Behavior and strength of laminated glass

Published experimental data indicate that under most conditions laminated glass strength equals or exceeds the strength of monolithic glass of the same nominal thickness. To date, these experimental data exist without a theoretical model. This paper presents a theoretical, engineering mechanics model that accounts for factors that affect laminated glass behavior including temperature, thickness of the interlayer, and composition of the interlayer. It presents additional fracture strength data for laminated glass lites with a thicker interlayer than in previous tests. Both the theoretical model and the new fracture strength data indicate that laminated glass strength increases as interlayer thickness increases and that laminated glass strength decreases as temperature increases. Although an increase in temperature beyond 38 degrees C (100 degrees F) leads to a decrease in laminated glass strength, the theoretical model indicates that laminated glass possesses significantly more strength than "layered glass," e.g., simply, two plies of glass with no shear transfer, at temperatures above 49 degrees C (120 degrees F).