Advancing front scanning approach for three-fringe photoelasticity

摘要

Three-fringe photoelasticity (TFP) is a single isochromatic color image based technique to obtain full-field fringe order data, by comparing RGB intensities of a pixel in the image with the calibration table. Fringe order resolving methods based on neighboring resolved pixels, like refined TFP (RTFP) or window search method, are used to ensure spatial continuity of the fringe order. It is shown in this paper that simple image scanning schemes used to implement such resolving methods result in some unresolved zones for complex shaped specimens that are frequently encountered in industrial applications. A new scanning method termed as advancing front scanning proposed in this paper progresses by resolving a pixel having maximum number of resolved neighboring pixels, starting from a seed point or multiple seed points. Advantages of the advancing front scanning method in conjunction with two-point color adaptation are demonstrated through two examples of specimens of which one is obtained by reflection photoelasticity and the other is a complex simply connected stress frozen slice.