Carbon fiber composites are becoming very popular in many industries, such as aerospace, automotive, and naval, due to their attractive strength to weight ratio and versatility. The brittle nature of the polymer used as a bonding agent in carbon fiber composites induces cracking behavior under high loading conditions. The research presented herein aimed to verify the independence of fracture toughness of said cracking behavior from the artificial stiffening of carbon fiber specimens with steel reinforcements. That is, the addition of steel reinforcements allows for evaluating if the fracture toughness is a material property instead of a structural property. Understanding how reinforcements on composite structures affect crack propagation is important for better mitigating damage and developing more resilient interlaminar matrix polymers for carbon fiber composites. Multiple Double Cantilever Beam (DCB) tests were performed on unidirectional composite carbon fiber laminates without steel reinforcements and with steel reinforcements adhered to the carbon fiber laminates with an epoxy. All DCB tests were performed at a quasi-static rate to eliminate inertial effects of dynamic systems on the specimens. Photos of the specimens during testing were taken at set time intervals to determine the rate of fracture growth and displacement of the overall specimen. Both the similarities and differences on various testing parameters critical to determining fracture toughness were observed for both tests and it was experimentally determined that, in fact, the steel reinforcements do not change the fracture toughness of the specimens and that the cracking behavior is similar for both cases. Ultimately it was also concluded that fracture toughness is a material property and independent of physical changes to the specimen. The results of this research were cross-checked with theory developed by the American Society for Testing and Materials (ASTM) and were found to consistent with the theory therein.

An Ion Doppler Spectrometer Diagnostic (IDS) system has been constructed to measure the temperature and velocity of C III and O II plasma impurity ions on the HIT-SI and HIT-SI3 spheromak devices. Accurate diagnosis of such ion dynamics is necessary to characterize the experiments, in pursuit of their goal of fusion energy. The demands of resolution and extent on the system are set temporally by the period of the perturbation applied to the plasma and the desire to collect data for the entire discharge, and spatially by the relatively small radius and the desire to extend spatial profiles as far as possible. These requirements are uniquely met by the present IDS construction with <=6.9 µS temporal and >=2.8 cm spatial resolution in the midplane (although only the upper half midplane is visible in HIT-SI). 72 fused-silica fiber channels in two bundles gather light from the plasma, and an f/8.5 Czerny-Turner spectrometer coupled to a fast camera digitizes the spectral lines. Because the Signal to Noise Ratio is likely to be small, Biorthogonal Decomposition is applied as a filtering technique, and the data is fit using the Levenberg-Marquardt algorithm. We find axisymmetric temperature profiles on HIT-SI3 for C III peaked near the inboard separatrix at approximately 40 eV. Axisymmetric displacement profiles have been found on HIT-SI3, peaked at the outboard separatrix with magnitude 8 cm. These agree with the half of the midplane accessible to HIT-SI. With its complete midplane view, HIT-SI3 has unambiguously extracted axysymmetric, toroidal current dependent rotations of up to 3 km/s. Finally, analysis of the temporal phase of the displacement uncovers a coherent structure, locked to the applied perturbation. Analysis is presented for O II and C III, for both toroidal current directions. These analysis results would not have been achievable on other existing IDS systems.

This project focuses on adding unique telemetry and communication capability to one of the largest and fastest growing areas in the Washington State aerospace industry: Unmanned Aerial Systems (UAS). These systems have the potential to revolutionize a wide variety of commercial applications such as precision agriculture, disaster management, mapping, and ecological/biological monitoring and represents a $13.6 billion civilian market. One of the main challenges for UAS integration is to provide reliable and effective guarantees for safe operation that in turn requires high-performance and flexible control/navigation of the aircraft and reliable transmission modes from air to a ground control station or operator. For example, a typical commercially available UAV will have 3 distinct sensor-processing-radio chains, one each for onboard camera, one for data telemetry (navigation and strategic command) and one for primary command & control data. This effort fundamentally seeks to mature ongoing work at UW and will allow for greater communication bandwidth, enhanced flexibility, and levels of control between the UAS and GCS and achieve the required situational awareness as mandated for UAS operations. The outcome of this project will be a modular, encapsulated radio system that can be used to combine the myriad data links between a UAS and the GCS into a single, robust, and reconfigurable link. The link quality will be tested using a bladeRF software defined radio paired with a student built, Pixhawk based octocopter. Several flights tests will be conducted by students using custom built software which will measure the strength of the UAV based link in various environments. This project encapsulates the construction of the octocopter, the build of the software defined radio system, and flight testing. A publicly accessible link quality database will be populated with fight test data in order to encourage further development of software defined based communication links.

The increase use of composites in manufacturing complex aerospace structure calls for a more robust method of inspection. Conventional metallic strain gauges currently used by the aerospace industry require extensive preparation and can be time consuming. An embedded sensor system could tremendously improve on inspection time, as well as continuously monitoring the health of a structure. The sensors being developed are able to withstand larger tensile strain compare to traditional metal based strain gauges, and can be manufactured inexpensively. The embedding offers additional protection against harsh environment for the sensor; however, the sensor could affect the performance of a composite as a foreign body defect. This study aims to investigate the capacity and effects of an embedded uniaxial fiber strain gauges, arranged in orthogonal grid network configuration, inside a fiberglass fabric-reinforced laminate. These sensor fibers are made by hot extrusion of thermoplastic elastomer, and finished with a piezoresistive chemical coating. Linear behavior of resistance changes by strains was observed when applied loadings. Bending and torsion tests have shown the embedded sensors network to be effective in distinguishing mode of deformation in the test specimens.