Scaling, Microstructure and Dynamic Fracture

Roger, Michel; Kumar, Mukul; Schwarz, Adam; Cazamias, J.

doi:10.1063/1.2263404

Cited by 14 publications

(4 citation statements)

References 7 publications

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“…The effect of the microstructure on the spall (damage) response has been studied extensively. The body of literature spans from the classic works by Barbee, Curran and Seaman, [10][11][12] to Meyers et al, 13 Gray et al, [6][7][8] and recently by Minich et al, [14][15][16] among many others. [17][18][19] However, most of the cited work has focused on the effects of microstructure on pull-back measurements in experiments in which the sample experienced complete failure.…”

Section: Introductionmentioning

confidence: 99%

Effects of grain size and boundary structure on the dynamic tensile response of copper

Escobedo¹,

Dennis-Koller²,

Cerreta³

et al. 2011

Journal of Applied Physics

168

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Plate impact experiments have been carried out to examine the influence of grain boundary characteristics on the dynamic tensile response of Cu samples with grain sizes of 30, 60, 100, and 200 lm. The peak compressive stress is $1.50 GPa for all experiments, low enough to cause an early stage of incipient spall damage that is correlated to the surrounding microstructure in metallographic analysis. The experimental configuration used in this work permits real-time measurements of the sample free surface velocity histories, soft-recovery, and postimpact examination of the damaged microstructure. The resulting tensile damage in the recovered samples is examined using optical and electron microscopy along with micro x-ray tomography. The free surface velocity measurements are used to calculate spall strength values and show no significant effect of the grain size. However, differences are observed in the free surface velocity behavior after the pull-back minima, when reacceleration occurs. The magnitude of the spall peak and its acceleration rate are dependent upon the grain size. The quantitative, postimpact, metallographic analyses of recovered samples show that for the materials with grain sizes larger than 30 lm, the void volume fraction and the average void size increase with increasing grain size. In the 30 and 200 lm samples, void coalescence is observed to dominate the void growth behavior, whereas in 60 and 100 lm samples, void growth is dominated by the growth of isolated voids. Electron backscatter diffraction (EBSD) observations show that voids preferentially nucleate and grow at grain boundaries with high angle misorientation. However, special boundaries corresponding to Rl (low angle, < 5) and R3 ($60 <111> misorientation) types are more resistant to void formation. Finally, micro x-ray tomography results show three dimensional (3D) views of the damage fields consistent with the two dimensional (2D) surface observations. Based on these findings, mechanisms for the void growth and coalescence are proposed. V

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Section: Introductionmentioning

confidence: 99%

Effects of grain size and boundary structure on the dynamic tensile response of copper

Escobedo¹,

Dennis-Koller²,

Cerreta³

et al. 2011

Journal of Applied Physics

168

View full text Add to dashboard Cite

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“…In the past, extensive research has focused on understanding the dynamic fracture response of both metals and alloys, especially in cases where the second phase additions are stiffer than the primary metallic phase. In the case of these single-phase ductile materials, it is widely accepted that microstructure affects the response of a material to dynamic loading, since voids tend to nucleate at heterogeneities in the microstructure such as vacancies, cracks, inclusions, and grain boundaries [1,2,3,4,5,6,7]. However, less is understood about this effect under conditions of two-phase boundaries or at bimetallic interfaces.…”

Section: Introductionmentioning

confidence: 96%

Nucleation and evolution of dynamic damage at Cu/Pb interfaces using molecular dynamics

Fensin¹,

Valone²,

Cerreta³

et al. 2017

AIP Conference Proceedings

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Abstract. For ductile metals, the process of dynamic fracture occurs through nucleation, growth and coalescence of voids. For high purity single-phase metals, it has been observed by numerous investigators that voids tend to heterogeneously nucleate at grain boundaries and all grain boundaries are not equally susceptible to void nucleation. However, for materials of engineering significance, especially those with second phase particles, it is less clear if the type of bi-metal interface between the two phases will affect void nucleation and growth. To approach this problem in a systematic manner two bi-metal interfaces between Cu and Pb have been investigated: {111} and {100}. Qualitative and quantitative analysis of the collected data from molecular dynamics shock and spall simulations suggests that Pb becomes disordered during shock compression and is the preferred location for void nucleation under tension. Despite the interfaces being aligned with the spall plane (by design), they are not the preferred location for void nucleation irrespective of interface type.

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“…However, all these corrections are based on the transmission of acoustic waves within the sample and do not take any microstructural information into account. This information is important because previous work has shown that voids nucleate preferentially at pre-existing flaws like dislocations, grain boundaries, and inclusions in a given material [2,3,[10][11][12][13][14][15]. But in addition to nucleation it has been shown the microstructure affects void growth and coalescence, which together comprise the total damage in the material [4,16,17].…”

Section: Introductionmentioning

confidence: 99%

Microstructure Based Failure Criterion For Ductile Materials

et al. 2018

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For ductile metals, the process of dynamic fracture occurs through nucleation, growth and coalescence of voids. The stress required to nucleate these voids is inferred from the velocimetry data (using the acoustic approach) and termed as the spall strength. This is a key parameter that is used to evaluate a material’s susceptibility to damage and failure. However, it is also well recognized that the dynamic parameters used to generate the shock state such as pulse duration, tensile strain-rate and peak stress coupled with material microstructure itself affect the material response in a complex manner. Yet, it is impossible to capture all this information by assessing only the spall strength measured from simple one-dimensional Photon Doppler Velocimetry measurements. Although, there exist widely used corrections proposed by Kanel et. al. that allow for the inclusion of some of these complexities into the measured spall strength but still does not take the microstructure into account. In this work, we propose another scheme for normalization of spall strength with a damage area to capture the complexities included in the damage and failure process especially pertaining to microstructure. We will also demonstrate the application of this scheme by applying to examples of materials such as Copper, Copper-24 wt%Ag, Copper-15 wt% Nb and additively manufactured 316L SS.

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Scaling, Microstructure and Dynamic Fracture

Cited by 14 publications

References 7 publications

Effects of grain size and boundary structure on the dynamic tensile response of copper

Effects of grain size and boundary structure on the dynamic tensile response of copper

Nucleation and evolution of dynamic damage at Cu/Pb interfaces using molecular dynamics

Microstructure Based Failure Criterion For Ductile Materials

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