An improved computational constitutive model for brittle materials

Johnson, Gordon R.; Holmquist, Timothy J.

doi:10.1063/1.46199

Cited by 453 publications

(310 citation statements)

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“…The model must take into account, in addition to strain, the strain rate (which in case of shock waves can be as high as 10 6 s -1 ) and the temperature (above melting point the material practically loses its shear strength and behaves as a fluid). Most used models are Johnson-Cook [14], Steinberg-Guinan [16] and Johnson-Holmquist [17].…”

Section: Materials Modelling and Advanced Simulation Toolsmentioning

confidence: 99%

An experiment to test advanced materials impacted by intense proton pulses at CERN HiRadMat facility

Bertarelli

Berthomé

Boccone

et al. 2013

Nuclear Instruments and Methods in Physics Research Section B:

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SummaryPredicting the consequences of highly energetic particle beams impacting protection devices as collimators or high power target stations is a fundamental issue in the design of state-ofthe-art facilities for high-energy particle physics. These complex dynamic phenomena, which may induce material phase transitions, extended density changes, shock waves generation, explosions, material fragment projections etc., have been successfully simulated resorting to highly non-linear numerical tools (Hydrocodes). In order to produce accurate results, however, these codes require reliable material constitutive models that, at the extreme conditions induced by a destructive beam impact, are scarce and often inaccurate. In order to derive or validate such models (Equations of State, Strength Models, Failure Models), a comprehensive, first-of-its-kind experiment has been recently carried out at CERN HiRadMat facility: performed tests entailed the controlled impact of intense and energetic proton pulses on a number of specimens made of six different materials. Experimental data were acquired, mostly in real time, relying on extensive embedded instrumentation (strain gauges, temperature and vacuum sensors) and on remote acquisition devices (laser Doppler vibrometer and high-speed camera). The dynamic ranges of the digital acquisition system were sufficient to acquire the very fast and intense shock waves generated by the impact. The high speed video camera allowed capturing a number of frames during the time of flight of the material fragments projected away from impacted specimens. This information is then benchmarked against advanced numerical simulations. Preliminary results of the tests are discussed. In depth post-irradiation analyses are foreseen once the specimens have reached a sufficiently low level of activation. The experimental method presented in this paper may find applications to test materials under very high strain rates and temperatures in domains well beyond particle physics (severe accidents in fusion and fission nuclear facilities, space debris impacts, fast and intense loadings on materials and structures etc.).-2 -

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Section: Materials Modelling and Advanced Simulation Toolsmentioning

confidence: 99%

An experiment to test advanced materials impacted by intense proton pulses at CERN HiRadMat facility

Bertarelli

Berthomé

Boccone

et al. 2013

Nuclear Instruments and Methods in Physics Research Section B:

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“…In our case, these parameters are deter mined by fitting (least squares) the pressure strength curves of the ceramic constitutive model JH2 [13] proposed experimentally by Cronin et al [47] for different ceramic materials.…”

Section: Parameter Calibrationmentioning

confidence: 99%

“…For instance, Malvar et al [27] proposed the widely used K&C model which uses a mixture law to determine the yield surface of the damage material, as considered by some authors for ceramic mate rials [13,15,19]. Also Zhou and Hao [28] used a mixture law driven by a scalar damage parameter to determine the yield stress of the damaged mortar in a mesoscale model for concrete submitted to impact loading; the yield stress of both undamaged and residual strength materials were defined through a piecewise pressure dependent law.…”

Section: Introductionmentioning

confidence: 99%

“…Similarly, Hentz et al [29] considered a Mohr Coulomb criterion to reproduce the pressure dependent behavior of concrete, reducing the slope and neglecting cohesion after fail ure. The Johnson Holmquist model [13], commonly used for cera mic materials, was enhanced by Riedel and co workers [30,31], leading to the RHT model. Several new features like strain harden ing, third invariant dependent yield surface, and an independent fracture strength surface, were incorporated to allow a more appropriate modelling of concrete softening.…”

Section: Introductionmentioning

confidence: 99%

“…The first version of the model, called the JH 1 [12], was developed to account for large deformations of brittle materials such as ceramics, rocks and concrete over a range of strain rates. The sec ond version, called JH 2 [13], took into consideration progressive degradation with increasing deformation through a damage evolu tion rule. Fahrenthold [14] developed a continuum model in which damage is described by a second order tensor.…”

Section: Introductionmentioning

confidence: 99%

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A constitutive equation for ceramic materials used in lightweight armors

Fernández-Fdz

Zaera

Fernández-Sáez

2011

Computers & Structures

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a b s t r a c tA constitutive model to simulate the behavior of ceramic materials under impact loading is proposed in order to achieve a better representation of the damage process due to the material fragmentation. To integrate the proposed constitutive equations, a semi implicit algorithm (implicit for the stresses and explicit for the damage variable) has been developed, leading to the generalized expressions of the clas sical return mapping algorithm. The model was implemented in a commercial finite element code and its performance was demonstrated by comparing its predictions with experimental results obtained by other authors.

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Numerical simulations of impact crater formation with dilatancy

2014

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Impact‐induced fracturing creates porosity that is responsible for many aspects of the geophysical signature of an impact crater. This paper describes a simple model of dilatancy—the creation of porosity in a shearing geological material—and its implementation in the iSALE shock physics code. The model is used to investigate impact‐induced dilatancy during simple and complex crater formation on Earth. Simulations of simple crater formation produce porosity distributions consistent with observations. Dilatancy model parameters appropriate for low‐quality rock masses give the best agreement with observation; more strongly dilatant behavior would require substantial postimpact porosity reduction. The tendency for rock to dilate less when shearing under high pressure is an important property of the model. Pressure suppresses impact‐induced dilatancy: in the shock wave, at depth beneath the crater floor, and in the convergent subcrater flow that forms the central uplift. Consequently, subsurface porosity distribution is a strong function of crater size, which is reflected in the inferred gravity anomaly. The Bouguer gravity anomaly for simulated craters smaller than 25 km is a broad low with a magnitude proportional to the crater radius; larger craters exhibit a central gravity high within a suppressed gravity low. Lower crustal pressures on the Moon relative to Earth imply that impact‐induced dilatancy is more effective on the Moon than Earth for the same size impact in an initially nonporous target. This difference may be mitigated by the presence of porosity in the lunar crust.

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An improved computational constitutive model for brittle materials

Cited by 453 publications

References 2 publications

An experiment to test advanced materials impacted by intense proton pulses at CERN HiRadMat facility

An experiment to test advanced materials impacted by intense proton pulses at CERN HiRadMat facility

A constitutive equation for ceramic materials used in lightweight armors

Numerical simulations of impact crater formation with dilatancy

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