Search NASA⌕ Search

SEARCH · Search NASA

Results for “continuous materials”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Experimental and Analytical Verification of ASME Section IiII Division 5 Creep-Fatigue Design Rules

The continuous advancement of structural materials and the growing demands for more reliable and economical structural components in high-temperature reactor applications have necessitated the development of comprehensive design methodologies and design rules. Mechanical degradation of structural components at elevated temperatures subjected to cyclic deformation is controlled by the creep-fatigue damage. Over the past few decades, diligent research efforts have been dedicated to refining the development of elevated temperature design rules in the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC), Section III, Division 5 and to develop conservative design rules that can effectively guard against the risk of creep-fatigue failure. In ASME Section III, Division 5, for a design to pass the creep-fatigue acceptance criteria, creep damage and fatigue damage are evaluated separately, and these damages must not violate the bi-linear creep-fatigue interaction diagram, i.e., the so-called D-diagram. The creep-fatigue damage evaluation procedure assumes that the effects of the actual cyclic loading sequence can be bounded by assuming that the individual loading cycles are uniformly distributed throughout the component design life. In this study, creep-fatigue experiments with variable amplitudes and loading sequencies were designed and performed on Alloy 617 at high temperatures. The results were analyzed to evaluate the loading history effect on creep-fatigue damage accumulation and to verify the assumptions for the creep-fatigue evaluation design rules.

36 - MATERIALS SCIENCE↗
NASA NTRS2014

Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000C. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200C, beta-SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Thermal and mechanical testing includes oxyacetylene torch testing and three point bend testing.

Ceramic Matrix Composites↗
NASA NTRS2014

Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000 deg C. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200 deg C, Beta-SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Thermal and mechanical testing includes oxyacetylene torch testing and three point bend testing.

Polymer Derived Ceramics↗
NASA NTRS2012

Custom Machines Advance Composite Manufacturing

Here is a brief list of materials that NASA will not be using to construct spacecraft: wood, adobe, fiberglass, bone. While it might be obvious why these materials would not make for safe space travel, they do share a common characteristic with materials that may well be the future foundation of spacecraft design: They all are composites. Formed of two or more unlike materials - such as cellulose and lignin in the case of wood, or glass fibers and plastic resin in the case of fiberglass-composites provide enhanced mechanical and physical properties through the combination of their constituent materials. For this reason, composites are used in everything from buildings, bathtubs, and countertops to boats, racecars, and sports equipment. NASA continually works to develop new materials to enable future space missions - lighter, less expensive materials that can still withstand the extreme demands of space travel. Composites such as carbon fiber materials offer promising solutions in this regard, providing strength and stiffness comparable to metals like aluminum but with less weight, allowing for benefits like better fuel efficiency and simpler propulsion system design. Composites can also be made fatigue tolerant and thermally stable - useful in space where temperatures can swing hundreds of degrees. NASA has recently explored the use of composites for aerospace applications through projects like the Composite Crew Module (CCM), a composite-constructed version of the aluminum-lithium Multipurpose Crew Capsule. The CCM was designed to give NASA engineers a chance to gain valuable experience developing and testing composite aerospace structures.

Source record↗
NASA NTRS2003

Flexible Composite-Material Pressure Vessel

A proposed lightweight pressure vessel would be made of a composite of high-tenacity continuous fibers and a flexible matrix material. The flexibility of this pressure vessel would render it (1) compactly stowable for transport and (2) more able to withstand impacts, relative to lightweight pressure vessels made of rigid composite materials. The vessel would be designed as a structural shell wherein the fibers would be predominantly bias-oriented, the orientations being optimized to make the fibers bear the tensile loads in the structure. Such efficient use of tension-bearing fibers would minimize or eliminate the need for stitching and fill (weft) fibers for strength. The vessel could be fabricated by techniques adapted from filament winding of prior composite-material vessels, perhaps in conjunction with the use of dry film adhesives. In addition to the high-bias main-body substructure described above, the vessel would include a low-bias end substructure to complete coverage and react peak loads. Axial elements would be overlaid to contain damage and to control fiber orientation around side openings. Fiber ring structures would be used as interfaces for connection to ancillary hardware.

Brown, Glen↗
NASA NTRS2005

An XML Representation for Crew Procedures

NASA ensures safe operation of complex systems through the use of formally-documented procedures, which encode the operational knowledge of the system as derived from system experts. Crew members use procedure documentation on the ground for training purposes and on-board space shuttle and space station to guide their activities. Investigators at JSC are developing a new representation for procedures that is content-based (as opposed to display-based). Instead of specifying how a procedure should look on the printed page, the content-based representation will identify the components of a procedure and (more importantly) how the components are related (e.g., how the activities within a procedure are sequenced; what resources need to be available for each activity). This approach will allow different sets of rules to be created for displaying procedures on a computer screen, on a hand-held personal digital assistant (PDA), verbally, or on a printed page, and will also allow intelligent reasoning processes to automatically interpret and use procedure definitions. During his NASA fellowship, Dr. Simpson examined how various industries represent procedures (also called business processes or workflows), in areas such as manufacturing, accounting, shipping, or customer service. A useful method for designing and evaluating workflow representation languages is by determining their ability to encode various workflow patterns, which depict abstract relationships between the components of a procedure removed from the context of a specific procedure or industry. Investigators have used this type of analysis to evaluate how well-suited existing workflow representation languages are for various industries based on the workflow patterns that commonly arise across industry-specific procedures. Based on this type of analysis, it is already clear that existing workflow representations capture discrete flow of control (i.e., when one activity should start and stop based on when other activities start and stop), but do not capture the flow of data, materials, resources or priorities. Existing workflow representation languages are also limited to representing sequences of discrete activities, and cannot encode procedures involving continuous flow of information or materials between activities.

Simpson, Richard C.↗
NASA NTRS1992

Electrochemical Impedance Of Inorganic-Zinc-Coated Steel

Report describes preliminary experiments to evaluate both direct-current and alternating-current electrochemical impedance measurements as candidate techniques for use in accelerated corrosion testing of mild-steel panels coated with inorganic zinc-rich primers and exposed to seaside air. Basic idea behind experiments to compare electrochemical impedance measurements with anticorrosion performances of coating materials to determine whether measurements can be used to predict performances. Part of continuing program to identify anticorrosion coating materials protecting steel panels adequately for as long as 5 years and beyond.

Macdowell, Louis G.↗
NASA NTRS1992

Speeds and accelerations of coronal mass ejections

More than 1300 coronal mass ejections have been detected in observations made by the coronagraph aboard SMM during 1980 and 1984-1989. The speed (projected onto the plane of the sky) for at least one morphoplogical feature in about half of these mass ejections could be measured. The average speed of all mass ejection features was about 350 km/s, but speeds range from a few 10s of km/s to more than 2000 km/s. There also appear to be significant variations between the speed distributions for different years. When a mass ejection feature appeared in three or more sequential images, its acceleration could also be calculated. But, because of the limited time a mass ejection remained in the SMM field of view, the ability to detect any given acceleration diminished with increasing mass ejection speed. In fact, the SMM observations do not reveal a discernable acceleration for most mass ejections. A modest yet credible acceleration was detected in 136 cases, while a deceleration was detected in only 7 cases. The LASCO coronagraph will have a more extensive field of view than the SMM instrument; hence, with these new SOHO (Solar and Heliospheric Observatory) observations, some of the challenging questions concerning mass ejection dynamics can be addressed. How far away from the Sun does the material in a mass ejection continue being accelerated? At what radial distance is the motion of the mass ejection dominated by deceleration as it interacts with the ambient interplanetary material?

St.cyr, O. Chris↗
NASA NTRS1991

Mottled terrain - A continuing Martian enigma

The mottled plains material found in the northern Martian lowlands is discussed in terms of Mariner and Viking images as well as geologic mapping based on Viking images. The mottling in Mariner 9 images of this area was associated with albedo contrasts between bright crater-ejecta blankets and dark intercrater material, and dark-crested knobs. The interpretation of the plains material based on the Mariner images is compared to an interpretation of the higher-quality Viking images. Based on the newer images, the mottled terrain is theorized to be comprised of the four constituent members of the Vastitas Borealis formation of Late Hesperian age. Fluvial, aeolian, and glaciotectonic processes are responsible for the extensive modifications of the apparently volcanic formations. The northern plains are not completely understood in spite of the Viking images, and the varied geology in those plains requires more sampling to confirm the theories.

Scott, D. H.↗
NASA NTRS1994

Analysis for Be-7 and Be-10 on LDEF materials and their sources

Work has continued on the search for 10Be on metals other than aluminum flown on LDEF. Much time-consuming extractive chemistry has been performed at Rutgers University on turnings obtained from the ends of two stainless steel trunnions from LDEF and prepared samples will be run on the University of Pennsylvania accelerator mass spectrometer. We have continued to investigate our discovery of naturally-occurring 10Be contamination in bauxite and industrial aluminum from different sources. Measurements of 10Be in ores from three different sites, and from four different samples of commercial aluminum have been made.

Gregory, John C.↗
NASA NTRS1991

Phase Transformations In Mullite-Precursor Xerogels

Report describes experimental study of phase transformations occurring in monophasic and diphasic xerogels of overall stoichiometric mullite composition during thermal treatment. Mullite valued as refractory material because of relatively high mechanical strength, excellent resistance to thermal shock, high resistance to creep, low density, low thermal conductivity, and stability at high temperature. Part of continuing effort to develop precursor materials transformed into mullite and sintered at temperatures low enough to avoid degradation of non-mullite reinforcing fibers in manufacture of mullite/fiber composites.

Hyatt, Mark J.↗
NASA NTRS2002

Observations and Laboratory Data of Planetary Organics

Many efforts are underway to search for evidence of prebiotic materials in the outer solar system. Current and planned Mars missions obtain remote sensing observations that can be used to address the potential presence of prebiotic materials. Additional missions to, and continuing earth-based observations of, more distant solar system objects will also provide remote sensing observations that can be used to address the potential presence of prebiotic materials. I will present an overview of on-going observations, associated laboratory investigations of candidate materials, and theoretical modeling of observational data. In the past the room temperature reflectance spectra of many residues created from HC-bearing gases and solids have been reported. The results of an investigation of what effect temperatures more representative of outer solar system surfaces (50-140K) have on the reflectance spectra of these residues, and the associated interpretations, will be presented. The relatively organic-rich Tagish Lake Meteorite has been suggested as a spectral analog for Dtype asteroids. Using a new approach that relies upon iterative use of Hapke theory and Kraniers-Kronig analysis the optical constants of TLM were estimated. The approach and results of the analysis will be presented. Use of optical constants in scattering theories, such as the Hapke theory, provide the ability to determine quantitative estimates of the relative abundances and grain sizes of candidate surface components. This approach has been applied to interpret the reflectance spectra of several outer solar system surfaces. A summary will be provided describing the results of such modeling efforts.

Roush, Ted L.↗
NASA NTRS1980

Recent depositional history of Apollo 16 and 17 cores

Measurements of Al-26 and Mn-53 in the Apollo 17 drive tube 76001 show a clear integral excess of activity above expected production down to a depth of at least 9 gm/sq cm. This excess is interpreted as a continuous accretion of highly irradiated surface material slowly transported downslope by impact or other processes at a buildup rate of 1.5 cm/m.y. This drive tube, 76001, was collected near a change in slope on the North Massif. Integral excesses have also been observed in other Apollo 16 and 17 cores. Evidence in the Al-26 and Mn-53 record for continuous accretion is shown for Apollo 16 cores 60007 and 60010 and the Apollo 16 deep drill string 70009-70001. This evaluation shows that accretion at specific sites, either through continuous downslope movement or regolith material on the moon, or simply through small impact redistribution, is common on both small and large scales.

Evans, J. C.↗
NASA NTRS1992

LDEF Materials Workshop 1991, part 2

The LDEF Materials Workshop 1991 was a follow-on to the Materials Sessions at the First LDEF Post-Retrieval Symposium held in Kissimmee, Florida, June 1991. The workshop comprised a series of technical sessions on materials themes, followed by theme panel meetings. Themes included materials, environmental parameters, and data bases; contamination; thermal control and protective coating and surface treatments; polymers and films; polymer matrix composites; metals, ceramics, and optical materials; lubricants adhesives, seals, fasteners, solar cells, and batteries. This document continues the LDEF Space Environmental Effects on Materials Special Investigation Group (MSIG) pursuit to investigate the effects of LEO exposure on materials which were not originally planned to be test specimens. Papers from the technical sessions are presented.

Stein, Bland A.↗
NASA NTRSDate not supplied

Mineralogical Variation of the C1 Lithologies in the Kaidun Meteorite

The Kaidun meteorite is a polymict microbreccia, characterized by the presence of numerous clasts of various chondritic and achondritic materials. Chondritic clasts are C1, C2, CM1, CM2, CV3, EH3-5, EL3, and ordinary chondrite-related materials [1,2]. There is significant evidence that aqueous alteration in the carbonaceous chondrite clasts in Kaidun occurred primarily in their parent bodies prior to accumulation to the Kaidun body. Thus, the observation of highly aqueously altered materials (C1 clasts) can provide quantitative constraints on the geologic history of the asteroidal parent bodies. Additionally, the lack of petrological features complicates the classification of C1 materials, but recent studies of new meteorite falls and Ryugu samples continue to emphasize the diversity of C1 materials [e.g., 3,4]. Considering the unprecedentedly diverse origin of clasts in Kaidun, it is expected to contain unknown C1 materials, including ungrouped C1, which will further increase the diversity of those materials. Therefore, this study aims to systematically understand C1 materials by comparing Kaidun C1 with known C1s such as CI1, CM1 and CR1. Since textural observations and chemical composition analyses of carbonates, sulfides, and phyllosilicates in C1 materials in Kaidun have not yet been adequately performed, this study focuses mainly on such analyses.

K. Ogiya↗
NASA NTRS1999

Preliminary Results of the Third Test Series of Nonmetal Material Flammability Evaluation In SKOROST Apparatus on the Space Station Mir

The work has been done according to the US/Russian Joint Project "Experimental Evaluation of the Material Flammability in Microgravity" a continued combustion study in the SKOROST test apparatus on the OS Mir. The objective of the project was to evaluate the flammability and flame-spread rate for the selected polymer materials in low velocity flow in microgravity. Lately, the issue of nonmetal material combustion in microgravity has become of great importance, based on the necessity to develop the fire safety system for the new International Space Station (ISS). Lack of buoyant flow in microgravity reduces oxygen transfer into the combustion zone, which leads to flame extinction when the flow velocity is less than the limiting flow velocity V(sub lim) for the material. The ISS FGB fire-safety system was developed based on this phenomenon. The existence of minimum flow velocity V(sub lim) to sustain fire for the selected materials was determined both theoretically and experimentally. In the latter, it is shown that, even for thermally thin nonmetal materials with a very low oxygen index C(sub lim) of 12.5% (paper sheets with the thickness of 0.1 mm), a limiting flow velocity V(sub lim) exists at oxygen concentration Co(sub OX) = 17-21%, and is about 1.0 - 0.1 cm/sec. This might be explained by the relative increase in thermal losses due to radiation from the surface and from the gaseous phase. In the second series of experiments in Skorost apparatus on Orbital Station Mir the existence of the limiting flow velocity V(sub lim) for combustion was confirmed for PMMA and glass-epoxy composite strip samples 2 mm thick at oxygen concentration C(sub OX) = 21.5%. It was concluded that V(sub lim) depends on C(sub OX) for the PMMA sample with a low oxygen index of 15.5%, the limiting flow velocity V(sub lim) was less than 0.5 cm/sec, and for the glass-epoxy composite sample with a high oxygen index of 19%, the limiting flow velocity V(sub lim) was higher than 15 cm/sec. As of now only those materials that maintain their integrity during combustion were investigated. The materials that disintegrate when burning present more danger for fire safety because the flame can spread farther with the parts of the structure, ejected melt drops, et cetera. Materials such as polyethylene are of great interest since they form a lengthy melt zone during the combustion in normal gravity. This melt zone generates drops of liquids that promote faster flame spread compared to usual combustion. The preliminary results of polyethylene insulation flammability evaluation in microgravity are shown in the NASA Wire Insulation Flammability (WIF) experiment during Space Shuttle flight STS-50. A lot of interesting data was collected during the WIF test program. However, one of the most important results was that, in microgravity, the extinction of the polyethylene occurred almost immediately when the flow of relatively low oxygen concentration (C(sub OX)=21%) was stopped. The purpose of the work reported here is to expand the existing data base on material flammability in microgravity and to conduct the third series of the space experiment using Skorost apparatus on Orbiatl Station Mir with melting polymers, which might increase the probability of fire and its propagation in ventilated microgravity environment of orbiting spacecraft.

Ivanov, A. V.↗