ISSN: 1945-7553
CODEN: JTEVAB
Published Online: 22 January 2013
Page Count: 5

Improved Digital Image Correlation Method for Eliminating Pixel Shape-Induced Errors in Shear-Strain Calculations

Peng, Bei
Univ. of Electronic Science and Technology of China, Dept. of Mechanical Engineering, Chengdu,
Univ. of Electronic Science and Technology of China, Dept. of Mechanical Engineering, Chengdu,

Huang, Chengcheng
Univ. of Electronic Science and Technology of China, Dept. of Mechanical Engineering, Chengdu,

Zhou, Wu
Univ. of Electronic Science and Technology of China, Dept. of Mechanical Engineering, Chengdu,

Yu, Huijun
Univ. of Electronic Science and Technology of China, Dept. of Mechanical Engineering, Chengdu,

Zeng, Zhi
Univ. of Electronic Science and Technology of China, Dept. of Mechanical Engineering, Chengdu,

(Received 23 March 2012; accepted 28 August 2012)

Abstract

Digital image correlation is widely used in non-contact displacement/strain measurements for numerous engineering applications. Under rigid body rotation or shear deformation, however, the calculated surface strain of specimens is unreliable when camera pixels are characterized by non-square geometry, that is, the width-to-height ratio of pixels is not 1. This study analyzes the computational errors introduced by cameras, and proposes a modified least-squares method that eliminates such errors when the strain field is calculated. Experimental results confirm that the algorithm validly and effectively computes shear strain.

Keywords:
digital image correlation, strain measurement, camera pixel, least-squares method

Paper ID: JTE20120085
DOI: 10.1520/JTE20120085
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