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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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Stress-intensity factors for internal surface cracks in cylindrical pressure vessels

The stress intensity factors were calculated by a three dimensional finite element method. The finite element models employed singularity elements along the crack front and linear strain elements elsewhere. The models had about 6500 degrees of freedom. The stress intensity factors were evaluated from a nodal force method. An equation for the stress intensity factors was obtained form the results of the present analysis. The equation applies over a wide range of configuration parameters and was within about 5 percent of the present results. A comparison was made between the present results and other analyses of internal surface cracks in cylinders. The results from a boundary integral equation method were in agreement (+ or - 2 percent) and those from another finite element were in fair agreement (+ or - 8 percent) with the present results.

Newman, J. C., Jr.↗
NASA NTRS1981

Lightweight cryogenic vessel

Thin cooling jacket of recirculating liquid nitrogen is contained by relatively thin walls. Nitrogen is maintained at slight positive pressure, unlike full atmospheric pressure of conventional Dewar design, eliminating need for evacuated insulating spaces and heavy-walled shells. Besides cryogenic applications, design keeps liquids hot when recirculating liquid hotter than nitrogen is used.

Lewis, J. C.↗
NASA NTRS1980

Atherosclerotic changes of vessels caused by restriction of movement

The effect of restriction of movement on the development of atheroscelerosis was studied in rabbits. Drastic restriction of movement for 20 and 30 days causes atherosclerotic alterations of the aorta and shifts in ECG which are characteristic of coronary atherosclerosis. At the same time, shortening of the duration of blood coagulation and an increase in the content of catecholamines and beta-lipoproteids occur.

Gvishiani, G. S.↗
NASA NTRS1985

Calibrating Droplet Generator for Pressurized Testing Vessel

Device helps to aline laser for droplet-sizing interferometer. Monodispersing Droplet Generator creates uniformly sized droplets. Laser source and receiver of interferometer alined and focused on droplets. MDG mounted in high-pressure flange on tank. Line extensions pass through flange to outside. Flange allows MDG to operate at high injector back pressures used for tests.

Defever, G. J.↗
NASA NTRS1986

Liquid-Level Monitor for Pressurized Vessels

Technique for monitoring water levels in pressurized stainless-steel cylinders, based on differences in gamma-ray attenuation coefficients in water and air, developed. Full-scale laboratory prototype system constructed to test technique. Technique usable with liquids other than water, since linear attenuation coefficients for intermediate-energy gamma rays in air considerably lower than in liquids. Also adaptable for continuous monitoring of liquid levels in resevoir systems and in underground storage tanks.

Singh, J. J.↗
NASA NTRS1984

Sintered plug flow modulation of a vapor-liquid phase separator for a helium II vessel

Presented is a system for modulation of a superfluid (helium II) flow in a vapor-liquid phase separator, for use in cryogenic storage tanks in future space missions. The system consists of a semicircular mechanically operated shutter, downstream of the separator plug, rotated at 0.1 rpm to control the operational surface area of the separator. The mass flow rate was varied from 10 to 22 mg/s. Pressure gradients across the plug are also discussed.

Frederking, T. H. K.↗
NASA NTRS1986

Oxygen recombination in individual pressure vessel nickel-hydrogen batteries

A metal-hydrogen cell is described which avoids damage and retards flooding of the hydrogen electrodes by providing for chemical recombination of oxygen and hydrogen in areas or sites remote from the hydrogen electrodes. In the metal-hydrogen cell, a plurality of electrical cell units are place in a back to back relationship. The cells may be lined with a wick, having one or more catalyzed sites on the inner surface of the cell. Separators disposed between the respective metal and hydrogen electrodes of each cell unit are provided with gas directing notches around their peripheries to facilitate the desired movement of gasses within the metal-hydrogen cell. Any two metal electrodes separated by a gas screen are provided with gas tight sealing means between the electrodes at each aperature. The sealing means may be a fing of rubber or elastomeric material which is somewhat compressible but nonreactive with other materials in the cell.

Smithrick, J. J.↗
NASA NTRS1985

The development of a containment vessel and Dewar for the particle astrophysics magnet facility (ASTROMAG)

The ASTROMAG facility is the heart of a large charged particle detection and resolution system. ASTROMAG utilizes a superconducting magnet consisting of a large superconducting magnet coil with a stored magnetic energy of approximately 15 MJ. The active coil will have a mass of 1200 kg. This magnet will be cooled by a cryostat using a liquid helium Dewar for storage. The cryostat will have a series of gas-cooled shields with an external guard vacuum shield and an internal Dewar. The magnet and cryostat will be designed for shuttle or Delta launch and will be designed to withstand the internal pressure of expanded helium under full quench conditions when venting is prevented. The external guard vacuum shell is required to maintain a vacuum for Earth based testing and for cold launch of the cryostat and magnet. The magnet is designed to operate at 4.4 K with a peak field of 7.0 tesla. The superconducting material within the magnet is niobium titanium in a conductive matrix.

Source record↗
NASA NTRS1992

Isotropic thin-walled pressure vessel experiment

The objectives are: (1) to investigate the stress and strain distributions on the surface of a thin walled cylinder subject to internal pressure and/or axial load; and (2) to relate stress and strain distributions to material properties and cylinder geometry. The experiment, supplies, and procedure are presented.

Denton, Nancy L.↗
NASA NTRS1994

Safety-Valve Mechanism For Pressure-Vessel Window

Pressure-activated valve mechanism seals small window in pressure chamber if window cracks or breaks, thereby preventing continued leakage or sudden decompression. Window used in experiments involving optical observation of processes in chamber. Valve mechanism activated by pressure from gas leaking through window.

Mccoomb, E. J.↗
NASA NTRS1995

Damage tolerance in filament-wound graphite/epoxy pressure vessels

Graphite/epoxy composites are extensively used in the aerospace and sporting goods industries due to their superior engineering properties compared to those of metals. However, graphite/epoxy is extremely susceptible to impact damage which can cause considerable and sometimes undetected reduction in strength. An inelastic impact model was developed to predict damage due to low-velocity impact. A transient dynamic finite element formulation was used in conjunction with the 3D Tsai-Wu failure criterion to determine and incorporate failure in the materials during impact. Material degradation can be adjusted from no degradation to partial degradation to full degradation. The developed software is based on an object-oriented implementation framework called Extensible Implementation Framework for Finite Elements (EIFFE).

Simon, William E.↗
NASA NTRS1995

Braiding And Wrapping Tape To Make A Composite Vessel

Braiding and forming combined in one-step process. In process, continuous plus or minus 45 degrees bias braided tape fabricated. Braiding done on site, and braided tape immediately wound on male mandrel in shinglelike configuration to make fabric preform. Subsequently, preform impregnated with matrix resin. Improved process does not produce stitches. Expected to yield consistent quality, to involve less handling of fabric, to produce less scrap, and thus to cost less.

Freitas, Glenn↗
NASA NTRS1996

An acoustic emission and acousto-ultrasonic analysis of impact damaged composite pressure vessels

The use of acoustic emission to characterize impact damage in composite structures is being performed on composite bottles wrapped with graphite epoxy and kevlar bottles. Further development of the acoustic emission methodology will include neural net analysis and/or other multivariate techniques to enhance the capability of the technique to identify dominant failure mechanisms during fracture. The acousto-ultrasonics technique will also continue to be investigated to determine its ability to predict regions prone to failure prior to the burst tests. Characterization of the stress wave factor before, and after impact damage will be useful for inspection purposes in manufacturing processes. The combination of the two methods will also allow for simple nondestructive tests capable of predicting the performance of a composite structure prior to its being placed in service and during service.

Workman, Gary L.↗
NASA NTRS1996

Endoscopic Shearography and Thermography Methods for Nondestructive Evaluation of Lined Pressure Vessels

The goal of this research effort was the development of methods for shearography and thermography inspection of coatings, bonds, or laminates inside rocket fuel or oxidizer tanks, fuel lines, and other closed structures. The endoscopic methods allow imaging and inspection inside cavities which are traditionally inaccessible with shearography or thermography cameras. The techniques are demonstrated and suggestions for practical application are made in this report. Drawings of the experimental setups, detailed procedures, and experimental data are included.

Lansing, Matthew D.↗
NASA NTRS1997

Endoscopic Shearography and Thermography Methods for Nondestructive Evaluation of Lined Pressure Vessels

The goal of this research effort was the development of methods for shearographic and thermographic inspection of coatings, bonds, or laminates inside rocket fuel or oxidizer tanks, fuel lines, and other closed structures. The endoscopic methods allow imaging and inspection inside cavities that are traditionally inaccessible with shearography or thermography cameras. The techniques are demonstrated and suggestions for practical application are made in this report. Drawings of the experimental setups, detailed procedures, and experimental data are included.

Russell, S. S.↗