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Technique uses explosive ribbon to join and seal tubes hermetically while totally confining explosive products, such as smoke, light, and sound. Only click is audible. Process yields joints of the same strengths as parent metal.
A workbook is presented to supplement an earlier NASA publication, which was intended to provide the designer and safety engineer with rapid methods for predicting damage and hazards from explosions of liquid propellant and compressed gas vessels used in ground storage, transport and handling. Information is presented in the form of graphs and tables to allow easy calculation, using only desk or handheld calculators. Topics covered in various chapters are: (1) estimates of explosive yield; (2) characteristics of pressure waves; (3) effects of pressure waves; (4) characteristics of fragments; and (5) effects of fragments and related topics.
A version of the two step Lax-Wendroff difference method with second order accuracy is used to seek solutions of the unsteady magnetohydrodynamic (MHD) equations for the study of an explosion in a non-homogeneous medium with and without magnetic fields. The explosion is initiated by introducing a finite amount of energy in a small volume of gas which leads to an instantaneous increase of gas temperature. Two types of magnetic field configurations (i.e. open and closed) are considered to illustrate the dependence and differences of magnetic and a non-magnetic flow motion. Numerical results show the strong dependence of induced MHD flow field on the magnetic field configuration and strength. The development and decay of the fast and slow MHD shock waves, as well as the ordinary gasdynamic shock waves, are also represented well by the present computer simulations. In conclusion, we have demonstrated that the numerical scheme we have used is a reliable one for studying 2-dimensional MHD problems in non-homogeneous medium.
The morphologies of certain of the smaller Martian volcanoes are discussed as possible results of explosive volcanic density currents. An examination of newly-photographed flank and caldera features of the Martian volcanoes Ceraunius Tholus, Uranius Tholus, Uranius Patera and Hecates Tholus, including steep slope angles, Krakatoa-type caldera morphologies, erosional features (radial channels and anastamosing gullies) and constructional features (blanketed flanks and possible lava deltas) reveals their similarity to terrestrial cones and composite volcanoes such as Barcena Volcano. Crater age data from the surface of Martian domes and shields indicates that such explosive activity occurred more frequently early in Martian geologic history, consistent with the view that the volcanic density currents were base surges rather than nuees ardentes, with the melting of permafrost supplying the water required in base surge generation.
It is proposed that a vapor explosion of a submerged pool of liquid sulfur will remove the crust overlying an area of about 50-km diam. Thermal radiation from the exposed liquid sulfur pool with a surface temperature of 600 K is then presumed to be responsible for the 5-micron outbursts that have been observed. The explosive volcanoes are expected to leave black sulfur calderas, which are, indeed, found on the surface. The 5-micron outburst observed by Sinton (1980), on June 11, 1979 (UT), is identified with a new caldera found on Voyager 2 photographs but which had not been present on Voyager 1 pictures.
In explosive joining technique, adapter flange from fuel channel machined to incorporate a V-notch interface. Ribbon explosive, 1/2 inch (1.3 cm) in width, drives V-notched wall of adapter into bellows assembly, producing atomic-level metallurgical bond. Ribbon charge yields joint with double parent metal strength.
Joining principles and variables, types of joints, capabilities, and current and potential applications are described for an explosive seam welding process developed at NASA Langley Research Center. Variable small quantities of RDX explosive in a ribbon configuration are used to create narrow (less than 0.5 inch), long length, uniform, hermetrically sealed joints that exhibit parent metal properties in a wide variety of metals, alloys, and combinations. The first major all application of the process is the repair of four nuclear reactors in Canada. Potential applications include pipelines, sealing of vessels, and assembly of large space structures.
From a reexamination of the medium and high-resolution Viking images of Amazonian and Hesperian age volcanic centers on Mars, it is believed that an excellent example of well-preserved explosive activity does indeed exist close to the summit of Hecates Tholus. A mantled region to the west of the summit caldera is seen as an example of a geologically very recent plinian air fall ash deposit. Morphological evidence is presented for describing this as explosively generated material, and numerical models of magma ascent and eruption in the Martian environment are used to estimate the physical characteristics (eruption cloud height, magma discharge rate, magma volatile content, duration of activity, and vent size) for this event. Attention is also given to the implication of this eruptive style for the composition of the erupted magma.
Explosive seam welding produces up to 100-percent joint strength. Ribbon explosive activated by remote energy source produces metallurgically sound joint. Success of technique verified for joints between like metals and joints between two different metals. Applications include structural assembly in toxic atmospheres and in radioactive or otherwise hazardous environments.
The service life evaluation of explosive devices used in a wide variety of aircraft escape systems is described. The purpose was to develop a service extension approach, supported by tests on candidate devices, to evaluate the effects of service, age, and degradation, and allow responsible, conservative, service life determinations. An overview is given on the recommended approach and experimental procedures for accurate service evaluations with test results on rigid and flexible explosive transfer lines, one-way transfers, and flexible linear shaped charges.
The chemical and isotopic stratifications of supernova exhalations are discussed, with reference to a number of theoretical estimates. Particular attention is given to the theoretical models of the major chemical zones of explosive exhalation of isotopes of Mg, Si, and Ti in intermediate size supernovae. The contribution of supernova exhalations to oxygen anomalies in the solar system is also discussed within the framework of the theoretical models of Clayton et al. (1977, 1978, 1979, 1981). The initial stratigraphy of the major elements in the explosive exhalation of a progenitor star of 25 solar mass is illustrated in a graph, on the basis of the theoretical estimates of Waver et al. (1978), and Weaver and Woolsey (1980).
The present investigation had the objective to develop models for the distribution of fragments which are ejected at a given velocity for both impact and explosion cratering. It is pointed out that the results have application to the physics of planetary accretion and the origin of meteorites. The impact ejection of fine dust into the earth's atmosphere has been proposed as a mechanism for extinctions which occurred at the end of the Cretaceous. A technique is developed for determining the distribution of fragments which are ejected at a given velocity. The experimental data base for the distribution fragments in the ejecta blankets of impact, explosion, and nuclear craters, are discussed. Attention is also given to impact flow field calculations, fragmentation theory, and the applications of the derived relations.
The time evolution of the near-earth man-made orbital debris environment modeled by numerical simulation is presented in this paper. The model starts with a data base of orbital debris objects which are tracked by the NORAD ground radar system. The current untrackable small objects are assumed to result from explosions and are predicted from data collected from a ground explosion experiment. Future collisions between earth orbiting objects are handled by the Monte Carlo method to simulate the range of collision possibilities that may occur in the real world. The collision fragmentation process between debris objects is calculated using an empirical formula derived from a laboratory spacecraft impact experiment to obtain the number versus size distribution of the newly generated debris population. The evolution of the future space debris environment is compared with the natural meteoroid background for the relative spacecraft penetration hazard.
It is pointed out that magnetospheric substorms are perhaps the most basic type of disturbances which occur throughout the magnetosphere. There is little doubt that the energy for magnetospheric substorms is delivered from the sun to the magnetosphere by the solar wind, and theoretical and observational studies have been conducted to uncover the processes associated with the energy transfer from the solar wind to the magnetosphere, and the subsequent processes leading to various magnetospheric substorm phenomena. It has been widely accepted that explosive magnetic reconnection supplies the energy for magnetospheric substorm processes. It is indicated that the auroral phenomena must be various manifestations of a large-scale electrical discharge process which is powered by the solar wind-magnetosphere dynamo. Certain problems regarding explosive magnetic reconnection are discussed.
Experimental observations of ignition in premixed gaseous reactants indicate that perfectly homogeneous initiation is practically unrealizable. Instead, combustion first sets in, as a rule, at small, discrete sites where inherent inhomogeneities cause chemical activity to proceed preferentially and lead to localized explosions. Combustion waves propagating away from these hot spots or reaction centers eventually envelop the remaining bulk. This study examines the spatial structure and temporal evolution of a hot spot for a model involving Arrhenius kinetics. The hot spot, characterized by peaks in pressure and temperature with little diminution in local density, is shown to have one of two possible self-similar structures. The analysis employs a combination of asymptotics and numerics, and terminates when pressure and temperature in the explosion have peaked.
Two investigations were undertaken to examine possible large scale explosive volcanic deposits on Mars. The first includes an analysis of Viking Infrared Thermal Mapper (IRTM) data covering the vast deposits in the Amazonis, Memnonia, and Aeolis regions. These postulated ignimbrites have been previously mapped, and at least five high resolution nighttime IRTM data tracks cross the deposits. Preliminary analysis of the data covering Amazonis Planitia show that local features have anomalous thermal inertias but the ignimbrites as a whole do not consistently have significantly different thermal inertias from their surroundings. Preliminary photogeologic and IRTM studies of the large and small highland paterae have also begun. The purpose of IRTM studies of postulated Martian explosive volcanic deposits is to determine the physical properties of the proposed ignimbrites. If volcanic deposits are exposed at the surface, high thermal inertias, as are observed for Apollinaris Patera, should be present.
A compilation of papers presented in a joint NASA, American Society for Metals, The George Washington University, American Welding Society, and Society of Manufacturing Engineers Conference on Welding, Bonding, and Fastening at Langley Research Center, Hampton, VA, on October 23 to 25, 1984 is given. Papers were presented on technology developed in current research programs relevant to welding, bonding, and fastening of structural materials required in fabricating structures and mechanical systems used in the aerospace, hydrospace, and automotive industries. Topics covered in the conference included equipment, hardware and materials used when welding, brazing, and soldering, mechanical fastening, explosive welding, use of unique selected joining techniques, adhesives bonding, and nondestructive evaluation. A concept of the factory of the future was presented, followed by advanced welding techniques, automated equipment for welding, welding in a cryogenic atmosphere, blind fastening, stress corrosion resistant fasteners, fastening equipment, explosive welding of different configurations and materials, solid-state bonding, electron beam welding, new adhesives, effects of cryogenics on adhesives, and new techniques and equipment for adhesive bonding.
Simulation results from both the EM collisionless particle code and the MHD particle code reveal an explosive reconnection process associated with nonlinear evolution of the coalescence instability. The explosive coalescence is a self-similar process of magnetic collapse, and ensuing amplitude oscillations in the magnetic and electrostatic energies and temperatures are modeled by an equation of motion for the scale factor in the Sagdeev potential. This phenomenon may explain the rapid energy release of a certain class of solar flares during their impulsive phase.