Study on several problems of automatic full-field isoclinic parameter measurement by digital phase shifting photoelasticity

The determination of isoclinic parameter from photoelastic fringe patterns is a key problem in photoelasticity. However, it is not a simple task due to the influence of the isochromatic parameter. The purpose of this paper is to achieve the full-field isoclinic parameter measurement automatically by six-step digital phase shifting photoelasticity. However, there are several key problems, such as the range of the isoclinic parameter, the isoclinic-isochromatic interaction, and the influence of special points such as free corner point, singular point and isotropic point. Through analyzing these problems, we present an appropriate algorithm to get the correct full-field isoclinic parameter automatically which is validated by simulation and experiment. This method is simple and effective to solve the problems of the isoclinic-isochromatic interaction and the isoclinic parameter error around the special points. (C) 2015 Elsevier GmbH. All rights reserved.