Dynamic crack-interface interactions in SGP laminated glass: An experimental investigation

The damage mode (crack arrest or bifurcation) that develops in SentryGlas® Plus (SGP) laminated glass under dynamic impact loading is investigated experimentally in this paper. An optical caustic method is employed - which allows simultaneous measurements of the spatial and temporal evolution of crack paths and the dynamic stress intensity factor at the crack tip(s) - to elucidate the effects of interface location and impact kinetic energy upon the fracture morphology, crack propagation velocity and the dynamic stress intensity factor in SENB (single-edge notch bend) test specimens loaded in three-point bending by a drop-weight impact system. Results reveal that there is a critical distance, between the interface and pre-crack tip, below which the propagating mode-I crack is arrested by the interface; otherwise, bifurcated mixed-mode cracks will always appear in the impacted glass layer. A maximum dynamic stress intensity factor criterion is shown to be capable of predicting whether bifurcated mixed-mode cracks would appear in the aforesaid.