Six-step Phase Shifting Method for Stress Analysis of Transparent Materials

Photoelastic method makes use of the gray information in images and then carries out unwrapping on the images to determine the whole field isochromatic fringe orders, so that the stress distribution can be worked out. In this paper, the Patterson and Wang's six-step phase shifting method and computer digital image processing technology were applied to the traditional photoelastic method, and the PMMA transparent materials model samples with accurate theoretical solution were tested. Through the implementation of one just shoot and one inclined shoot, combined with image processing technology, transparent material stress distribution was determined. Then the test results and the theoretical solution were compared. The relative error was 7.9%. Several factors have been analyzed at length. Above all, the feasibility of using this method to study PMMA stress distribution was inferred at the end of this paper.