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Advisor(s)
Abstract(s)
Structural components may contain cracks, and for these components a crack
tip represents a highly singular stress. The evaluation of the associated strain
gradient is difficult to achieve with experimental discrete methods. An efficient
alternative are the optical techniques which are non-contact, and so delivering
continuous information of the displacement fields and associated derivatives
for strain evaluation. This paper describes some experimental methods to fully
characterize the displacement field near a crack tip existing in flat plates.
Three optical field techniques based on image analysis were used in the
present work; respectively, Electronic Speckle Pattern Interferometry, Moir ´e
Interferometry, and Digital Image Correlation. These methods allow different
resolutions which can be adjusted according to the expected strain gradient.
While the first method depends on the laser wavelength and position of the
illumination sources, the second depends on the grating pitch and the last on
the surface texture or painted speckle. Algorithms to derivate and filtering the
displacement field are developed to compute the strain field and will be used
for further works.
Description
Keywords
Digital image correlation Fracture mechanics Interferometry moiré Optical methods Speckle interferometry
Citation
Ribeiro, J.E.; Vaz, M.A.P.; Lopes, H.; Melo, F.; Monteiro, J. (2015). Assessment of the displacement field along a surface crack in a flat plate using optical techniques. Experimental Techniques. ISSN 0732-8818. 39:5, p. 10-20.
Publisher
Wiley Online Library