating that such phase change is chemical in nature. The elastic-plastic transition is characterized by shear stress relaxation and atomic-level slip, and phenolic resin shows strong strain hardening. Shock loading of the CNT-resin composites is applied parallel or perpendicular to the CNT axis, and the composites demonstrate anisotropy in wave propagation, yield and CNT deformation. The CNTs induce stress concentrations in the composites and may increase the yield strength. Our simulations suggest that the bulk shock response of the composites depends on the volume fraction, length ratio, impact cross-section, and geometry of the CNT components; the short CNTs in current simulations have insignificant effect on the bulk response of resin polymer.

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“…4͑b͒ and 4͑c͔͒, similar to a shocked metallic glass. 31 The elastic precursor is not definitely identified in our simulations, similar to experiments. 1,3 The shock front ͓Fig.…”

Section: -supporting

confidence: 46%

Section: -mentioning

confidence: 99%

Section: -4mentioning

confidence: 99%

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Dynamic response of phenolic resin and its carbon-nanotube composites to shock wave loading

Arman

Luo

et al. 2011

Journal of Applied Physics

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“…Thus, the off-GB voids are nucleated on the slip planes or disordered sites 29,30 that can be traced back to the GBs, and such nucleation is a GB effect. We have shown that there is no "homogeneous" void nucleation for both crystalline and amorphous metallic solids, 20,29,31 i.e., void nucleation has to start from "defective," "disordered," or highly sheared sites. So void nucleation is essentially a matter of defect or plasticity nucleation.…”

Section: -5mentioning

confidence: 99%

Shock wave loading and spallation of copper bicrystals with asymmetric Σ3⟨110⟩ tilt grain boundaries

Luo¹,

Germann²,

Tonks³

et al. 2010

Journal of Applied Physics

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We investigate the effect of asymmetric grain boundaries ͑GBs͒ on the shock response of Cu bicrystals with molecular dynamics simulations. We choose a representative ⌺3͗110͘ tilt GB type, ͑110͒ 1 / ͑114͒ 2 , and a grain size of about 15 nm. The shock loading directions lie on the GB plane and are along ͓001͔ and ͓221͔ for the two constituent crystals. The bicrystal is characterized in terms of local structure, shear strain, displacement, stress and temperature during shock compression, and subsequent release and tension. The shock response of the bicrystal manifests pronounced deviation from planar loading as well as strong stress and strain concentrations, due to GBs and the strong anisotropy in elasticity and plasticity. We explore incipient to full spallation. Voids nucleate either at GBs or on GB-initiated shear planes, and the spall damage also depends on grain orientation.

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“…Moreover, this micro-voids dominated fracture process has also been observed in atomic scale during molecular dynamics simulations. Arman et al [4] investigated the dynamic response of a CuZr metallic glass with MD simulations and found that spallation process of this material is accompanied by nucleation and growth of micro-voids. In order to reveal the intrinsic mechanism that governs the fracture process in different metallic glasses, Murali et al [5] performed MD simulations on two typical metallic glasses which were brittle FeP and ductile CuZr.…”

Section: Introductionmentioning

confidence: 99%

Cavitation instability in bulk metallic glasses

Dai

Huang

Zhong

2015

EPJ Web of Conferences

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Abstract.Recent experiments have shown that fracture surfaces of bulk metallic glasses (BMGs) usually exhibit an intriguing nanoscale corrugation like fractographic feature mediated by nanoscale void formation. We attribute the onset of this nanoscale corrugation to TTZs (tension transformation zones) mediated cavitation. In our recent study, the spall experiments of Zr-based BMG using a single-stage light gas gun were performed. To uncover the mechanisms of the spallation damage nucleation and evolution, the samples were designed to be subjected to dynamic tensile loadings of identical amplitude but with different durations by making use of the multi-stress pulse and the double-flyer techniques. It is clearly revealed that the macroscopic spall fracture in BMGs originates from the nucleation, growth and coalescence of micro-voids. Then, a microvoid nucleation model of BMGs based on free volume theory is proposed, which indicates that the nucleation of microvoids at the early stage of spallation in BMGs is resulted from diffusion and coalescence of free volume. Furthermore, a theoretical model of void growth in BMGs undergoing remote dynamic hydrostatic tension is developed. The critical condition of cavitation instability is obtained. It is found that dynamic void growth in BMGs can be well controlled by a dimensionless inertial number characterizing the competition between intrinsic and extrinsic time scales. To unveil the atomic-level mechanism of cavitation, a systematic molecular dynamics (MD) simulation of spallation behaviour of a binary metallic glass with different impact velocities was performed. It is found that micro-void nucleation is determined TTZs while the growth is controlled by shear transformation zones (STZs) at atomic scale.

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Dynamic response ofCu46Zr54metallic glass to high-strain-rate shock loading: Plasticity, spall, and atomic-level structures

Cited by 94 publications

References 66 publications

Dynamic response of phenolic resin and its carbon-nanotube composites to shock wave loading

Dynamic response of phenolic resin and its carbon-nanotube composites to shock wave loading

Shock wave loading and spallation of copper bicrystals with asymmetric Σ3⟨110⟩ tilt grain boundaries

Cavitation instability in bulk metallic glasses

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