Abstract
BackgroundHigh-resolution Digital Image Correlation (DIC) measurements have previously been produced by stitching of neighboring images, which often requires short working distances. Separately, the image processing community has developed super resolution (SR) imaging techniques, which improve resolution by combining multiple overlapping images.ObjectiveThis work investigates the novel pairing of super resolution with digital image correlation, as an alternative method to produce high-resolution full-field strain measurements.MethodsFirst, an image reconstruction test is performed, comparing the ability of three previously published SR algorithms to replicate a high-resolution image. Second, an applied translation is compared against DIC measurement using both low- and super-resolution images. Third, a ring sample is mechanically deformed and DIC strain measurements from low- and super-resolution images are compared.ResultsSR measurements show improvements compared to low-resolution images, although they do not perfectly replicate the high-resolution image. SR-DIC demonstrates reduced error and improved confidence in measuring rigid body translation when compared to low resolution alternatives, and it also shows improvement in spatial resolution for strain measurements of ring deformation.ConclusionsSuper resolution imaging can be effectively paired with Digital Image Correlation, offering improved spatial resolution, reduced error, and increased measurement confidence.
Highlights
Digital Image Correlation (DIC) is a non-contacting technique used to examine localized strain across a material’s surface [1]
The comparison of the three chosen super resolution (SR) algorithms to low resolution (LR) imaging techniques is supported by the results of the three tests: The SR algorithm initial comparison, the rigid body translation test, and the mechanical deformation test
The application of super resolution (SR) algorithms was investigated as a method of increasing the resolution of DIC strain measurements for samples at long working distances
Summary
Digital Image Correlation (DIC) is a non-contacting technique used to examine localized strain across a material’s surface [1]. By comparing images of a sample before, during, and after load application, DIC can calculate surface deformation and strain at any point which is visible to cameras This method allows for measurements to be taken at a variety of length scales without a loss of quality in the measurement for different physical scales [2]. To maximize the benefits of the full-field measurements from DIC compared to single averaged measurements from strain gauges, higher resolution images allow for smaller physical subset sizes which produce each “pointwise” measurement. This is especially true when it is necessary to perform DIC over small regions of interest. Conclusions Super resolution imaging can be effectively paired with Digital Image Correlation, offering improved spatial resolution, reduced error, and increased measurement confidence
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