Direct measurement of rate-dependent mode I and mode II traction-separation laws for cohesive zone modeling of laminated glass

This paper reports a combined experimental-modeling study on the adhesion at glass/poly(vinyl butyral) (PVB) interfaces. PVB is a critical component in laminated glasses that provides impact resistance and prevents spallation in the event of glass breakage. We characterize the mode I (normal) and mode II (shear) interfacial fracture behaviors in glass/PVB/glass laminates and obtained independent cohesive (traction-separation) laws for the two modes. We observe a pronounced rate dependence of both traction-separation laws. Specifically, with increasing loading rate, the interfacial stiffness, the peak stress, and the fracture toughness increase while the critical opening or shear displacement decreases. These measured traction-separation laws are used as inputs in finite element analysis to predict the mechanical behavior of the peel test, which agrees reasonably well with the experimental results. Finite element analysis of a glass laminate subjected to impact loading demonstrates how the measured interfacial properties can be used to predict the mechanical behavior and failure of laminated glass.