GENERALIZED MAXWELL MODEL FOR THE VISCOELASTIC BEHAVIOR OF A SODA-LIME-SILICA GLASS UNDER LOW-FREQUENCY SHEAR LOADING

The linear viscoelastic behavior of a soda-lime-silica glass under low frequency shear loading is investigated in the glass transition range . Using the time-temperature superposition technique, the master curve s of the shear dynamic relaxation moduli are obtained at a reference t emperature of 566 degrees C. A method to determine the viscoelastic co nstants from dynamic relaxation moduli is proposed. However, some visc oelastic constants cannot be directly measured from the experimental c urves and others cannot be precisely obtained due to non-linearity eff ects at very low frequencies. The generalized Maxwell model is investi gated from the experimental dynamic moduli without fixing the viscoela stic constants. A set of parameters is shown to be in good agreement w ith the experimental dynamic relaxation moduli, but does not give the correct values of the viscoelastic constants of the investigated glass . The soda-lime-silica glass exhibits a non-linear viscoelastic behavi or at very low stress level which is usually observed for organic glas ses. This non-linear behavior is questioned.