JET INITIATION PHENOMENA LEARNED FROM AUSTRALIA

摘要

The threshold values of the initiation of high explosive charges by shaped charge jets depend beside the charge type remarkably of the test condition. If the test charge is in direct contact to the barrier then the charge behaves less sensitively compared to an arrangement with an air gap between. These effects were found and reported by the Australians Chick and Hart for the first time and they have studied this topic further in much more detail. This behaviour was confirmed with other shaped charges and high explosive acceptor charges by the author. The different sensitivities of the acceptor charges in an air gap arrangement compared to direct contact can be explained by the bulging behaviour of the barrier material during the shaped charge jet perforation. This causes a pre-compression of the acceptor charges in a ramp wave which is desensitising the acceptor charges, which is well known. The phenomena first found in Australia with, at that time, very surprising results have lead to the fundamental understanding of the initiation behaviour of shaped charge jets. This is very important for the layouts and defeating mechanisms of explosive reactive armours (ERA) and the design of ammunitions, which should be less sensitive or less vulnerable against the attack of shaped charge warheads. The initiation phenomena can be very well visualised by frames of high speed cameras with 10~6 frames per second, whereas the build-up distances and delay times can be much more accurately analysed by the simultaneously gained streak records.