Development of a small-scale testing machine for use with interferometric monitoring methods

Abstract

Material testing procedures are increasingly using image-based methods for strain field measurements, with extensive usage of Digital Image Correlation in particular. Nonetheless, there is interest in extending this use to other image-based interferometric methods with increased resolution, such as Electronic Speckle Pattern Interferometry (ESPI) and Shearography. In particular, ESPI requires very stable conditions for measurement, usually achieved by assembly on an optical table.Therefore, this work reports the development of a portable testing machine that can be assembled on INEGI’s optical table and is compatible with our previously developed 3D ESPI setup. The machine is an inexpensive custom design for static or quasi-static loading, with the main objective of withstanding a maximum load and velocity of 20 kN and 240 mm/min, respectively. The machine was built around a brushless dc motor and controller, both from Trinamic, and is currently being successfully used with ESPI methodology.