Preventing failure of soda lime cover glasses by design optimization

In order to quantify the requirements of headlamp cover glasses with regard to impact and thermal shock resistance, special tests have been devised by the automobile industry. The development of cracks and flaws which are responsible for the mechanical strength of glass is governed by the specific processing conditions. It is therefore difficult to predict the mechanical performance of a glass on the basis of a theoretical model. Based on a modified Hertizian theory a numerical analysis has been carried out to optimize the resistance to impact of the glass. The actual temperature distribution on a reference cover glass of the desired final shape is taken as the boundary condition for the computer simulation of the thermal shock resistance. The results of the numerical analysis are compared with results achieved by experimental tests. (C) 2000 Elsevier Science Ltd. All rights reserved.