In-Situ X-ray Tomography Observation of Structure Evolution in 1,3,5-Triamino-2,4,6-Trinitrobenzene Based Polymer Bonded Explosive (TATB-PBX) under Thermo-Mechanical Loading

Abstract

In order to study the fracture behavior and structure evolution of 1,3,5-Triamino-2,4,6-Trinitrobenzene (TATB)-based polymer bonded explosive in thermal-mechanical loading, in-situ studies were performed on X-ray computed tomography system using quasi-static Brazilian test. The experiment temperature was set from −20 °C to 70 °C. Three-dimensional morphology of cracks at different temperatures was obtained through digital image process. The various fracture modes were compared by scanning electron microscopy. Fracture degree and complexity were defined to quantitatively characterize the different types of fractures. Fractal dimension was used to characterize the roughness of the crack surface. The displacement field of particles in polymer bonded explosive (PBX) was used to analyze the interior structure evolution during the process of thermal-mechanical loading. It was found that the brittleness of PBX reduced, the fracture got more tortuous, and the crack surface got smoother as the temperature rose. At lower temperatures, especially lower than glass transition temperature of binders, there were slipping and shear among particles, and particles tended to displace and disperse; while at higher temperatures, especially above the glass transition temperature of binders, there was reorganization of particles and particles tended to merge, disperse, and reduce sizes, rather than displacing.

Microcomputed X-Ray Tomographic Imaging and Image Processing for Microstructural Characterization of Explosives

“…These difficulties are exacerbated in cases where the material is close to theoretical maximum density, or when the composite explosive is very highly loaded (>90% HE). In short, measurement of “real” explosives with µCT has been generally limited to detecting voids or cracks [ 25 , 29 , 30 ], and fully segmentable microstructures have only been obtained by using engineered or optimized samples [ 23 , 24 , 31 ]. An analysis of voids and cracks is still useful for safety and initiation modeling [ 8 , 32 , 33 ], but full spatial information would greatly enhance these efforts while also enabling real microstructures (i.e., accurately described crystal and binder distribution) to be used for mesoscale simulations (e.g., [ 34 ]).…”