Synchronous multi-scale observations on rock damage and rupture

Xu, X. H.; Ma, Shuping; Xia, Mingji; Ke, Fu Jiu; Bai, Yilong

doi:10.1016/j.tafmec.2005.06.003

Cited by 20 publications

(7 citation statements)

References 11 publications

(11 reference statements)

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“…A rock's microstructural heterogeneity produces a spatially inconsistent strain response to the external stress field, which causes multiscale (specimen‐scale to grain‐scale) fluctuations/localizations in strain redistribution (Blair & Cook, ; Bornert et al, ; Dautriat et al, ). Global mean field or specimen‐scale measurements assume that the strains released from a broken mesoscopic unit are shared uniformly by all intact units (Xia et al, ; Xu et al, ). At reduced scales of measurement, localized strain fluctuations become much more evident as the strains from a broken unit flow locally only to the neighboring units (Xu et al, ; Xu, Xia, et al, ).…”

Section: Resultsmentioning

confidence: 99%

“…Global mean field or specimen‐scale measurements assume that the strains released from a broken mesoscopic unit are shared uniformly by all intact units (Xia et al, ; Xu et al, ). At reduced scales of measurement, localized strain fluctuations become much more evident as the strains from a broken unit flow locally only to the neighboring units (Xu et al, ; Xu, Xia, et al, ). Consequently, the critical value of extensile strain (ε c ) was evaluated at three scales: (i) specimen‐scale, (ii) pixel‐scale, and (iii) grain‐scale (Figure ).…”

Section: Resultsmentioning

confidence: 99%

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Experimental Relationship Between Compressional Wave Attenuation and Surface Strains in Brittle Rock

2019

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Linear ultrasonic testing (LUT) has been extensively used as a tool for the evaluation of damage processes in various materials ranging from synthetic metals to natural geomaterials, such as rocks. A key limitation of LUT‐based damage studies to date is the lack of explicit evidence used in associating material damage with the changes in measured LUT attributes (e.g., ultrasonic wave amplitude and velocity). In this study, the evolution of the full‐field strains in brittle rock specimens (Lyons sandstone) subjected to failure are analyzed in real time and linked with the changes in the ultrasonic wave amplitude in localized areas illuminated by ultrasonic beams, termed as the ultrasonic image areas. The noncontact optical full‐field displacement measurement method of 2‐D digital image correlation is implemented in combination with the LUT procedure to continuously track changes in the ultrasonic wave amplitude with the evolution of strains across the surface of the uniaxially loaded intact rock specimens. The ultrasonic amplitude showed near‐linear correlation with the intensity of inelastic tensile strain recorded in the rock specimens. The results from the study corroborate that the ultrasonic changes are in fact influenced by the regions of tensile cracking, which is the primary inelastic deformation mechanism in brittle rocks.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Experimental Relationship Between Compressional Wave Attenuation and Surface Strains in Brittle Rock

2019

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“…DSCM is a non-contact optical method for full-field displacement and strain measurements that require digital images captured before and after deformation. 19 In the present measurements, the surface of the sample was firstly spray-painted to generate artificial speckles and then illuminated by two fibre optic white light sources during loading. The painted surface of the sample under the indenter is shown in Fig.…”

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confidence: 99%

Temperature dependent dynamics transition of intermittent plastic flow in a metallic glass. I. Experimental investigations

Liu

Wang

Chan

et al. 2013

Journal of Applied Physics

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Cooling shrinkage can increase the atomic packing density of metallic glasses, which can influence their elastic and plastic behaviour. In the present study, the compressive deformation behaviour of a Zr-based metallic glass at temperatures well below the glassy transition temperature, say 123 K to room temperature, is experimentally revealed. The elastic modulus and the shear modulus at different temperatures are measured to elucidate the yield strength changes with temperature according to the model of shear transformation zones. In the plastic regime, based on the SEM observation and the digital scattering correlation method, an enhanced interaction between the elastic shear strain fields initiated by neighbouring shear bands is discussed, which explains the amplitude of serration events decreasing with the temperature decreasing. V C 2013 AIP Publishing LLC.

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“…Digital speckle pattern metrology [30,31] has been widely applied to the measurement of deformation of materials and structures. Also, digital speckle correlation method (DSCM) [28,32] has been applied to measure deformation field of rock. In this paper, in order to explore the process from localization to eventual rupture, a similar digital speckle correlation method is adopted to examine the spatio-temporal pattern of the surface deformation fields of specimens.…”

Section: Experimental Methods For Surface Strain-field Measurementmentioning

confidence: 99%

Relationship between strain localization and catastrophic rupture

Hao¹,

Wang²,

Xia³

et al. 2007

Theoretical and Applied Fracture Mechanics

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In order to explore a prior warning to catastrophic rupture of heterogeneous media, like rocks, the present study investigates the relationship between surface strain localization and catastrophic rupture. Instrumented observations on the evolution of surface strain field and the catastrophic rupture of a rock under uniaxial compression were carried out. It is found that the evolution of surface strain field displays two phases: at the early stage, the strain field keeps nearly uniform with weak fluctuations increasing slowly; but at the stage prior to catastrophic rupture, a certain accelerating localization develops and a localized zone emerges. Based on the measurements, an analysis was performed with local mean-field approximation. More importantly, it is found that the scale of localized zone is closely related to the catastrophic rupture strain and the rupture strain can be calculated in accord with the local-mean-field model satisfactorily. This provides a possible clue to the forecast of catastrophic rupture.

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Synchronous multi-scale observations on rock damage and rupture

Cited by 20 publications

References 11 publications

Experimental Relationship Between Compressional Wave Attenuation and Surface Strains in Brittle Rock

Experimental Relationship Between Compressional Wave Attenuation and Surface Strains in Brittle Rock

Temperature dependent dynamics transition of intermittent plastic flow in a metallic glass. I. Experimental investigations

Relationship between strain localization and catastrophic rupture

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