Temperature and time dependences of fragment generation and out-of-plane deformation in fractured tempered glass laminates

Abstract

The fragment number and out-of-plane deformation in tempered glass laminated with temperature- and time-dependent interlayers, which are important results after glass breakage, significantly affect the tension stiffening effect in post-fracture laminated glass (LG) and its geometrical imperfection, respectively. This paper explored the two objective physical quantities based on the fragmentation experiment. The study would contribute to the performance assessment and prediction of LG in the Post Fracture Limit State. The ionomer (SentryGlas®, SG), modified ethylene-vinyl acetate (PVE®), and PVE-based composite interlayers (SGE®) were considered. The testing temperatures were set at 20 °C, 50 °C, and 80 °C. Besides, long-term monitoring of the examined objectives was conducted based on voice recording and distance measurement. The results reveal that a stiffer interlayer can restrict the fragment generation and number in LG compared with monolithic glass (MG), whereas the influence weakens with increasing temperature. The fragment number in SG LG decreases by 30.91 % and 27.98 % compared to MG with the same surface stress at 20 °C and 50 °C, respectively. In addition, the temperature rise for all series and the thicker polycarbonate layer for SGE series result in decreased out-of-plane deformation. The stiffer SGE has a weaker restriction on the fragment number. Furthermore, the fragment number gradually increases due to the generation of secondary cracks. The increase within the first 15 min after glass fracture becomes more pronounced as the temperature rises. The time dependence of fracture-induced out-of-plane deformation in LG exhibits complicated patterns, where the variation trend at 20 °C is contrary to that observed at 50 °C and 80 °C.