Abstract
A method for automatic measurement of principal-stress directions in the entire field of a model is developed based on the results of photoelastic experiments. This method uses a set of color photoelastic images, which is obtained by rotating polaroids in dark-field polariscopes. Second, a set of monochrome photoelastic images is obtained by dividing the sum of light intensities at the same point in the red, green and blue images at the same rotation angle of polaroids by the sum of the maximum light intensities in each set of red, green and blue images. Lastly, the principal-stress directions are obtained by applying the generalized phase-shift method to a set of monochrome photoelastic images. The proposed method is applied to a circular disk subjected to a concentrated load. Results show that the principal-stress directions obtained by this method are in good agreement with the theoretically determined directions.
