Determination of the Surface Displacement Field under Dynamic Loads by the Method of Phase-Shifting Correlation Speckle Pattern Interferometry

Abstract

A brief review of known digital speckle pattern interferometry methods for retrieving the surface displacement and deformation fields under dynamic loads is presented. A new nondestructive test method of three-step phase-shifting correlation speckle pattern interferometry to study the dynamic loads of structural materials is proposed. In this method three speckle interferograms (SIs) of the specimen surface, differing only by arbitrary unknown phase shifts, are recorded before the loading and one SI is recorded under the dynamic load. The surface displacement field under dynamic loading is determined using the obtained SIs. Two algorithms for the implementation of the method are proposed. They use an integrating bucket technique to record SIs and make it possible to determine the phase maps of the surface displacement fields at any moment of applying the dynamic load. We can use this method to produce a temporal sequence of surface displacement fields during loading.