A 3D computation method for evaluating the impact of heat transfer on residual stress in thermal tempering of flat glass

A model to calculate the residual tempering stresses arising during the thermal tempering of flat glass in a static position in an industrial tempering unit has been developed. The model is a 3D finite-element model, based on the computational fluid dynamics (CFD) estimation of the heat transfer distribution on the glass surface, and takes structural and stress relaxations into account. First, the inhomogeneous distribution of the residual stresses for a reference air-impinging velocity value are presented and validated by photoelasticity measurements of the surface compression. For other velocities corresponding to the unit's processing capabilities, the numerical results highlight the relationship between heat transfer and stress in terms of average values and inhomogeneities on the glass surface.