Abstract

In this paper a review of progresses occurred along the years in measuring residual stresses by optical methods is presented. These methods allow to implement the hole drilling procedure for residual stress profile measuring, without applying the strain gage rosette. This approach presents several advantages such as easier and cheaper preparation of the test beside the possibility to avoid eccentricity issues and to increase the amount of available data in view of the fact that each pixel can be considered as a measure point. In particular the evolution of the Electronic Speckle Pattern Interferometry (ESPI) technique will be presented showing how set up, methodologies and calculation approaches have developed along the last three decades.