The Grid Method

 The grid method is a technique suitable for measuring in-plane displacement and strain maps in experimental mechanics.

 It relies on regular markings of the surface of specimens. The displacement field is proportional to the phase change between current and reference grid images. Consequently the idea is first to extract phase changes between current and reference grid images, then to express the current phase distribution in the coordinate system of the reference one, and finally to deduce the displacement field by subtracting the phase distributions of the back-deformed and the reference grid images.

 Various versions of this measuring technique have been proposed in the past. The programs corresponding to one of these techniques, namely the Localized Spectrum Analyzis, are given here to help experimentalists using the grid method to measure displacement and strain fields. 

 A document explaining how to install the programs is available here along with several typical examples. They are offered to assist the reader to acquire the necessary skills to process then autonomously his own grid images.  The corresponding images are included in the package containing the programs.

 The reader interested in the literature on this technique will find here a list of publications. These publications either deal with the development of the method itself, or with some applications of this technique in experimental mechanics. In particular, a comprehensive review on the grid method is available here.

 Should you have any questions or comments, please contact thegridmethod [at] gmail.com.


Michel GREDIAC, Institut Pascal, Clermont-Ferrand, France

Frédéric SUR, LORIA, Nancy, France

Benoît BLAYSAT, Institut Pascal, Clermont-Ferrand, France