Digital Image Correlation to Evaluate Shear Banding in Dilative Sands

Rechenmacher, Amy L.; Finno, Richard J.

doi:10.1520/gtj10864

Cited by 120 publications

(73 citation statements)

References 19 publications

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“…Rechenmacher & Finno, 2004;Sachan et al, 2006) to analyse local strains in experiments. Such analyses are based on an analysis of the displacements of the particles on the exterior of the specimen.…”

Section: Analysis Of Local Strainsmentioning

confidence: 99%

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An analysis of the triaxial apparatus using a mixed boundary three-dimensional discrete element model

2007

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The triaxial test is probably the most important fundamental laboratory test for geotechnical engineers. The objective of the study presented here was to gain insight into the micro-scale interactions experienced by particles during a triaxial test using the distinct element method (DEM). To achieve this objective, a novel DEM modelling environment to simulate triaxial tests on ideal granular materials was implemented, as described here. In this test environment, both the stress conditions and boundary conditions in the physical tests can be accurately reproduced. This approach was quantitatively validated by simulating a number of physical triaxial tests on specimens of steel spheres. A comparison between the circumferential periodic boundaries used here and the circumferential rigid boundaries used by other researchers emphasises the significance of maintaining a continuous particle-particle contact network orthogonal to the major principal stress direction.Results of an analysis of the micro-scale response in a triaxial simulation are analysed in detail, including the stresses, the distribution of contact forces, the evolution of fabric, the distribution of local strains, and the particle rotations. Significant non-uniformities in the stresses, strains and contact fabric were observed.

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Section: Analysis Of Local Strainsmentioning

confidence: 99%

“…Researchers have also used image analysis to look at the distribution of particle displacements (and hence strains) along the exterior of the sample (e.g. Rechenmacher & Finno, 2004;Sachan et al, 2006). All of these methods focus on the local response on the exterior of the sample.…”

Section: Introductionmentioning

confidence: 99%

An analysis of the triaxial apparatus using a mixed boundary three-dimensional discrete element model

2007

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“…In contrast, some of the high-end testing techniques mentioned above, specifically the CT digital imaging technique, can very well be combined with existing computer tools that permit an accurate quantification of material heterogeneity in soil samples. Examples of such techniques include digital image processing (DIP) for quantifying the spatial density variation and digital image correlation (DIC) for tracking the motion of a group of particles contained in a 'meso-element' having the size of a pixel [3,4].…”

Section: Introductionmentioning

confidence: 99%

Capturing strain localization in dense sands with random density

Andrade

Borja

2006

Numerical Meth Engineering

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SUMMARYThis paper presents a three-invariant constitutive framework suitable for the numerical analyses of localization instabilities in granular materials exhibiting unstructured random density. A recently proposed elastoplastic model for sands based on critical state plasticity is enhanced with the third stress invariant to capture the difference in the compressive and extensional yield strengths commonly observed in geomaterials undergoing plastic deformation. The new three-invariant constitutive model, similar to its two-invariant predecessor, is capable of accounting for meso-scale inhomogeneities as well as material and geometric nonlinearities. Details regarding the numerical implementation of the model into a fully nonlinear finite element framework are presented and a closed-form expression for the consistent tangent operator, whose spectral form is used in the strain localization analyses, is derived. An algorithm based on the spectral form of the so-called acoustic tensor is proposed to search for the necessary conditions for deformation bands to develop. The aforementioned framework is utilized in a series of boundary-value problems on dense sand specimens whose density fields are modelled as exponentially distributed unstructured random fields to account for the effect of inhomogeneities at the meso-scale and the intrinsic uncertainty associated with them.

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“…White et al, 2003); and to measure local strains and study strain localisation in laboratory element tests on plane strain or circular cylindrical specimens tested outside a triaxial cell (e.g. Liang et al, 1997;Macari et al, 1997;Alshibli and Al-Hamdan, 2001;Rechenmacher and Finno, 2004;Gachet et al, 2007;Sevi et al, 2009). In the current study, the image-based deformation measurement method developed by Bhandari et al (2012), Triax-DIC, which uses ray-tracing to account for refraction through the triaxial cell wall and confining fluid, was used.…”

Section: Image-based Local Deformation Measurementmentioning

confidence: 99%

A behavioural framework for fibre-reinforced gravel

et al. 2017

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The mechanical behaviour of granular materials is known to be influenced by the addition of fibres. However, most previous research has been carried out on materials with relatively small grains (sands), and its application to larger grains is not well documented. This paper reports an investigation into the mechanical behaviour of a fibre reinforced granular material having a relatively large grain size corresponding to 1/3 rd and 1/5 th scaled railway ballast. The investigation was carried out by means of triaxial tests incorporating a fullfield, image-based deformation measurement technique; this enabled detailed observations to be made of each triaxial test specimen during shearing. The test data demonstrate the benefits of random fibre reinforcement for aggregates having a relatively large grain size. Analysis taking into account the effect of fibre tension on the effective stresses experienced by the granular skeleton provides new insights into the mechanisms of reinforcement in larger sized granular materials.

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Digital Image Correlation to Evaluate Shear Banding in Dilative Sands

Cited by 120 publications

References 19 publications

An analysis of the triaxial apparatus using a mixed boundary three-dimensional discrete element model

An analysis of the triaxial apparatus using a mixed boundary three-dimensional discrete element model

Capturing strain localization in dense sands with random density

A behavioural framework for fibre-reinforced gravel

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