Effect of preloading on the strength of soda-lime glass

Static fatigue and bending experiments were carried out on as-cut soda-lime glass to investigate the effect of preloading on the residual strength. Ambient air or semi-controlled dry air was used for the preloading. The results show that preloading increases both the static fatigue life and bending strength. The static fatigue life increases with preloading load, and is longer after preloading in air than in dry air. In bending tests, the bending strength increases with preloading time. The improvements of the strength of glass by preloading are interpreted as stress enhanced aging. Two dominant mechanisms for aging, the crack blunting model and stress release model, were examined by using the present experimental results.