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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 1,297 records · Page 72

All sources NASA NTRS DOE OSTI

NASA NTRS1973

Oxidation resistant carbon-carbon composite for Space Shuttle application.

An oxidation resistant carbon-carbon composite has been developed for use on the NASA Space Shuttle Orbiter Vehicle which can function on the high temperature surfaces to satisfy the 100 mission reuse capability requirement. This paper describes the design requirements, materials and processes developed, and the successful testing of simulated full-scale prototype hardware. Materials considerations are illustrated, including strength and oxidation testing, along with physical property determinations, characterizing the material over the predicted temperature range of use.

Rogers, D. C.↗

NASA NTRS1990

Electro-optic network analyzer

The bandwidth of frequency domain measurement methods of electrical signals has usually been far greater than the bandwidth of time domain methods. The primary limits of the time domain approach have been the 20 to 30 GHz bandwidth limit for electronic waveform acquisition instrumentation, and the lack of usable electrical pulse generators for excitation of a test device. The bandwidth of frequency domain network analysis appears to have reached a plateau of between 100 to 200 GHz, while time domain measurement have improved markedly in both bandwidth and sensitivity with the introduction of the pulsed laser based electro-optic sampling approach. Network analysis or the measurement of device scattering parameters provides information necessary to the design of electronic network such as high frequency amplifiers, mixers, and phase shifter. The bandwidth of frequency domain network analysis is currently being exceeded by the next generations of high frequency transistors and devices. Thus the electro-optic approach is a natural means of extending network analysis into the range above 100 GHz by employing time domain methods. In this approach, a suitable electrical excitation pulse is generated and propagated along a transmission line toward a test device. In the picosecond domain, laser driven photoconductive switches provide a unique method of generating electrical transients. Several materials were studied for generating short electrical pulses using photoconductive switches. The various semiconductive materials tested for photoconductive switching, and the electro-optic measurement technique used to characterize the material performance are described.

Jackson, Todd A.↗

NASA NTRS1992

HAZBOT - A hazardous materials emergency response mobile robot

The authors describe the progress that has been made towards the development of a mobile robot that can be used by hazardous materials emergency response teams to perform a variety of tasks including incident localization and characterization, hazardous material identification/classification, site surveillance and monitoring, and ultimately incident mitigation. In September of 1991, the HAZBOT II vehicle performed its first end-to-end demonstration involving a scenario in which the vehicle: navigated to the incident location from a distant (150-200 ft.) deployment site; entered a building through a door with thumb latch style handle and door closer; located and navigated to the suspected incident location (a chemical storeroom); unlocked and opened the storeroom's door; climbed over the storeroom's 12 in. high threshold to enter the storeroom; and located and identified a broken container of benzene.

Stone, H. W.↗

NASA NTRS2003

Micromechanics-Based Computational Simulation of Ceramic Matrix Composites

Advanced high-temperature Ceramic Matrix Composites (CMC) hold an enormous potential for use in aerospace propulsion system components and certain land-based applications. However, being relatively new materials, a reliable design properties database of sufficient fidelity does not yet exist. To characterize these materials solely by testing is cost and time prohibitive. Computational simulation then becomes very useful to limit the experimental effort and reduce the design cycle time, Authors have been involved for over a decade in developing micromechanics- based computational simulation techniques (computer codes) to simulate all aspects of CMC behavior including quantification of scatter that these materials exhibit. A brief summary/capability of these computer codes with typical examples along with their use in design/analysis of certain structural components is the subject matter of this presentation.

Murthy, Pappu L. N.↗

NASA NTRS2008

Materials, Processes and Manufacturing in Ares 1 Upper Stage: Integration with Systems Design and Development

Ares I Crew Launch Vehicle Upper Stage is designed and developed based on sound systems engineering principles. Systems Engineering starts with Concept of Operations and Mission requirements, which in turn determine the launch system architecture and its performance requirements. The Ares I-Upper Stage is designed and developed to meet these requirements. Designers depend on the support from materials, processes and manufacturing during the design, development and verification of subsystems and components. The requirements relative to reliability, safety, operability and availability are also dependent on materials availability, characterization, process maturation and vendor support. This paper discusses the roles and responsibilities of materials and manufacturing engineering during the various phases of Ares IUS development, including design and analysis, hardware development, test and verification. Emphasis is placed how materials, processes and manufacturing support is integrated over the Upper Stage Project, both horizontally and vertically. In addition, the paper describes the approach used to ensure compliance with materials, processes, and manufacturing requirements during the project cycle, with focus on hardware systems design and development.

Bhat, Biliyar N.↗

NASA NTRS2012

Multiscale Modeling of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2: Application to Lattice Thermal Conductivity

We are developing a multiscale framework in computational modeling for the ultra high temperature ceramics (UHTC) ZrB2 and HfB2. These materials are characterized by high melting point, good strength, and reasonable oxidation resistance. They are candidate materials for a number of applications in extreme environments including sharp leading edges of hypersonic aircraft. In particular, we used a combination of ab initio methods, atomistic simulations and continuum computations to obtain insights into fundamental properties of these materials. Ab initio methods were used to compute basic structural, mechanical and thermal properties. From these results, a database was constructed to fit a Tersoff style interatomic potential suitable for atomistic simulations. These potentials were used to evaluate the lattice thermal conductivity of single crystals and the thermal resistance of simple grain boundaries. Finite element method (FEM) computations using atomistic results as inputs were performed with meshes constructed on SEM images thereby modeling the realistic microstructure. These continuum computations showed the reduction in thermal conductivity due to the grain boundary network.

Lawson, John W.↗

NASA NTRS2012

Multiscale Modeling of UHTC: Thermal Conductivity

Lawson, John W.↗

DOE OSTI2022

Exploration of the Application of Machine Learning to the improvement of Interatomic Potentials

Current methods for atomistic simulations of material systems suffer from limitations which restrict the ability of the simulation to correctly characterize certain material behavior and physical phenomena. Small scale ab initio (AIMD) modeling is highly accurate but is computationally expensive. Classical molecular dynamics (CMD) simulations use interatomic potentials (IPs) to describe larger systems at a reduced computational cost, but with a reduced accuracy. Creating more robust IPs enable more precise CMD simulations. In this thesis, the application of a specific machine learning process,artifical neural networks (ANNs), to the improvement of IPs and MD simulation is discussed.

O'Connor, Sean↗

DOE OSTI2020

High-Temperature and High-Pressure In Situ Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy

Nuclear magnetic resonance (NMR) spectroscopy represents an important technique to understand the structure and bonding environment of molecules. There exists a drive to conduct characterization experiment under conditions relevant to the chemical process of interest. To address this, in situ high-temperature, high-pressure MAS NMR methods have been developed to enable the observation of chemical interactions over a range of pressures (vacuum to several hundred bar) and temperatures (well below 0°C to 250°C). Further, the chemical identity of the samples can be comprised of solids, liquids, and gases or mixtures of the three. The method incorporates all-zirconia NMR rotors (sample holder for MAS NMR) which can be sealed using a threaded cap to compress an O-ring. This rotor exhibits great chemical resistance, temperature compatibility, low NMR background, and can withstand high pressures. These factors combined enable its use in a wide range of system combinations which permit its use in diverse fields as carbon sequestration, catalysis, material science, geochemistry, and biology. The flexibility of this technique makes it an attractive option for scientists from numerous disciplines.

Nuclear Magnetic Resonance, NMR, in situ, spectros↗

NASA NTRS2001

Fabrication and Characterization of SMA Hybrid Composites

Results from an effort to fabrication shape memory alloy hybrid composite (SMAHC) test specimens and characterize the material system are presented in this study. The SMAHC specimens are conventional composite structures with an embedded SMA constituent. The fabrication and characterization work was undertaken to better understand the mechanics of the material system, address fabrication issues cited in the literature, and provide specimens for experimental validation of a recently developed thermomechanical model for SMAHC structures. Processes and hardware developed for fabrication of the SMAHC specimens are described. Fabrication of a SMA14C laminate with quasi-isotropic lamination and ribbon-type Nitinol actuators embedded in the 0' layers is presented. Beam specimens are machined from the laminate and are the focus of recent work, but the processes and hardware are readily extensible to more practical structures. Results of thermomechanical property testing on the composite matrix and Nitinol ribbon are presented. Test results from the Nitinol include stress-strain behavior, modulus versus temperature. and constrained recovery stress versus temperature and thermal cycle. Complex thermomechanical behaviors of the Nitinol and composite matrix are demonstrated, which have significant implications for modeling of SMAHC structures.

Turner, Travis L.↗

NASA NTRS1993

Probabilistic material degradation under high temperature, fatigue, and creep

A methodology has been developed and embodied in two computer codes for quantitatively characterizing the material strength degradation of aerospace propulsion system structural components that are subjected to various random effects over the course of their service lives. The codes, PROMISS and PROMISC, constitute a material-resistance model that is used in the NESSUS aerospace structural-reliability program. NESSUS addresses the service life-reducing effects of high temperature, mechanical fatigue, and creep.

Boyce, L.↗

NASA NTRS1968

Properties of optics at high temperature and their measurement, a study

Bibliography lists, the sources containing emissivity and absorptivity data on materials at extremely high temperatures. The experimental techniques, equipment and efforts of the experimenters to characterize the materials used and methods to evaluate the errors are given in the sources in this bibliography.

Gates, D. W.↗

NASA NTRS1992

Scanning electron acoustic microscopy of residual stresses in ceramics: Theory and experiment

Several reviews have highlighted a number of applications of scanning electron acoustic microscopy (SEAM) to metals and semiconductors which show that SEAM can provide new information on surface and near-surface features of such materials, but there have been few studies attempting to determine the capabilities of SEAM for characterizing ceramic materials. We have recently observed image contrast in SEAM from residual stress fields induced in brittle materials by Vickers indentations that is strongly dependent on the electron beam chopping frequency. We have also recently developed a three-dimensional mathematical model of signal generation and contrast in SEAM, appropriate to the brittle materials studied, that we use as a starting point in this paper for modeling the effect of residual stress fields on the generated electron acoustic signal. The influence of the electron beam chopping frequency is also considered under restrictive assumptions.

Cantrell, John H.↗

NASA NTRS1986

The effects of space radiation on a chemically modified graphite-epoxy composite material

The effects of the space environment on the engineering properties and chemistry of a chemically modified T300/934 graphite-epoxy composite system are characterized. The material was subjected to 1.0 x 10 to the 10th power rads of 1.0 MeV electron irradiation under vacuum to simulate 30 years in geosynchronous earth orbit. Monotonic tension tests were performed at room temperature (75 F/24 C) and elevated temperature (250 F/121 C) on 4-ply unidirectional laminates. From these tests, inplane engineering and strength properties (E sub 1, E sub 2, Nu sub 12, G sub 12, X sub T, Y sub T) were determined. Cyclic tests were also performed to characterize energy dissipation changes due to irradiation and elevated temperature. Large diameter graphite fibers were tested to determine the effects of radiation on their stiffness and strength. No significant changes were observed. Dynamic-mechanical analysis demonstrated that the glass transition temperature was reduced by 50 F(28 C) after irradiation. Thermomechanical analysis showed the occurrence of volatile products generated upon heating of the irradiated material. The chemical modification of the epoxy did not aid in producing a material which was more radiation resistant than the standard T300/934 graphite-epoxy system. Irradiation was found to cause crosslinking and chain scission in the polymer. The latter produced low molecular weight products which plasticize the material at elevated temperatures and cause apparent material stiffening at low stresses at room temperature.

Reed, S. M.↗

NASA NTRS1981

Statistical distribution of mechanical properties for three graphite-epoxy material systems

Graphite-epoxy composites are playing an increasing role as viable alternative materials in structural applications necessitating thorough investigation into the predictability and reproducibility of their material strength properties. This investigation was concerned with tension, compression, and short beam shear coupon testing of large samples from three different material suppliers to determine their statistical strength behavior. Statistical results indicate that a two Parameter Weibull distribution model provides better overall characterization of material behavior for the graphite-epoxy systems tested than does the standard Normal distribution model that is employed for most design work. While either a Weibull or Normal distribution model provides adequate predictions for average strength values, the Weibull model provides better characterization in the lower tail region where the predictions are of maximum design interest. The two sets of the same material were found to have essentially the same material properties, and indicate that repeatability can be achieved.

Reese, C.↗

NASA NTRSDate not supplied

Overview of the MISSE-16 Mission and Preliminary Characterization of Novel Space Weathered Materials

The Materials International Space Station Experiment (MISSE) project is a series of experiments that began in 2001, involving the deployment of external experiment platforms on the International Space Station (ISS). Since then, more than 4,000 materials were tested yielding valuable data and insights into the performance of materials and coatings in the harsh space environment, as well as providing a platform for testing and validating new materials and technologies. The results of the MISSE experiments have contributed to the development of more durable and reliable spacecraft and equipment, as well as improving our understanding of the space environment and its effects on human space exploration. To gain deeper insights into the changes in material properties of both novel and heritage spacecraft materials over the course of a mission, we proposed to enhance the MISSE hardware. This was achieved by integrating a high-resolution camera that can capture both RGB and IR color data, along with an updated illumination scheme. The identical sets of selected materials were mounted on the Zenith, Ram, and Wake faces of the ISS to expose them to predominant vacuum ultraviolet (VUV), atomic oxygen, and high-energy electron conditions. In addition, we exposed flight duplicates of these materials to a simulated space environment, which included sequential exposure to the same irradiation species on the ground. This allowed us to study the effects of space exposure on the materials in a controlled manner and to compare their behavior in both real and simulated space environments. The MISSE-FF flight sample collection comprised different classes of polymers, including polyimides from the Kapton family, manufactured by E.I du Pont de Nemours and Co., Polyethylene terephthalate (PET) materials, liquid crystal polymers, PI/Polyhedral Oligomeric Silsesquioxanes (POSS), and carbon and glass fiber reinforced polymers. The experimental cadence during the MISSE-16 mission (~6 months) included daily images of each sample for the first week, weekly for the next 2 months, and monthly the remaining duration of the mission. This paper will focus on the flight duplicate as well as the postflight optical characterization of novel and heritage materials currently under observation on the MISSE-FF.

Jainisha R Shah↗

NASA NTRS2014

NASA's Asteroid Redirect Mission: A Robotic Boulder Capture Option for Science, Human Exploration, Resource Utilization, and Planetary Defense

NASA is examining two options for the Asteroid Redirect Mission (ARM), which will return asteroid material to a Lunar Distant Retrograde Orbit (LDRO) using a robotic solar electric propulsion spacecraft, called the Asteroid Redirect Vehicle (ARV). Once the ARV places the asteroid material into the LDRO, a piloted mission will rendezvous and dock with the ARV. After docking, astronauts will conduct two extravehicular activities (EVAs) to inspect and sample the asteroid material before returning to Earth. One option involves capturing an entire small (~4 - 10 m diameter) near-Earth asteroid (NEA) inside a large inflatable bag. However, NASA is also examining another option that entails retrieving a boulder (~1 - 5 m) via robotic manipulators from the surface of a larger (~100+ m) pre-characterized NEA. The Robotic Boulder Capture (RBC) option can leverage robotic mission data to help ensure success by targeting previously (or soon to be) well- characterized NEAs. For example, the data from the Japan Aerospace Exploration Agency's (JAXA) Hayabusa mission has been utilized to develop detailed mission designs that assess options and risks associated with proximity and surface operations. Hayabusa's target NEA, Itokawa, has been identified as a valid target and is known to possess hundreds of appropriately sized boulders on its surface. Further robotic characterization of additional NEAs (e.g., Bennu and 1999 JU3) by NASA's OSIRIS REx and JAXA's Hayabusa 2 missions is planned to begin in 2018. This ARM option reduces mission risk and provides increased benefits for science, human exploration, resource utilization, and planetary defense. Science: The RBC option is an extremely large sample-return mission with the prospect of bringing back many tons of well-characterized asteroid material to the Earth-Moon system. The candidate boulder from the target NEA can be selected based on inputs from the world-wide science community, ensuring that the most scientifically interesting boulder be returned for subsequent sampling. In addition, the material surrounding the boulder can be collected from the surface, thus providing geological contextual information and additional samples of NEA regolith. The robotic manipulators used for capturing the boulder will ensure some of the surface remains undisturbed and that the boulder will retain its structural integrity, which will preserve the context of any samples collected by the astronauts and ensure a high level of science return. Human Exploration: Due to the coherent nature of the boulder that will be collected, entire encapsulation of the asteroid material is not required. This facilitates exploration and sample collection of the boulder by astronauts in a variety of ways. The total time for EVA during the crew portion of the mission is very limited. Current estimates are that each of the two EVAs will only last four hours. The RBC option will allow crew members to have good situational awareness of the work site and quickly identify sample sites of interest. In addition, the samples to be collected can be readily accessed without having to deal with removal of an encapsulation system, which adds extra complexity and risk for the astronauts during EVA. Resource Utilization: One of the most crucial aspects for resource utilization is the identification and collection of appropriate materials (e.g., volatiles, organics, metals, etc.) that contain components of interest. Prior characterization of NEAs is required in order to increase the likelihood that appropriate materials will be returned. Ground-based observations of small (<10 m) NEAs are challenging, but characterization efforts of larger targets have demonstrated that NEAs with volatiles and organics have been identified. Two potential targets for the RBC option (Bennu and 1999 JU3) have been previously identified as potentially rich in resources, and both are already targets of currently planned robotic missions that will characterize their physical properties in great detail. Planetary Defense: The RBC option involves interaction with a well- characterized potentially hazardoussized NEA that would enable NASA to conduct one or more planetary defense demonstrations. The primary method would use the collected boulder to augment the mass of the ARV and perform an Enhanced Gravity Tractor (EGT) demonstration on the NEA. Additionally, other approaches could be demonstrated during the mission, such as Ion Beam Deflection (IBD) and/or observation of a Kinetic Impactor (KI). The relative effectiveness of a slow push-pull method such as the EGT or IBD could be directly compared and contrasted with the results of the more energetic KI method on the target NEA. Conclusions: This boulder option for NASA's ARM can leverage knowledge of previously characterized NEAs from prior robotic missions, which provides more certainty of the target NEA's physical characteristics and reduces mission risk. This increases the return on investment for NASA's future activities with respect to human exploration, resource utilization, and planetary defense.

Abell, P.↗

DOE OSTI2026

A Review of Advanced Characterization Methods and Techniques for Amorphous and Poorly Crystalline Materials Applicable to Cementitious Waste Forms

This review covers advanced characterization methods of cementitious materials. The particular focus is to understand cementitious compositions with amorphous content because conventional techniques such as X-ray diffraction are more applicable to materials with long range order. Also of interest is advanced characterization that provides deeper insights into properties such as porosity. There are five groups of characterization methods discussed in this review which are: electron beam/microscopy, X-ray, neutron diffraction and scattering, nuclear magnetic resonance, and optical techniques. The techniques can be further grouped by the categories of nanoscale structural understanding (transmission electron microscopy and pair distribution function), microscale structural understanding (focused ion beam and x-ray tomography), microscopic elemental distributions (energy dispersive spectroscopy and X-ray fluorescence), and chemical binding information (electron energy loss spectroscopy, x-ray absorption spectroscopy, nuclear magnetic resonance, Raman spectroscopy, and infrared spectroscopy), with advantages and disadvantages of each method discussed. The recommendation for further research is to begin with techniques that are easier to prepare samples for, measure, and analyze, such as the optical techniques of Raman and infrared spectroscopy. If more information is needed, pursue collaborations, other techniques, or proposals for beam time at the synchrotron sources.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗