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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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Residual stress effect on stress-strain curve of uniaxial composite consisting of stainless steel wire and aluminum alloy matrix
Algebra of factorized Regge pole residues applied to obtain relations between meson-baryon and baryon-baryon exchange processes
Results for the residual circulation in the stratosphere and lower mesosphere between September, 1991, and February, 1994, are presented.
The formation of ice on aircraft is a highly dynamic process during which ice will expand and contract upon freezing and undergoing changes in temperature. Finite Element Analysis (FEA) simulations were performed investigating the stress build up in a simplified case with uniform temperature changes between an idealized ice sample and acrylic substrate. These results were used to place strain gages on custom-built acrylic and aluminum specimens; these specimens were then placed in icing conditions such that ice was grown on top of the specimen. Tee rosettes were placed in two configurations adjacent to thermocouple sensors. It was hypothesized that the ice would expand on freezing and contract as the temperature of the interface returned to the equilibrium conditions. While results from the aluminum specimens matched this hypothesis, results from the acrylic specimens show a short period of contraction followed by a much larger expansion at the interface, indicating more complex ice growth thermodynamics than anticipated. Samples were observed to delaminate, and the data suggests that the residual strain is significant to the shedding of ice for in-flight applications.
It has been observed that 3D woven materials are highly susceptible to processes induced defects including tow misalignment, intratow and intertow cracking and/or voids. Adequate process modeling of 3D woven Polymer Matrix Composites (PMCs) is necessary to predict and estimate the effects of the manufacturing process on these defects. A preliminary step towards this is achieved with the commercial Finite Element Analysis (FEA) tool Abaqus complemented with written user subroutines to account for the effect of shrinkage and thermoelastic properties evolution as a function of the degree of cure of the bulk matrix phase in a 3D woven composite repeating unit cell (RUC). As a pathfinder, the process modeling framework is demonstrated on a simplified 3D woven RUC of an AS4/RIMR 135 system. Curing simulations are performed on the 3D woven RUC to observe the processing induced residual stresses. The results of the analysis show that high stress concentrations, present within the 3D intertow matrix bordering the binder tow, coincide with X-Ray computed tomography (X-Ray-CT) scan data depicting cracking in the same location
A study was performed to examine the effect of various broaching machining parameters on high temperature fatigue lives of a nickel-based Low Solvus High Refractory (LSHR) powder metallurgy disk alloy. The work was done to gain a better understanding of the effect of various broaching variables on the integrity and the durability of these fracture critical components. The influence of tool wear and broaching speed were examined in terms of their effect on residual stresses, cold work and surface roughness. These variables were shown to have a substantial effect on fatigue lives and the failure mode. The relationships between these parameters and fatigue crack initiation mechanisms are detailed. Statistical analyses evaluating these relationships are presented.
Differential orbit improvement with the use of rotated residuals
Residual static strength of titanium & stainless steel alloys and one superalloy at various temperatures
Influence of residual gas atmosphere in space chambers on neutral efflux and critical temperature of tungsten ionizers
Residual effects of storm conditions at sea upon postural equilibrium functioning of vestibular normal and vestibular defective human subjects
System for transferring cryogenic liquids to a dewar prevents boiloff of residual liquid by venting the boiloff to the atmosphere during the transfer tube cooling period. The system is most useful with liquids having very small heat of vaporization.
Photometric analyzer measures NVR /nonvolatile residue/ in trichloroethylene and other organic solvents. The analyzer converts the liquid solvent to aerosol and passes it between an optically focused light beam and a photodetector that is connected to standard amplifying and readout equipment.
Numerical residual perturbation solution for prediction of satellite position in restricted three-body problem
Salt stress corrosion of residually stressed titanium-aluminum-molybdenum-vanadium alloy sheet after high temperature exposure
Fatigue tests and fatigue life evaluation for titanium-aluminum-molybdenum sheet at elevated temperatures with residual stress
Range residuals of very high frequency radar tracking data of ionosphere
Residual gas analysis with mass spectrometer used for testing spacecraft and its components
Stratigraphic distribution of carbohydrate residues in middle Devonian Onondaga beds of Pennsylvania and western New York and application to paleontology and paleoecology