Abstract
An achromatic quarter-wave plate is used to determine the principal-stress directions from color photoelastic fringes obtained in a semicircular polariscope, which is composed of a plane polariscope with a quarter-wave plate. Four phase-shifted photoelastic fringe images are acquired using the polariscope, and used to obtain the wrapped principal-stress direction using a phase-shifting technique. To investigate the effectiveness of the quarter-wave plate, the principal-stress directions from color photoelastic fringes of a circular disk subjected to a concentrated load are determined. Results show that the quarter-wave plate is effective for determining the principal-stress direction.
