Pulsed Microwave Plasma Instrumentation for Investigation of Plasma-Tuned Multiphase Combustion

Strategies to control solid rocket propellant regression rate require a robust throttling technique applicable to high performance propellant formulations. Currently, several methods to control and throttle either motors or subscale propellant strands exist, including chamber pressure control (e.g. pintle nozzles or rapid depressurization quench), infrared laser irradiation of the burning surface to increase burning rates, development of inherently unstable combustion chamber geometries (producing either local pressure or velocity perturbations), and electrically sensitive hydroxylammonium nitrate (HAN)-based formulations in which burning rate is controlled by a voltage potential. However, these techniques are limited in that they either can only be used with low flame temperature (low specific impulse) propellants, result in low propulsion system mass fraction (pintle), are only capable of producing a single perturbation, or are formulation specific.

Posted in: Briefs, Aerospace, Energy, Materials, Power Transmission, Propulsion, RF & Microwave Electronics, Instrumentation

Microstructural and Mechanical Characterization of 2-D and 3-D SiC/SiNC Ceramic-Matrix Composites

The purpose of this endeavor was to investigate the effect of 3-D weave architecture on PIP-processed ceramic-matrix composites (CMC). Microstructural studies were performed to document the resulting microstructure and mechanical testing was performed to determine the high-temperature durability of the five different variants of SiC/SiNC CMC investigated.

Posted in: Briefs, Aerospace, Imaging, Ceramics, Composites, Materials, Mechanical Components

Evaluation of Peel Ply Surface Preparation of Composite Surfaces for Secondary Bonding

Lightweight composite structures offer significant long-term cost-saving opportunities for the U.S. Army as replacements for traditional metal structures. However, high-strength economical bonding processes must be developed to join composites in order for them to be viable replacements. The Army is exploring approaches, also under evaluation in the commercial aerospace industry, to reduce the process steps associated with composite bonding.

Posted in: Briefs, Aerospace, Defense, Manufacturing & Prototyping, Ceramics, Materials, Metals, Joining & Assembly, Mechanical Components

Enhanced Contacts for Inverted Metamorphic Multi-Junction Solar Cells Using Carbon Nanotube Metal Matrix Composites

In order to address issues related to mechanical and vibrational stresses that are commonly experienced in mounting, launch, and deployment of spacecraft, metal matrix composite (MMC) electrodes were fabricated with carbon nanotubes (CNTs) as reinforcement. The research plans were centered on first developing and selecting appropriate processes for fabricating CNT-MMCs based on characterization of their material properties, followed by optimizing MMC designs based on electrical testing under stress. Efforts in the program were also directed toward implementing the CNT-MMCs into solar cell device processing in a process compatible with standard clean room procedures.

Posted in: Briefs, Aerospace, Defense, Energy, Energy Efficiency, Energy Storage, Renewable Energy, Solar Power, Materials, Metals, Mechanical Components, Nanotechnology, Measuring Instruments, Test & Measurement

Burner Rig Testing of A500® C/SiC

There is growing interest in developing, testing, and deploying ceramic-matrix composites (CMCs) into commercial and military aerospace gas turbine engines due to their durability under extreme conditions and weight-savings potential. For military applications, the focus is on the afterburning section of the turbine engine, including the flameholder, augmentor liner, and both the convergent and divergent segments of the exhaust nozzle. These are demanding applications because of the high temperatures and rapid thermal cycles.

Posted in: Briefs, Aerospace, Composites, Materials, Instrumentation, Measuring Instruments, Monitoring, Test & Measurement

Space Debris Orbit and Attitude Prediction for Enhanced and Efficient Space Situational Awareness

This research deals with the problem of modelling the orbit and attitude motion of uncontrolled manmade objects in orbit about the Earth, which tumble due to the natural influences of the near-Earth space environment. A mathematical, physics-based and computational approach is taken to model the forces and torques that drive the orbit and attitude evolution of such objects. The main influence modelled is solar radiation pressure (SRP), which is the interaction of solar electromagnetic radiation with the surface of an object, leading to both forces and torques that influence the orbital and attitude motion. Other influences, such as the gravitational field of the Earth, are also modelled.

Posted in: Briefs, Aerospace, Imaging, Materials, Simulation Software, Transportation

Fundamental Aspects of Single Molecule and Zeptomole Electroanalysis

The objective of this research program was to provide the fundamental understanding required for using the principles of electroanalytical chemistry to detect target molecules at very low concentration, including single molecules, with high specificity, simplicity, and low power.

Posted in: Briefs, Aerospace, Defense, Materials, Nanotechnology, Inspection Equipment, Instrumentation, Measuring Instruments, Monitoring, Test & Measurement, Testing Procedures

Integrated Magneto-Optical Devices for On-Chip Photonic Systems

The magneto-optical (MO) oxide layer consists of (Bi,Y)3Fe5O12 or BiYIG, bismuth garnet. This material was selected because it has a better figure of merit than the CeYIG previously used, especially at lower wavelengths (1310 nm vs. 1550 nm). A top-down deposition process was developed in which BiYIG/YIG stacks are grown on the Si waveguide with YIG on top. The stack is annealed at 800°C/5 min to crystallize both layers, with the YIG templating the BiYIG leading to garnet phases rather than other oxides, and the BiYIG is directly on the Si waveguide. Initial attempts led to a film with Bi oxide phases, because the Bi was in excess and could not escape during the anneal as occurs in Si/YIG/BiYIG stacks. Hence the composition was adjusted to include slightly more Fe, which yielded films with only garnet peaks.

Posted in: Briefs, Aeronautics, Aerospace, Aviation, Electronic Components, Electronics, Electronics & Computers, Manufacturing & Prototyping, Materials, Optical Components, Optics, Photonics, Semiconductors & ICs

Low Power Optical Phase Array Using Graphene on Silicon Photonics

Despite enormous advances in integrated photonics over the last decade, an efficient integrated phase delay remains to be demonstrated. This problem is fundamental – most monolithic thin film deposition relies on centro symmetric materials (such as silicon, silicon dioxide, silicon nitride), which by definition do not have an electro-optic effect. Such materials have been shown to be excellent transparent materials, however they are either optically passive, or rely on very small plasma dispersion effect or power-hungry thermo-optic effect for tunability. These phase change materials have losses associated due to heating or carrier injection in the waveguides. This research shows that graphene can be used to provide electro-optic properties to traditionally passive optical materials.

Posted in: Briefs, Aerospace, Electronic Components, Electronics, Electronics & Computers, Materials, Optical Components, Optics, Photonics

Hydraulic Testing of Polymer Matrix Composite 102mm Tube Section

The objective of this research was to hydraulically pressurize the internal diameter of one 102mm Polymer Matrix Composite (PMC) over-wrapped cylinder up to 25,000 pounds per square inch (psi) and during pressurization, in real time, collect and store pressure and strain data simultaneously. Strain data must be captured from the inside diameter of the oil filled metallic cylinder and from the outside diameter of the composite over-wrap material.

Posted in: Briefs, Aerospace, Data Acquisition, Electronic Components, Electronics, Electronics & Computers, Manufacturing & Prototyping, Composites, Materials, Metals, Joining & Assembly, Mechanical Components, Inspection Equipment, Instrumentation, Measuring Instruments, Monitoring, Test & Measurement