Camera array-based digital image correlation for high-resolution strain measurement

Xinxing Shao; Zhenning Chen; Xiangjun Dai; Xiaoyuan He

doi:10.1063/1.5050187

Camera array-based digital image correlation for high-resolution strain measurement

Rev Sci Instrum. 2018 Oct;89(10):105110. doi: 10.1063/1.5050187.

Authors

Xinxing Shao¹, Zhenning Chen², Xiangjun Dai³, Xiaoyuan He¹

Affiliations

¹ Department of Engineering Mechanics, Southeast University, Nanjing, China.
² State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, China.
³ School of Transportation and Vehicle Engineering, Shandong University of Technology, Zibo, China.

PMID: 30399961
DOI: 10.1063/1.5050187

Abstract

Digital image correlation (DIC) is a well-known technique for non-contact, non-destructive, full-field deformation measurement in experimental solid mechanics. Although DIC has been widely used in science and engineering, the resolution of strain measurement with DIC is limited by imaging resolution and is much lower than that obtained with a strain gauge. To achieve a breakthrough in strain measurement using DIC, a camera array-based DIC method is proposed herein for high-resolution strain measurement. Twenty-five industrial cameras were assembled into a plane array, with each camera capturing a part of the specimen. A novel calibration-based image stitching method is proposed and was applied to these images and their corresponding displacement fields. The strain field was then calculated based on the stitched displacement fields. The use of the camera array greatly improved the measurement spatial resolution of DIC and made high-resolution strain measurement possible. Both static error analysis and four point-bending experiments were performed to demonstrate the feasibility and effectiveness of the proposed method, and a full-field strain resolution of 10 $μ ε$ was achieved.