RGB photoelasticity applied to the analysis of membrane residual stress in glass

Abstract

The measurement of residual stresses is of great relevance in the glass industry. The analysis of residual stress in glass is usually made by photoelastic methods because glass is a photoelastic material. This paper considers the determination of membrane residual stresses in glass plates by automatic digital photoelasticity in white light (RGB photoelasticity). The proposed method is applied to the analysis of membrane residual stresses in some tempered glass. The proposed method can effectively replace manual methods based on the use of white light, which are currently provided by some technical standards.

Review of RGB photoelasticity

“…In certain cases, it is appropriate to use the self-calibration procedure that does not require a calibration specimen [63]. This procedure is outlined in Section 7.2.1.…”

“…The effect of the different dispersion of the birefringence between the material of the test and that of the calibration specimen is considered in [63].…”

“…In the case of glass, material by which it is difficult to realize the calibration specimen, the self-calibration procedure (see Section 7.2.1) has been proposed in [63]; by operating on the same material, it takes into account both the difference of colours and the dispersion of the birefringence.…”

“…Applications of the RGB method to the membranal residual stresses on glass plates are cited by Lavrador et al [91], while this application have been recently developed by Ajovalasit et al [63,65,74,92].…”

“…classic RGB photoelasticity by self-calibration procedure [63]; RGB photoelasticity by means of the test fringes method (TF-RGB: Test fringes RGB Method) [74];…”