Strain Measurement in Wood using A Digital Image Correlation Technique

Audrey G. Zink, Robert W. Davidson, Robert B. Hanna


The suitability of the Digital Image Correlation Technique (DICT) for full-size test specimens of wood and wood-based composites was evaluated in this study. The technique utilizes pairs of digitized video images of undeformed and deformed test specimens and an image correlation computer routine to measure the displacements of any or all points on the surface of the test specimen. New methods for image acquisition and image correlation were developed and evaluated in this study.

Evaluation and calibration were performed using an aluminum alloy block for comparison and axial compression of small, clear specimens of wood and in accordance with ASTM D143-83 (1986a). Comparison of strain measurements obtained using an independent measurement technique and strain obtained with the DICT showed close agreement. Utilizing DICT for full-field strain distributions through an increasing load series revealed progressive failure development in the wood specimens, the eventual failure mode, and a shift in strain concentrations during load application.


Strain measurement;image analysis;mechanical testing

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