CORNER TURNING RIB TESTS ON LX-17

A circularly curved piece of LX-17 of square cross section was detonat ed at one end with a plane-wave lens. Detonation velocities along the inner and outer edge were measured with pins and a streak camera measu red the detonation front curvature on the end face. A steady state ''s hadow'' or inner curve velocity of 7.13 mm/mu s was measured for rib r adii of 89 mm and 114 mm. Time constants for the change to steady stat e on the curve were derived. The outer time constant is set by the tim e for the energy to flow across the explosive, not by the reaction zon e length, and this results in a considerable tilt of the front. The ti lt causes the leading point of the front to move far inward, close to the inner edge. A simple theory for reaction zone lengths is used firs t on slabs and then on the rib. Because the tilt directs the front awa y from the inner edge, the inner edge of the rib can sustain a shadow velocity lower than the failure velocity of the cylinder or slab. The rib has been modeled with Ignition and Growth th in DYNA2D, producing a smooth set of detonation velocities that are slightly low. The produ ction beta/program burn package in VHEMP produces a less smooth set of velocities that are too high.