Confined Creep Testing of Plastic-Bonded Explosives

: A considerable amount of data has been compiled on the strain response of plastic bonded explosives to uniaxial stress. In real world applications, however, these materials are most likely to be subjected to more complex stress states. In an effort to better understand the behavior of this material under multi-axial stress conditions, a series of experiments was performed to measure the effect of confinement on the compressive creep behavior of LX-17-1, a highly filled explosive composite consisting of 92.5% crystalline energetic and 7.5% polymer binder. These experiments were conducted using our Livermore-developed creep measurement apparatus in conjunction with a gas charged confinement fixture. Measurements of axial creep were made at temperatures ranging from 24 C to 70 C, with axial stresses ranging from 1.9 MPa to 5.4 MPa gage. Confinement pressures ranged from 0 MPa gage, up to levels equal to the applied axial stress. In all, approximately 25 experiments were performed. Design details relating to the creep measurement and confinement apparatus are presented, along with experimental results and analysis. Within the range of temperatures and pressures tested, creep rates were found to correlate reasonably well with the differential between the axial and confining stresses.