Review of the Main Mechanical Testing Methods for Interlayer Characterization in Laminated Glass

In the last decades, the use of structural glass has increased exponentially. The reliability of brittle structural glass elements is considerably improved if laminated glass elements are chosen because, in this case, a redistribution of internal forces is permitted once a limited breakage occurs. Thus, instead of monolithic glass, composite materials consisting of two or more glass plies bonded together using a polymeric film as an interlayer are used. In the event of glass failure, because of the chemical bond between the different materials, the adhesion to the interlayer prevents glass fragments from scattering. To design structural elements, the definition of the mechanical features of the interlayer is necessary. However, several standards and techniques can be applied, considering the characterization of either the interlayer itself or the laminated glass. The paper reviews the main existing methods and focuses on the standard suggested by the CEN/TS 19100:2021, analyzing in detail the effect of the different parameters involved. A numerical model is presented to account for the effect of the stress level, glass, and interlayer thickness. Although the standard leaves a certain degree of freedom in choosing those parameters, in some cases the results can differ.

Automated summary

The use of structural glass has increased significantly in recent decades. Choosing laminated glass elements improves the reliability of brittle structural glass by allowing for redistribution of internal forces after breakage. Composite materials consisting of bonded glass plies with an interlayer film are used to prevent scattering of glass fragments in case of failure. This paper reviews different methods for characterizing the interlayer and focuses on the standard suggested by the CEN/TS 19100:2021, analyzing the effect of various parameters. A numerical model is presented to account for stress level, glass, and interlayer thickness. Although the standard provides some flexibility in parameter selection, results may differ in certain cases.