Creep Measurements on Plastic Bonded Explosives

We report on the development of hardware and methodologies used to measure creep and recovery in PBX materials. Specific emphasis is on measurements involving the insensitive high explosives (IHEs) including LX-17-1 and PBX-9502. The work described includes constant-stress, uniaxial creep performed at temperatures ranging from as low as 24 ̊C, up to 70 ̊C, with stresses ranging from approximately 1.7 to 5.4 Mpa. In addition to uniaxially loaded, unconfined creep measurements, we also report on experiments in which the materials tested were under a state of lateral confinement. Several sensor types are used in our experiments, so that load-creep-unload-recovery strain histories are derived through hybridization of the data from the two sensor types. Prior to the onset of material failure, strain-time plots for these materials have been shown to be accurately fit using simple log expressions. This serves to facilitate extrapolation and assists in the creation of computer-based models. In addition to compression creep, we also discuss our early efforts directed toward measuring creep in tension using digital image correlation (DIC).