Search NASA⌕ Search

SEARCH · Search NASA

Results for “COLLAPSE”

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.

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

At least 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

SRB attrition rate study of the aft skirt due to water impact cavity collapse loading

A methodology was presented so that realistic attrition prediction could aid in selecting an optimum design option for minimizing the effects of updated loads on the Space Shuttle Solid Rocket Booster (SRB) aft skirt. The updated loads resulted in water impact attrition rates greater than 10 percent for the aft skirt structure. Adding weight to reinforce the aft skirt was undesirable. The refined method treats the occurrences of the load distribution probabilistically, radially and longitudinally, with respect to the critical structural response.

Crockett, C. D.↗
NASA NTRS1976

SRM attrition rate study of the aft motor case segments due to water impact cavity collapse loading

The attrition assessment of the aft segments of Solid Rocket Motor due to water impact requires the establishment of a correlation between loading occurrences and structural capability. Each discrete load case, as identified by the water impact velocities and angle, varies longitudinally and radially in magnitude and distribution of the external pressure. The distributions are further required to be shifted forward or aft one-fourth the vehicle diameter to assure minimization of the effect of test instrumentation location for the load determinations. The asymmetrical load distributions result in large geometric nonlinearities in structural response. The critical structural response is progressive buckling of the case. Discrete stiffeners have been added to these aft segments to aid in gaining maximum structural capability for minimum weight addition for resisting these loads. This report presents the development of the attrition assessment of the aft segments and includes the rationale for eliminating all assessable conservatisms from this assessment.

Crockett, C. D.↗
NASA NTRS1976

Flux-flow voltages during guided flux collapse from hollow superconducting cylinders

Voltages across diametrically opposite contact pairs on the outer surface of superconducting Nb tubes are found to depend dramatically upon the spatial configuration of the voltage-measuring leads relative to the positions of the moving magnetic flux lines. Experiments have been conducted to study these voltages for different wall thicknesses and for a variety of arrangements of the leads when flux in the hole and the wall of the Nb tube is made to exit or enter, completely or partially, by applying heat at a narrow strip along its length. Using the critical-state concept, a model for the change of flux and the resulting electric fields in the Nb tube on application of a heat pulse is presented. The resulting time-dependent and time-integrated voltages are calculated in excellent quantitative agreement with the experimental results. These results show that the flux-flow voltages across two contact points on a superconductor arise from the generation of an induced electric field over a chosen path in the superconductor between the contact points and from a change of magnetic flux through the surface bounded by the measuring leads and the chosen path in the superconductor.

Khanna, S. M.↗
NASA NTRS1978

Collapsible module extends tenfold in height

Low-cost hollow module rapidly converts into elevated platform for field applications. Module can be used as support for communication antennas or for TV or movie cameras operated by news reporters. Alternatively, it can be used as extendible boom on vehicles.

Mcdougal, A. R.↗
NASA NTRS1979

Gravitational collapse in dust lanes and the appearance of spiral structure in galaxies

The possibility is considered that there are two types of spiral for each spiral galaxy: an underlying spiral of relatively old stars seen in red and IR photographs and a spiral outlined by H II regions and young bright blue stars. The origin of the first spiral is attributed to large-scale spiral density waves, and the second spiral is identified as a stochastic spiral. It is suggested that there is a physical or causal connection between the two spirals and that dust lanes play the role of intermediary. An analysis is performed which shows that such a model can account for the formation and destruction of giant molecular cloud complexes and for observed spiral structure in one simple unified theory.

Elmegreen, B. G.↗
NASA NTRS1982

Extensional collapse modes of structural members

Attenuation of the load transmitted to a vehicle occupant by the structure, either by modifying structural assembly, changing geometry of its elements, or adding specific load limiting devices to help dissipate kinetic energy was studied. General aviation aircraft have fuselage subfloors of a built up structure which are generally very stiff perpendicular to the floor of the cabin. The subfloor structure, designed to crush at an appropriate force level, can be used to advantage in a crash by dissipating energy through plastic buckling of the floor beams and frames. Simple closed form solutions to predict the mean crushing force levels of subfloor designs is useful in engineering practice. The crushing process of thin walled, plate formed, open structures with particular emphasis on L and cruciform shapes was analyzed. Lower and upper bound solutions for the mean crushing strength of cruciforms are obtained by considering modes of deformation which account for both bending and extensional deformation. It is the importance of extensional deformation to the energy absorption process, representing at least one third of the dissipated energy is shown.

Hayduk, R. J.↗
NASA NTRS1983

On the dynamic response and collapse of slender guyed booms for space application

A procedure is developed for the analysis of the nonlinear transient response of an initially imperfect slender guyed boom having a concentrated mass at the tip. The analysis is compared with laboratory experiments, and the validated procedure is employed to study the transient response of a boom to suddenly applied step loads and prescribed initial velocities. Both cases approximate the transient conditions associated with commencing and terminating a slewing maneuver in space. Two nonlinear effects are examined, namely cable slackening and beam column behavior. It is shown that dynamic buckling of the boom may occur with excitations which result in slackening of a cable. It is also shown that transverse boom tip deflections are sensitive only to initial eccentricities when certain threshold values are exceeded. Design guidelines are established for combinations of pulse level and duration which meet performance requirements for allowable deflections.

Housner, J. M.↗
NASA NTRS1985

Joint For Erectable and Collapsible Frames

Joint mechanism allows truss structure to be folded and stowed in small space. Mechanism includes hinge attached to two truss elements connected by two links, tension bar, and compression bar. When folded elements are released, springs in joint mechanism rotate truss elements about hinge and lock mechanism to form single member. Developed for structures erected in space (antennas, solar panels, solar sails, and masts), joint mechanism adaptable to window-opening struts, folding furniture and television antennas.

Pelischek, T. E.↗
NASA NTRS1983

The collapse of the local, Spitzer-Haerm formulation and a global-local generalization for heat flow in an inhomogeneous, fully ionized plasma

The breakdown of the classical (CBES) field aligned transport relations for electrons in an inhomogeneous, fully ionized plasma as a mathematical issue of radius of convergence is addressed, the finite Knudsen number conditions when CBES results are accurate is presented and a global-local (GL) way to describe the results of Coulomb physics moderated conduction that is more nearly appropriate for astrophysical plasmas are defined. This paper shows the relationship to and points of departure of the present work from the CBES approach. The CBES heat law in current use is shown to be an especially restrictive special case of the new, more general GL result. A preliminary evaluation of the dimensionless heat function, using analytic formulas, shows that the dimensionless heat function profiles versus density of the type necessary for a conduction supported high speed solar wind appear possible.

Scudder, J. D.↗
NASA NTRS1984

Extensional collapse modes of structural members

Attenuation of the load transmitted to a vehicle occupant by the structure, either by modifying structural assembly, changing geometry of its elements, or adding specific load limiting devices to help dissipate kinetic energy was studied. General aviation aircraft have fuselage subfloors of a built up structure which are generally very stiff perpendicular to the floor of the cabin. The subfloor structure, designed to crush at an appropriate force level, can be used to advantage in a crash by dissipating energy through plastic buckling of the floor beams and frames. Simple closed form solutions to predict the mean crushing force levels of subfloor designs is useful in engineering practice. The crushing process of thin walled, plate formed, open structures with particular emphasis on L and cruciform shapes was analyzed. Lower and upper bound solutions for the mean crushing strength of cruciforms are obtained by considering modes of deformation which account for both bending and extensional deformation. It is the importance of extensional deformation to the energy absorption process, representing at least one third of the dissipated energy is shown. Previously announced in STAR as N82-33765

Hayduk, R. J.↗
NASA NTRS1986

Numerical studies of collapsing interstellar clouds

Numerical simulation of the structure and evolution of interstellar clouds was initiated. Steps were taken toward an integrated treatment of the dynamical, thermal, and chemical processes entering model calculations. A detailed study was made of radiative transfer in molecular lines to allow model predictions to be tested against empirical data. The calculations have successfully reproduced and explained several observed cloud properties, including abundances of complex molecular species and the apparent depletion of CO in dense cores.

Bodenheimer, P. H.↗