Glass sagging simulation with improved calculation of radiative heat transfer by the optimized reciprocity Monte Carlo method

International audienceGlass sagging is used to process glass industrial products such as windscreens, mirrors or lenses. A 2D glass sagging process, simulated with the Finite Element Method (FEM), is presented in this work. Different thermal cases are reviewed with special care brought to radiative transfer model, with an optimized reciprocity Monte Carlo method used as the reference. Results show that ignoring radiative transfer is a too rough hypothesis. This leads to large errors on the glass temperature distribution, on the forming process and on the final shape in case of glass sagging without mold. However, predefining glass temperature or using Rosseland approximation give acceptable results, less accurate than Monte Carlo simulations especially for a fine prediction of the transfer as a function of time, but with smaller CPU times

Combined Temperature and Deformation Measurement During Glass Forming in a Real Scale Setup

International audienceAn experimental setup has been built and instrumented with non intrusive measurement methods aiming at measuring temperature fields and deformations of a soda-lime-silica glass piece during thermoforming process. A real scale furnace has been used and a realistic thermal load case applied. Infrared measurements based on the Christiansen effect have been performed on the present glass sample, providing the temperature distribution on the sample surface through IR images at 7.8 mu m. Piece deformation has been registered simultaneously, using a DIC (Digital Image Correlation) technique combined with a fringe projection method. Results have been analysed in a combined manner, showing a non symmetrical deformation despite a quite homogeneous thermal field, which could be explained by mould/glass contact problems. The non intrusive measurement technique has been proven to be relevant for a possible control of the thermal environment of the piece during the thermoforming process. Further tests should be carried out on a wide range of shapes and glass types