3D nondestructive imaging techniques for mesoscale damage analysis of composite materials

ABSTRACT: Energetic materials may be subjected to severe environments of pressure and shear loading, causing damage that leads to premature initiation or suboptimal performance. This damage is at the mesoscale, at and below the grain size of the particles, in the range of 5-400 microns. X-ray computed microtomography is a 3D non-destructive technique that can be used for imaging this damage. It enables acquisition of valuable 3D microstructure data that can be input into damage models and simulations of fracture. We propose to capture the evolution of damage in representative composite materials, such as plastic bonded explosive simulants, through ex situ and in situ mechanical testing combined with X-ray tomography (XRT). Quantitative measurements of changes in microstructure features (such as cracks, voids, and particle shearing) during fracture will be extracted from the XRT data. Because contrast levels between particles and polymer binder are often difficult to discern, image processing and segmentation development will also be addressed. Lastly, potential damage models that incorporate the 3D microstructure data will be investigated. BENEFIT: 3D nondestructive imaging and analysis tools: o Proof of feasibility: Utilization of XRT with PBX simulant o Image segmentation development: Always a limiting step, so this will aid future efforts in moving towards automatic data processing o Method for studying damage evolution: ex situ and in situ combined mechanical and XRT experiments provide way for fabricating and studying various stages of microstructure damage. Predictive damage model, for evaluating performance o Preliminary development and validation of models that can make damage initiation and performance of energetics predictable. o Applicable to other material systems.