Abstract
This study was aimed at evaluations of the blast characteristics by the arrival time of blast wave in the air. Some experimental explosions with small explosives less than a hundred gram were carried out in an explosion chamber. The signal from a handmade blast switch, which used aluminum foil as a blast-pressure acceptor, showed the same time to the edge position of time-pressure waveform observed by piezoelectric pressure sensor. It meant the arrival time of shock wave could be measured by the blast switch. According to the result of some experiments with several weights of Composition C-4, it was recognized that the arrival time apparently followed Sachs' scaling law because the plots of scaled arrival time against scaled distance came together on a line. The performance of Chlorate explosive, a mixture of potassium chlorate and sugar, was examined. The Composition C-4 equivalence of the chlorate explosive was led by two parameters that were peak overpressure and arrival time. The values 42.3% and 36.0% were given by the two parameters respectively.
A measuring method of the arrival time for explosion accompanied with fragments was also examined. Composition C-4 put in a round-bottom flask was applied to the experiment. While the face-on blast switch was interfered by numerous glass particles scattered by the explosion, the side-on blast switch could avoid the glass particles clearly. The result suggested that the arrival time could be measured in spite of an explosion with scattering of fragments by the side-on blast switch.
