Robust Modal Filtering In Flexible Aircraft and Other Structures
These lighter and more flexible aircraft tend to be subject to increased aeroelastic phenomena, leading to higher wing loads and gust responses. Divergence, flutter, and other instability can also appear that, if uncontrolled, can lead to catastrophic wing failure. Avoidance of flutter through such methods as notch filtering must be replaced with active control if flutter exists inside the controller bandwidth. Therefore, Armstrong's algorithms are being developed as one component that may lead to practical active flutter suppression as well as load control. Having a modal filtering system that senses the total state of the aircraft's structure can enable active and timely intervention for control and performance optimization. Armstrong has conducted simulations of this technology using computer models with positive results, and flight validation efforts are forthcoming.
Activated Metal Treatment System (AMTS) for Paints
PCBs have been shown to cause cancer in animals and to have other adverse effects on immune, reproductive, nervous, and endocrine systems. Although the production of PCBs in the United States has been banned since the late 1970s, many surfaces are still coated with PCB-laden paints. The presence of PCBs in paints adds complexity and expense for disposal. Some treatment methods (e.g., use of solvents, physical removal via scraping) are capable of removing PCBs from surfaces, but these technologies create a new waste stream that must be treated. Other methods, like incineration, can destroy the PCBs but destroy the painted structure as well, preventing reuse. To address limitations with traditional abatement methods for PCBs in paints, researchers at NASAs Kennedy Space Center (KSC) and the University of Central Florida have developed the Activated Metal Treatment System (AMTS) for Paints. This innovative technology consists of a solvent solution (e.g., ethanol, d-limonene) that contains an activated zero-valent metal. AMTS is first applied to the painted surface either using spray-on techniques or wipe-on techniques. The solution then extracts the PCBs from the paint. The extracted PCBs react with the microscale activated metal and are degraded into benign by-products. This technology can be applied without removing the paint or dismantling the painted structure. In addition, the surface can be reused following treatment.
materials and coatings
Liquid Coating for Corrosion Prevention in Rebar
NASA's highly reliable, low-cost liquid-applied coating offers companies the ability to conveniently protect embedded steel rebar surfaces from corrosion. The inorganic, galvanic coating contains one or more of the following metallic particles: magnesium, zinc, or indium. In addition, the coating may contain moisture-attracting compounds that facilitate the protection process. After the coating is applied to the outer surface of reinforced concrete, an electrical current is established between the metallic particles and the surfaces of the embedded steel rebar. This electrical (ionic) current is responsible for providing the necessary cathodic protection for the embedded rebar surfaces. Coating performance has been characterized by KSC's Materials Science Laboratory and Beach Corrosion Test Site. Early tests determined that the coating met National Association of Corrosion Engineers (NACE) RP0290-90 100-millivolt (mV) polarization development/decay depolarization criteria for complete protection of steel rebar embedded in concrete. Other tests verified that the embedded rebar became negatively polarized, indicating the presence of a positive current flow with a shift in potential of over 400 mV. Accelerated life tests, tests with chlorides to simulate contamination, and compound optimization tests are currently being performed.
materials and coatings
Sensory Metallic Materials
While almost all advancements in nondestructive evaluation (NDE) focus on improving the NDE equipment and techniques, any testing is inherently limited by the response of the materials being tested. This technology seeks to improve the response of the material itself by embedding shape memory alloy (SMA) particles in the metallic structural alloy in a manner that does not compromise the structural integrity of the material. These SMA particles undergo a martensitic phase change (crystallographic change) in response to strain (e.g., a crack tip causing local deformation). The phase change produces an acoustic emission and a change in magnetic properties that can easily be detected and monitored, providing a means for enhanced NDE. The advantage is either that (1) the technology makes available existing NDE techniques that were not applicable before because of the type of structural material being used (the particles add new physics to the base structure) or (2) the technology enhances NDE because the SMA particles create conditions that are easier to detect damage relative to the equivalent level of damage in a structure without particles.
Piezoelectric Fiber Composite Actuator Portfolio
The NASA Langley Composite Actuator portfolio utilizes a NASA-patented (US 6,629,341) and commercialized MFC piezoelectric fiber composite actuator platform. This actuator platform enables compact, lightweight electroactive actuators, which can be broadly applied to a variety of actuator applications. NASA Langley has developed novel patent-pending actuator designs using the MFC actuator platform and other piezoelectric fiber composites to advance the performance of tunable fiber-optic lasers for distributed FBG sensing. The use of distributed fiber-optic-based sensors has enabled robust, low-cost, intrinsically safe measurement of physical parameters like stress, temperature, pressure, and the presence of certain chemicals. However, widely tunable, mode-hop-free, narrowband laser sources are required to interrogate current NASA-built distributed FBG sensing systems, and traditional diode- and fiber-based lasers cannot meet these requirements. To address these tunable laser shortcomings, NASA Langley has developed a portfolio of actuator architectures CASF, IDEAS, and CMFC. When an optical fiber containing FBGs is strained by the NASA Langley MFC actuators, it shifts the reflected wavelength of the FBG and can be used to tune an optical fiber laser to a specific, mode-hop-free, narrowband output. In addition to providing a wide (4 nm and larger) tuning range, the NASA actuators can also tune the fiber laser at high frequencies (up to 100 Hz), which enables the high-speed interrogation required for NASA distributed sensing systems. The CMFC is also envisioned for applications requiring larger (>25 nm) displacements, yet can be provided in a smaller, lighter form factor than microstages.
Ultrasonic Stir Welding
Ultrasonic Stir Welding is a solid state stir welding process, meaning that the weld work piece does not melt during the welding process. The process uses a stir rod to stir the plasticized abutting surfaces of two pieces of metallic alloy that forms the weld joint. Heating is done using a specially designed induction coil. The control system has the capability to pulse the high-power ultrasonic (HPU) energy of the stir rod on and off at different rates from 1-second pulses to 60-millisecond pulses. This pulsing capability allows the stir rod to act as a mechanical device (moving and stirring plasticized nugget material) when the HPU energy is off, and allowing the energized stir rod to transfer HPU energy into the weld nugget (to reduce forces, increase stir rod life, etc.) when the HPU energy is on. The process can be used to join high-melting-temperature alloys such as titanium, Inconel, and steel.
materials and coatings
Functionally Graded Metal-Metal Composite Structures
In order to improve the properties of monolithic metallic materials, alloying additions are made that create secondary phases and/or precipitate structures. These improvements must occur during melt solidification and are governed by the thermodynamics of the process. That is, optimizing the metallic alloy is possible only as much as thermodynamics allow. Developing novel methods to combine metallic compositions/alloys into a fully dense material is of interest to create materials with novel property combinations not available with monolithic alloys.While various approaches for layering two-dimensional materials exist, their capabilities are typically limited and non-isotropic. Further, while three-dimensional composites may be formed with conventional powder metallurgy processes, it is generally very difficult to control the arrangement of the phases, for example due to randomness created by mixing powders. This invention is method for creating a multiple alloy composite structures by forming a three-dimensional arrangement of a first alloy composition, in which the three-dimensional arrangement has a substantially open and continuous porosity. The three-dimensional arrangement of the first alloy composition is infused with at least a second alloy composition. The three-dimensional arrangement is then consolidated into a fully dense solid structure.
information technology and software
The Hilbert-Huang Transform Real-Time Data Processing System
The present innovation is an engineering tool known as the HHT Data Processing System (HHTDPS). The HHTDPS allows applying the Transform, or 'T,' to a data vector in a fashion similar to the heritage FFT. It is a generic, low cost, high performance personal computer (PC) based system that implements the HHT computational algorithms in a user friendly, file driven environment. Unlike other signal processing techniques such as the Fast Fourier Transform (FFT1 and FFT2) that assume signal linearity and stationarity, the Hilbert-Huang Transform (HHT) utilizes relationships between arbitrary signals and local extrema to find the signal instantaneous spectral representation. Using the Empirical Mode Decomposition (EMD) followed by the Hilbert Transform of the empirical decomposition data, the HHT allows spectrum analysis of nonlinear and nonstationary data by using an engineering a-posteriori data processing, based on the EMD algorithm. This results in a non-constrained decomposition of a source real value data vector into a finite set of Intrinsic Mode Functions (IMF) that can be further analyzed for spectrum interpretation by the classical Hilbert Transform. The HHTDPS has a large variety of applications and has been used in several NASA science missions. NASA cosmology science missions, such as Joint Dark Energy Mission (JDEM/WFIRST), carry instruments with multiple focal planes populated with many large sensor detector arrays with sensor readout electronics circuitry that must perform at extremely low noise levels. A new methodology and implementation platform using the HHTDPS for readout noise reduction in large IR/CMOS hybrid sensors was developed at NASA Goddard Space Flight Center (GSFC). Scientists at NASA GSFC have also used the algorithm to produce the first known Hilbert-Transform based wide-field broadband data cube constructed from actual interferometric data. Furthermore, HHT has been used to improve signal reception capability in radio frequency (RF) communications. This NASA technology is currently available to the medical community to help in the diagnosis and prediction of syndromes that affect the brain, such as stroke, dementia, and traumatic brain injury. The HHTDPS is available for non-exclusive and partial field of use licenses.
materials and coatings
High-Performance Polyimide Powder Coatings
Powder coatings are used throughout industry to coat a myriad of metallic objects. This method of coating has gained popularity because it conserves materials and eliminates volatile organic compounds. Resins traditionally chosen for powder coatings have low melting points that enable them to melt and flow into a smooth coating before being cured to a durable surface. High-performance resins, such as Teflon, nylon, and polyimide, have not been found suitable for use in powder coatings because of their high melting points. However, KSC's newly developed polyamic acid resins with low melting points can be used in a powder coating. These polyamic acid resins, when sprayed onto metal surfaces, can be cured in conventional powder coating ovens to deliver high-performance polyimide powder coatings. The polyimide powder coatings offer superior heat and electrical stability as well as superior chemical resistance over other types of powder coatings.
mechanical and fluid systems
Fluid Structure Coupling Technology
FSC is a passive technology that can operate in different modes to control vibration: Harmonic absorber mode: The fluid can be leveraged to act like a classic harmonic absorber to control low-frequency vibrations. This mode leverages already existing system mass to decouple a structural resonance from a discrete frequency forcing function or to provide a highly damped dead zone for responses across a frequency range. Shell mode: The FSC device can couple itself into the shell mode and act as an additional spring in a series, making the entire system appear dynamically softer and reducing the frequency of the shell mode. This ability to control the mode without having to make changes to the primary structure enables the primary structure to retain its load-carrying capability. Tuned mass damper mode: A small modification to a geometric feature allows the device to act like an optimized, classic tuned mass damper.