SEARCH · Engineering Papers

Results for “EXPLOSIVE”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,333 records · Page 74

All sources NASA NTRS DOE OSTI

NASA NTRS1978

The role of thermal shock in cyclic oxidation

The effect of thermal shock on the spalling of oxides from the surfaces of several commercial alloys was determined. The average cooling rate was varied from approximately 240 C/sec to less than 1.0 C/sec during cyclic oxidation tests in air. The tests consisted of one hundred cycles of one hour at the maximum temperature (1100 or 1200 C). The alloys were HOS-875, TD-Ni, TD-NiCrAl, IN-601, IN-702, and B-1900 plus Hf. Thermal shock resulted in deformation of the metal which in turn resulted, in most cases, in changing the oxide failure mode from compressive to tensile. Tensile failures were characterized by cracking of the oxide and little loss, while compressive failures were characterized by explosive loss of platelets of oxide. The thermally shocked oxides spalled less than the slow cooled samples with the exception of TD-NiCrAl. This material failed in a brittle manner rather than by plastic deformation. The HOS-875 and the TD-Ni did not spall during either type of cooling. Thus, the effect of thermal shock on spalling is determined, in large part, by the mechanical properties of the metal.

Lowell, C. E.↗

NASA NTRS1978

Collision frequency of artificial satellites - The creation of a debris belt

As the number of artificial satellites in earth orbit increases, the probability of collisions between satellites also increases. Satellite collisions would produce orbiting fragments, each of which would increase the probability of further collisions, leading to the growth of a belt of debris around the earth. This process parallels certain theories concerning the growth of the asteroid belt. The debris flux in such an earth-orbiting belt could exceed the natural meteoroid flux, affecting future spacecraft designs. A mathematical model was used to predict the rate at which such a belt might form. Under certain conditions the belt could begin to form within this century and could be a significant problem during the next century. The possibility that numerous unobserved fragments already exist from spacecraft explosions would decrease this time interval. However, early implementation of specialized launch constraints and operational procedures could significantly delay the formation of the belt.

Donald J Kessler↗

NASA NTRS1977

Volatile metal deposits on lunar soils - Relation to volcanism

Parallel leaching and volatilization experiments conducted on lunar samples and similar experiments on sphalerite do not supply the information needed to resolve the question of the chemical nature of Pb-204, Zn, Bi, and Tl deposits on lunar soil surfaces. It is proposed that in Apollo 17 mare and terra soils the fractions of Pb-204, Zn, and Tl that are insoluble under mild, hot pH 5 HNO3, leaching conditions and involatile at 600 C were originally surface deposits which became immobilized by migration into the silicate substrate or by chemisorption. Most of the Bi does not seem to be the result of such a deposit. The implication is also that the soils, over their respective times of evolution, were exposed to heavy metal vapors or that an episodic exposure occurred after they had evolved. A sequence of events is proposed to account for orange 74220 and black 74001 glasses by lava fountaining and for soil 74241 as tephra from an explosive volcanic eruption.

Reed, G. W., Jr.↗

NASA NTRS1978

Ionization of interstellar H2 clouds by supernovae

Two destruction mechanisms for molecular hydrogen in the H I regions of the interstellar medium were given by Stecher and Williams (1967). The first is dominant in weak radiation fields and involves photon excitation (at about 1000 A) to the first excited electronic state with a subsequent decay into the vibrational continuum of the ground state. The second destruction mechanism is dominant in the strong photon fields that exist when a supernova explosion occurs. It involves photoionization (at about 1000 A) from metastable high vibrational levels produced by photon excitation (in the same wavelength range) to an excited electronic state and subsequent decay to bound vibrational levels. It is shown that ionization of molecular hydrogen can occur at considerable distances from such supernova events while the atomic hydrogen remains neutral. The effect should be observable in the dispersion measures of new pulsars.

Stecher, T. P.↗

NASA NTRS1977

Pre-impact conditions and cratering processes at the Flynn Creek crater, Tennessee

A description is presented of a preliminary outline for the cratering processes at Flynn Creek, Tennessee, a large, flat-floored, terrestrial impact crater with a central uplift. The initial preimpact conditions in terms of terrain, target media, and structure are defined, taking into account the possibility of impact into a shallow sea. A brief outline is provided of the generalized sequence of events from the time of entry of the impacting body into the atmosphere through the termination of late-stage cratering motions. The abbreviated sequence of cratering events is based upon a composite of recently assembled physical constraints, including new field data, experimental laboratory impact and field explosion trials, and theoretical numerical simulation studies.

Roddy, D. J.↗

NASA NTRS1975

Seismically induced modification of lunar surface features

The formation of large impact craters and basins produced not only large volumes of ejecta but also catastrophic seismic waves. Theoretical models, extrapolation of terrestrial explosion data, and extrapolation of lunar impact data suggest surface displacements of 1-10 m at four crater radii from a Copernicus-size impact (4 x 10 to the 30th power ergs). Independent estimates of impact-generated stresses indicate that regions within 4 crater radii of an impact will receive shock waves with pressures exceeding 1 kbar. Greater areas also may receive shock effects as elastic waves following deep ray paths transform into shock waves near the surface. Additional seismic energy will be generated by impacts from secondary ejecta. The resulting large and long-lasting surface movement may contribute to the subdued appearance of the continuous ejecta blanket and secondary craters around large impact craters and to the degradation of small craters outside these zones.

Schultz, P. H.↗

NASA NTRS1978

Gamma-ray astronomy and the origin of cosmic rays

Recent observations of cosmic gamma radiation are reviewed. It is shown that this radiation consists of an extragalactic background as well as a bright band of galactic radiation lying in the plane of the Milky Way and produced primarily by cosmic-ray collisions with interstellar gas atoms. The galactic gamma radiation is divided into a near component apparently associated with Gould's belt and a far component originating about 15,000 light years away and narrowly confined to the galactic plane. A Great Galactic Ring is identified which is 35,000 light years in diameter and in which most galactic cosmic rays are produced and supernovae and pulsars are concentrated. The physical mechanisms responsible for the production of most of the cosmic gamma rays in the Galaxy are examined, and the origin of galactic cosmic rays is considered. It is concluded that the cosmic rays are produced either in supernova explosions or in the pulsars they leave behind

Stecker, F. W.↗

NASA NTRS1977

Energetic solar flare particles and interplanetary shock waves

Estimates from hard X-ray measurements show that for many flares the bulk of the flare energy is released in the form of approximately 10-100-keV energy electrons. The interaction of these electrons with the solar atmosphere can produce the optical, UV, EUV, and radio emissions observed during the flare impulsive phase. In addition, explosive heating and evaporation of the chromosphere by these electrons can produce the roughly 10 million K soft X-ray plasma. For the large solar flares which produce interplanetary shock waves, the accelerated approximately 10-100-keV electron population may produce the heating and mass motion required for mass ejection and the formation of the shock wave. The shock wave can in turn accelerate ions and electrons to higher energy as it travels through the corona and interplanetary medium.

Lin, R. P.↗

NASA NTRS1979

All-electric gas detector

Modified optoacoustic gas detector identifies gases by measuring pressure-induced voltage charge in electric signals. Can detect water vapor, atmospheric fluorocarbons, or certain nitrous or nitric compounds that indicate presence of explosives.

Margolis, J. S.↗

NASA NTRS1979

Monitoring harmful gases

Instruments are developed for monitoring presence of hydrazine and nitrogen dioxide in air. Nitrogen dioxide and hydrazine are highly toxic and explosive substances used in propellants for rocket engines. Instruments discussed are inexpensive and most useful for detecting above substances in concentrations as low as few parts per million.

Helms, W. R.↗

NASA NTRS1980

Gage for 3-d contours

Simple gage, used with template, can help inspectors determine whether three-dimensional curved surface has correct contour. Gage was developed as aid in explosive forming of Space Shuttle emergency-escape hatch. For even greater accuracy, wedge can be made of metal and calibrated by indexing machine.

Haynie, C. C.↗

NASA NTRS1980

Safety shield for vacuum/pressure-chamber windows

Optically-clear shatter-resistant safety shield protects workers from implosion and explosion of vacuum and pressure windows. Plastic shield is inexpensive and may be added to vacuum chambers, pressure chambers, and gas-filling systems.

Shimansky, R. A.↗

NASA NTRS1979

Synthesis of national risk profile

The methodology used and results obtained in computing the national risk profile for carbon fibers (CF) released after an aircraft accident (fire or explosion) are presented. The computation was performed by use of twenty-six individual conditional risk profiles, together with the extrapolation of these profiles to other U.S. airports. The risk profile was obtained using 1993 CF utilization forecasts, but numbers of facilities were taken from 1972 and 1975 census data, while losses were expressed in 1977 dollars.

Source record↗

NASA NTRS1978

Transient processes in the combustion of nitramine propellants

A transient combustion model of nitramine propellants is combined with an isentropic compression shock formation model to determine the role of nitramine propellant combustion in DDT, excluding effects associated with propellant structural properties or mechanical behavior. The model is derived to represent the closed pipe experiment that is widely used to characterize explosives, except that the combustible material is a monolithic charge rather than compressed powder. Computations reveal that the transient combustion process cannot by itself produce DDT by this model. Compressibility of the solid at high pressure is the key factor limiting pressure buildups created by the combustion. On the other hand, combustion mechanisms which promote pressure buildups are identified and related to propellant formulation variables. Additional combustion instability data for nitramine propellants are presented. Although measured combustion response continues to be low, more data are required to distinguish HMX and active binder component contributions. A design for a closed vessel apparatus for experimental studies of high pressure combustion is discussed.

Cohen, N. S.↗

NASA NTRS1977

Lithium cell test results

Three lithium SO2 cells, two lithium CF cells, and a vinyl chloride cell, all with crimped seals, and all strictly experimental, were independently discharged on resistors. Three temperatures were used and several different storage temperatures. Discharge rate generally on the nominal discharges were 0.1 amp, 0.5 amp, and 1 amp. Tests results show that the crimp seals are inadequate, especially for the SO2 cells. Normal discharges present no hazards. All cells discharge to zero. The problem of lithium cell explosions, such as occurred during off-limits testing, is discussed.

Bragg, B. J.↗

NASA NTRS1978

Hazards of lithium thionyl chloride batteries

Two different topics which only relate in that they are pertinent to lithium thionyl chloride battery safety are discussed. The first topic is a hazards analysis of a system (risk assessment), a formal approach that is used in nuclear engineering, predicting oil spills, etc. It is a formalized approach for obtaining assessment of the degree of risk associated with the use of any particular system. The second topic is a small piece of chemistry related to the explosions that can occur with lithium thionyl chloride systems. After the two topics are presented, a discussion is generated among the Workshop participants.

Parry, J. M.↗

NASA NTRS1979

Impact cratering calculations. Part 1: Early time results

Early time two dimensional finite difference calculations of laboratory scale hypervelocity impact of 0.3 g spherical 2024 aluminum projectiles into homogeneous plasticene clay targets were performed. Analysis of resulting material motions showed that energy and momentum were coupled quickly from the aluminum projectile to the target material. In the process of coupling, some of the plasticene clay target was vaporized while the projectile become severely deformed. The velocity flow field developed within the target was shown to have features similar to those found in calculations of near surface explosion cratering. Specific application of Maxwell's analytic Z-Model showed that this model can be used to describe the early time flow fields resulting from the impact cratering calculations as well, provided the flow field centers are located beneath the target surface and most of the projectile momentum is dissipated before the model is applied.

Thomsen, J. M.↗

NASA NTRS1964

Fused switch

An electric switch device is described which can be used safely even in an explosive environment. The switch has an operating arm, and a moveable actuator which is engaged by the arm and moved between a number of positions in which the arm opens or closes the switch. A fuse is slidably positioned in a passage through the actuator. The fuse can be replaced in the passage by another fuse when the actuator is in one of its many positions. The device is lightweight and compact, is capable of withstanding severe shock, and is not adversely affected by extremes of temperature.

Weber, G. J.↗