The Use of Digital Image Processing in Monitoring Shear Band Development

Liang, Liqun; Saada, Adel S.; Figueroa, J. Ludwig; Cope, C.T.

doi:10.1520/gtj19970008

Cited by 28 publications

(16 citation statements)

References 8 publications

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“…Yoshida et al [4] studied the shear band generation in sand specimens under plane strain conditions by calculating the displacements of lattice points printed on a membrane. Similar observations using a printed membrane have been done by Liang et al [5], Hayano et al [6], and Kodaka et al [7]. In order to observe the strain localization inside specimens, X-rays or X-ray CTs have been used by many researchers [1,[8][9][10][11].…”

Section: Introductionmentioning

confidence: 63%

Effects of sample shape on the strain localization of water‐saturated clay

Kodaka

Higo

Kimoto

et al. 2007

Num Anal Meth Geomechanics

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SUMMARYStrain localization is an important geotechnical problem related to large deformations and the onset of failure, such as slope failure. It is necessary, therefore, to clarify the mechanisms of the strain localization of geomaterials in order to predict large deformations of the ground. For the last two decades, many researchers have studied the strain localization of geomaterials through both experimental and numerical works. Most of the works, however, particularly the numerical studies, have been treated as two-dimensional plane strain problems for the sake of simplicity, even though the actual phenomena are generally three dimensional.In order to understand the deformation, the failure, and the strain localization of clay under threedimensional conditions, triaxial tests on clay and their numerical simulation are performed in the present study. In particular, focus is mainly placed on the effects of sample shape on the localization behaviour of normally consolidated and overconsolidated clays. A series of undrained triaxial compression tests, using rectangular clay specimens with different shapes and strain rates, is conducted. Localized shear strain distributions are successfully observed with an image analysis of digital photographs. It is seen that the shape of a specimen affects the various bifurcation phenomena of clay, e.g. the formation and the progress of various three-dimensional shear bands, failure with buckling, etc. The numerical simulation using the finite element method, with an elasto-viscoplastic model and considering structural changes, can reproduce the generation and the growing process of shear bands well. A comparison between the results of the experiment and the simulation offers new findings regarding the strain localization of clay under threedimensional conditions.

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Section: Introductionmentioning

confidence: 63%

Effects of sample shape on the strain localization of water‐saturated clay

Kodaka

Higo

Kimoto

et al. 2007

Num Anal Meth Geomechanics

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“…Whereas friction, rolling resistance and plasticity parameters had a limited in uence in changing the shear-bands width, a small amount of cohesive traction had a large impact. Moreover, many experimental studies have revealed that in sands, shear bands typically have a thickness around 20 grain diameters (Finno et al, 1996, Liang et al, 1997. In contrast, powdered metals exhibit wider shear bands.…”

Section: In Uence Of Cohesionmentioning

confidence: 99%

Shear bands in dense metallic granular materials

2004

Journal of the Mechanics and Physics of Solids

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“…Shear bands in sands are of considerable thickness, with values reported on the scale of about 8-25 grain diameters, e.g., [2,3,14,21,30,34]. The displacement field within the shear band is of particular interest, as once the shear band forms, all significant material straining is confined only to within the shear band, e.g., [30]: subscale kinematics within this material zone then govern macroscopic stress evolution from softening to critical state.…”

Section: Introductionmentioning

confidence: 99%

Characterization of mesoscale instabilities in localized granular shear using digital image correlation

Rechenmacher

Abedi

Chupin³

et al. 2011

Acta Geotech.

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Within shear bands in sands, deformation is largely non-affine, stemming primarily from buckling of well-known force chains and also from vortex-like structures. In the spirit of current trends toward multiscale modeling, understanding the links between these mesoscale deformational entities and corresponding macroscale response will form the basis for the next generation of sand behavioral models and may also aid in efforts to understand jamming-unjamming transitions in dense granular flows in general. Experimental methods to quantify and characterize such subscale kinematics, in particular in real sands, will play critical roles in these efforts. Digital Image Correlation (DIC) is a fast growing experimental technique to nondestructively measure surface displacements from digital images. Here, DIC has been employed to identify and characterize the development of vortex structures inside shear bands formed in dense sands during plane strain compression. A rigorous assessment of the DIC method has been performed, in particular for subscale behavioral characterization in unbonded granular solids, and guidelines are offered for accurate implementation. While DIC systematically overestimates shear band thickness, a methodology has been devised to compensate for this overestimation. Shear band thickness for four different uniform sands were found to range between 6 and 9 grain diameters, and for a well-graded sand between 8 and 9.5 grain diameters. These determinations agree with visual inspections of grain kinematics from the image data, as well as recent theoretical predictions.

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The Use of Digital Image Processing in Monitoring Shear Band Development

Cited by 28 publications

References 8 publications

Effects of sample shape on the strain localization of water‐saturated clay

Effects of sample shape on the strain localization of water‐saturated clay

Shear bands in dense metallic granular materials

Characterization of mesoscale instabilities in localized granular shear using digital image correlation

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