Second-order moiré method for accurate deformation measurement with a large field of view

Qinghua Wang, Shigesato Okumura, Shien Ri, Peng Xia, Hiroshi Tsuda, Shinji Ogihara

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

In this study, we propose a second-order moiré method by performing digital sampling at two stages to realize high-accuracy deformation measurement in a wide field of view, where a grid image is recorded at a low magnification. Simulations have verified that this method has high strain measurement accuracy when the grid pitch is close to or even smaller than two pixels for both parallel and oblique grids with random noise. As an application, the two-dimensional microscale strain distributions of a carbon fiber reinforced plastic specimen when the grid pitch was about 2.1 pixels were presented. Shear strain concentration was detected before an interlaminar crack emerged, and tensile strain concentration was found prior to the occurrence of a transverse crack. The proposed method makes the two-step phase-shifting technique achieved indirectly, not only enlarging the field of view, but also maintaining the measurement accuracy.

Original languageEnglish
Pages (from-to)7498-7514
Number of pages17
JournalOptics Express
Volume28
Issue number5
DOIs
Publication statusPublished - 2 Mar 2020

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