Novel full-field automated photoelastic analysis technique

Abstract

In phase shifting in photoelasticity, phase unwrapping is one of the crucial steps in the processing of determining the total fringe or- ders. This task is tedious, particularly when ambiguity exists in an irregu- lar phase map. Currently the phase-unwrapping process is usually per- formed line by line with prior knowledge of the total fringe order for at least one point after eliminating the isoclinic ambiguity. In this paper, a novel method is proposed, which can automatically perform the phase- unwrapping process directly based on the result of phase-shifting inde- pendent of the status of ambiguity and no prior knowledge is needed of the total fringe order for at least one point. The basic idea of this method is to exploit the relationships between phase retardations caused by three different loads applied on a specimen to find directly the total fringe order at each point. Experiments on a 'C' shape specimen under com- pression are provided as demonstrations. © 2000 Society of Photo-Optical In- strumentation Engineers. (S0091-3286(00)00910-7)