On the dynamic response of laminated glass exposed to impact before blast loading

Abstract

In this study, the effect of fragment or bullet impact before blast loading on laminated glass is studied experimentally. First, laminated windows consisting of two 3.8 mm thick annealed float glass plates and a 1.52 mm thick PVB interlayer were blast loaded in a shock tube with various pressures as a reference. In these tests, the blast loading was successively increased until fracture occurred not only in the glass plates but also in the PVB interlayer. Second, a diamond drill was used to make a 5 mm diameter centrally placed hole in some windows before they were blast loaded with the same pressures as those used for the undamaged windows. Third, windows were impacted by 7.62 mm AP bullets, both with and without the brass jacket, before they were blast loaded. Such bullets may have similar mass and velocity to typical primary fragments from an explosive detonation. The results are finally compared with each other and discussed with respect to the blast protection offered. It is found that the capacity is significantly reduced if the laminated glass is perforated by a fragment or a bullet before it is blast loaded and that such impacts should be considered in the design of blast-resistant windows.