Numerical And Experimental Investigations On The Residual Stresses At The Centre Of Flat Glass Disks After Thermal Tempering

Flat glass disks are thermally tempered by air-cooling with two air jets at the centre of their surfaces. Numerical modelling and photoelasticity measurements are proposed to analyse the distribution of the residual stresses through the glass thickness at the centre of the tempered disks. For the modelling, glass properties dependant of the temperature are used for the conductive heat transfer. Radiation is modelled by an improved approximation method. By taking both structural and stress relaxation into account, the transient and residual stresses are computed along the disk thickness. For experimentation, a complete procedure is proposed to access to the stress state in the centre of the disks using a scattered light polariscope.