Development of a Digital Image Correlation controlled fatigue crack propagation experiment

Durif, Emilien; Frégonèse, Marion; Réthoré, Julien; Combescure, Alain

doi:10.1051/epjconf/20100631012

Cited by 10 publications

(4 citation statements)

References 8 publications

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“…These conditions could also be studied thanks to the analysis of SIF histories [5]. Crack propagation laws were also determined when the crack tip position was optically determined when using a long-distance microscope [7], or by using the crack opening displacements [8]. In the following, another will be followed to determine the crack tip position.…”

Section: Introductionmentioning

confidence: 99%

Identification of a crack propagation law by digital image correlation

Mathieu

Hild

Roux

2012

International Journal of Fatigue

116

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It is proposed to use digital image correlation (DIC) to identify parameters governing crack propagation of commercially pure titanium. To achieve this goal, crack tip location, stress intensity factor, T -stress and plastic zone size are sought. Most of the DIC approaches are based upon local analyses of displacements, and their subsequent projection onto a set of mechanically relevant fields. It is proposed to perform these two sequential steps in a unique (and integrated) way, and to compare the results with a global approach to DIC with subsequent post-processing. A priori performances of two global approaches are compared, and a propagation law is identified form the series of raw images of a fatigue test on commercially pure titanium with the integrated approach that yields better results.

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Section: Introductionmentioning

confidence: 99%

Identification of a crack propagation law by digital image correlation

Mathieu

Hild

Roux

2012

International Journal of Fatigue

116

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“…• Control of an experiment from learning schemes based on identification and DIC is a very promising direction [46][47][48]. The methodology proposed in the present paper is one of the building bricks involved in such a goal.…”

Section: Discussionmentioning

confidence: 99%

Image-based identification procedure of a crack propagation law

Mathieu

Hild

Roux

2013

Engineering Fracture Mechanics

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A novel methodology to identify a fatigue crack propagation law is proposed. It is based on an optimization scheme that directly interrogates the images from the sought law rather than using a sequence of fitting schemes. Two procedures are presented and tested first on artificial data with a known law, and second on an actual image series obtained from a fatigue test performed on a thin titanium sheet. The results demonstrate the ability of the proposed procedures to deal with inherently noisy data, and yet obtain an accurate propagation law. As a side result "admissible" time series of stress intensity factors and crack advance are obtained that fulfill the identified law and are constrained by the registration of actual images, rather than being simply filtered from the data in a post-processing step.

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“…Various applications of DIC to monitor cracks in fatigue tests have been reported. In many cases DIC is used to assess the strain field at the crack tip 3,4,5 and determine stress intensity factors 6,7,8 or detect fatigue damages on a microscopic scale 9,10 . In these cases, microscopic images are used to investigate areas of interest in the range of a few millimeters.…”

Section: Introductionmentioning

confidence: 99%

Crack Monitoring in Resonance Fatigue Testing of Welded Specimens Using Digital Image Correlation

Friedrich

Ehlers

2019

JoVE

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A procedure using digital image correlation (DIC) to detect cracks on welded specimens during fatigue tests on resonance testing machines is presented. It is intended as a practical and reproducible procedure to identify macroscopic cracks at an early stage and monitor crack propagation during fatigue tests. It consists of strain field measurements at the weld using DIC. Images are taken at fixed load cycle intervals. Cracks become visible in the computed strain field as elevated strains. This way, the whole width of a small-scale specimen can be monitored to detect where and when a crack initiates. Subsequently, it is possible to monitor the development of the crack length. Because the resulting images are saved, the results are verifiable and comparable. The procedure is limited to cracks initiating at the surface and is intended for fatigue tests under laboratory conditions. By visualizing the crack, the presented procedure allows direct observation of macrocracks from their formation until rupture of the specimen. Video Link The video component of this article can be found at https://www.jove.com/video/60390/ With the advance of computational technologies, DIC is becoming more and more popular for industrial and research applications. Several commercial measurement software systems as well as open-source software are available 1. The proposed procedure offers another use of a technology already available in an increasing number of research facilities in mechanical and civil engineering. Compared to visual inspections or dye penetration testing, the proposed procedure is not based on subjective perception, which depends on an operator's experience and the local geometry at the weld toe. Even with high magnification it may be challenging to detect cracks at an early stage (i.e., crack initiation), especially if the exact location is not known in advance. Furthermore, using DIC the results are saved and therefore reproducible and comparable, whereas visual inspection is possible only momentarily. Using a full-field measurement the procedure allows monitoring the whole width of the specimen or length of the weld. Using strain gauges, it would be necessary to apply several gauges over the specimen width, because their measurement is localized. The changes in the strain gauge signal would depend on the distance and the position relative to the crack. The result would depend on whether the crack would initiate in between two gauges or by chance in front of one.

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Development of a Digital Image Correlation controlled fatigue crack propagation experiment

Cited by 10 publications

References 8 publications

Identification of a crack propagation law by digital image correlation

Identification of a crack propagation law by digital image correlation

Image-based identification procedure of a crack propagation law

Crack Monitoring in Resonance Fatigue Testing of Welded Specimens Using Digital Image Correlation

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