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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

High-Resolution Rotary-To-Linear Motion Converter

Compact rotary-to-linear motion converter combines high load-carrying ability with finely resolvable movement. Simple and inexpensive to manufacture. Helical coil of metal ribbon wrapped around spool. Bearing supports spool on fixed base. Restraining bar prevents collar from rotating, but allows it to rise and fall. 1,000-turn coil of ribbon 0.010 in. thick provides for translation of collar over distance of 10 inches. Coil made from flattened roll-formed wire. Material inexpensive, strong, and resistant to fatigue.

Millam, M. Bruce↗
NASA NTRS1993

Powder-Metallurgical Bearings For Turbopumps

Bearings fabricated by powder metallurgy developed for use in machines subjected to extremes of temperature, rolling-contact cyclic stresses, and oxidizing or otherwise corrosive fluids. Bearings also extend operating lives of other machines in which bearings required to resist extreme thermal, mechanical, and chemical stresses. One alloy exhibiting outstanding properties was MRC-2001. Resistance to fatigue, stress corrosion cracking, and wear found superior to that of 440C stainless steel.

Bhat, B. N.↗
NASA NTRS1996

Damage accumulation in closed cross-section, laminated, composite structures

The need for safe, lightweight, less expensive, and more reliable launch vehicle components is being driven by the competitiveness of the commercial launch market. The United States has lost 2/3 of the commercial lunch market to Europe. As low cost Russian and Chinese vehicles become available, the US market share could be reduced even further. This international climate is driving the Single Stage To Orbit (SSTO) program at NASA. The goal of the SSTO program is to radically reduce the cost of safe, routine transportation to and from space with a totally reusable launch vehicle designed for low-cost aircraft-like operations. Achieving this goal will require more efficient uses of materials. Composite materials can provide this program with the material and structural efficiencies needed to stay competitive in the international launch market place. In satellite systems the high specific properties, design flexibility, improved corrosion and wear resistance, increased fatigue life, and low coefficient of thermal expansion that are characteristic of composite materials can all be used to improve the overall satellite performance. Some of the satellites that may be able to take advantage of these performance characteristics are the Tethered Satellite Systems (TOSCIFER, AIRSEDS, TSS2, SEDS1, and SEDS2), AXAF, GRO, and the next generation Hubble Space Telescope. These materials can also be utilized in projects at the NASAIMSFC Space Optics Technology and System Center of Excellence. The successful implementation of composite materials requires accurate performance characterization. Materials characterization data for composite materials is typically generated using flat coupons of finite width. At the free edge of these coupons the stress state is exacerbated by the presence of stiffness and geometric discontinuities. The exacerbated stress state has been shown to dominate the damage accumulation in these materials and to have a profound affect on the material constants. Space structures typically have closed cross-sections, absent of free edges. As a result, composite material characterization data generated using finite width flat specimens does not accurately reflect the performance of the composite materials used in a closed cross-section structural configuration. Several investigators have recognized the need to develop characterization techniques for composite materials in closed cross-sectioned structures. In these investigations test methods were developed and cylindrical specimens were evaluated. The behavior of the cylindrical specimens were observed to depart from behavior typical of flat coupons. However, no attempts were made to identify and monitor the progression of damage in these cylindrical specimens during loading. The identification and monitoring of damage is fundamental to the characterization of composite materials in closed cross-section configurations. In the study reported here, a closed cross-sectioned test method was developed to monitor damage progression in 2 in. diameter cylindrical specimens and 1.5 in. finite width flat coupons subjected to quasi-static, tensile loading conditions. Damage in these specimen configurations was monitored using pulse echo ultrasonic, acoustic emission, and X-ray techniques.

Bucinell, Ronald B.↗
NASA NTRS1996

Mechanics Methodology for Textile Preform Composite Materials

NASA and its contractors have completed a program to develop a basic mechanics underpinning for textile composites. Three major deliverables were produced by the program: 1. A set of test methods for measuring material properties and design allowables; 2. Mechanics models to predict the effects of the fiber preform architecture and constituent properties on engineering moduli, strength, damage resistance, and fatigue life; and 3. An electronic data base of coupon type test data. This report describes these three deliverables.

Poe, Clarence C., Jr.↗
NASA NTRS2004

Microstructural Evaluation of KM4 and SR3 Samples Subjected to Various Heat Treatments

The gamma-gamma microstructures of two advanced powder metallurgy disk alloys, KM4 and SR3, were quantified after a series of heat treatments using transmission electron microscopy and image analysis. Relationships between the heat treatments and the resulting gamma distributions were evaluated. Statistical correlations between the gamma distributions and the reported tensile strengths, creep resistances, and dwell crack growth resistances were separately assessed for each alloy. To avoid the effects of grain size related mechanisms, the grain size of the samples used in the correlations for each alloy were limited to narrow ranges of about 1.5 in ASTM grain size number. In both alloys, yield and tensile strength increased with increasing fraction of medium sized gamma. The strength increased as the size of the medium gamma decreased and the size of the fine gamma increased. Time to 0.2 percent creep in SR3 increased with increasing medium gamma volume fraction, and decreasing fine gamma sizes. However, 0.2 percent creep time was not clearly correlated with the gamma microstructures of KM4 specimens, apparently due to effects of stabilization heat treatments which greatly suppress creep resistance. Dwell fatigue crack growth rate decreased with increasing medium gamma volume fraction, indicating more medium gamma is beneficial. The crack growth rate also decreased with decreasing gamma size, indicating finer gamma is better.

Ellis, David↗
NASA NTRS1999

Contractile function is unaltered in diaphragm from mice lacking calcium release channel isoform 3

Skeletal muscle expresses at least two isoforms of the calcium release channel in the sarcoplasmic reticulum (RyR1 and RyR3). Whereas the function of RyR1 is well defined, the physiological significance of RyR3 is unclear. Some authors have suggested that RyR3 participates in excitation-contraction coupling and that RyR3 may specifically confer resistance to fatigue. To test this hypothesis, we measured contractile function of diaphragm strips from adult RyR3-deficient mice (exon 2-targeted mutation) and their heterozygous and wild-type littermates. In unfatigued diaphragm, there were no differences in isometric contractile properties (twitch characteristics, force-frequency relationships, maximal force) among the three groups. Our fatigue protocol (30 Hz, 0.25 duty cycle, 37 degrees C) depressed force to 25% of the initial force; however, lack of RyR3 did not accelerate the decline in force production. The force-frequency relationship was shifted to higher frequencies and was depressed in fatigued diaphragm; lack of RyR3 did not exaggerate these changes. We therefore provide evidence that RyR3 deficiency does not alter contractile function of adult muscle before, during, or after fatigue.

Non-NASA Center↗
NASA NTRS2001

Improved Method Being Developed for Surface Enhancement of Metallic Materials

Surface enhancement methods induce a layer of beneficial residual compressive stress to improve the impact (FOD) resistance and fatigue life of metallic materials. A traditional method of surface enhancement often used is shot peening, in which small steel spheres are repeatedly impinged on metallic surfaces. Shot peening is inexpensive and widely used, but the plastic deformation of 20 to 40 percent imparted by the impacts can be harmful. This plastic deformation can damage the microstructure, severely limiting the ductility and durability of the material near the surface. It has also been shown to promote accelerated relaxation of the beneficial compressive residual stresses at elevated temperatures. Low-plasticity burnishing (LPB) is being developed as an improved method for the surface enhancement of metallic materials. LPB is being investigated as a rapid, inexpensive surface enhancement method under NASA Small Business Innovation Research contracts NAS3-98034 and NAS3-99116, with supporting characterization work at NASA. Previously, roller burnishing had been employed to refine surface finish. This concept was adopted and then optimized as a means of producing a layer of compressive stress of high magnitude and depth, with minimal plastic deformation (ref. 1). A simplified diagram of the developed process is given in the following figure. A single pass of a smooth, free-rolling spherical ball under a normal force deforms the surface of the material in tension, creating a compressive layer of residual stress. The ball is supported in a fluid with sufficient pressure to lift the ball off the surface of the retaining spherical socket. The ball is only in mechanical contact with the surface of the material being burnished and is free to roll on the surface. This apparatus is designed to be mounted in the conventional lathes and vertical mills currently used to machine parts. The process has been successfully applied to nickel-base superalloys by a team from the NASA Glenn Research Center, Lambda Research, and METCUT Research, as supported by the NASA Small Business Innovation Research Phase I and II programs, the Ultra Safe program, and the Ultra- Efficient Engine Technology (UEET) Program.

Gabb, Timothy P.↗
NASA NTRS2007

The Naturalistic Flight Deck System: An Integrated System Concept for Improved Single-Pilot Operations

This paper reviews current and emerging operational experiences, technologies, and human-machine interaction theories to develop an integrated flight system concept designed to increase the safety, reliability, and performance of single-pilot operations in an increasingly accommodating but stringent national airspace system. This concept, know as the Naturalistic Flight Deck (NFD), uses a form of human-centered automation known as complementary-automation (or complemation) to structure the relationship between the human operator and the aircraft as independent, collaborative agents having complimentary capabilities. The human provides commonsense knowledge, general intelligence, and creative thinking, while the machine contributes specialized intelligence and control, extreme vigilance, resistance to fatigue, and encyclopedic memory. To support the development of the NFD, an initial Concept of Operations has been created and selected normal and non-normal scenarios are presented in this document.

Schutte, Paul C.↗
NASA NTRS2011

Inadequate Loading Stimulus on ISS Results in Bone and Muscle Loss

INTRODUCTION Exercise has been the primary countermeasure to combat musculoskeletal changes during International Space Station (ISS) missions. However, these countermeasures have not been successful in preventing loss of bone mineral density (BMD) or muscle volume in crew members. METHODS We examined lower extremity loading during typical days on-orbit and on Earth for four ISS crew members. In-shoe forces were monitored using force-measuring insoles placed inside the shoes. BMD (by DXA), muscle volumes (by MRI), and strength were measured before and after long-duration spaceflight (181 +/- 15 days). RESULTS The peak forces measured during ISS activity were significantly less than those measured in 1g for the same activities. Typical single-leg loads on-orbit during walking and running were 0.89 +/- 0.17 body weights (BW) and 1.28 +/- 0.18 BW compared to 1.18 +/- 0.11 BW and 2.36 +/- .22 BW in 1g, respectively [2]. Crew members were only loaded for an average of 43.17 +/- 14.96 min a day while performing exercise on-orbit even though 146.8 min were assigned for exercise each day. Areal BMD decreased in the femoral neck and total hip by 0.71 +/- 0.34% and 0.81 +/- 0.21% per month, respectively. Changes in muscle volume were observed in the lower extremity (-10 to -16% calf; -4 to -7% thigh) but there were no changes in the upper extremity (+0.4 to -0.8%). Decrements in isometric and isokinetic strength at the knee (range: -10.4 to -24.1%), ankle (range: -4 to -22.3%), and elbow (range: -7.5 to - 16.7%) were also observed. Knee extension endurance tests showed an overall decline in total work (-14%) but an increased resistance to fatigue post-flight. DISCUSSION AND CONCLUSIONS Our findings support the conclusion that the measured exercise durations and/or loading stimuli were insufficient to protect bone and muscle health.

Rice, A. J.↗
NASA NTRS2023

Effects of Strain Rate and Surface Finish on Tensile Properties in High Pressure Hydrogen — A Case Study for LP-DED NASA HR-1

NASA has advanced NASA HR-1 as a solution for liquid rocket engine components that operate in hydrogen rich environments using various AM techniques. The NASA HR-1 for AM applications was specifically formulated for high ductility in high pressure gaseous hydrogen environment in addition to high strength and low cycle fatigue (LCF) resistance. NASA HR-1 meets materials requirements for liquid rocket engine components, including good hydrogen resistance, high conductivity, good LCF performance, and high elongation and strength for components in medium heat flux environments. NASA has completed fabrication of several subscale and full-scale channel wall nozzles in LP-DED NASA HR-1 and completed hot-fire testing. This includes refinement of the process to produce thin-walls and various channel geometries to meet the requirements for channel wall nozzle applications. The main objective of this investigation is to better understand the effects of tensile test strain rate and specimen surface finish on the amount of tensile ductility degradation in high pressure gaseous hydrogen environments. Performing smooth tensile tests in high pressure hydrogen and nitrogen environments can serve as a rapid and economical screening method to determine the relative susceptibility of materials to HEE. This paper presents the tensile test results for LP-DED NASA HR-1 in hydrogen and details the material evaluation on the effects of strain rate and surface finish condition on surface cracking behavior and fracture characteristics. The resistance to HEE for LP-DED NASA HR-1 and the wrought alloy is compared under the same testing conditions. Loss of tensile ductility is quantified in terms of changes in elongation at failure in hydrogen to compare HEE susceptibility. The most suitable strain rate and specimen surface finish condition for future HEE screening testing at MSFC are recommended.

Additive manufacturing↗
NASA NTRS2000

Effect of Crystal Orientation on Analysis of Single-Crystal, Nickel-Based Turbine Blade Superalloys

High-cycle fatigue-induced failures in turbine and turbopump blades is a pervasive problem. Single-crystal nickel turbine blades are used because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities. Single-crystal materials have highly orthotropic properties making the position of the crystal lattice relative to the part geometry a significant and complicating factor. A fatigue failure criterion based on the maximum shear stress amplitude on the 24 octahedral and 6 cube slip systems is presented for single-crystal nickel superalloys (FCC crystal). This criterion greatly reduces the scatter in uniaxial fatigue data for PWA 1493 at 1,200 F in air. Additionally, single-crystal turbine blades used in the Space Shuttle main engine high pressure fuel turbopump/alternate turbopump are modeled using a three-dimensional finite element (FE) model. This model accounts for material orthotrophy and crystal orientation. Fatigue life of the blade tip is computed using FE stress results and the failure criterion that was developed. Stress analysis results in the blade attachment region are also presented. Results demonstrate that control of crystallographic orientation has the potential to significantly increase a component's resistance to fatigue crack growth without adding additional weight or cost.

Swanson, G. R.↗
NASA NTRS2002

Effect of Crystal Orientation on Fatigue Failure of Single Crystal Nickel Base Turbine Blade Superalloys

High cycle fatigue (HCF) induced failures in aircraft gas turbine and rocket engine turbopump blades is a pervasive problem. Single crystal nickel turbine blades are being utilized in rocket engine turbopumps and jet engines throughout industry because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over polycrystalline alloys. Currently the most widely used single crystal turbine blade superalloys are PWA 1480/1493, PWA 1484, RENE' N-5 and CMSX-4. These alloys play an important role in commercial, military and space propulsion systems. Single crystal materials have highly orthotropic properties making the position of the crystal lattice relative to the part geometry a significant factor in the overall analysis. The failure modes of single crystal turbine blades are complicated to predict due to the material orthotropy and variations in crystal orientations. Fatigue life estimation of single crystal turbine blades represents an important aspect of durability assessment. It is therefore of practical interest to develop effective fatigue failure criteria for single crystal nickel alloys and to investigate the effects of variation of primary and secondary crystal orientation on fatigue life. A fatigue failure criterion based on the maximum shear stress amplitude /Delta(sub tau)(sub max))] on the 24 octahedral and 6 cube slip systems, is presented for single crystal nickel superalloys (FCC crystal). This criterion reduces the scatter in uniaxial LCF test data considerably for PWA 1493 at 1200 F in air. Additionally, single crystal turbine blades used in the alternate advanced high-pressure fuel turbopump (AHPFTP/AT) are modeled using a large-scale three-dimensional finite element model. This finite element model is capable of accounting for material orthotrophy and variation in primary and secondary crystal orientation. Effects of variation in crystal orientation on blade stress response are studied based on 297 finite element model runs. Fatigue lives at critical points in the blade are computed using finite element stress results and the failure criterion developed. Stress analysis results in the blade attachment region are also presented. Results presented demonstrates that control of secondary and primary crystallographic orientation has the potential to significantly increase a component S resistance to fatigue crack growth with- out adding additional weight or cost. [DOI: 10.1115/1.1413767]

Arakere, N. K.↗
NASA NTRS2000

Effect of Crystal Orientation on Fatigue Failure of Single Crystal Nickel Base Turbine Blade Superalloys

High Cycle Fatigue (HCF) induced failures in aircraft gas-turbine engines is a pervasive problem affecting a wide range of components and materials. HCF is currently the primary cause of component failures in gas turbine aircraft engines. Turbine blades in high performance aircraft and rocket engines are increasingly being made of single crystal nickel superalloys. Single-crystal Nickel-base superalloys were developed to provide superior creep, stress rupture, melt resistance and thermomechanical fatigue capabilities over polycrystalline alloys previously used in the production of turbine blades and vanes. Currently the most widely used single crystal turbine blade superalloys are PWA 1480/1493 and PWA 1484. These alloys play an important role in commercial, military and space propulsion systems. PWA1493, identical to PWA1480, but with tighter chemical constituent control, is used in the NASA SSME (Space Shuttle Main Engine) alternate turbopump, a liquid hydrogen fueled rocket engine. Objectives for this paper are motivated by the need for developing failure criteria and fatigue life evaluation procedures for high temperature single crystal components, using available fatigue data and finite element modeling of turbine blades. Using the FE (finite element) stress analysis results and the fatigue life relations developed, the effect of variation of primary and secondary crystal orientations on life is determined, at critical blade locations. The most advantageous crystal orientation for a given blade design is determined. Results presented demonstrates that control of secondary and primary crystallographic orientation has the potential to optimize blade design by increasing its resistance to fatigue crack growth without adding additional weight or cost.

Arakere, Nagaraj K.↗
NASA NTRS2003

Versatile Turbine Disk Alloy Designed and Processed for Higher Temperature Applications

Advanced turbine engine configurations using higher temperature combustor and airfoil concepts require compressor and turbine disks that can withstand temperatures higher than the 650 C typical of current engines. This requires disk alloy and processing improvements. A versatile disk alloy was needed that could be given either fine grain heat treatments for high strength and fatigue and creep resistance up to 704 C or given coarse grain heat treatments for high strength and creep and dwell crack-growth resistance at higher temperatures. This alloy could produce disks with uniform microstructures and properties, as well as with varied, optimized microstructures at disk bore and rim sections. A series of experimental disk alloys were designed and processed to give subscale disks about 13 cm in diameter and 4 cm thick. These alloys had varying levels of key elements to affect mechanical properties and change the "solvus" solution heat-treatment temperature necessary to produce coarse grain microstructures. Disks were given coarse grain heat treatments followed by rapid oil quenching and slower fan air quenching. These heat treatments were intended to simulate the cooling paths of rapidly cooled full-scale disks at the outermost rim and interior bore locations, respectively. Preliminary quench tests of tensile specimens and coin-size minidisks had indicated that alloys having high solvus temperatures were more prone to cracking during rapid quenching from coarse grain heat treatments. These findings were confirmed in the subscale disks, where such alloys did form undesirable quench cracks. Mechanical tests were performed on specimens from subscale disks given these coarse grain heat treatments, as well as on specimens given a fine grain heat treatment. Tensile, creep, and crack growth tests were performed at 704 C and higher temperatures. A versatile alloy was identified that had a low solvus temperature for resistance to quench cracking as well as an optimal combination of high levels of strengthening refractory elements that produced balanced high mechanical properties for both fine grain and coarse grain microstructures. This low-solvus, high-refractory (LSHR) alloy has been scaled-up to produce prototype full-scale turbine disks typical of regional jet turbofan engines. Disks were successfully heat treated to give uniform coarse grain and uniform fine grain microstructures. Additional disks were given a NASA dual microstructure heat treatment (DMHT) that intentionally varied the solution heat-treatment temperatures between the disk rim and bore (re f. 1). The disk rim was heated to a high enough temperature to produce a coarse grain microstructure, while the bore was maintained at a lower temperature to produce a fine grain microstructure (see the figure). This DMHT can produce optimal high strength, fatigue, and creep resistance up to 704 C in the cooler running disk bore, and high strength, creep resistance, and dwell crack growth resistance at higher temperatures for the hotter disk rim. Extensive mechanical testing is being initiated to compare the mechanical properties of the uniform and DMHT disks.

Gabb, TImothy P.↗