Dynamic fragmentation of graphite under laser-driven shocks: Identification of four damage regimes

Seisson, Gabriel; Prudhomme, G.; Frugier, Pierre; Hebert, David G.; Lescoute, E.; Sollier, Arnaud; Videau, L.; Mercier, Patrick P.; Boustie, M.; Berthe, Laurent

doi:10.1016/j.ijimpeng.2015.12.012

Cited by 17 publications

(26 citation statements)

References 30 publications

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“…§2b(ii)); -its behaviour in regime R1 is satisfactory (cf. §3b); and -the value Pl = 150 MPa is closer to the spall stress of 135 MPa deduced from other dynamic experiments [25].…”

Section: (D) Graphite Damage Modelsupporting

confidence: 82%

Hypervelocity impacts into porous graphite: experiments and simulations

Hebert

Seisson

Rullier

et al. 2017

Phil. Trans. R. Soc. A.

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We present experiments and numerical simulations of hypervelocity impacts of 0.5 mm steel spheres into graphite, for velocities ranging between 1100 and 4500 m s Experiments have evidenced that, after a particular striking velocity, depth of penetration no longer increases but decreases. Moreover, the projectile is observed to be trapped below the crater surface. Using numerical simulations, we show how this experimental result can be related to both materials, yield strength. A Johnson-Cook model is developed for the steel projectile, based on the literature data. A simple model is proposed for the graphite yield strength, including a piecewise pressure dependence of the Drucker-Prager form, which coefficients have been chosen to reproduce the projectile penetration depth. Comparisons between experiments and simulations are presented and discussed. The damage properties of both materials are also considered, by using a threshold on the first principal stress as a tensile failure criterion. An additional compressive failure model is also used for graphite when the equivalent strain reaches a maximum value. We show that the experimental crater diameter is directly related to the graphite spall strength. Uncertainties on the target yield stress and failure strength are estimated.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

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“…§2b(ii)); -its behaviour in regime R1 is satisfactory (cf. §3b); and -the value Pl = 150 MPa is closer to the spall stress of 135 MPa deduced from other dynamic experiments [25].…”

Section: (D) Graphite Damage Modelsupporting

confidence: 82%

Hypervelocity impacts into porous graphite: experiments and simulations

Hebert

Seisson

Rullier

et al. 2017

Phil. Trans. R. Soc. A.

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“…In future, the degree of confidence in the soft recovered technique must be evaluated and recognized. While, some researchers have suggested the improved recovery means by optimizing the metal target structure or choosing the collector material with density close to the water, 33 so as to reduce the possibility of secondary fragmentation during the soft recovery process.…”

Section: Discussionmentioning

confidence: 99%

Fragment size distribution statistics in dynamic fragmentation of laser shock-loaded tin

He¹,

Xin²,

Zhao³

et al. 2017

AIP Advances

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This work investigates the geometric statistics method to characterize the size distribution of tin fragments produced in the laser shock-loaded dynamic fragmentation process. In the shock experiments, the ejection of the tin sample with etched V-shape groove in the free surface are collected by the soft recovery technique. Subsequently, the produced fragments are automatically detected with the fine post-shot analysis techniques including the X-ray micro-tomography and the improved watershed method. To characterize the size distributions of the fragments, a theoretical random geometric statistics model based on Poisson mixtures is derived for dynamic heterogeneous fragmentation problem, which reveals linear combinational exponential distribution. The experimental data related to fragment size distributions of the laser shock-loaded tin sample are examined with the proposed theoretical model, and its fitting performance is compared with that of other state-of-the-art fragment size distribution models. The comparison results prove that our proposed model can provide far more reasonable fitting result for the laser shock-loaded tin. © 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

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“…The spall strength can be obtained from the tensile stress amplitude, which can be calculated from the measured free surface velocities of V max and V min when the impact compression stress is below HEL [39][40][41][42][43] …”

Section: Effect Of Shock Compression Stress On the Shock And Spall Bementioning

confidence: 99%

Shock and spall behaviors of a high specific strength steel: Effects of impact stress and microstructure

Wang

Zhang

Yang

et al. 2017

Journal of Applied Physics

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A series of plate-impact experiments were conducted to investigate the influences of impact stress and microstructure on the shock and spall behaviors of a high specific strength steel (HSSS). The HSSS shows a strong positive strain rate sensitivity on the yield strength. With increasing impact stress up to about 6 GPa, the spall strength is found to decrease significantly and then levels off with further increasing impact stress. This trend is proposed to be attributed to the accumulation damage within the target as the initial shock-induced compression wave propagates through the target. The microcracks are clearly observed to nucleate from the interfaces between γ-austenite and B2 phase and propagate along the interfaces or cut through the B2 phase in the HSSS during the spalling process. The Hugoniot elastic limit and the spall strength were found to be highly dependent on the microstructure. The spall strength was found to be higher when the density of the void nucleation sites is lower, indicating that the spall strength should be a microstructure parameter of the HSSS under impact tensile conditions depending on the density of phase interfaces. It was also found that there is a tradeoff between the specific yield strength and the spall strength for this HSSS; thus, the current findings should provide insights for achieving an optimal combination of both mechanical properties for impact-resistant applications by tailoring the microstructure.

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Dynamic fragmentation of graphite under laser-driven shocks: Identification of four damage regimes

Cited by 17 publications

References 30 publications

Hypervelocity impacts into porous graphite: experiments and simulations

Hypervelocity impacts into porous graphite: experiments and simulations

Fragment size distribution statistics in dynamic fragmentation of laser shock-loaded tin

Shock and spall behaviors of a high specific strength steel: Effects of impact stress and microstructure

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