NDT&E using shearography with impulsive thermal stressing and clustering phase extraction

Out-of-plane displacement field measurement by shearography

“…These distinct advantages make shearography a full-field non-contact practical technique with great potential for in situ measurements among interferometric methods. In the light of recent developments, shearography has been widely used in industrial applications such as routine tire evaluation in the rubber industry, structure evaluation in the aerospace industry, and residual stress evaluation [14][15][16]. As an interferometric technique, shearography can provide micron-and submicron-order resolutions while also greatly relaxing the normally stringent environmental stability requirements of interferometric techniques.…”

Real-time monitoring of phase maps of digital shearography

“…[1][2][3][4][5][6] Of these techniques, digital shearography has demonstrated many advantages for realworld applications. [7][8][9][10][11] Unlike other techniques, digital shearography uses a special shearing device to directly measure a displacement gradient rather than the displacement itself. This significant feature is particularly important for field NDT applications.…”

“…In the last decade, different research groups have reported their attempts for measuring a phase distribution using only one speckle interference pattern acquired under dynamic conditions, such as N þ 1 (N ¼ 3, 4, and 5) clustering methods, N þ 1 least squares methods, and N þ 1 temporal phase shifting methods (also called as filtered secondary speckle interferograms methods). 1,2,8,[29][30][31] The clustering algorithm is able to determine a phase change using only one loaded image; however, to determine the phase change on each single point, it needs the information from its multiple adjacent points, which requires high intensive computation. The algorithm is good for postprocessing instead of on-line and real-time test.…”

Dynamic Phase Measurement in Shearography by Clustering Method

“…In our previous research [7][8][9], the authors had proposed a clustering method for dynamic phase measurement which utilizes the phase clustering effect and the prior knowledge of the speckle field to extract the deformed phase map from one single deformed speckle pattern. The clustering method, however, generate low quality wrapped phase map with abundant phase residues at areas with extensive noise or large phase gradient, rendering phase unwrapping a difficult or impossible work.…”