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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

A fission gas release correlation for uranium nitride fuel pins

A model was developed to predict fission gas releases from UN fuel pins clad with various materials. The model was correlated with total release data obtained by different experimentors, over a range of fuel temperatures primarily between 1250 and 1660 K, and fuel burnups up to 4.6 percent. In the model, fission gas is transported by diffusion mechanisms to the grain boundaries where the volume grows and eventually interconnects with the outside surface of the fuel. The within grain diffusion coefficients are found from fission gas release rate data obtained using a sweep gas facility.

Weinstein, M. B.↗
NASA NTRS1973

Optimal use of double pin ionization gauges for shock wave detection.

A study was conducted to investigate the response of the gauges to ionization in the gas and to discover, if possible, how the circuitry could be modified to make the system operable over a wider range of operating conditions. Shock wave velocities in the range from 3.5 to 27 km/sec were used in the studies. The electronic circuit developed is capable of producing a trigger pulse at a given voltage level across the gauge pins.

Mcclenahan, J. O.↗
NASA NTRS1974

Solar X-ray photography with multiplex pin-hole camera

A scatter-hole X-ray camera has been designed and flown in a rocket to measure solar X radiation. Its distinguishing feature is that many single pin-hole images are allowed to overlap - a multiplexing approach that saves space, gives practical signal-to-fog ratio, and requires special object reconstruction techniques. It was possible to reconstruct the appearance of the dominant source of solar emission on the day of rocket flight with better than one arc minute resolution. The coronal X-ray region had the same general shape and intensity distribution as the associated calcium K-line region.

Blake, R. L.↗
NASA NTRS1977

Paddle-pin alinement test

Segmented insulated test bar speeds up patch distributor paddle-pin test. Device eliminates need to disconnect cables or remove distributor. Printed circuit cable and connector reduces weight on bar, adding to tester portability.

Gilliam, D. M.↗
NASA NTRS1977

Fly-away restraint pin mechanism for the Army's PATRIOT missile system

The development of the longitudinal restraint mechanism for the PATRIOT missile system is reviewed. Two approaches for the restraint pin design are discussed: an initial ordnance mechanism, and a passive fly-away mechanism. Because of reliability problems and a desire to reduce cost the fly-away restraint mechanism was chosen.

Knight, F. W.↗
NASA NTRS1977

Stress intensities for cracks emanating from pin-loaded holes

A series of stress freezing photoelastic experiments were conducted on large plates containing central holes with cracks emanating from the edge formed by the intersection of the hole with the plate surface. Loads were applied through rigid pins with neat fits in the holes. Stress-intensity factors (SIF) were estimated by a computer assisted least squares analysis of the photoelastic data taken from slices near the points of intersection of the flaw border with the hole boundary and the plate surface. Results indicate that the local mode of loading changes from Mode 1 near the hole boundary to mixed mode near the plate surface. The analysis is extended to include mixed mode loading, and results are compared with an existing approximate theory.

Smith, C. W.↗
NASA NTRS1979

Wear of aluminum and hypoeutectic aluminum-silicon alloys in boundary-lubricated pin-on disk sliding

The friction and wear of pure aluminum and a number of hypoeutectic aluminum-silicon alloys (with 3 to 12 wt %Si) were studied with a pin-on-disk apparatus. The contacts were lubricated with mineral oil and sliding was in the boundary-lubrication regime at 2.6 cm/sec. Surfaces were analyzed with photomicrographs, scanning electron microscopy, X-ray dispersive analysis, and diamond pyramid hardness measurements. There were two wear regimes for the alloys - high and low - whereas pure aluminum exhibited a high wear rate throughout the test period. Wear rate decreased and the transition stress from high to low wear increased with increasing hardness. There was no correlation between friction coefficient and hardness. A least squares curve fit indicated a wear-rate dependence greater than the inverse first power of hardness. The lower wear rates of the alloys may be due to the composites of silicon platelets in aluminum resulting in increased hardness and thus impairing the shear of the aluminum.

Ferrante, J.↗
NASA NTRS1981

Stress-concentration factors for finite orthotropic laminates with a pin-loaded hole

Stresses were calculated for finite size orthotropic laminates loaded by a frictionless steel pin in a circular hole of the same diameter. The calculations were based on finite element analyses for six laminates. Stress concentration factors, based on nominal bearing stress, were determined for wide ranges of the ratios of width to diameter, w/d and edge distance to diameter, e/d. An infinite laminate case was analyzed for each laminate. Orthotropy had a significant influence on the tensile stress concentration at the hole. For example, the stress concentration factors for the infinite laminate cases ranged from 0.82 to 2.16, compared with 0.87 for the quasi-isotropic laminate. The finite widths and edge distances strongly influenced the tensile stress concentration. For the practical range w/d or = 3, the peak tensile stresses were as much as 80% larger than the infinite laminate reference value. For e/d or = 3, these stresses were amplified by as much as 50%. In contrast, the finite width and edge distance had little effect on shear-out and bearing stress concentrations.

Crews, J. H., Jr.↗