A novel method for the evaluation of stress-optic coefficient of commercial float glass

The measurement of residual stress in float glass is important in glass industries as they affect their cutting quality. Photoelasticity can be used for residual stress analysis of float glass as they exhibit stress induced birefringence. Stress measurement using photoelasticity necessitates the knowledge of the stress-optic coefficient of float glass. Carrier fringe method in conjunction with digital photoelasticity is used for the photoelastic calibration of float glass. The conventional method of photoelastic calibration is improved to calibrate float glass with residual stress which eliminates the need for annealing them. The new method developed is self consistent as the results are verified by the reconstruction of the composite fringe pattern. The use of the improved method is recommended for calibration of float glass as it takes into account the residual stress in glass sample apart from its potential for automation.