THE ACOUSTIC PRESSURE WAVE-FORM FROM SMALL UNCONFINED CHARGES OF PLASTIC EXPLOSIVE

The pressure waveform has been measured at distances to 1000 m from 12 5-g and 1-kg unconfined charges of plastic explosive. Pressure wavefor ms in free air have been compared with other published data and TNT eq uivalence factors for PE4 are given. Propagation over concrete and wat er are shown to yield similar waveforms, although the yield factor of the charge appears to be somewhat less over water. Propagation over gr ass gives waveforms of quite a different character, with much of the h igh-frequency content being removed. The positive peak overpressure de cays more rapidly with distance than it does over concrete. ANSI Stand ard S2.20-1983 is shown to be more suitable for predicting the peak ov erpressure over concrete or water than over grass. The sound exposure level (SEL) is calculated and empirical expressions are given in terms of charge size, distance, and surface. The effects of C-weighting are considered, and it is concluded that errors in the application of emp irical equations are likely to be increased because of the effects of scaling on the frequency content.