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Additive manufacturing has the potential to fundamentally change how military expeditionary operations are conducted. By manufacturing spare parts in remote sites, rather than relying on lengthy and extensive supply chains or remaining tethered to an "iron mountain" of logistics support, the expeditionary units have the potential to be more agile, to maintain their readiness at high levels while deployed, and to extend their operational reach. We describe how the additive manufacturing capability can be combined with a networked logistics approach for the U.S. Marine Corps. The ultimate goal is to develop a logistics support structure that is more resilient to enemy attacks and provides improved support to the forward units. ; Naval Postgraduate School Acquisition Research Program

17 USC 105 interim-entered record; under review. ; The article of record as published may be found at https://doi.org/10.3390/nano11092168 ; Epoxy resins for adhesive and structural applications are widely employed by various industries. The introduction of high aspect ratio nanometric conductive fillers, i.e., carbon nanotubes, are well studied and are known to improve the electrical properties of the bulk material by orders of magnitude. This improved electrical conductivity has made carbon nanotube-based nanocomposites an attractive material for applications where their weight savings are at a premium. However, the analytical methods for validating carbon nanotube (CNT) nanofiller dispersion and for assuring that the properties they induce extend to the entire volume are destructive and inhibited by poor resolution between matrix and tube bundles. Herein, rare-earth oxide nanoparticles are synthesized on CNT walls for the purpose of increasing the contrast between their network and the surrounding matrix when studied by imaging techniques, alleviating these issues. The adherence of the synthesized nanoparticles to the CNT walls is documented via transmission electron microscopy. The crystalline phases generated during the various fabrication steps are determined using X-ray diffraction. Deep ultraviolet-induced fluorescence of the Eu:Y2 O3 -CNT nanostructures is verified. The impacts to nanocomposite electrical properties resulting from dopant introduction are characterized. The scanning electron microscopy imaging of CNT pulp and nanocomposites fabricated from untreated CNTs and Eu:Y2O3-CNTs are compared, resulting in improved contrast and detection of CNT bundles. The micro-CT scans of composites with similar results are presented for discussion. ; U.S. Government affiliation is unstated in article text.

17 USC 105 interim-entered record; under review. ; The article of record as published may be found at http://dx.doi.org/10.1016/j.compositesb.2021.108874 ; The properties of CNT composites are known to suffer changes when exposed to space conditions or simulated space environments. A more in-depth understanding of the magnitude of those changes could help improve the design of systems that contain them, produce more accurate predictions of their performance, or even open the possibility of new applications. In this study, the electrical properties of CNT epoxy composites containing low CNT loadings (less than 1%) were measured in-situ while the specimens were exposed to diverse simulated space conditions. A thermal vacuum chamber was employed to produce the low pressures and temperatures associated with low earth orbit. A solar simulator was used to replicate solar irradiance. A convection oven was used to determine the effects that could only be attributed to temperature variations. The changes in resistivity exhibited by the composite specimens are reported for each scenario along possible mechanisms that could explain the observed behavior. The microstructural and thermogravimetric characterization of the composites for the diverse loadings is also presented. Resistivity reductions of up to 40% were observed by the simultaneous application of high temperatures and low pressures, while the application of simulated sunlight with the concomitant surge in temperature, showed a maximum decrease of 58%. Outgassing and an increase in the number of charge carriers at the higher temperatures promoted by the simulated sunlight treatment, are believed to be responsible for the recorded reductions in resistivity. A qualitative analysis of the resistivity changes noted when the composites are exposed back to atmospheric conditions is included. ; U.S. Government affiliation is unstated in article text.

Proceedings of the 16th Annual Acquisition Research Symposium; Thursdays sessions; Volume II ; Additive manufacturing has the potential to fundamentally change how military expeditionary operations are conducted. By manufacturing spare parts in remote sites, rather than relying on lengthy and extensive supply chains or remaining tethered to an "iron mountain" of logistics support, the expeditionary units have the potential to be more agile, to maintain their readiness at high levels while deployed, and to extend their operational reach. We describe how the additive manufacturing capability can be combined with a networked logistics approach for the U.S. Marine Corps. The ultimate goal is to develop a logistics support structure that is more resilient to enemy attacks and provides improved support to the forward units. ; Naval Postgraduate School Acquisition Research Program ; Approved for public release; distribution is unlimited.

The article of record as published may be found at http://dx.doi.org/10.3390/inorganics2030377 ; This manuscript summarizes the failure mechanisms found in inorganic fullerene-type tungsten disulfide (IF-WS2) nanoparticles treated with diverse pressure loading methods. The approaches utilized to induce failure included: the use of an ultrasonic horn, the buildup of high pressures inside a shock tube which created a shock wave that propagated and impinged in the sample, and impact with military rounds. After treatment, samples were characterized using electron microscopy, powder X-ray diffraction, energy dispersive X-ray spectroscopy, and surface area analysis. The microstructural changes observed in the IF-WS2 particulates as a consequence of the treatments could be categorized in two distinct fracture modes. The most commonly observed was the formation of a crack at the particles surface followed by a phase transformation from the 3D cage-like structures into the 2D layered polymorphs, with subsequent agglomeration of the plate-like sheets to produce larger particle sizes. The secondary mechanism identified was the incipient delamination of IF-WS2. We encountered evidence that the IF-WS2 structure collapse initiated in all cases at the edges and vertices of the polyhedral particles, which acted as stress concentrators, independent of the load application mode or its duration.