Quality Assisted Three Fringe Photoelasticity for Autonomous Evaluation of Total Fringe Order

Abstract

Three fringe photoelasticity (TFP) is a technique for determining the total fringe order from a single colour isochromatic fringe field. In TFP, the total fringe order is obtained by comparing the colour of the unknown photoelastic fringe pattern with a calibration specimen. Comparison is conventionally done by minimising the colour difference error. This leads to incorrect evaluation of fringe order in some regions showing itself as noise when these values are plotted as an image. In this paper, a new autonomous quality based approach is developed to identify and remove this noise. The method is explained by evaluating the total fringe order for the problem of a disc under diametral compression. The application of this methodology is demonstrated by solving two other example problems.