Analysis of dynamic fracture and fragmentation of graphite bricks by combined XFEM and cohesive zone approach

Crump, Timothy; Jivkov, Andrey P.; Mummery, Paul; Ferté, Guilhem; Tran, Van-Xuan

doi:10.1016/j.ijpvp.2019.02.013

Cited by 3 publications

(3 citation statements)

References 11 publications

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“…Furthermore, fast cracking at one keyway is anticipated to trigger a secondary crack at another, potentially opposite keyway, leading to brick disintegration. This phenomenon, known as prompt secondary cracking has been investigated in detail by dynamic fracture analysis, with results clearly confirming the anticipation (Crump et al, 2017;Crump et al, 2019).…”

Section: 𝜀 𝑡ℎ = 𝛼 ∆𝑇mentioning

confidence: 62%

Large-Scale Modeling of Damage and Failure of Nuclear Graphite Moderated Reactor

Farrokhnia

Jivkov

Hall

et al. 2022

Journal of Pressure Vessel Technology

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The UK Advanced Gas-Cooled reactors (AGRs) have cores made of graphite bricks with dual functions: as structural elements of the core, providing space for and separating fuel and control rods; and as moderator of the nuclear reaction. Nuclear graphite is a quasi-brittle material, where the dominant mechanism for failure is cracking. While cracking of isolated bricks is expected due to operation-induced changes in graphite microstructure and stress fields, these could be tolerated as far as the overall structural function of the core is maintained. Assessment of the whole core behaviour has been previously done with whole scale models where bricks have been considered as rigid body elements connected by elastic-brittle springs. This approach does not allow for the realistic assessment of the stresses in the bricks and associated brick cracking. Reported here are results from an ongoing project, which addresses this shortcoming. The proposed model uses deformable bricks with appropriate interactions, allowing for physically realistic whole core analysis. The results are focused on the damage that a graphite moderated reactor develops during a life cycle, how this affects the behaviour of the whole core, and how changes in bricks' behaviour impacts the core integrity. The proposed methodology is a major step towards high-fidelity assessment of AGRs' fitness for service, required for supporting continuous safe operation and life-extension decisions.

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Section: 𝜀 𝑡ℎ = 𝛼 ∆𝑇mentioning

confidence: 62%

Large-Scale Modeling of Damage and Failure of Nuclear Graphite Moderated Reactor

Farrokhnia

Jivkov

Hall

et al. 2022

Journal of Pressure Vessel Technology

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“…Later simulations of this same type of test were performed using XFEM [ 27 , 28 ] and configurational mechanics, which similar to XFEM models discrete, mesh-independent fractures [ 29 -31 ]. Later work simulating this test with XFEM included dynamic effects and cohesive tractions [ 32 ].…”

Section: Fracture Propagation Modelingmentioning

confidence: 99%

“…Crump et al [ 32 ] presented an analysis of the fracture and fragmentation of graphite bricks performed using XFEM and cohesive zone modeling approach, which they call XCZM. The capability was implemented into Code_Aster, which was developed by Électricité de France, and used for modeling fragmentation in a 3D AGR brick.…”

Section: Fracture Propagation Modelingmentioning

confidence: 99%

Initial Fracture Propagation Modeling of Graphite Components with Grizzly

Spencer,

Munday,

Singh

et al. 2023

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Graphite has historically been extensively used in power reactor cores and will be used in multiple types of advanced reactors currently under development. These graphite structural components can experience significant stresses due to nonuniform volumetric strains induced by irradiation and thermal expansion, which can lead to fracture. Robust tools for predicting fracture initiation and propagation in graphite structural components in nuclear reactors are important for evaluating component integrity, developing design standards, and interpreting experimental results to characterize graphite performance. The U.S. Department of Energy's Nuclear Energy Advanced Modeling and Simulation program has been developing degradation models for other structural components in nuclear reactors within the Grizzly and BlackBear codes. This report documents an effort to develop initial capabilities for modeling graphite fracture within these codes, building on prior efforts to model fracture in other materials. Major elements of this effort include developing a new system for modeling fracture nucleation and growth in two dimensions using the extended finite element method and incorporating a damage and plasticity model. These capabilities are applied here to model a representative graphite component and a splitting disc experiment used to obtain tensile strength.

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An adaptive dynamic phase-field method using the variable-node elements for cohesive dynamic fracture

Zhang,

Hirshikesh,

et al. 2023

Computer Methods in Applied Mechanics and Engineering

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Analysis of dynamic fracture and fragmentation of graphite bricks by combined XFEM and cohesive zone approach

Cited by 3 publications

References 11 publications

Large-Scale Modeling of Damage and Failure of Nuclear Graphite Moderated Reactor

Large-Scale Modeling of Damage and Failure of Nuclear Graphite Moderated Reactor

Initial Fracture Propagation Modeling of Graphite Components with Grizzly

An adaptive dynamic phase-field method using the variable-node elements for cohesive dynamic fracture

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