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Keywords:

  • Digital Image Correlation;
  • Strain Distribution;
  • Crack;
  • High-speed Camera;
  • Large Deformation;
  • Measurement accuracy

Abstract

Over the last few decades, many experimental methods using digital image correlation (DIC) have been developed as displacement measurement techniques because DIC offers a simple, noncontact procedure for full-field measurement. However, in addition to high spatial resolutions, it is now necessary to measure deformation at higher temporal resolution to understand in more detail the time evolution of microscale deformation, and to evaluate high-speed microscale phenomena such as crack growth. Therefore, we developed a system for measuring deformation fields at high spatial and temporal resolutions using a high-speed camera, zoom lens, DIC, and incremental evaluation method. We evaluated its accuracy, and used it to measure the deformation field around a crack tip in carbon steel. First, we performed three types of accuracy estimation for rigid displacement. Second, we applied this system to a smooth specimen of carbon steel subjected to tensile loading, and verified the measurement accuracy. Third, we applied this system to a Mode I crack in carbon steel and obtained the evolution of the strain distribution around the crack tip, where a large inhomogeneous deformation had occurred.