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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

The dual element method of strain gauge temperature compensation

The use of a known temperature compensation technique is suggested to reduce the overall temperature sensitivity of a PdCr strain gauge system being developed for turbine engine research. The temperature compensation technique proposed for this application uses a resistance thermometer in an adjacent leg of the strain gauge bridge circuit to cancel the thermally generated resistance change of the strain gauge. Equations for calculating the required compensation resistor values and the sensitivity of the resulting strain gauge bridge to both temperature and strain are presented.

Englund, David R.↗
NASA NTRS2020

NASA Engineering and Safety Center Technical Bulletin No. 20-07: Evaluating and Mitigating Liner Strain Spikes in COPV's

Unexpected cracking and leaking in bonded composite overwrapped pressure vessel (COPV) liners occurring in recent test programs have been attributed to liner strain spikes observed through measurement and predicted by analysis. Diminished load transfer between the liner and composite overwrap can lead to localized excessive liner yielding in the dome section. This diminished constraint can occur due to yielding of the adhesive or a manufacturing unbond defect. COPVs should be assessed for susceptibility to this new failure mode.

Evaluating↗
NASA NTRS1985

Development of thermomechanical life prediction models for thermal barrier coatings

Thermal barrier coatings (TBCs) for turbine airfoils in high-performance engines represent an advanced materials technology with both performance and durability benefits. The foremost TBC benefit is the reduction of heat transferred into air-cooled components. To achieve these benefits, however, the TBC system must be reliable. Mechanistic thermomechanical and thermochemical life models and statistically significant design data are therefore required for the reliable exploitation of TBC benefits on gas turbine airfoils. Garrett's NASA-HOST Program (NAS3-23945) is designed to fulfill these requirements. This program focuses on predicting the lives of two types of strain-tolerant and oxidation-resistant TBC systems that are produced by commercial coating suppliers to the gas turbine industry. The plasma-sprayed TBC system, composed of a low-pressure plasma-spray (LPPS) applied oxidation resistant NiCrAlY bond coating, and an air-plasma-sprayed yttria partially stabilized zirconia insulated layer is applied by both Chromalloy and Klock. The second type of TBC is applied by the electron beam-physical vapor deposition process by Temescal. Thermomechanical life models are being tailored to predict TBC strain tolerance in terms of materials, engine, and mission parameters. Continuum and fracture mechanics approaches and statistical methods are being evaluated to develop tensile and compressive strain functions required to drive a mission analysis capable thermomechanical life model for TBCs. Results of initial testing to calibrate these life models will be presented.

Strangman, T. E.↗
NASA NTRS2024

Synthetic Biology to Support Human Exploration of Deep Space

The International Space Station (ISS) has enabled a continuous human presence in space since November 2000. The ISS is in low Earth orbit, facilitating regular resupply missions to deliver air, water, food, spare parts, and science experiments. NASA’s Moon to Mars campaign seeks to return humans to the Moon and prepare for crewed missions to Mars. Increased distance from Earth poses logistical challenges to provide all resources needed by humans for deep space missions. NASA Ames Research Center is conducting a series of synthetic biology projects to test the use of microbes for on-demand biosynthesis of human micronutrients. The BioNutrients spaceflight experiments test an implementation concept to produce fermented food products in which microbe growth enhances micronutrient content. On-demand production of carotenoids was engineered into two yeast (Saccharomyces cerevisiae) strains that have been tested in nearly 5 years of storage. One of the BioNutrients strains will be incorporated into the Lunar Explorer Instrument for Space Biology Applications (LEIA) project. LEIA is developing an instrument suite to be delivered to the lunar south pole region by the Commercial Lunar Payload Services (CLPS) program. The LEIA instrument suite will be used to measure multiple yeast strains for growth, metabolic activity, and synthetic biology-enabled production of carotenoids, while taking real time measurements of biologically relevant radiation exposure on the lunar surface. LEIA data will be used to assess the impact of lunar surface radiation and reduced gravity on the production of engineered traits.

Synthetic Biology↗
NASA NTRS2013

Optical Strain and Crack-Detection Measurements on a Rotating Disk

The development of techniques for the in-situ measurement and structural health monitoring of the rotating components in gas turbine engines is of major interest to NASA. As part of this on-going effort, several experiments have been undertaken to develop methods for detecting cracks and measuring strain on rotating turbine engine like disks. Previous methods investigated have included the use of blade tip clearance sensors to detect the presence of cracks by monitoring the change in measured blade tip clearance and analyzing the combined disk-rotor system's vibration response. More recently, an experiment utilizing a novel optical Moiré based concept has been conducted on a subscale turbine engine disk to demonstrate a potential strain measurement and crack detection technique. Moiré patterns result from the overlap of two repetitive patterns with slightly different spacing. When this technique is applied to a rotating disk, it has the potential to allow for the detection of very small changes in spacing and radial growth in a rotating disk due to a flaw such as a crack. This investigation was a continuation of previous efforts undertaken in 2011-2012 to validate this optical concept. The initial demonstration attempted on a subscale turbine engine disk was inconclusive due to the minimal radial growth experienced by the disk during operation. For the present experiment a new subscale Aluminum disk was fabricated and improvements were made to the experimental setup to better demonstrate the technique. A circular reference pattern was laser etched onto a subscale engine disk and the disk was operated at speeds up to 12 000 rpm as a means of optically monitoring the Moiré created by the shift in patterns created by the radial growth due the presence of the simulated crack. Testing was first accomplished on a clean defect free disk as a means of acquiring baseline reference data. A notch was then machined in to the disk to simulate a crack and testing was repeated for the purposes of demonstrating the concept. Displacement data was acquired using external blade tip clearance and shaft displacement sensors as a means of confirming the optical data and for validating other sensor based crack detection techniques.

Woike, Mark↗
NASA NTRS2013

Optical Strain and Crack-Detection Measurements on a Rotating Disk

The development of techniques for the in-situ measurement and structural health monitoring of the rotating components in gas turbine engines is of major interest to NASA. As part of this on-going effort, several experiments have been undertaken to develop methods for detecting cracks and measuring strain on rotating turbine engine like disks. Previous methods investigated have included the use of blade tip clearance sensors to detect the presence of cracks by monitoring the change in measured blade tip clearance and analyzing the combined disk-rotor system's vibration response. More recently, an experiment utilizing a novel optical Moiré based concept has been conducted on a subscale turbine engine disk to demonstrate a potential strain measurement and crack detection technique. Moiré patterns result from the overlap of two repetitive patterns with slightly different spacing. When this technique is applied to a rotating disk, it has the potential to allow for the detection of very small changes in spacing and radial growth in a rotating disk due to a flaw such as a crack. This investigation was a continuation of previous efforts undertaken in 2011 to 2012 to validate this optical concept. The initial demonstration attempted on a subscale turbine engine disk was inconclusive due to the minimal radial growth experienced by the disk during operation. For the present experiment a new subscale Aluminum disk was fabricated and improvements were made to the experimental setup to better demonstrate the technique. A circular reference pattern was laser etched onto a subscale engine disk and the disk was operated at speeds up to 12 000 rpm as a means of optically monitoring the Moiré created by the shift in patterns created by the radial growth due the presence of the simulated crack. Testing was first accomplished on a clean defect free disk as a means of acquiring baseline reference data. A notch was then machined in to the disk to simulate a crack and testing was repeated for the purposes of demonstrating the concept. Displacement data was acquired using external blade tip clearance and shaft displacement sensors as a means of confirming the optical data and for validating other sensor based crack detection techniques.

Woike, Mark↗
NASA NTRS1990

Effect of tensile mean stress on fatigue behavior of single-crystal and directionally solidified superalloys

Two nickel base superalloys, single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf, were studied in view of the potential usage of the former and usage of the latter as blade materials for the turbomachinery of the space shuttle main engine. The baseline zero mean stress (ZMS) fatigue life (FL) behavior of these superalloys was established, and then the effect of tensile mean stress (TMS) on their FL behavior was characterized. At room temperature these superalloys have lower ductilities and higher strengths than most polycrystalline engineering alloys. The cycle stress-strain response was thus nominally elastic in most of the fatigue tests. Therefore, a stress range based FL prediction approach was used to characterize both the ZMS and TMS fatigue data. In the past, several researchers have developed methods to account for the detrimental effect of tensile mean stress on the FL for polycrystalline engineering alloys. However, the applicability of these methods to single crystal and directionally solidified superalloys has not been established. In this study, these methods were applied to characterize the TMS fatigue data of single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf and were found to be unsatisfactory. Therefore, a method of accounting for the TMS effect on FL, that is based on a technique proposed by Heidmann and Manson was developed to characterize the TMS fatigue data of these superalloys. Details of this method and its relationship to the conventionally used mean stress methods in FL prediction are discussed.

Kalluri, Sreeramesh↗
NASA NTRS1956

Initial results of a flight investigation of the wing and tail loads on an airplane equipped with a vane-controlled gust-alleviation system

Results are given of an analysis of wing and horizontal-tail spar strains measured on a twin-engine light transport airplane which was modified for the installation of a control system to alleviate airplane motions in turbulent air and thus improve passenger comfort. From a sample of the measurements obtained in flight through clear-air turbulence, normal acceleration at the airplane center of gravity was reduced 43 percent, wing main-spar bending strains were reduced, and wing-spar shear strains were increased. Horizontal-tail shear and bending strains were increased. Measurements of aerodynamic loads obtained in a pull-up with the gust-alleviation system in operation are also presented.

LOADS AND STRESSES, STRUCTURAL - DYNAMIC↗
NASA NTRS2001

A Thin Film Multifunction Sensor for Harsh Environments

The status of work at NASA Glenn Research Center to develop a minimally intrusive integrated sensor to provide realtime measurement of strain, heat flux and flow in high temperature environments is presented in this paper. The sensor can be beneficial as a single package to characterize multiple stress and strain modes simultaneously on materials and components during engine development and validation. A major technical challenge is to take existing individual gauge designs and modify them into one integrated thin film sensor. Ultimately, the goal is to develop the ability to deposit the sensors directly onto internal engine parts or on a small thin substrate that can be attached to engine components. Several prototype sensors constructed of platinum, platinum-rhodium alloy, and alumina on constant-strain alumina beams have been built and bench-tested. The technical challenges of the design. construction, and testing are discussed. Data from the preliminary testing of the sensor array is presented. The future direction for the sensor development is discussed as well.

Wrbanek, John D.↗
NASA NTRS1973

Space Shuttle Orbiter engine main combustion chamber cooling and life

A reusable life requirement of 100 missions is met by controlling the combustion chamber hot-gas wall temperature and strain levels. Maximum life, maximum performance, and minimum engine weight are attained through a descriptive parametric assessment of the regenerative cooling circuit, combustor length, contraction area ratio, and coolant passage geometry. Life is categorized by low-cycle fatigue and creep-stress rupture. Relationships are developed to determine the impact of heat transfer rate, thermal strain level, and geometric influence parameters on life. It is empirically shown that a throat heat flux of 100 Btu/sq in./sec can be accommodated.

Cook, R. T.↗
NASA NTRS2011

The J-2X Fuel Turbopump - Turbine Nozzle Low Cycle Fatigue Acceptance Rationale

The J-2X Fuel Turbopump (FTP) turbine, which drives the pump that feeds hydrogen to the J-2X engine for main combustion, is based on the J-2S design developed in the early 1970 s. Updated materials and manufacturing processes have been incorporated to meet current requirements. This paper addresses an analytical concern that the J-2X Fuel Turbine Nozzle Low Cycle Fatigue (LCF) analysis did not meet safety factor requirements per program structural assessment criteria. High strains in the nozzle airfoil during engine transients were predicted to be caused by thermally induced stresses between the vane hub, vane shroud, and airfoil. The heritage J-2 nozzle was of a similar design and experienced cracks in the same area where analysis predicted cracks in the J-2X design. Redesign options that did not significantly impact the overall turbine configuration were unsuccessful. An approach using component tests and displacement controlled fracture mechanics analysis to evaluate LCF crack initiation and growth rate was developed. The results of this testing and analysis were used to define the level of inspection on development engine test units. The programmatic impact of developing crack initiation/growth rate/arrest data was significant for the J-2X program. Final Design Certification Review acceptance logic will ultimately be developed utilizing this test and analytical data.

Hawkins, Lakiesha V.↗
NASA NTRS1985

Strain isolated ceramic coatings

Plasma sprayed ceramic coatings are used in gas turbine engines to improve component temperature capability and cooling air efficiency. A compliant metal fiber strain isolator between a plasma sprayed ceramic coating and a metal substrate improves ceramic durability while allowing thicker coatings for better insulation. Development of strain isolated coatings has concentrated on design and fabrication of coatings and coating evaluation via thermal shock testing. In thermal shock testing, five types of failure are possible: buckling failure im compression on heat up, bimetal type failure, isothermal expansion mismatch failure, mudflat cracking during cool down, and long term fatigue. A primary failure mode for thermally cycled coatings is designated bimetal type failure. Bimetal failure is tensile failure in the ceramic near the ceramic-metal interface. One of the significant benefits of the strain isolator is an insulating layer protecting the metal substrate from heat deformation and thereby preventing bimetal type failure.

Tolokan, R. P.↗
NASA NTRS1972

Development and Design Application of Rigidized Surface Insulation Thermal Protection Systems, Volume 1

Materials and design technology of the all-silica LI-900 rigid surface insulation (RSI) thermal protection system (TPS) concept for the shuttle spacecraft is presented. All results of contract development efforts are documented. Engineering design and analysis of RSI strain arrestor plate material selections, sizing, and weight studies are reported. A shuttle prototype test panel was designed, analyzed, fabricated, and delivered. Thermophysical and mechanical properties of LI-900 were experimentally established and reported. Environmental tests, including simulations of shuttle loads represented by thermal response, turbulent duct, convective cycling, and chemical tolerance tests are described and results reported. Descriptions of material test samples and panels fabricated for testing are included. Descriptions of analytical sizing and design procedures are presented in a manner formulated to allow competent engineering organizations to perform rational design studies. Results of parametric studies involving material and system variables are reported. Material performance and design data are also delineated.

Source record↗
NASA NTRS2006

Thin Film Ceramic Strain Sensor Development for Harsh Environments: Identification of Candidate Thin Film Ceramics to Test for Viability for Static Strain Sensor Development

The need to consider ceramic sensing elements is brought about by the temperature limits of metal thin film sensors in propulsion system applications. In order to have a more passive method of negating changes of resistance due to temperature, an effort is underway at NASA GRC to develop high temperature thin film ceramic static strain gauges for application in turbine engines, specifically in the fan and compressor modules on blades. Other applications include on aircraft hot section structures and on thermal protection systems. The near-term interim goal of this research effort was to identify candidate thin film ceramic sensor materials to test for viability and provide a list of possible thin film ceramic sensor materials and corresponding properties to test for viability. This goal was achieved by a thorough literature search for ceramics that have the potential for application as high temperature thin film strain gauges, reviewing potential candidate materials for chemical & physical compatibility with NASA GRC's microfabrication procedures and substrates.

Wrbanek, John D.↗
NASA NTRS2006

Thin Film Ceramic Strain Sensor Development for Harsh Environments: Interim Report on Identification of Candidate Thin Film Ceramics to Test for Viability for Static Strain Sensor Development

The need to consider ceramic sensing elements is brought about by the temperature limits of metal thin film sensors in propulsion system applications. In order to have a more passive method of negating changes of resistance due to temperature, an effort is underway at NASA Glenn to develop high temperature thin film ceramic static strain gauges for application in turbine engines, specifically in the fan and compressor modules on blades. Other applications can be on aircraft hot section structures and on thermal protection systems. The near-term interim goal of the research effort was to identify candidate thin film ceramic sensor materials to test for viability and provide a list of possible thin film ceramic sensor materials and corresponding properties to test for viability. This goal was achieved by a thorough literature search for ceramics that have the potential for application as high temperature thin film strain gauges, reviewing potential candidate materials for chemical and physical compatibility with our microfabrication procedures and substrates.

Wrbanek, John D.↗
NASA NTRS2007

Thin Film Ceramic Strain Sensor Development for Harsh Environments

The need to consider ceramic sensing elements is brought about by the temperature limits of metal thin film sensors in propulsion system applications. In order to have a more passive method of negating changes of resistance due to temperature, an effort is underway at NASA GRC to develop high temperature thin film ceramic static strain gauges for application in turbine engines, specifically in the fan and compressor modules on blades. Other applications include on aircraft hot section structures and on thermal protection systems. The near-term interim goal of this research effort was to identify candidate thin film ceramic sensor materials to test for viability and provide a list of possible thin film ceramic sensor materials and corresponding properties to test for viability. This goal was achieved by conducting a thorough literature search for ceramics that have the potential for application as high temperature thin film strain gauges chemically and physically compatible and selecting potential candidate materials for with NASA GRC's microfabrication procedures and substrates.

Wrbanek, John D.↗
NASA NTRS2007

Thin Film Ceramic Strain Sensor Development for Harsh Environments

The need to consider ceramic sensing elements is brought about by the temperature limits of metal thin film sensors in propulsion system applications. In order to have a more passive method of negating changes of resistance due to temperature, an effort is underway at NASA GRC to develop high temperature thin film ceramic static strain gauges for application in turbine engines, specifically in the fan and compressor modules on blades. Other applications include on aircraft hot section structures and on thermal protection systems. The near-term interim goal of this research effort was to identify candidate thin film ceramic sensor materials to test for viability and provide a list of possible thin film ceramic sensor materials and corresponding properties to test for viability. This goal was achieved by conducting a thorough literature search for ceramics that have the potential for application as high temperature thin film strain gauges chemically and physically compatible and selecting potential candidate materials for with NASA GRC's microfabrication procedures and substrates.

Fralick, Gustave C.↗
NASA NTRS1992

Laboratory experiments from the toy store

The following is a laboratory experiment designed to further understanding of materials science. This material could be taught to a typical student of materials science or manufacturing at the high school level or above. The objectives of this experiment are as follows: (1) to qualitatively demonstrate the concepts of elasticity, plasticity, and the strain rate and temperature dependence of the mechanical properties of engineering materials; (2) to qualitatively demonstrate the basics of extrusion including material flow, strain rate dependence of defects, lubrication effects, and the making of hollow shapes by extrusion (the two parts may be two separate experiments done at different times when the respective subjects are covered); and (3) to demonstrate the importance of qualitative observations and the amount of information which can be gathered without quantitative measurements.

Mcclelland, H. T.↗