Determining displacement and strain maps immune from aliasing effect with the grid method

• A rigorous analysis of aliasing in grid methods.
• A simple method to circumvent aliasing.
• An illustration with numerical and real experiments.

Spatial aliasing may affect methods based on grid image processing to retrieve displacement and strain maps in experimental mechanics. Such methods aim at estimating these maps on the surface of a specimen subjected to a loading test. Aliasing, which is often not noticeable to the naked eye in the grid images, may give spurious fringes in the strain maps. This paper presents an analysis of aliasing in this context and provides the reader with simple guidelines to minimize the effect of aliasing on strain maps extracted from grid images.