抄録
This paper describes a phase measuring technique that uses eight images through a circular polariscope. The phase measuring technique is applied to the digital measurements of isochromatics and isoclinics, respectively, from photoelastic fringes. Isochromatics can directly be obtained by using wrapped isoclinic phases calculated by the arc tangent operator which is the four-quadrant operator from - π to π. It is not required to unwrap isoclinic phases for the calculations of isochromatics. Isoclinic parameters are directly determined from unwrapped isochromatic parameters. The developed technique is applied to obtain the distributions of isochromatics and isoclinics along a horizontal line and an inclined line of a horseshoe-type curved beam under tension load. Generally, digitally measured isochromatics using the developed phase-shifting method agree with those expected by theory. Experimental isochromatics on the horizontal line, where isoclinics are almost constant and near zeroes, are in close agreement to theoretical calculations. However, experimental isochromatics along the inclined line, where isoclinics are changed at every point, are more or less different from theoretical expectations. Distributions of isoclinics are directly obtained by using unwrapped isochromatic parameters. Distributions of digitally measured isoclinics are in good agreement to those of theoretical calculations except in a few region.
