Complete fringe order determination in digital photoelasticity using fringe combination matching

A novel approach is presented for obtaining the complete (integer and fractional) value of isochromatic parameters in digital imaging photoelasticity. This takes the form of a new variant on the existing technique of RGB photoelasticity, involving the matching of combinations of isochromatic fringe value measured on the three colour planes or channels rather than the usual RGB method of matching colour combinations directly. The new variant of RGB photoelasticity avoids the need for calibration for specific materials. This approach is demonstrated with real photoelastic data and compared with results from a conventional unwrapping process and from manual readings.