Numerical Simulation of Forming Process of Glass-Lens Using Finite Element Method

In the present paper, numerical simulation about press forming process of glass lens using finite element method is investigated. It is well known that constitutive equation (elastic constants) of glass depend on time-history and temperature. Therefore, stress relaxation or creep arise on the glass subjected to applied loading, and these behaviors vary drastically depending on the temperature. In the present study, creep test has been conducted to determine the thermo-viscoelastic properties of glass. The creep function obtained by the experiment has been transformed into relaxation function employing Laplace transform and its inversion. Shift factor which gives the relation between the time and temperature can be determined by creep test under several temterature, too. Using typical glass “TaF-3” which has been used for press forming, some numerical simulation by FEM are demonstrated. Residual stresses and residual deformations under some processing conditions are estimated, and the optimal conditions of forming process for glass lens are discussed in detail.