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2013
Conference Paper
Titel
Microstructural metrics and damage quantification in energetic materials
Titel Supplements
Abstract
Abstract
Polymer bonded explosives (PBXs) are complex composites consisting of explosive crystals in a polymeric binder. The mesostructure of these explosives greatly affects the initiation and sensitivity of the material. As the materials are prepared in high shear mixers, the initial particles can be damaged and the resulting microstructure is not simply additive from the constituents. Additionally, mechanical loading, such as occurs in a split Hopkinson pressure bar or shock loading experiment, can induce damage, which can lead to increased sensitivity. Damage may be defined as increased numbers of hot spots, which may be represented microstructurally as increased particle-particle contacts, binder debonding, and creation of new void spaces. These microstructural features may be identified using optical microscopy and X-Ray Computed Microtomography (XCMT). Optical microscopy provides only a two dimensional representation of the material, while XCMT provides three dimensional data. However, the limited contrast between explosive crystals and binder due to their similar densities can make it difficult to perform quantitative characterization on XCMT images. In this study, "as mixed" and explosively loaded samples are compared using quantitative techniques to identify correlations between microstructural features - Including convexity by area and perimeter, grain size distribution, and minimum nearest neighbor distance - and measured run-to-detonation using a custom gap test.