symposium 8 - Crack Paths 2024

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Crack tip detection and advanced crack tip field characterization in digital image correlation data
Eric Breitbarth, German Aerospace Center (DLR), Germany
Keywords: digital image correlation (DIC), crack path segmentation, crack tip loadings, plastic zone
Innovative new measurement methods have generally always led to new scientific findings. Nowadays, modern techniques like Digital Image Correlation (DIC) are utilized for acquiring full-field displacement and strain data in mechanical experiments. This enables the capture of actual deformation behaviour of a specimen during an experiment. Particularly in the sphere of fracture mechanics, DIC provides enriched information about the crack itself. Initially, it is essential to identify the crack path and, most importantly, the location of the crack tip in the data. Crack tip loadings can be calculated by techniques such as the J-Integral, Interaction-Integral, Christopher-James-Patterson (CJP) model or the Williams series expansion. This enables the quantification of crack tip loads or crack closure effects that occur in reality. High resolution imaging also allows accessing the plastic zone at the crack tip or localised Crack Tip Opening Displacement (CTOD) measurements. Finally, the Williams series expansion can condense the complexity of the crack tip field to a few single values. This enables the search for new correlations with a data-centred approach:
  • Advanced digital image correlation (DIC) techniques
  • Segmentation of the crack in experimental data
  • Calculation of crack tip loads
  • Fracture mechanics with multiple parameters
  • Plastic zone at the crack tip
  • Evaluation focused on data

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