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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Bearing and gear steels for aerospace applications

Research in metallurgy and processing for bearing and gear steels has resulted in improvements in rolling-element bearing and gear life for aerospace application by a factor of approximately 200 over that obtained in the early 1940's. The selection and specification of a bearing or gear steel is dependent on the integration of multiple metallurgical and physical variables. For most aerospace bearings, through-hardened VIM-VAR AISI M-50 steel is the material of preference. For gears, the preferential material is case-carburized VAR AISI 9310. However, the VAR processing for this material is being replaced by VIM-VAR processing. Since case-carburized VIM-VAR M-50NiL incorporates the desirable qualities of both the AISI M-50 and AISI 9310 materials, optimal life and reliability can be achieved in both bearings and gears with a single steel. Hence, this material offers the promise of a common steel for both bearings and gears for future aerospace applications.

Zaretsky, Erwin V.↗
NASA NTRS1992

The development of nickel-metal hydride technology for use in aerospace applications

The nickel metal hydride technology for battery application is relatively immature even though this technology was made widely known by Philips' scientists as long ago as 1970. Recently, because of the international environmental regulatory pressures being placed on cadmium in the workplace and in disposal practices, battery companies have initiated extensive development programs to make this technology a viable commercial operation. These hydrides do not pose a toxilogical threat as does cadmium. Also, they provide a higher energy density and specific energy when compared to the other nickel based battery technologies. For these reasons, the nickel metal hydride electrochemisty is being evaluated as the next power source for varied applications such as laptop computers, cellular telephones, electric vehicles, and satellites. A parallel development effort is under way to look at aerospace applications for nickel metal hydride cells. This effort is focused on life testing of small wound cells of the commercial type to validate design options and development of prismatic design cells for aerospace applications.

Rampel, Guy↗
NASA NTRSDate not supplied

Principles of Directed Energy Deposition for Aerospace Applications

Metal Additive Manufacturing is changing how components are being fabricated for rocket propulsion and aerospace applications. Many additive manufacturing technologies are evolving, and active research is being conducted across academia, industry, and government to advance processes, materials, design, post-processing, and applications. While much focus has been on Laser Powder Bed Fusion (L-PBF) techniques, several large-scale techniques are also rapidly evolving using directed energy deposition (DED) techniques. This lecture will provide an overview of various DED technologies, a comparison among the technologies, various materials, parameters used to deposit, and several examples of DED applications for propulsion and aerospace components.

Additive Manufacturing↗
NASA NTRS2018

Summary of 2017 NASA Workshop on Assessment of Advanced Battery Technologies for Aerospace Applications

A workshop on assessment of battery technologies for future aerospace applications was held in Cleveland, OH on August 16-17. The focus of the workshop, hosted by NASA GRC, was to assess (1) the battery needs for future aerospace missions, (2) the state of battery technology and projected technology advances, and (3) the need for additional investments for future aerospace missions. The workshop had 109 attendees that included internationally recognized technology leaders from academia and national laboratories, high level executives from government and industry, small businesses, and startup companies. A significant portion of the workshop was focused on batteries for electrified aircraft. The presentation will summarize the finding on the state of battery technologies for electrified aircraft and will include assessment of current state of battery technology, gaps in battery technology for application in electrified aircraft, and recommended technology development options for meeting near-term and long-term needs of electrified aircraft.

Misra, Ajay↗
NASA NTRSDate not supplied

Evaluating Crystallinity in Thermoplastic Composites for Aerospace Applications

Polymer matrix composites (PMCs) offer many benefits for the aerospace industry due to their potential for weight reduction when compared to metal or ceramic based materials. Most PMCs currently in flight use thermoset matrices, however, thermoplastic resins are being explored as alternatives due to their ability to be remelted, which is of particular interest due to the potential for in-situ repair and faster production. Most thermoplastic resins are semicrystalline polymers. The properties of semicrystalline thermoplastics are directly influenced by their crystallinity, which can vary due to many factors including thermal treatments, environmental conditions, and mechanical deformation. Within thermoplastic PMC parts, crystallinity gradients can arise due to variations in part geometry, across part thicknesses, and along bonded joints. Monitoring the crystallinity of thermoplastic composites is key to ensuring these materials meet the high demands required for aerospace. Several different analytical techniques exist that can be used to characterize the bulk crystallinity of thermoplastic materials. However, many existing methods lack the specificity required to identify the subtle variations in crystallinity that may play a significant role in the performance and durability of PMC parts. Because of this, a significant amount of work is still required to fully characterize and understand the crystallinity profiles of thermoplastic PMCs and the resulting impact to material properties. This talk discusses the use of multiple techniques such as Differential Scanning Calorimetry, Polarized Light Optical Microscopy, and Fourier-Transform Infrared Spectroscopy to characterize the crystallinity in carbon fiber/thermoplastic composites. Samples of different crystallinity profiles were manufactured using various cooling procedures. This work aims to provide the fundamental data necessary to understand the effects of crystallinity on thermoplastic PMCs, which is key to advancing their use in aerospace applications.

Thermoplastics↗
NASA NTRS1994

Actively controlled shaft seals for aerospace applications

This study experimentally investigates an actively controlled mechanical seal for aerospace applications. The seal of interest is a gas seal, which is considerably more compact than previous actively controlled mechanical seals that were developed for industrial use. In a mechanical seal, the radial convergence of the seal interface has a primary effect on the film thickness. Active control of the film thickness is established by controlling the radial convergence of the seal interface with piezoelectric actuator. An actively controlled mechanical seal was initially designed and evaluated using a mathematical model. Based on these results, a seal was fabricated and tested under laboratory conditions. The seal was tested with both helium and air, at rotational speeds up to 3770 rad/sec, and at sealed pressures as high as 1.48 x 10(exp 6) Pa. The seal was operated with both manual control and with a closed-loop control system that used either the leakage rate or face temperature as the feedback. The output of the controller was the voltage applied to the piezoelectric actuator. The seal operated successfully for both short term tests (less than one hour) and for longer term tests (four hours) with a closed-loop control system. The leakage rates were typically 5-15 slm (standard liters per minute), and the face temperatures were generally maintained below 100 C. When leakage rate was used as the feedback signal, the setpoint leakage rate was typically maintained within 1 slm. However, larger deviations occurred during sudden changes in sealed pressure. When face temperature was used as the feedback signal, the setpoint face temperature was generally maintained within 3 C, with larger deviations occurring when the sealed pressure changed suddenly.

Salant, Richard F.↗
NASA NTRS1995

Actively Controlled Shaft Seals for Aerospace Applications

This study experimentally investigates an actively controlled mechanical seal for aerospace applications. The seal of interest is a gas seal, which is considerably more compact than previous actively controlled mechanical seals that were developed for industrial use. In a mechanical seal, the radial convergence of the seal interface has a primary effect on the film thickness. Active control of the film thickness is established by controlling the radial convergence of the seal interface with a piezoelectric actuator. An actively controlled mechanical seal was initially designed and evaluated using a mathematical model. Based on these results, a seal was fabricated and tested under laboratory conditions. The seal was tested with both helium and air, at rotational speeds up to 3770 rad/sec, and at sealed pressures as high as 1.48 x 10(exp 6) Pa. The seal was operated with both manual control and with a closed-loop control system that used either the leakage rate or face temperature as the feedback. The output of the controller was the voltage applied to the piezoelectric actuator. The seal operated successfully for both short term tests (less than one hour) and for longer term tests (four hours) with a closed-loop control system. The leakage rates were typically 5-15 slm (standard liters per minute), and the face temperatures were generally maintained below 100C. When leakage rate was used as the feedback signal, the setpoint leakage rate was typically maintained within 1 slm. However, larger deviations occurred during sudden changes in sealed pressure. When face temperature was used as the feedback signal, the setpoint face temperature was generally maintained within 3 C, with larger deviations occurring when the sealed pressure changes suddenly. the experimental results were compared to the predictions from the mathematical model. The model was successful in predicting the trends in leakage rate that occurred as the balance ratio and sealed pressure changed, although the leakage rates were not quantitatively predicted with a high degree of accuracy. This model could be useful in providing valuable design information for future actively controlled mechanical seals.

Salant, Richard F.↗
NASA NTRS2021

Modeling and Analysis of Fluted-Core Composite Structures for Aerospace Applications

Fiber-reinforced composites are becoming more frequently used for aerospace applications, and because of mass and stiffness requirements, sandwich composites are often selected where shell-type structures are needed. However, traditional-core sandwich composites can exhibit certain manufacturing and in-service problems that have the potential to be alleviated through the use of other sandwich composite concepts. Fluted-core sandwich composite structures, which consist of integral angled web members with structural radius fillers, or noodles, spaced between laminate face sheets, is one such alternative and is considered herein. Because the noodles can consist of unidirectional fiber and can represent a significant amount of the total fluted-core cross section, accurate prediction of the structural response requires that the noodles be modeled with sufficient detail. Previous work showed that the structural response of fluted-core sandwich composite structures could be accurately represented with detailed finite element analysis using a combination of solid and shell elements. In these models, solid elements were used to represent the noodles and shell elements were used to represent the webs and faces. However, this previous solid-noodle modeling approach was also quite computationally intensive, and therefore not practical for large or complicated structures. In this document, a less computationally intensive shell-noodle approach, wherein the entire fluted-core sandwich composite construction is modeled with shell elements, is discussed and predicted structural responses are compared with those of the solid-noodle approach. It is found that by proper selection of certain geometric parameters (thickness and offset of the shell elements that represent the noodle), the shell-noodle modeling approach can be made “structurally equivalent” to the solid-noodle modelling approach.

Leonard Oremont↗
NASA NTRS2006

Novel Nanolaminates for Aerospace Applications

Nanolaminate manufacturing (NLM) is a new way of developing materials whose properties can far exceed those of homogeneous materials. Traditional alloys, composites and bulk laminates tend to average the properties of the materials from which they were made. With nanostructured materials, the high density of interfaces between dissimilar materials results in novel material properties. For example, materials made -from alternating nanoscale layers of metals and oxides have exhibited thermal conductivities far below those of the oxides themselves. Also, metallic nanolaminates can have peak strengths 100 times lager than the bulk constituent metals. Recent work at MSFC has focused on the development of nickel/aluminum oxide (Ni/Al2O3)) nanolaminates. Ni/Al2O3 nanolaminates are expected to have better strength, creep and fatigue resistance, oxygen compatibility, and corrosion resistance than the traditional metal-matrix composites of this material, which has been used in a variety of aerospace applications. A chemical vapor deposition (CW) system has been developed and optimized for the deposition of nanolaminates. Nanolaminates with layer thicknesses between 10 and 300 nm have been successfully grown and characterization has included scanning electron microscopy (SEM) and atomic force microscopy (AFM) Nanolaminates have a large variety of potential applications. They can be tailored to have both very small and anisotropic thermal conductivities and are promising as thermal coatings for both rock$ engine components and aerobraking structures. They also have the potential to be used in aerospace applications where strength at high temperatures, corrosion resistance or resistance to hydrogen embrittlement is important. Both CVD and magnetron sputtering facilities are available for the deposition of nanolayered materials. Characterization equipment includes SEM, AFM, X-ray diffraction, transmission electron microscopy, optical profilometry, and mechanical tensile pull testing.

Volz, Martin↗
NASA NTRS1998

Key Issues for Aerospace Applications of Ceramic Matrix Composites

Ceramic matrix composites (CMC) offer significant advantages for future aerospace applications including turbine engine and liquid rocket engine components, thermal protection systems, and "hot structures". Key characteristics which establish ceramic matrix composites as attractive and often enabling choices are strength retention at high temperatures and reduced weight relative to currently used metallics. However, due to the immaturity of this class of materials which is further compounded by the lack of experience with CMC's in the aerospace industry, there are significant challenges involved in the development and implementation of ceramic matrix composites into aerospace systems. Some of the more critical challenges are attachment and load transfer methodologies; manufacturing techniques, particularly scale up to large and thick section components; operational environment resistance; damage tolerance; durability; repair techniques; reproducibility; database availability; and the lack of validated design and analysis tools. The presentation will examine the technical issues confronting the application of ceramic matrix composites to aerospace systems and identify the key material systems having potential for substantial payoff relative to the primary requirements of light weight and reduced cost for future systems. Current programs and future research opportunities will be described in the presentation which will focus on materials and processes issues.

Clinton, R. G., Jr.↗
NASA NTRS1991

Aerospace Applications of Magnetic Suspension Technology, part 1

Papers presented at the conference on aerospace applications of magnetic suspension technology are compiled. The following subject areas are covered: pointing and isolation systems; microgravity and vibration isolation; bearing applications; wind tunnel model suspension systems; large gap magnetic suspension systems; control systems; rotating machinery; science and application of superconductivity; and sensors.

Groom, Nelson J.↗
NASA NTRS1993

A Knowledge-Based System Developer for aerospace applications

A prototype Knowledge-Based System Developer (KBSD) has been developed for aerospace applications by utilizing artificial intelligence technology. The KBSD directly acquires knowledge from domain experts through a graphical interface then builds expert systems from that knowledge. This raises the state of the art of knowledge acquisition/expert system technology to a new level by lessening the need for skilled knowledge engineers. The feasibility, applicability , and efficiency of the proposed concept was established, making a continuation which would develop the prototype to a full-scale general-purpose knowledge-based system developer justifiable. The KBSD has great commercial potential. It will provide a marketable software shell which alleviates the need for knowledge engineers and increase productivity in the workplace. The KBSD will therefore make knowledge-based systems available to a large portion of industry.

Shi, George Z.↗
NASA NTRS2004

Advanced Materials and Coatings for Aerospace Applications

In the application area of aerospace tribology, researchers and developers must guarantee the highest degree of reliability for materials, components, and systems. Even a small tribological failure can lead to catastrophic results. The absence of the required knowledge of tribology, as Professor H.P. Jost has said, can act as a severe brake in aerospace vehicle systems-and indeed has already done so. Materials and coatings must be able to withstand the aerospace environments that they encounter, such as vacuum terrestrial, ascent, and descent environments; be resistant to the degrading effects of air, water vapor, sand, foreign substances, and radiation during a lengthy service; be able to withstand the loads, stresses, and temperatures encountered form acceleration and vibration during operation; and be able to support reliable tribological operations in harsh environments throughout the mission of the vehicle. This presentation id divided into two sections: surface properties and technology practice related to aerospace tribology. The first section is concerned with the fundamental properties of the surfaces of solid-film lubricants and related materials and coatings, including carbon nanotubes. The second is devoted to applications. Case studies are used to review some aspects of real problems related to aerospace systems to help engineers and scientists to understand the tribological issues and failures. The nature of each problem is analyzed, and the tribological properties are examined. All the fundamental studies and case studies were conducted at the NASA Glenn Research Center.

Miyoshi, Kazuhisa↗
NASA NTRS1983

Advantage of resonant power conversion in aerospace applications

An ultrasonic, sinusoidal aerospace power distribution system is shown to have many advantages over other candidate power systems. These advantages include light weight, ease of fault clearing, versatility in handling many loads including motors, and the capability of production within the limits of present technology. References are cited that demonstrate the state of resonant converter technology and support these conclusions.

Hansen, I. G.↗
NASA NTRS1993

Aerospace applications of batteries

NASA has developed battery technology to meet the demanding requirements for aerospace applications; specifically, the space vacuum, launch loads, and high duty cycles. Because of unique requirements and operating environments associated with space applications, NASA has written its own standards and specifications for batteries.

Habib, Shahid↗