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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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Kevlar aramid fiber, fabric, rope and cable performance are reviewed along with the economics relevant to the material, structural, and reliability aspects of lighter than air craft.
The behavior of two types of Langmuir probes, one with electrodes made of low-sulfur stainless steel and one with electrodes made of aluminum coated with Aquadag, has been compared on two rocket flights. Each rocket payload included one Langmuir probe of each type. The electron temperatures measured with the stainless-steel electrodes were about 15% higher than the electron temperatures measured with the Aquadag-coated electrodes at 150 km on ascent and about 10% higher at 180 km. These results imply that the use of Aquadag coated electrodes or electrodes of other carefully chosen materials permits greater reliability in the measurement of electron temperatures in the ionosphere by the Langmuir probe technique.
The production of failure-free hardware is discussed. The elements required to achieve such hardware are: technical expertise to design, analyze, and fully understand the design; use of high reliability parts and materials control in the manufacturing process; and testing to understand the system and weed out defects. The durability of the Hughes family of satellites is highlighted.
The fatigue response of a ((0/45/90/-45)(sub s))(sub 4) T300-5208 graphite-epoxy laminate with a drilled center-hole subjected to various components of tensile and compressive cyclic loads was investigated. Damage evaluation techniques such as stiffness monitoring, penetrant-enhanced X-ray radiography, C-scan, laminate deply and residual strength measurement were used to establish the mechanisms of damage development as well as the effect of such damage on the laminate strength, stiffness and life. Damage modes consisted of transverse matrix cracks, initiating at the hole, in all plies, followed by delamination between plies of different orientation. A characteristic stiffness repsonse during cyclic loading at two load levels was identified and utilized a more reliable indicator of material and residual properties than accumulated cycles. For the load ratios of tension-compression loading, residual tensile strength increased significantly above the virgin strength early in the fatigue life and remained approximately constant to near the end of life. A technique developed for predicting delamination initiation sites along the hole boundary correlated well with experimental evidence.
Fast fracture, stress rupture, and cyclic high temperature durability characterizations have been conducted for advanced silicon carbide and silicon nitride ceramics applicable to gas turbine hot section components. The fast fracture and stress rupture tests were conducted in four-point flexure at temperatures of up to 1540 C; the durability tests involved cycling specimens to temperatures of 1370 C and air quenching at 200 C for up to 3500 hrs. Materials with further reliability improvements are noted to be required for gas turbine hot section component applications.
This paper presents experimental data from two independent tests, designed to determine the long-term reliability of composite materials. The technique of accelerated aging at elevated temperatures is employed. In the first set, graphite fiber, epoxy composites in five ply layups are manufactured and tested in the standard short-beam shear mode. In the second set, Nomex honeycomb, graphite fiber/epoxy composite face and rear sheet sandwich coupons are tested. After satisfying simple consistency checks, data interpretation is attempted within the framework of an Arrhenius degradation model. The elevated temperature is assumed to influence the degradation according to this temperature-dependent rate law. From these tests on five-ply composites and honeycomb sandwiches, it is concluded that aging is not a serious problem.
NASA Lewis Research Center has organized a component technology program as part of the efforts to develop Stirling converter technology for space power applications. The Stirling Space Power Program is part of the NASA High Capacity Power Project of the Civil Space Technology Initiative (CSTI). NASA Lewis is also providing technical management for the DOE/Sandia program to develop Stirling converters for solar terrestrial power producing electricity for the utility grid. The primary contractors for the space power and solar terrestrial programs develop component technologies directly related to their goals. This Lewis component technology effort, while coordinated with the main programs, aims at longer term issues, advanced technologies, and independent assessments. An overview of work on linear alternators, engine/alternator/load interactions and controls, heat exchangers, materials, life and reliability, and bearings is presented.
Infrared imaging and image-data-processing system shows temperatures of joint during welding and provides data from which rates of heating and cooling determined. Information used to control welding parameters to ensure reliable joints, in materials which microstructures and associated metallurgical and mechanical properties depend strongly on rates of heating and cooling. Applicable to variety of processes, including tungsten/inert-gas welding; plasma, laser, and resistance welding; cutting; and brazing.
NASA Lewis Research Center has organized a component technology program as part of the efforts to develop Stirling converter technology for space power applications. The Stirling Space Power Program is part of the NASA High Capacity Power Project of the Civil Space Technology Initiative (CSTI). NASA Lewis is also providing technical management for the DOE/Sandia program to develop Stirling converters for solar terrestrial power producing electricity for the utility grid. The primary contractors for the space power and solar terrestrial programs develop component technologies directly related to their goals. This Lewis component technology effort, while coordinated with the main programs, aims at longer term issues, advanced technologies, and independent assessments. An overview of work on linear alternators, engine/alternator/load interactions and controls, heat exchangers, materials, life and reliability, and bearings is presented.
A prototype Cold Hydrogen Maser (CHM) was being developed for the past year. The features of this CHM, which is designed to operate initially at 4.2 K, are the use of low loss alumina, and later sapphire, in the fabrication of the microwave cavity; possible use of superconductors for shielding; use of a cryogenic amplifier; possible coating material; and a reliable RF discharge circuit for the dissociation of hydrogen. A numerical simulation was performed to find the dimensions of the microwave cavity for the TE011 mode and the model was confirmed experimentally. The system will be used to test various wall coatings adsorbed on top of a PTFE buffer underlayer. The CHM is expected to be used as a flywheel frequency standard at the NPL with medium-term stability of one part in 10(exp 14) or better.
Pressure is one of the most important parameters measured when testing models in wind tunnels. For models tested in the cryogenic environment of the National Transonic Facility at NASA Langley Research Center, the technique of utilizing commercially available multichannel pressure modules inside the models is difficult due to the small internal volume of the models and the requirement of keeping the pressure transducer modules within an acceptable temperature range well above the -173 degrees C tunnel temperature. A prototype multichannel pressure transducer module has been designed and fabricated with stable, repeatable sensors and materials optimized for reliable performance in the cryogenic environment. The module has 16 single crystal silicon piezoresistive pressure sensors electrostatically bonded to a metalized Pyrex substrate for sensing the wind tunnel model pressures. An integral temperature sensor mounted on each silicon micromachined pressure sensor senses real-time temperature fluctuations to within 0.1 degrees C to correct for thermally induced non-random sensor drift. The data presented here are from a prototype sensor module tested in the 0.3 M cryogenic tunnel and thermal equilibrium conditions in an environmental chamber which approximates the thermal environment (-173 degrees C to +60 degrees C) of the National Transonic Facility.
Two series of low cycle fatigue (LCF) test data for two groups of different aircraft gas turbine engine compressor disk geometries were reanalyzed and compared using Weibull statistics. Both groups of disks were manufactured from titanium (Ti-6Al-4V) alloy. A NASA Glenn Research Center developed probabilistic computer code Probable Cause was used to predict disk life and reliability. A material-life factor A was determined for titanium (Ti-6Al-4V) alloy based upon fatigue disk data and successfully applied to predict the life of the disks as a function of speed. A comparison was made with the currently used life prediction method based upon crack growth rate. Applying an endurance limit to the computer code did not significantly affect the predicted lives under engine operating conditions. Failure location prediction correlates with those experimentally observed in the LCF tests. A reasonable correlation was obtained between the predicted disk lives using the Probable Cause code and a modified crack growth method for life prediction. Both methods slightly overpredict life for one disk group and significantly under predict it for the other.
An emerging new mission for aeronautics is Urban Air Mobility (UAM), a concept for air transportation around metropolitan areas with passenger-carrying operations. UAM vehicles must be capable of vertical take-off and landing, and this requirement presents unique technical challenges for electric and hybrid-based vertical take-off and landing (eVTOL). A critical challenge for UAM market growth is to gain public acceptance for being as safe as - or safer than - commercial air travel and automotive transportation. There is a lack of data for propulsion systems, components, and the associated thermal management systems for UAM eVTOL propulsion systems. The new mission, new propulsion system concepts, safety criticality of propulsion component performance during vertical take-off and lift operations, and lack of data presents many research challenges and opportunities. NASA has developed and published UAM vehicle concept studies. For a subset of the said concept vehicles, NASA has contracted for a study to identify failure modes and hazards associated with the propulsion systems of the concept vehicles and to perform functional hazard analyses (FHA) and failure modes and effects criticality analyses (FMECA) for each. From the completed study results, it was recommended for NASA to support research toward developing electric/hybrid-electric propulsion components with improved reliability and to explore powertrain architectures that can take advantage of higher reliability components to achieve inherent air-vehicle safety. NASA has started a research effort for UAM propulsion with a focus toward improving safety and reliability. Recent results and research strategy will be discussed toward the goals by means of: 1) improving individual component reliability through advanced materials and design methods, 2) improving the thermal management system, and 3) designing propulsion system architectures to provide inherent UAM vehicle safety.
The Water Recovery System (WRS) is a critical component of life support aboard the International Space Station (ISS) and will play an essential role in future missions beyond Low Earth Orbit (LEO). Its primary functional units – the Urine Processor Assembly (UPA), Brine Processor Assembly (BPA), and Water Processor Assembly (WPA) – must be evaluated for extended operation, dormancy resilience, material obsolescence, and reliability under exploration-driven constraints. Ground testing is vital for developing these technologies and generating statistically relevant reliability assessments, which requires extended runtime under integrated, Flight-like conditions. Currently, no high-fidelity, fully integrated WPA ground test bed exists to support these objectives. To address this gap, NASA is developing a WPA test bed at Marshall Space Flight Center (MSFC) that combines downgraded ISS flight hardware with functionally flight-like components in a cost-effective configuration while maintaining priority hardware investigations. This paper describes the current status of hardware assembly and integration, outlines key challenges such as simulating microgravity effects and mitigating obsolescence, and presents future test objectives including software development, reliability assessments, dormancy studies, and exploration-oriented upgrades.
The Water Recovery System (WRS) is a critical component of life support aboard the International Space Station (ISS) and will play an essential role in future missions beyond Low Earth Orbit (LEO). Its primary functional units – the Urine Processor Assembly (UPA), Brine Processor Assembly (BPA), and Water Processor Assembly (WPA) – must be evaluated for extended operation, dormancy resilience, material obsolescence, and reliability under exploration-driven constraints. Ground testing is vital for developing these technologies and generating statistically relevant reliability assessments, which requires extended runtime under integrated, Flight-like conditions. Currently, no high-fidelity, fully integrated WPA ground test bed exists to support these objectives. To address this gap, NASA is developing a WPA test bed at Marshall Space Flight Center (MSFC) that combines downgraded ISS flight hardware with functionally flight-like components in a cost-effective configuration while maintaining priority hardware investigations. This paper describes the current status of hardware assembly and integration, outlines key challenges such as simulating microgravity effects and mitigating obsolescence, and presents future test objectives including software development, reliability assessments, dormancy studies, and exploration-oriented upgrades.
The concentrating Solar Power (CSP) Optical Facilities at NREL comprise unique optical tools and facilities for testing and characterizing concentrating solar optical components. These facilities are maintained to aid researchers and industry efforts to reduce market barriers, improve the performance, reduce the cost, and improve the lifetime and reliability of CSP materials, components, subsystems, and integrated concepts, where accurate and timely characterization methods are needed. To reach this goal, NREL is committed to collaborating in ongoing and projected research needs for industry, academia, and government entities, in the development and characterization of low-cost, high-performance reflector and absorber materials in addition to their components-a key element in the conversion of concentrated sunlight into energy. To accomplish this mission, the core laboratory includes the Advanced Optical Materials Laboratory, indoor and outdoor accelerated weather testing tools, "Distant Observer" for parabolic troughs, the High Flux Solar Furnace, and the ultra-accelerated weather testing tools. This equipment enables to rapidly respond to new challenges with novel solutions that align with the goals of the Solar Energy Technology Office (SETO) at the U.S. Department of Energy. The goal of this paper is to present the state-of art-optical facilities available at NREL that can help support the research needs of the CSP community. Therefore, we review here the different components of the CSP Optical Facilities at NREL and highlight their characteristics and importance for the CSP community.
The poster reports the accomplishments of EDT-Electric Motor Thermal Management consortium project for 2024 VTO Annual Merit Review (AMR). The overall aims of the project are to support research enabling compact, reliable, low-cost, and efficient electric machines aligned with roadmap research areas; to collaborate with ORNL, Ames, and SNL to provide motor thermal analysis support, reliability evaluation, and material measurements on related motor research at national laboratories; and collaborate with university partners including Georgia Institute of Technology and University of Wisconsin Madison to support university-led motor thermal management research efforts.
Material response models are used to assess reliability using variances in the bond-line temperature predictions based on uncertainties in trajectory, aerothermal environment, and material properties. A key deficiency in the current approach is that input uncertainties are too often subjective, empirical, or ad-hoc, and are not rigorously linked to the arc-jet test data used to develop the TPS material model. While materials such as PICA are well understood, future missions may require more novel materials such as HEEET where unknown uncertainties have real consequences on the ability to assess reliability. A quantifiable estimate of reliability requires an iterative methodology where the parameters driving the variance in bond-line temperature (for example) are systematically identified. A test campaign to collect data or develop new models can then be identified to reduce those input uncertainties. A Bayesian inference loop defines these connections mathematically, i.e., prior knowledge about uncertainty is updated based on observation. While these concepts are well known (and often applied intuitively in a non-rigorous approach), only recent advances in reduced-order modelling have made them computationally viable methods for engineering. By replacing deterministic inverse methods with stochastic approaches, the hope is new materials proposed for future missions can more rapidly be developed with a greater understanding of the TPS material reliability. Two additional steps for the analysis of arc jet test data are discussed. The first is ability to construct a reduced-order model using material response simulations (Icarus/US3D) of the arc-jet test articles, and the second is the inclusion of this surrogate model in the Bayesian inversion process. Both capabilities will be demonstrated using prior PICA arc-jet test data. The quality of a surrogate model will be investigated and the variances on the calibrated material properties will be compared to our current understanding of the PICA material model.