Failure and re-initiation detonation phenomena in NM/PMMA-GMB mixtures

The addition of a small amount of glass microballoons (GMB) on nitromethane/polymethylmethacrylate (NM/PMMA) mixture reduces strongly the failure thickness and increases the detonation sensitivity. Based in an explosive mixture of NM/PMMA (96/4 by weight) with 1% of GMB (QCel 520 FPS, mean particle diameter of 45 μm), the failure and re-initiation phenomena are investigated experimentally using the corner turning experiments. The printed erosion figure on a polished copper plate, is used as a witness surface. This witness plate not only shows the shock oblique waves but also, around the corner, the re-initiation points and curves. In the dark zone two re-initiation fronts are observed. Two detonation curve fronts can be observed, corresponding to behaviours of homogeneous and heterogeneous explosives. In order to evaluate the influence of shear and normal stress waves, the original set-up has been modified, fixing a thin sheet of a kapton barrier (50 μm thickness) at different angles from the corner. It h...