An Eight-Inch Diameter, Heavily Confined Card Gap Test

An instrumented card gap test which is useful for investigating the response of explosives to low pressure, long duration shock stimuli has been developed. The test was designed to screen for an explosive's propensity to detonate or react violently as result of shock induced sympathetic detonation of large ordnance such as general purpose bombs. Both donor and acceptor are encased in an 8-in. outside diameter by 0.35-in. wall steel pipe. Plexiglass of varying thickness and steel end plates are used to control the shock amplitude transmitted to the acceptor. The acceptor is instrumented with piezoelectric time of arrival pins and an armor witness plate. Hydrocode calculations show that the end plates result in significantly longer pressure durations and lower peak pressures than other gap test and is a more realistic mock of the shock loading experienced in large ordnance sympathetic detonation experiments. The results presented includes data for tritonal, composition B, TNT/wax and TNT/NQ/ wax. The range of pressure resulting in transition to detonation for different explosives is narrower for this test than that measured in experiments such as the NOL LSGT.