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

Microstructural characterization of composite high explosives (HEs) has become increasingly important over the last several decades in association with the development of high fidelity mesoscale modeling and an improved understanding of ignition and detonation processes. HE microstructure influences not only typical material properties (e.g.

Volumetric analysis and mesh generation of real and artificial microstructural geometries.

Producing a viable finite element mesh of realistic microstructural structural geometry is a critical step in analyzing the thermo-mechanical behavior of complex multi-material composites. Advancements in imaging technology such as micro computed tomography have allowed modelers to access high resolution mesoscale geometries for direct numerical simulation. However, converting from voxel based 3D images to usable finite element meshes has been challenging.

In Situ Imaging during Compression of Plastic Bonded Explosives for Damage Modeling.

The microstructure of plastic bonded explosives (PBXs) is known to influence behavior during mechanical deformation, but characterizing the microstructure can be challenging. For example, the explosive crystals and binder in formulations such as PBX 9501 do not have sufficient X-ray contrast to obtain three-dimensional data by in situ, absorption contrast imaging. To address this difficulty, we have formulated a series of PBXs using octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) crystals and low-density binder systems.

Probing interfaces between pharmaceutical crystals and polymers by neutron reflectometry.

Pharmaceutical powder engineering often involves forming interfaces between the drug and a suitable polymer. The structure at the interface plays a critical role in the properties and performance of the composite. However, interface structures have not been well understood due to a lack of suitable characterization tool.

Characterization of flexible ECoG electrode arrays for chronic recording in awake rats.

We developed a 64-channel flexible polyimide ECoG electrode array and characterized its performance for long-term implantation, chronic cortical recording and high resolution mapping of surface-evoked potentials in awake rats. To achieve the longest possible recording periods, the flexibility of the electrode array, adhesion between the metals and carrier substrate, and biocompatibility were critical for maintaining the signal integrity. Experimental testing of thin film adhesion was applied to a gold-polyimide system in order to characterize relative interfacial fracture energies for several different adhesion layers, yielding an increase in overall device reliability.