【报  告  人】 Prof Michel GREDIAC,Blaise Pascal University, France
【时        间】 2018年6月22日（星期五）下午3:00
【地        点】 力一楼237会议室

Abstract: The metrological performance of full-field measurement systems like DIC strongly depends on various parameters, among which the quality of the pattern. It was found that checkerboard patterns can maximize the image gradient, which means that such patterns minimize sensor noise propagation in final deformation maps. Checkerboards are however periodic patterns. As such, they are not used in DIC because periodicity induces convergence issues. As a consequence, optimized patterns proposed for DIC are deliberately different from checkerboards to fulfil the requirement of pattern randomness. It is worth mentioning that DIC is nothing but a numerical tool minimizing iteratively the optical residual in the real domain. Minimizing this optical residual had a direct solution in the Fourier domain when periodic patterns are processed by a Fourier-based method such as the Localized Spectrum Analysis (LSA), which has been confirmed with 2D-grids. This presentation will show that checkerboards can also be successfully processed by LSA. The technique will be briefly presented. Suitable experiments enable then to compare the noise level in deformation fields obtained with speckles and DIC, and with checkerboards and LSA. Experimental results proved that a significantly lower noise can be obtained with checkerboards and LSA than with speckles and DIC.

Biography: Prof Michel GREDIAC obtained his doctoral degree in 1989 from the University of Lyon in France with top honours. He was promoted to full professor in 1997. Presently, he is at the second step of the exceptional class professor in Blaise Pascal University, which is the highest level and recognition for professor in France. His main research interests lie in developing full-field measurement techniques in experimental solid mechanics and characterising material and structure. He won the B.J. Lazan Award issued by the Society of Experimental Mechanics in 2015 for his pioneering work towards establishing a new paradigm in materials testing coupling full-field deformation measurements with inverse identification. So far, he published two books and more than 110 refereed international journal papers with more than 5200 citations.