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hal-00749804, version 1

Towards deconvolution to enhance the grid method for in-plane strain measurement

Frédéric Sur (Author to contact preferably, http://www.loria.fr/~sur/) 1, Michel Grédiac 2

N° RR-8126 (2012)

Abstract: The grid method is one of the available techniques to measure in-plane displacement and strain components on a deformed material. A periodic grid is first transferred on the specimen surface, and then images of the grid are compared before and after deformation. Windowed Fourier analysis-based techniques then permits to estimate the in-plane displacement maps and the strain components. In this report, we give a precise analysis of this estimation process. We show that the retrieved displacement maps and strain components are actually a tight approximation of the convolution of the actual displacements and strains with the analysis window. We also characterize the effect of digital image noise on the retrieved quantities and we prove that the resulting noise can be approximated by a stationary spatially correlated noise. These results are of utmost importance to enhance the metrological performance of the grid method, as shown in a separate report.

  • 1:  MAGRIT (INRIA Nancy - Grand Est / LORIA)
  • CNRS : UMR7503 – INRIA – Université de Lorraine
  • 2:  Institut Pascal
  • Université Blaise Pascal - Clermont-Ferrand II – CNRS : UMR6602
  • Domain : Computer Science/Signal and Image Processing
    Engineering Sciences/Signal and Image processing
    Physics/Mechanics/Mechanics of the solides
    Engineering Sciences/Mechanics/Mechanics of the solides
  • Keywords : Experimental solid mechanics – grid method – windowed Fourier analysis – correlated noise.
  • Internal note : RR-8126
 
  • hal-00749804, version 1
  • oai:hal.inria.fr:hal-00749804
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  • Submitted on: Thursday, 8 November 2012 13:58:42
  • Updated on: Friday, 9 November 2012 15:55:33