Investigation of Oblique Shocks and Edge Effects for Underground Targets. Volume I. Oblique Shocks.

摘要

This report summarizes results of a six-month test and analysis program to establish the effects of oblique shock waves on buried concrete structures. The objective of this program was to generate basic test which would show the effects of various corner angles (20 to 160 degrees) on a shock wave impinging a buried structure. The transmitted impulse was measured by photographic and electronic means. The initial velocity of a steel fly-off plate was obtained from high-speed photography. Quartz pressure gages were used to measure maximum force and total impulse as a function of the corner angle. Maximum force was found to be relatively constant at 20-, 30-, and 45-degree corner angles, drop sharply at 60 degrees and climb steadily from 90- to 160-degree corner angles. Initial fly-off velocity followed a similar pattern decreasing at 60 degrees, then rising steadily. The force reduction at 60 degrees may be the result of the formation of a Mach stem along the cone surface. Recommendations are to use hydrodynamic computer codes to better identify the mechanism involved, and to continue experimentation using the quartz pressure gages and very charge weight, stand-off, and other parameters to fully resolve effects of shock coupling with oblique geometries. (Author)