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Results for “COLUMNS, TUBULAR”

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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

A new method for the preparation of polymeric porous layer open tubular columns for GC application

A new method to prepare polymeric PLOT columns by using in situ polymerization technology is described. The method involves a straightforward in situ polymerization of the monomer. The polymer produced is directly coated on the metal tubing. This eliminates many of the steps needed in conventional polymeric PLOT column preparation. Our method is easy to operate and produces very reproducible columns, as shown previously (T. C. Shen. J. Chromatogr. Sci. 30, 239, 1992). The effects of solvents, tubing pretreatments, initiators and reaction temperatures in the preparation of PLOT columns are studied. Several columns have been developed to separate (1) highly polar compounds, such as water and ammonia or water and HCN, and (2) hydrocarbons and inert gases. A recent improvement has allowed us to produce bonded polymeric PLOT columns. These were studied, and the results are included also.

NASA Discipline Exobiology↗
NASA NTRS1978

Structural efficiency of long lightly loaded truss and isogrid columns for space applications

The general mass characteristics of long lightly loaded columns for space applications are investigated by studying four column concepts. The first is a simple tubular column, the second is a three longeron truss column constructed of tubular members, the third is a three longeron truss column constructed of solid rod members, and the fourth is an open grid work isogrid wall tubular column. Design procedures, which include an initial imperfection in the straightness of the column, are developed for the different concepts and demonstrated numerically. A new set of structural efficiency parameters are developed for lightly loaded columns and are used to show a comparison of the masses of the four column concepts investigated.

Mikulas, M. M., Jr.↗
NASA NTRS1980

A design procedure for a tension-wire stiffened truss-column

A deployable, tension wire stiffened, truss column configuration was considered for space structure applications. An analytical procedure, developed for design of the truss column and exercised in numerical studies, was based on equivalent beam stiffness coefficients in the classical analysis for an initially imperfect beam column. Failure constraints were formulated to be used in a combined weight/strength and nonlinear mathematical programming automated design procedure to determine the minimum mass column for a particular combination of design load and length. Numerical studies gave the mass characteristics of the truss column for broad ranges of load and length. Comparisons of the truss column with a baseline tubular column used a special structural efficiency parameter for this class of columns.

Greene, W. H.↗
NASA NTRS1983

Stability, vibration and passive damping of partially restrained imperfect columns

A theoretical and experimental study of slender tubular columns for possible use in space structures is conducted in the presence of partial rotational end restraints. Explicit formulas are derived for computing the buckling load and the lowest natural frequency of perfectly straight uniform elastic members with rotational end restraints possessing linear moment-rotation characteristics. An exact solution in the form of a transcendental equation, and a numerical solution using second-order finite-differences are also presented. The presence of an initial imperfection is also incorporated into the numerical procedure. Vibration tests are conducted on an imperfect tubular steel member in the absence of an axial load. A damping concept consisting of a string-mass assembly is explored. Three passive damping configurations involving combinations of three lead shots were investigated. The three lead shot configurations provided considerably greater damping than the single lead shot.

Razzaq, Z.↗
NASA NTRS1980

Structural members, method and apparatus

A method and apparatus for fabricating a structural member such as truss from flexible sheet material in compacted form are disclosed. A number of generally tubular columns are progressively formed from the sheet material and deployed generally parallel to one another. Adjacent pairs of the columns are interconnected by respective side members, each of which is comprised of a strip of the sheet material. The sheet material is fastened together by self-attaching fasteners integrally formed from the sheet material of the columns and side members themselves.

Kinzler, J. A.↗
NASA NTRS1981

Sensitivity of optimum solutions to problem parameters

In an aircraft configuration optimization, the information of interest is the sensitivity of optimal block fuel consumption and wing aspect ratio and area, to variations of required range and payload. The objectives of this study are: (1) to show how the equations capable of yielding the sensitivity derivatives (the sensitivity equations) can be obtained for a constrained optimum regardless of the type of optimization algorithm that was used to arrive at the optimum point, (2) to review the solvability of the sensitivity equations and (3) to report on applications on structural optimization. Numerical examples, which demonstrate the sensitivity analysis, include a tubular column and a three-bar truss for which closed form solutions are obtained, a ten-bar truss that requires the use of a finite element analysis, and a thin-walled beam characterized by strongly nonlinear constraints for local buckling. It is concluded that a practically significant extrapolation accuracy may be obtained for a reasonably broad range of parameter changes; and that accuracy does not depend strongly on the degree of convergence of the optimum solution from which the sensitivity derivatives are obtained.

Sobieszczanski-Sobieski, J.↗
NASA NTRS1992

In-situ polymerization PLOT columns I: divinylbenzene

A novel method for preparation of porous-layer open-tubular (PLOT) columns is described. The method involves a simple and reproducible, straight-forward in-situ polymerization of monomer directly on the metal tube.

NASA Center ARC↗
NASA NTRS1992

In-situ polymerization PLOT columns I: divinylbenzene

A novel method for preparation of porous-layer open-tubular (PLOT) columns is described. The method involves a simple and reproducible, straight-forward in-situ polymerization of monomer directly on the metal tube.

NASA Center ARC↗
NASA NTRS1994

In-situ polymerized PLOT columns III: divinylbenzene copolymers and dimethacrylate homopolymers

Studies of divinylbenzene copolymers and dimethacrylate homopolymers indicate that the polymer pore size controls the separation of water and ammonia on porous-layer-open-tubular (PLOT) columns. To a lesser degree, the polarity of the polymers also affects the separation of a water-ammonia gas mixture. Our results demonstrate that the pore size can be regulated by controlling the cross-linking density or the chain length between the cross-linking functional groups. An optimum pore size will provide the best separation of water and ammonia.

NASA Discipline Exobiology↗
NASA NTRS1980

Mechanical end joint for structural columns

Connector for tubular struts permits construction of lightweight frames without tools or assembly equipment. Two main components are node fitting and strut element. Components are aleaned approximately and pushed together. Design accommodates reasonable axial and rotational misalignment of nodes and struts. Also, individual columns can be inserted into receptacle and given slight push by operator, trigger pins release ratchet, allowing energy stored in springs to rotate screw into nut in receptacle.

Bush, H. G.↗
NASA NTRS1957

Practical solution of plastic deformation problems in elastic-plastic range

A practical method for solving plastic deformation problems in the elastic-plastic range is presented. The method is one of successive approximations and is illustrated by four examples which include a flat plate with temperature distribution across the width, a thin shell with axial temperature distribution, a solid cylinder with radial temperature distribution, and a rotating disk with radial temperature distribution.

COLUMNS, TUBULAR↗
NASA NTRS1976

Flight contaminant trace analyser. Phase 1: Chromatographic input system

The purpose of this investigation was to develop two chromatographic columns which would enable a mass spectral identification of 40 specified compounds. The columns are for use in a toxic gas analyzer, which incorporates an automated gas chromatograph-mass spectrometer. Different types of stationary phases were investigated. The columns used were of the open tubular capillary type and were made of nickel. Limitations of initial and final temperature of operation led to final development of a column which could resolve most of the compounds required. The few unresolved components are capable of resolution and identification by the mass spectrometer. The columns (182m Ni x 0.8m 0.D x 0.5mm I.D) coated with Witconal La 23, yielded in excess of 200,000 theoretical plates and completed the analysis in less than 90 minutes using a carrier gas flow rate of 4 cc/min hydrogen.

Zlatkis, A.↗
NASA NTRS2004

Multifunctional Inflatable Structure Being Developed for the PowerSphere Concept

NASA has funded a collaborative team of The Aerospace Corporation, ILC Dover, Lockheed Martin, and NASA Glenn Research Center to develop the Multifunctional Inflatable Structure (MIS) for a "PowerSphere" concept through a NASA Research Announcement. This power system concept has several advantages, including a high collection area, low weight and stowage volume, and the elimination of all solar array pointing mechanisms. The current 3-year effort will culminate with the fabrication and testing of a fully functional engineering development unit. The baseline design of the Power-Sphere consists of two opposing semispherical domes connected to a central spacecraft. Each semispherical dome consists of hexagonal and pentagonal solar cell panels that together form a geodetic sphere. Inflatable ultraviolet (UV) rigidizable tubular hinges between the solar cell panels and UV rigidizable isogrid center columns with imbedded flex circuitry form the MIS. The reference configuration for the PowerSphere is a 0.6-m-diameter (fully deployed) spacecraft with a total mass budget of 4 kg (1 kg for PowerSphere, 3 kg for spacecraft) capable of producing 29 W of electricity with 10-percent-efficient thin-film solar cells. In a stowed configuration, the solar cell panels will be folded sequentially to the outside of the instrument decks. The center column will be z-folded between the instrument decks and the spacecraft housing for packaging. The instrument panel will secure the z-folded stack with launch ties. After launch, once the release tie is triggered, the center column and hinge tubes will inflate and be rigidized in their final configurations by ultraviolet radiation. The overall PowerSphere deployment sequence is shown pictorially in the following illustration.

Peterson, Todd T.↗
NASA NTRS1985

Mechanical features of the shuttle rotating service structure

With the development of the space shuttle launching facilities, it became mandatory to develop a shuttle rotating service structure to provide for the insertion and/or removal of payloads at the launch pads. The rotating service structure is a welded tubular steel space frame 189 feet high, 65 feet wide, and weighing 2100 tons. At the pivot column the structure is supported on a 30 inch diameter hemispherical bearing. At the opposite terminus the structure is supported on two truck assemblies each having eight 36 inch diameter double flanged wheels. The following features of the rotating service structure are discussed: (1) thermal expansion and contraction; (2) hurricane tie downs; (3) payload changeout room; (4) payload ground handling mechanism; (5) payload and orbiter access platforms; and (6) orbiter cargo bay access.

Crump, J. M.↗