Using text as a native speckle pattern in digital image correlation

Abstract

In certain applications, native surface patterns can be used in place of speckle patterns in digital image correlation (DIC). This paper explores the feasibility of using text as a native speckle pattern in DIC. Five text speckle patterns are tested in three different scenarios: a rigid body translation test, a rigid body rotation test, and an out of plane bending test. The patterns are benchmarked against a sixth, random speckle pattern applied using traditional DIC speckling methods. Rigid body translation tests are additionally performed on text patterns with varying font types and line spacings. In general, text patterns have good contrast, but low density as line spacing increases. Measurement uncertainty for the text patterns was comparable to measurement uncertainty in the random speckle pattern. Results from these tests show that while text patterns cannot be expected to perform better than a traditional DIC speckle pattern, text patterns can be effective speckle patterns in situations where already present on a specimen and applying a traditional speckle pattern is difficult.

The Calibration Process and Setting of Image Brightness to Achieve Optimum Strain Measurement Accuracy Using Stereo-Camera Digital Image Correlation

“…Fringe patterns combined with speckle patterns were used in displacement and strain [12] or vibrational analyses [13] using single-camera DIC. Craig et al [14] analysed an unconventional approach to creating a speckle pattern by photocopying or printing passages from several publications. They concluded that the uncertainty of the measurements using text patterns is comparable to those using random speckle patterns.…”

Investigation of the Crack Propagation in the Graphene/Synthetic Rubber Nanocomposite Materials with DIC Technique

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