Mechanical properties of solid high explosives under intense shock loading

A number of techniques employed to perform dynamic tests of samples and dev ices made of high explosives (HE) is briefly described and some results of tests are discussed. Samples were pressurized using special explosion-drive n loading devices producing pressure pulses with prescribed parameters. The refore along with data on the kinetics of explosive conversions we thorough ly analyzed a poorly studied area of dynamic strength of samples and parts made of solid HE: stress-strain (sigma-epsilon) diagrams of dynamic compression of some solid HE (various TNT-RDX melts and HMX-based HE) were plotted using the data of measurements by a modified (with loading by explosion) Hopkinson method of sectional rods (HSR), the strain rate varied between 200 and 500 s(-1) and sample temperature, from -20 to + 80 degrees C; a technique developed on the basis of HSR is used to gain data on dynamic r esistance to cracks (stress intensity coefficient, k(1d)) Of solid HE; a k( 1d) dependence on the pressurization rate is determined for three HE at var ious temperatures; spalling strength of bye explosive compositions (TNT, tw o RDX-based HE, and two HMX-based HE) is determined. The spalling strength values are measured at the stage of destruction commencement at a character istic loading time t = 1.5.10(-6) s (impact of a plate on an HE sample); the dependence of dynamic yield strength on the normal pressure behind SW i n four HE is derived from direct recording of principal stresses behind the shock wave (SW) front with the aid of manganin gauges (the pressure at the SW front amounted to 2.5 GPa); explosion-driven devices for shock tests of large-scale constructions conta ining HE are described. Objects tested are loaded at the active portion of their acceleration trajectory. Loading pulses specified by the following pa rameters: pressure rise at the front, pulse duration and pressure decay, ar e produced by explosion pressure generators with a reliable localization of the explosion products. The decelerating system used allows the constructi on tested to be caught and examined visually.