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Article
Accurate Measurements of High Strain Gradients near Notches Using a Feature-Based DIC Algorithm
Author(s)
Giancarlo L. G. Gonzáles, Leonardo D. Rodrigues and José L. F. Freire
Full-Text PDF XML 727 Views
DOI:10.17265/2159-5275/2017.01.004
Affiliation(s)
ABSTRACT
In this work, the
efficiency of a feature-based DIC (digital image correlation) algorithm for
measuring high strain gradients was investigated
by means of numerical and actual experiments. The so-called SIFT-Meshless
method consisted of a novel formulation involving the SIFT (scale-invariant
feature transform) feature detector with a self-adaptive meshless formulation.
Whereas the numerical experiments aimed to evaluate the accuracy and the
spatial resolution, the actual experiments aimed to demonstrate in practice the
above findings. A stereoscopic system and a micro-stereoscopic system were used
to perform high strain gradient measurements in notched specimens of different
materials and notch sizes. This paper concludes that the feature-based
algorithm is able to provide accurate strain measurements at high strain
gradient regions, even under conditions of plasticity. Moreover, the algorithm
showed its efficiency to capture the peak strain near the notch boundary.
Lastly, a spatial resolution study proposes a link between the desired accuracy
and the pixel resolution required to perform accurate measurements of high strain gradients.
KEYWORDS
High strain gradients, digital image correlation, SIFT, meshless.
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