Whole-field digital measurements of isochromatics and isoclinics in photoelastic coatings

Whole-field digital determination of fringe order and principal stress dire ction in photoelastic-coating fringe patterns is studied. Two-wavelength me thod and polarization-stepping method are introduced to automate the determ ination of fringe order and the principal stress direction. The theoretical aspects related to the implementation of the two digital methods to the co ating's fringes is outlined. Experimental demonstration of the methods on a circular disk subjected to compressive loading is performed. Test results are given and compared well to the results measured manually. (C) 1999 Publ ished by Elsevier Science Ltd. All rights reserved.