Advances in Two-Dimensional and Three-Dimensional Computer Vision

Sutton, Michael A.; McNeill, Stephen R.; Helm, Jeffrey D.; Chao, Yuh J.

doi:10.1007/3-540-48800-6_10

Cited by 438 publications

(308 citation statements)

References 39 publications

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“…For instance, crack tip opening angles [11] or crack tip opening displacements [12] can be measured with a very good accuracy by means of digital image correlation. In most of the ¡ to whom correspondence should be addressed.…”

Section: Vision-based Techniques Have Been Utilized To Analyze Cracksmentioning

confidence: 99%

“…distance microscope is used to observe a small zone around the notch to detect the onset of cracking. By acquiring pictures at each load level and using a charge-coupled device (CCD) camera, it is possible to determine the in-plane displacement field by matching different zones of two pictures [12].…”

Section: Sandwiched-beam Technique For Precrackingmentioning

confidence: 99%

“…Values as small as 1.1 µm separation can be resolved at 15 cm from the surface. This type of technique was successfully used to detect the crack tip in a 2024-T3 aluminum alloy with an artificial pattern [11,12]. A brightfield illumination is used in the present case and no special sample preparation is needed.…”

Section: Detection Of the Crack Tip Location By Dicmentioning

confidence: 99%

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A method to determine the macroscopic toughness scatter of brittle materials

Forquin

Rota

Charles

et al. 2004

International Journal of Fracture

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Abstract. An experimental procedure is developed to determine the scatter of the macroscopic toughness of brittle materials. First, samples are precracked to obtain a sharp precrack. The toughness is then determined by using a standard three-point flexural test. Digital image correlation is used to analyze displacement fields of cracked samples. Based upon the resolution and the spatial resolution of the measurement technique, a detection criterion is proposed and validated. It allows for an accurate estimate of the crack tip location so that the presence of a crack and its size at arrest can be monitored. As an example, the toughness distribution of 18 samples made of silicon carbide is evaluated. By using a simple macro-micro transition, an analysis of the scatter in toughness is related to that in strength for the material with no macrocracks.

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Section: Vision-based Techniques Have Been Utilized To Analyze Cracksmentioning

confidence: 99%

Section: Sandwiched-beam Technique For Precrackingmentioning

confidence: 99%

Section: Detection Of the Crack Tip Location By Dicmentioning

confidence: 99%

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A method to determine the macroscopic toughness scatter of brittle materials

Forquin

Rota

Charles

et al. 2004

International Journal of Fracture

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“…Only a few strain gauges are used to analyse the complex behaviour of a material submitted to a high rate impact. Unlike conventional strain measurement techniques such as extensometers or strain gauges, full-field measurement techniques such as digital image correlation (DIC) [6] and the grid method [7] provide much richer experimental information. It is therefore natural to expect that this new wealth of information will lead to an in-depth revisit of the high strain rate testing procedures.…”

Section: Introductionmentioning

confidence: 99%

Exploration of Saint-Venant’s Principle in Inertial High Strain Rate Testing of Materials

Zhu

Pierron

2015

Exp Mech

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Current high strain rate testing procedures of materials are limited by poor instrumentation which leads to the requirement for stringent assumptions to enable data processing and constitutive model identification. This is the case for instance for the well known Split Hopkinson Pressure Bar (SHPB) apparatus which relies on strain gauge measurements away from the deforming sample. This paper is a step forward in the exploration of novel tests based on time and space resolved kinematic measurements obtained through ultra-high speed imaging. The underpinning idea is to use acceleration fields obtained from temporal differentiation of the full-field deformation maps measured through techniques like Digital Image Correlation (DIC) or the grid method. This information is then used for inverse identification with the Virtual fields Method. The feasibility of this new methodology has been verified in the recent past on a few examples. The present paper is a new contribution towards the advancement of this idea. Here, inertial impact tests are considered. They consist of firing a small steel ball impactor at rectangular free standing quasi-isotropic composite specimens. One of the main contributions of the work is to investigate the issue of through-thickness heterogeneity of the kinematic fields through both numerical simulations (3D finite element model) and actual tests. The results show that the parasitic effects arising from non-uniform through-the-thickness loading can successfully be mitigated by the use of longer specimens, making use of Saint-Venant's principle in dynamics.

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“…Performing reliable and reproductive tests on damage samples made of brittle material is difficult, especially under tensile loading or more generally under positive hydrostatic stresses. Note that recent experimental measurement devices such as digital image correlation techniques can help to perform such delicate tests [Sutton et al, 2000, Fayolle et al, 2007. An alternative for identification procedure is the concept of "virtual testing" or "cross-identification", in which a numerical discrete or damage model is preferred (see for example [Garboczi et al, 2004, Sun et al, 2007, Gonzlez and LLorca, 2007 for recent applications).…”

Section: Introductionmentioning

confidence: 99%

Tensile damage response from discrete element virtual testing

Delaplace

2009

Geomechanics and Geoengineering

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Depending on the loading conditions on brittle materials, damage can generally not be reduced to a simple scalar. Microcrack orientation affects the stiffness in a preferential direction perpendicular to the crack lips. Taking into account the damage anisotropy in phenomenological models is a possible option, but the identification of the corresponding models with respect to damage anisotropy is not an easy task, usually because of the limited number of experimental results. Handling and performing tensile experiments on damaged samples made of quasi-brittle heterogeneous material is quite delicate. Then, one can consider virtual testing for the identification of specific properties. We propose in the present work such a protocol, based on the use of discrete element models and codes as a virtual testing machine. Discrete models are based on a material description at the microscopic scale by an assembly of particles. Cracks (and cracks orientations) are naturally described by broken connections between particles. After a brief description of the chosen model, a cross-identification procedure is proposed for the determination of an hydrostatic sensitivity parameter of an anisotropic damage model. A second application deals with the description of the evolution of the strength envelope under different isotropic and anisotropic damage states. These examples show the interest of virtual testing by discrete modeling for material behavior characterization at fine scale.

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Advances in Two-Dimensional and Three-Dimensional Computer Vision

Cited by 438 publications

References 39 publications

A method to determine the macroscopic toughness scatter of brittle materials

A method to determine the macroscopic toughness scatter of brittle materials

Exploration of Saint-Venant’s Principle in Inertial High Strain Rate Testing of Materials

Tensile damage response from discrete element virtual testing

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