Home › Cell Biology › Full-field Strain Measurements for Microstructurally Small Fatigue Crack Propagation Using Digital Image Correlation Method
Cell Biology JoVE (Open Access) Citable · DOI

Full-field Strain Measurements for Microstructurally Small Fatigue Crack Propagation Using Digital Image Correlation Method

DOI: 10.3791/59134-v
What you'll learn
  • ✓ Apply digital image correlation to measure full-field strain in fatigue crack specimens
  • ✓ Quantify microstructurally small crack growth rates at sub-grain resolution
  • ✓ Prepare and characterize metallographic samples for strain-field analysis
  • ✓ Interpret cumulative deformation patterns during fatigue propagation
Protocol

Biopharma Insights Microstructurally small fatigue crack growth behavior is investigated using a novel methodological approach combining crack growth rate measurement and strain-field analysis to reveal the cumulative deformation field at sub-grain level.

Difficulty
advanced
Total time
~5–7 days per sample (including annealing, pre-cracking, fatigue cycling, and image acquisition)

Steps

1
Prepare and anneal fatigue test specimens

Machine metallic specimens to specification and perform controlled thermal annealing to establish baseline microstructure for subsequent fatigue testing.

▶ 01:54
2
Conduct fatigue pre-cracking under controlled loading

Apply cyclic loading to initiate reproducible fatigue cracks of defined size and geometry as starting point for microstructurally small crack growth study.

▶ 02:49
3
Characterize microstructure via optical/electron microscopy

Perform metallographic analysis to document grain structure, phase distribution, and crack location relative to microstructural features.

▶ 03:21
4
Apply speckle pattern for digital image correlation

Deposit fine random speckle pattern (paint or coating) on specimen surface to enable sub-pixel displacement tracking during image correlation analysis.

▶ 03:53
5
Measure crack growth and strain fields quantitatively

Acquire high-resolution images during fatigue cycling and process via DIC software to extract crack length evolution and full-field strain tensor components.

▶ 04:54
6
Present representative strain and crack growth results

Display maps of cumulative plastic strain, crack path visualization, and crack growth rate curves illustrating sub-grain deformation localization.

▶ 05:36
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