Traceable technique for an in situ full field in-plane measurement validation of digital image correlation

Abstract

Abstract. For digital image correlation to be firmly accepted as a validated displacement measurement system in the industrial arena, a measurement must be captured by the analysis system at time of test which confirms that the image correlation hardware and software system is performing as expected. To this end, a method for validating stereo digital image correlation optical test setups is presented, which is traceable to the length standard. The method employs a screen, on which is displayed a randomized speckle pattern of appropriate pitch for the test in question. This speckle pattern is then artificially translated by a known number of pixels on the screen, and image pairs captured of the original and translated speckles. Processing of these data image pairs with image correlation, and calibration of the pixel pitch of the display screen using a traceable measurement system, allows the image correlation test setup to be traceably calibrated in terms of in-plane displacement. The method is shown to be sufficiently sensitive and repeatable to provide a reasonably accurate, traceable validation in a practical environment. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

An efficient approach for stereo matching of planar objects in stereo-digital image correlation

“…Methods for efficient stereo matching of curved surfaces will be studied in the future. However, in many mechanical tests, the surfaces of specimens are planar in both reference and deformed stages [1,13], and then the proposed method can be adopted.…”

“…In many mechanical tests and all the 2D-DIC applications, such as tensile tests [10], bending tests [11] and high speed tests [12], the surfaces of specimens to be measured are planar, as shown in figure 1. Besides, in industrial measurements, stereo-DIC is often used for measurements of flat or initially flat specimens, undergoing in-plane deformation [13]. When using stereo-DIC for deformation measurement, the planar surfaces have some special characteristics, compared to the curved surfaces.…”

Research on the Effects of Calibrated Position on Digital Image Correlation Measurement of Dual Camera in Engineering Application

“…Digital image correlation (DIC) of dual cameras is an optical measurement method based on digital image processing and numerical calculation [1]. It has the advantages of non-contact and full-field measurement.…”