A constitutive model based on the evolution and coalescence of elliptical micro-cracks for quasi-brittle materials

Ning, Jianguo; Ren, Huilan; Fang, Min-Jie

doi:10.1007/s11434-012-5319-4

Cited by 10 publications

(9 citation statements)

References 29 publications

(33 reference statements)

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“…Moreover, cracks are one of the main hidden defects in concrete structures; they cause brittle fractures, shorten the service life, and lower the durability [ 1 ]. Generally, the damage and failure of concrete are caused by the nucleation, growth, and coalescence of microcracks [ 2 , 3 , 4 ]. One strategy to inhibit the formation of cracks is to randomly introduce short, discrete microfibers (e.g., steel fiber or polypropylene fiber) into concrete [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Properties of Cement Mortar and Ultra-High Strength Concrete Incorporating Graphene Oxide Nanosheets

Ouyang

2017

Nanomaterials

111

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In this work, the effect of graphene oxide nanosheet (GONS) additives on the properties of cement mortar and ultra-high strength concrete (UHSC) is reported. The resulting GONS-cement composites were easy to prepare and exhibited excellent mechanical properties. However, their fluidity decreased with increasing GONS content. The UHSC specimens were prepared with various amounts of GONSs (0–0.03% by weight of cement). Results indicated that using 0.01% by weight of cement GONSs caused a 7.82% in compressive strength after 28 days of curing. Moreover, adding GONSs improved the flexural strength and deformation ability, with the increase in flexural strength more than that of compressive strength. Furthermore, field-emission scanning electron microscopy (FE-SEM) was used to observe the morphology of the hardened cement paste and UHSC samples. FE-SEM observations showed that the GONSs were well dispersed in the matrix and the bonding of the GONSs and the surrounding cement matrix was strong. Furthermore, FE-SEM observation indicated that the GONSs probably affected the shape of the cement hydration products. However, the growth space for hydrates also had an important effect on the morphology of hydrates. The true hydration mechanism of cement composites with GONSs needs further study.

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Section: Introductionmentioning

confidence: 99%

Properties of Cement Mortar and Ultra-High Strength Concrete Incorporating Graphene Oxide Nanosheets

Ouyang

2017

Nanomaterials

111

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“…Moreover, cracks are one of the main hidden defects in concrete structures; they cause brittle fracture, shorten the service life, and lower the durability [ 2 , 3 , 4 , 5 ]. Generally, the damage and failure of concrete are caused by the nucleation, growth, and coalescence of microcracks [ 6 , 7 , 8 ]. One strategy to inhibit the formation of cracks is to randomly introduce short discrete fibers into concrete [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Durability of Ultra High Strength Concrete Incorporating Multi-Walled Carbon Nanotubes

Ouyang

2016

Materials

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In this work, the effect of the addition of multi-walled carbon nanotubes (MWCNTs) on the mechanical properties and durability of ultra high strength concrete (UHSC) is reported. First, the MWCNTs were dispersed by a nano sand-mill in the presence of a surfactant in water. The UHSC specimens were prepared with various amounts of MWCNTs, ranging from 0% to 0.15% by weight of cement (bwoc). Results indicated that use of an optimal percentage of MWCNTs (0.05% bwoc) caused a 4.63% increase in compressive strength and a 24.0% decrease in chloride diffusion coefficient of UHSC at 28 days curing. Moreover, the addition of MWCNTs also improved the flexural strength and deformation ability. Furthermore, a field-emission scanning electron microscopy (FE-SEM) was used to observe the dispersion of MWCNTs in the cement matrix and morphology of the hardened cement paste containing MWCNTs. FE-SEM observation revealed that MWCNTs were well dispersed in the matrix and no agglomerate was found and the reinforcing effect of MWCNTs on UHSC was thought to be pulling out and microcrack bridging of MWCNTs, which transferred the load in tension.

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“…Following the work [16,17], ARK N methods can be used to solve the equations of the form: [5] that adopted in this work are third-order, fourth-order, and fifth-order ARK2 methods, respectively. Meanwhile, the non-stiff convective term in this paper was numerically discretized in space using fifth-order WENO scheme [22][23][24][25][26][27][28][29].…”

Section: Methodsmentioning

confidence: 99%

Additive Runge-Kutta methods for H2/O2/Ar detonation with a detailed elementary chemical reaction model

Ren

Ning

2013

Chin. Sci. Bull.

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We report here the additive Runge-Kutta methods for computing reactive Euler equations with a stiff source term, and in particular, their applications in gaseous detonation simulations. The source term in gaseous detonation is stiff due to the presence of wide range of time scales during thermal-chemical non-equilibrium reactive processes and some of these time scales are much smaller than that of hydrodynamic flow. The high order, L-stable, additive Runge-Kutta methods proposed in this paper resolved the stiff source term into the stiff part and non-stiff part, in which the stiff part was solved implicitly while the non-stiff part was handled explicitly. The proposed method was successfully applied to simulating the gaseous detonation in a stoichiometric H 2 /O 2 /Ar mixture based on a detailed elementary chemical reaction model comprised of 9 species and 19 elementary reactions. The results showed that the stiffly accurate additive Runge-Kutta methods can capture the discontinuity well, and describe the detonation complex wave configurations accurately such as the triple wave structure and cellular pattern. Reacting flows, specifically in gaseous combustion, have been a significant topic of active research for more than one hundred years. The strong coupling between hydrodynamic flow and chemical kinetics is complex and even today many phenomena are not very well understood yet. Gaseous detonation is a process of supersonic combustion in which a shock wave is propagated and supported by the energy release in a reaction zone behind it. It is the more powerful and destructive of the two general classes of combustion, the other one being deflagration. The primary difficulty in computing reacting flows is the source term stiffness inherent in the reactive Euler equations in temporal integrations. Besides, the viscous stress and heat flux terms in the boundary layers can cause the stiffness too. The source terms are stiff because the thermal-chemical non-equilibrium reactive processes possess a wide range of time scales and some of them are much smaller than that of hydrodynamic flow [1]. The simulation will be inefficient when the explicit methods rather than the implicit methods are used, because the time-step sizes dictated by the stability restraint in explicit methods are much smaller than those required by the CFL condition. Due to these limitations in explicit methods, the implicit methods are normally required to simulate gaseous detonation. The practical implicit methods for gaseous detonation simulation can be categorized into two classes, i.e. the time-splitting method and the additive semi-implicit method [2,3].The time-splitting methods [4][5][6][7][8], resolve the source term of reactive Euler equations into ( ) ( ),   t

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A constitutive model based on the evolution and coalescence of elliptical micro-cracks for quasi-brittle materials

Cited by 10 publications

References 29 publications

Properties of Cement Mortar and Ultra-High Strength Concrete Incorporating Graphene Oxide Nanosheets

Properties of Cement Mortar and Ultra-High Strength Concrete Incorporating Graphene Oxide Nanosheets

Mechanical Properties and Durability of Ultra High Strength Concrete Incorporating Multi-Walled Carbon Nanotubes

Additive Runge-Kutta methods for H2/O2/Ar detonation with a detailed elementary chemical reaction model

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