Finite element computation of residual stresses near holes in tempered glass plates

International audienceThis work presents numerical results of the thermal tempering simulation by the finite element method in order to calculate residual stresses near edges of a glass plate (2D calculation) and near chamfered holes (3D calculation). During thermal tempering, glass is considered as a viscoelastic material. Narayanaswamy's model is used; it takes into account the structural relaxation phenomena. Particular difficulty is the correct modelling of heat transfers since residual stresses strongly depend on the history of temperature within the plate, close to the edges and in the vicinity of the hole. Both the forced convection due to the blowing of air and the radiative heat transfer are modelled numerically. The semi-transparency of glass in the near infrared range is considered. The convective heat transfer coefficients on the edge and hole walls are identified thanks to a specific experimental setup and validated from simulations of heat transfer tests. The computed residual stresses are checked against photoelastic measurements