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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 505 records · Page 28
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NASA NTRS2019

Utilizing Shape Memory Alloys for Novel, Non-Pneumatic Tire Design - Designing for the Best of Both Worlds

Materials are a fundamental building block that often get overlooked as a critical component that shapes our world. Numerous products that impact our lives are enabled by the materials from which they are made. With regard to Martian and lunar rover applications, conventional mobility elements, such as pneumatic tires, suffer from a number of issues related to reliability. Two of the more prevalent problems are the high likelihood of single point failure owing to puncture (i.e. flat tire), and loss of efficiency due to reduction in tire pressure over time. Solid, rigid wheels suffer from the inability to handle the high, localized loads while encountering rugged terrain and also produce relatively poor traction and operating efficiency. In an effort to overcome these problems, non-pneumatic, compliant tire designs are being developed, using Nickel-Titanium (NiTi), a thermally activated shape memory alloy (SMA), that is less sensitive to temperature and exhibits much greater plastic deformation than do conventional vulcanized rubber pneumatic tires.

Padula, Santo, II↗
NASA NTRS1992

Accuracy of critical-temperature sensitivity coefficients predicted by multilayered composite plate theories

An assessment is made of the accuracy of the critical-temperature sensitivity coefficients of multilayered plates predicted by different modeling approaches, based on two-dimensional shear-deformation theories. The sensitivity coefficients considered measure the sensitivity of the critical temperatures to variations in different lamination and material parameters of the plate. The standard of comparison is taken to be the sensitivity coefficients obtained by the three-dimensional theory of thermoelasticity. Numerical studies are presented showing the effects of variation in the geometric and lamination parameters of the plate on the accuracy of both the sensitivity coefficients and the critical temperatures predicted by the different modeling approaches.

Noor, Ahmed K.↗
NASA NTRSDate not supplied

Developing Materials and Coating Technologies for Mitigation of Lunar Dust Adhesion and Abrasion

In order to support long duration missions on the Moon’s surface, materials resistant to the harsh lunar environment are critically needed. Lunar dust poses a major threat to the durability of components and vehicles due to its fine, jagged morphology and highly abrasive nature, enabling the particles to adhere and embed onto surfaces of components and devices and potentially leading to premature failure. There is significant effort within NASA to develop novel materials and coating technologies to mitigate lunar dust adhesion and abrasion. This effort has been exploring a variety of production routes and examining properties of candidate material systems, including ceramic, metallic and polymeric. Manufacturing methods investigated include ceramic powder processing, additive manufacturing and surface modification via laser ablation patterning of bulk materials and coatings. An overview of ongoing NASA materials and coating research and development efforts to enable lunar surface exploration will be presented.

Materials, Coatings, lunar dust mitigation↗
NASA NTRSDate not supplied

Developing Materials and Coating Technologies for Mitigation of Lunar Dust Adhesion and Abrasion

In order to support long duration missions on the Moon’s surface, materials resistant to the harsh lunar environment are critically needed. Lunar dust poses a major threat to the durability of components and vehicles due to its fine, jagged morphology and highly abrasive nature, which enables the particles to adhere and embed into surfaces of components and devices potentially leading to premature failure. Consequently, significant effort within NASA aims to develop novel materials and coating technologies to limit lunar dust adhesion and abrasion by exploring a variety of production routes and examining properties of candidate material systems, including ceramic, metallic and polymeric. Manufacturing methods investigated include traditional powder processing, additive manufacturing and surface modification via laser ablation patterning of bulk materials and coatings. An overview of ongoing NASA materials and coating research and development to enable lunar exploration will be presented.

Materials↗
NASA NTRS1987

Improved oil-off survivability of tapered roller bearings

The aim of this program is to improve the oil-off survivability of a tapered roller bearing when applied to a helicopter transmission, since the tapered bearing has shown a performance advantage in this application. However, the critical roller end-rib conjunction is vulnerable to damage in an oil-off condition. Three powdered metal materials were selected to use as the rib material for oil-off evaluation. These were: M2 steel to a 65% density, CBS 1000M 65% density, and CBS 1000M 75% density. The bearing styles tested were ribbed cone (inner race) and ribbed cup (outer race). Carburized solid CBS 600 was also used as a ribbed material for comparison of oil-off results. The tests were conducted at six speeds from 4000 rpm (0.26 million DN) through 37000 rpm (2.4 million DN).The ribbed cup style bearing achieved longer lives than the ribbed cone style. A standard bearing lasted only 10 minutes at 4000 rpm; however, the 30-min oil-off goal was achieved through 11000 rpm using the survivable ribbed cup bearing. The oil-off lives at 37000 rpm were less than 10 seconds. The grinding of the powder metal materials and surface preparation to achieve an open porosity is extremely critical to the oil-off performance of the powder metal component.

Kreider, Gary E.↗
NASA NTRS2010

Comparison of Autoclave and Out-of-Autoclave Composites

The National Aeronautics and Space Administration (NASA) Exploration Systems Mission Directorate initiated an Advanced Composite Technology Project through the Exploration Technology Development Program in order to support the polymer composite needs for future heavy lift launch architectures. As an example, the large composite dry structural applications on Ares V inspired the evaluation of autoclave and out-of-autoclave (OOA) composite materials. A NASA and industry team selected the most appropriate materials based on component requirements for a heavy lift launch vehicle. Autoclaved and OOA composites were fabricated and results will highlight differences in processing conditions, laminate quality, as well as initial room temperature thermal and mechanical performance. Results from this study compare solid laminates that were both fiber-placed and hand-laid. Due to the large size of heavy-lift launch vehicle composite structures, there is significant potential that the uncured composite material or prepreg will experience significant out-life during component fabrication. Therefore, prepreg out-life was a critical factor examined in this comparison. In order to rigorously test material suppliers recommended out-life, the NASA/Industry team extended the out-time of the uncured composite prepreg to values that were approximately 50% beyond the manufacturers out-time limits. Early results indicate that the OOA prepreg composite materials suffered in both composite quality and mechanical property performance from their extended out-time. However, the OOA materials performed similarly to the autoclaved composites when processed within a few days of exposure to ambient "shop" floor handling. Follow on studies evaluating autoclave and OOA aluminum honeycomb core sandwich composites are planned.

Sutter, James K.↗
NASA NTRS2004

Inflatable space structures technology development for large radar antennas.

There has been recent interest in inflatable space-structures technology for possible applications on US. Department of Defense (DOD) missions because of the technology's potential for high mechanical-packaging efficiency, variable stowed geometry, and deployment reliability. In recent years, the DOD-sponsored Large Radar Antenna Program (LRA) applied this new technology to a baseline concept: an inflatablehigidizable (lU) perimeter-truss structure supporting a meshhet parabolic-reflector antenna. The program addressed (a) truss concept development, (b) rigidizable materials concepts assessment, (c) meshhet concept selection and integration, and (d) developed potential mechanical-system p erformance estimates. Critical and enabling technologies were validated, especially orbital radiation durable rigidized materials, and high modulus, inflatable-deployablet russ numbers.

Willis, Paul↗
NASA NTRS1993

Ultrasonic Polishing

The ultrasonic polishing process makes use of the high-frequency (ultrasonic) vibrations of an abradable tool which automatically conforms to the work piece and an abrasive slurry to finish surfaces and edges on complex, highly detailed, close tolerance cavities in materials from beryllium copper to carbide. Applications range from critical deburring of guidance system components to removing EDM recast layers from aircraft engine components to polishing molds for forming carbide cutting tool inserts or injection molding plastics. A variety of materials including tool steels, carbides, and even ceramics can be successfully processed. Since the abradable tool automatically conforms to the work piece geometry, the ultrasonic finishing method described offers a number of important benefits in finishing components with complex geometries.

Gilmore, Randy↗
NASA NTRS1990

Reusable structure for the Advanced Launch System

The U.S. Advanced Launch System (ALS) effort has been established to reduce the cost of payload mass to orbit and increase launch reliability. One approach to reducing costs of primarily expendable launch vehicles is to recover and reuse the most costly elements (i.e., the main engines and the avionics hardware); this is the mission of the propulsion/avionics (P/A) module. This study was conducted to identify material and design options for P/A module structure. A critical structural element is the aeroshell which: (1) provides the reentry aerodynamic surface, (2) shields other subcomponents from reentry heating, and (3) absorbs touchdown loads. Two P/A module types are required for the ALS: one that flies a high-temperature return from orbit profile and another that flies a cooler suborbital profile. For system cost benefits, common structure is desired for both types. A design concept is developed for a honeycomb sandwich structure that can survive the suborbital-reentry heating rates and the return-from-orbit heating rates with an ablative thermal protection system. Thermal analyses show that structural temperatures from aerodynamic heating are within material capabilities. Stress analyses indicate the structural design can support the critical loads.

Gibbins, Martin N.↗
NASA NTRS1971

Development of the activated diffusion brazing process for fabrication of finned shell to strut turbine blades

The activated diffusion brazing process was developed for attaching TD-NiCr and U700 finned airfoil shells to matching Rene 80 struts obstructing the finned cooling passageways. Creep forming the finned shells to struts in combination with precise preplacement of brazing alloy resulted in consistently sound joints, free of cooling passageway clogging. Extensive tensile and stress rupture testing of several joint orientation at several temperatures provided a critical assessment of joint integrity of both material combinations. Trial blades of each material combination were fabricated followed by destructive metallographic examination which verified high joint integrity.

Wilbers, L. G.↗
NASA NTRS1972

Characterization of GTA weldments in 10Ni-8CO-2Cr-1MO steel

This study of 10Ni-8Co-2Cr-1Mo steel includes evaluations of tensile, impact, hardness, fracture toughness properties, and metallographic features. Base plate and three weldments in one-inch thicknesses were examined to compare as-welded properties with those obtained after reaging, and results of welding the 10%Ni alloy with 9-4-20 wire as opposed to a matching weld wire composition. Critical crack sizes are calculated for the material. The most desirable weld properties are obtained using the matching weld wire and a reaging cycle. However, the improvement gained through reaging is probably not sufficient to justify the additional cost for most practical applications.

Stonesifer, F. R.↗
NASA NTRS1972

Experimental studies and applications of vanadium oxides.

The electrical and electrochemical properties of V-5 and V-7 vanadium oxides were investigated. The effects of pressure, temperature and moisture on the bulk resistivity of the oxides in powder, sintered, and crystalline form were determined, and the static and dynamic volt-ampere characteristics were obtained. Sintered samples tested showed better electrical stability than the compressed powder samples. Two types of commercially available vanadium pentoxide were heat-treated to obtain various crystalline oxide forms which were mounted on alumina substrates and terminated by thick-film conductors for making electrical connections. Indications are that these materials could have applications as sensors, critical-temperature resistors, high-speed switches, and temperature-compensation elements in hybrid microelectronic circuits.

Williams, L., Jr.↗
NASA NTRS1975

On fracture toughness evaluation for semi-brittle fracture

The existing methods of assessing the fracture toughness of materials exhibiting semi-brittle fracture are critically reviewed. The methods concern the Crack Growth Resistance (R-curve), the Crack Opening Displacement (COD), and the J-integral. An analysis of the shortcomings of the methods described makes it possible to formulate a new definition of fracture toughness appropriate to semi-brittle fracture. An improved simple experimental method for measuring fracture toughness for semi-brittle fracture is proposed which takes into account both crack growth and plastic nonlinear effects at crack front. The proposed method is shown to be free of the theoretical and experimental discrepancies encountered in the R-curve, COD, and J-integral methods.

Eftis, J.↗
NASA NTRS1976

Summary of studies for a solar optical telescope in space: 1968-1976

The primary objective of this review is to tabulate the basic recommendations of several solar telescope studies. A primary matrix, listing some of the basic optical parameters, was compiled and forms the basis for a table. From this table it is apparent that a strong consensus exists on the configuration of the telescope and on its fundamental dimensionless parameters. Other tables presented in this document address the basic approach of each study to the telescope design as well as to the design of critical subsystems. These subsystem problems include the material, coating, configuration, mounting, launch locks, and thermal control of the primary mirror, the structure of the main telescope and the instrument bay, the mechanisms for radiation rejection, thermal control, and meteoroid shielding, and methods of maintaining image quality by proper alignment and by image motion compensation.

Bremer, J.↗
NASA NTRS1980

Technologies involved in configuring an advanced earth-to-orbit transport for low structural mass

A tradeoff study for a single-stage, earth-to-orbit transport spacecraft configured with low structural mass as the prime objective is presented. Among the major design elements affecting vehicle mass are: maneuverability and re-entry heating, the compatibility of an irregular cargo bay geometry to future mission requirements, the fabrication and assembly of large honeycomb structure fuselage sections, and the development of LOX/LH2 engine extendable nozzles and dual-propulsion schemes. It is shown that vehicle geometry and materials and structural technologies will be the critical areas in the development of such a system.

Macconochie, I. O.↗
NASA NTRS1982

Finite-element analysis of initiation, stable crack growth and instability using a crack-tip-opening displacement criterion

An elastic-plastic (incremental and small strain) finite element analysis was used with a crack growth criterion to study crack initiation, stable crack growth, and instability under monotonic loading to failure of metallic materials. The crack growth criterion was a critical crack-tip-opening displacement (CTOD) at a specified distance from the crack tip, or equivalently, a critical crack-tip-opening angle (CTOA). Whenever the CTOD (or CTOA) equaled or exceeded a critical value, the crack was assumed to grow. Single values of critical CTOD were used in the analysis to model crack initiation, stable crack growth, and instability for 7075-T651 and 2024-T351 aluminum alloy compact specimens. Calculated and experimentally measured CTOD values at initiation agreed well for both aluminum alloys. These critical CTOD values were also used to predict failure loads on center-crack tension specimens and a specially-designed three-hole-crack tension specimen made of the two aluminum alloys and of 304 stainless steel. All specimens were 12.7 mm thick. Predicted failure loads for 7075-T651 aluminum alloy and 304 stainless steel specimens were generally within + or - 15 percent of experimental failure loads, whereas the predicted failure loads for 2024-T351 aluminum alloy specimens were generally within + or - 5 percent of the experimental loads.

Newman, J. C., Jr.↗
NASA NTRS1985

What determines the location of satellites and planets?

The discrete structural pattern in the distribution of the satellites and planets around their primaries has since its discovery been thought to hold the key to the origin and evolution of the solar system. Different attempts to rationalize this distribution are reviewed with emphasis on theories with foundation in verifiable physical processes. Foremost among these is the band structure theory, which relates the emplacement of interstellar dust and gas source material around the magnetized primarily to the critical velocity for ionization of the four major interstellar gas components. The uncertainties, that are inevitable in all reconstructions, are in this theory compensated by the support from precise manifestations of the 2/3 effect in the Saturnian ring system and in the asteroid belt, and by the reproduction of related phenomena in laboratory and space experiments.

Arrhenius, G.↗