1,003
1.0K
May 22, 2011
05/11
by
Campbell, Frank J
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The Navy is experiencing a severe aircraft electrical wiring maintenance problem as a result of the extensive use of an aromatic polyimide insulation that is deteriorating at a rate that was unexpected when this wire was initially selected. This problem has significantly affected readiness, reliability, and safety and has greatly increased the cost of ownership of Naval aircraft. Failures in wire harnesses have exhibited arcing and burning that will propagate drastically, to the interruption of...
Topics: BEAMS (SUPPORTS), JOINTS (JUNCTIONS), SPACE ERECTABLE STRUCTURES, TRUSSES, AXES OF ROTATION,...
179
179
Jun 3, 2011
06/11
by
Glassman, Nanci A.; Perry, Jeannine B.; Giersch, Christopher E.; Lambert, Matthew A.; Pinelli, Thomas E
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eye 179
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NASA CONNECT is a research-, inquiry, and standards-based, integrated mathematics, science, and technology series of 30-minute instructional distance learning (television and web-based) programs for students in grades 6 8. Respondents who evaluated the programs in the series over the first five seasons (1998-99 through 2002-03) reported that (1) they used the programs in the series; (2) the goals and objectives for the series were met; (3) the programs were aligned with the national...
Topics: MARS ATMOSPHERE, ROVING VEHICLES, SPACE PLATFORMS, STABILIZED PLATFORMS, MARS SURFACE, NITROGEN,...
The use of aluminum beam lead devices in hybrid circuits is described by modification of existing processing equipment. Principles, procedures, and methods of application of Al beam lead devices are discussed in terms of processing the devices onto hybrids.
Topics: NASA Technical Reports Server (NTRS), ALUMINUM, BEAMS (SUPPORTS), CERAMIC BONDING, LEAD (METAL),...
A quality assurance program was developed which included specifications for celion/LARC-160 polyimide materials and quality control of materials and processes. The effects of monomers and/or polymer variables and prepeg variables on the processibility of celion/LARC prepeg were included. Processes for fabricating laminates, honeycomb core panels, and chopped fiber moldings were developed. Specimens and conduct tests were fabricated to qualify the processes for fabrication of demonstration...
Topics: NASA Technical Reports Server (NTRS), COMPOSITE MATERIALS, GRAPHITE, POLYIMIDES, BEAMS (SUPPORTS),...
245
245
May 31, 2011
05/11
by
Pettegrew, Richard D.; Struk, Peter M.; Watson, John K.; Haylett, Daniel R
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The National Center for Microgravity Research, NASA Glenn Research Center, and NASA Johnson Space Center are conducting an experimental program to explore the influence of reduced gravity environments on the soldering process. An improved understanding of the effects of the acceleration environment is important to application of soldering during current and future human space missions. Solder joint characteristics that are being considered include solder fillet geometry, porosity, and...
Topics: DATA REDUCTION, IMPACT TESTS, METAL PLATES, BEAMS (SUPPORTS), FUSELAGES, FINITE ELEMENT METHOD,...
A composite element is presented which includes the effects of warping and offset shear centers. It is shown to be mathematically consistent with thin walled open beam theory and can be incorporated into any structural analysis program by use of NASTRAN'S standard elements. A numerical example analyzing the vibration of a channel beam is presented, and, by using the composite element, the numerical results agreed well with theoretical data.
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), SHEAR PROPERTIES, WARPAGE, STRUCTURAL...
495
495
May 29, 2011
05/11
by
Colbourne, Jason D.; Frost, Chad R.; Tischler, Mark B.; Ciolani, Luigi; Sahai, Ranjana; Tomoshofski, Chris; LaMontagne, Tro
texts
eye 495
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Developing autonomous flying vehicles has been a growing field in aeronautical research within the last decade and will continue into the next century. With concerns about safety, size, and cost of manned aircraft, several autonomous vehicle projects are currently being developed; uninhabited rotorcraft offer solutions to requirements for hover, vertical take-off and landing, as well as slung load transportation capabilities. The newness of the technology requires flight control engineers to...
Topics: BEAMS (SUPPORTS), GEARS, VIBRATION, TRANSMISSIONS (MACHINE ELEMENTS), TORQUE, BENDING MOMENTS,...
266
266
May 27, 2011
05/11
by
Matting, Fred W.; Chapman, Dean R.; Nyholm, Jack R.; Thomas, Andrew G
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eye 266
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Results are given of local skin-friction measurements in turbulent boundary layers over an equivalent air Mach number range from 0.2 to 9.9 and an over-all Reynolds number variation of 2 x 10(exp 6) to 100 x 10(exp 6). Direct force measurements were made by means of a floating element. Flows were two-dimensional over a smooth flat surface with essentially zero pressure gradient and with adiabatic conditions at the wall. Air and helium were used as working fluids. An equivalence parameter for...
Topics: DYNAMIC STRUCTURAL ANALYSIS, STRUCTURAL VIBRATION, BEAMS (SUPPORTS), GRAPHS (CHARTS), TABLES...
437
437
Jun 1, 2011
06/11
by
Rothrock, Addison M
texts
eye 437
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For a period of ten to fifteen years intensive research and development has been conducted on turbojet propulsion systems for aircraft. During this period much has been learned about the system both from the standpoint of current usage and of future development possibilities. It is the purpose of this report to discuss the current status of the turbojet engine as produced in the United States and to discuss the future possibilities for improvement in the engine and in the fuel. The engine and...
Topics: FUSELAGES, STIFFNESS, TENSILE TESTS, PANELS, THIN WALLS, COMPRESSION LOADS, MECHANICAL PROPERTIES,...
260
260
May 31, 2011
05/11
by
Ottens, Andrew K.; Griffin, Timothy P.; Helms, William R.; Yost, Richard A
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To enter orbit the Space Shuttle burns 1.8 million liters of liquid hydrogen combined with 0.8 million liters of liquid oxygen through three rocket engines mounted in the aft. NASA monitors the nitrogen-purged aft compartment for increased levels of hydrogen or oxygen in order to detect and determine the severity of a cryogenic fuel leak. Current monitoring is accomplished with a group of mass spectrometer systems located as much as 400 feet away from the shuttle. It can take up to 45 seconds...
Topics: EIGENVALUES, ESTIMATING, VIBRATION, BEAMS (SUPPORTS), LOADS (FORCES), FLAT PLATES, DIFFERENTIAL...
217
217
Jul 11, 2010
07/10
by
Brown, P. A.; Vernikos-Danellis, J
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eye 217
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Evidence of gastric ulceration or severe erosion of the gastric mucosa was sought in rats following 19.5 days of spaceflight on the Cosmos 782 Biological Satellite. The stomachs from the flight animals were compared macroscopically and histologically with stomachs removed from animals in the synchronous and vivarium control groups. None of the animals in the flight or the control groups ulcerated, and there were no obvious histologic differences in gastric erosion among the groups. The reasons...
Topics: DYNAMIC STRUCTURAL ANALYSIS, FINITE DIFFERENCE THEORY, STRUCTURAL STABILITY, TRIGONOMETRIC...
Two cubic spline based approximation schemes for the estimation of structural parameters associated with the transverse vibration of flexible beams with tip appendages are outlined. The identification problem is formulated as a least squares fit to data subject to the system dynamics which are given by a hybrid system of coupled ordinary and partial differential equations. The first approximation scheme is based upon an abstract semigroup formulation of the state equation while a...
Topics: NASA Technical Reports Server (NTRS), APPROXIMATION, BEAMS (SUPPORTS), SPLINE FUNCTIONS, TIPS,...
114
114
Jul 23, 2010
07/10
by
Garland, D. B
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A large-scale, ejector-lift V/STOL Model, powered by a J-97 engine, was tested at the NASA Ames Research Center Outdoor Aerodynamics Research Facility. The model incorporated the external augmentor concept developed by DHC. Since the first test at Ames in 1979, the fuselage augmentor nozzle array has been redesigned with a larger pitch and notched nozzles instead of plain slot nozzles. Thrust augmentation of the ejector as measured at Ames Research Center was lower than that measured in the DHC...
Topics: BEAMS (SUPPORTS), STRESSES, DYNAMIC STRUCTURAL ANALYSIS, FINITE ELEMENT METHOD, PLATES (STRUCTURAL...
260
260
Jul 11, 2010
07/10
by
Bernatowicz, D. T
texts
eye 260
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Modern high performance cells made for space are discussed. The major recent developments that are expected to influence what solar cells will be available in five years or so are described.
Topics: ALUMINUM ALLOYS, SHEAR STRENGTH, STRUCTURAL ANALYSIS, BORON ALLOYS, SPACE SHUTTLES, SPACECRAFT,...
1,327
1.3K
May 28, 2011
05/11
by
NON
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The Air Transport Research Group of the World Conference on Transportation Research (WCTR) Society was formally launched as a special interest group at the 7th Triennial WCTR in Sydney, Australia in 1995. Since then, our membership base has expanded rapidly, and now includes over 400 active transportation researchers, policy-makers, industry executives, major corporations and research institutes from 28 countries. It became a tradition that the ATRG would hold an international conference at...
Topics: MANUFACTURING, ALTERNATING CURRENT, COST REDUCTION, BEAMS (SUPPORTS), MICROMECHANICS, OSCILLATIONS,...
Algorithms to optimally locate and design dampers for large space structures were developed. The requirements for distributed sensing and actuation in control of structural systems were determined. Mathematical programming was used to solve for optimum damping rate and location. Actuator dynamics were considered to solve for optimum actuator mass.
Topics: NASA Technical Reports Server (NTRS), ACTUATORS, ALGORITHMS, BEAMS (SUPPORTS), DAMPING, LARGE SPACE...
The use of NASTRAN model synthesis capability is illustrated. A classical truss problem is examined and the results are compared to results from other methods to test for accuracy. The problem is examined using both fixed interface modes and free interface modes. The solution is carried out for an applied dynamic load as far as recovery of forces in individual members as a function of time. Another small beam problem is used to compare different means of combining substructures.
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), NASTRAN, STRUCTURAL ANALYSIS, TRUSSES,...
203
203
May 31, 2011
05/11
by
Chen, Yen-Sen; Liu, Jiwen; Zhang, Siju
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Laser powered propulsion systems involve complex fluid dynamics, thermodynamics and radiative transfer processes. Based on an unstructured grid., pressure-based computational aerothermodynamics, platform, several sub-nio'''dels describing such underlying physics as laser ray tracing and focusing, thermal non-equilibrium, plasma radiation and air spark ignition have been developed. This proposed work shall extend the numerical platform and existing sub-models to include the aluminum wall surface...
Topics: MULTIDISCIPLINARY DESIGN OPTIMIZATION, APPROXIMATION, ALGORITHMS, LOADS (FORCES), TRUSSES, BEAMS...
389
389
May 30, 2011
05/11
by
Thomas, Russell H.; Kinzie, Kevin W.; Pao, S. Pau
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In typical engine installations, the pylon of an engine creates a flow disturbance that interacts with the engine exhaust flow. This interaction of the pylon with the exhaust flow from a dual stream nozzle was studied computationally. The dual stream nozzle simulates an engine with a bypass ratio of five. A total of five configurations were simulated all at the take-off operating point. All computations were performed using the structured PAB3D code which solves the steady, compressible,...
Topics: FREE VIBRATION, MONTE CARLO METHOD, MATHEMATICAL MODELS, LAMINATES, BEAMS (SUPPORTS), SYMMETRY, PLY...
The techniques, processes, and equipment required for automatic fabrication and assembly of structural elements in space using the space shuttle as a launch vehicle and construction base were investigated. Additional construction/systems/operational techniques, processes, and equipment which can be developed/demonstrated in the same program to provide further risk reduction benefits to future large space systems were included. Results in the areas of structure/materials, fabrication systems...
Topics: NASA Technical Reports Server (NTRS), LARGE SPACE STRUCTURES, ORBITAL ASSEMBLY, SPACE SHUTTLES,...
After buckling, statically indeterminate trusses, beams, and other strictly symmetric structures may collapse under loads which reach limiting magnitudes. Optimal design is discussed for prescribed values of these collapse loads.
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), BUCKLING, OPTIMIZATION, STRUCTURAL DESIGN,...
For abstract, see N78-25111.
Topics: NASA Technical Reports Server (NTRS), LARGE SPACE STRUCTURES, ORBITAL ASSEMBLY, SPACE SHUTTLES,...
The method of retroduction, adapted from the doctoral thesis of Dr. A. Croce, relies on a process of dialectic questioning that begins with the information sought, proceeds to Given items (either in the form of dimensions or limits of research). and to Known mathematical forms of analysis in design or to principles of study in research. Finally, analysis and synthesis are used to abstract the dielectic questions and to arrive at the information desired. This method is used to solve the...
Topics: NASA Technical Reports Server (NTRS), BOLTS, DYNAMIC LOADS, NUTS (FASTENERS), VIBRATION, BEAMS...
The lower right aluminum beam cap roll forming mill was delivered and installed in the beam builder. The beam was brought to full operational status and beams of one to six bay lengths were produced to demonstrate full system capability. Although the cap flange waviness problem persists, work is progressing within cost and schedule.
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), FABRICATION, ORBITAL ASSEMBLY, SPACE...
The development of an algorithm that will determine actuator and sensor locations on a flexible beam is discussed. Large space structures will have many locations where actuators can be placed. This research seeks to determine the optimum locations. In addition, the best locations are determined while certain constraints are satisfied which guarantee that mission performance requirements are achieved. The approach adopted is to consider actuators and sensors to be collocated so as to produce an...
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), FLEXIBILITY, LARGE SPACE STRUCTURES,...
By expressing partial differential equations of motion in matrix notation, utilizing the integrating matrix as a spatial operator, and applying the boundary conditions, the resulting ordinary differential equations can be cast into standard eigenvalue form upon assumption of the usual time dependence. As originally developed, the technique was limited to beams having continuous mass and stiffness properties along their lengths. Integrating matrix methods are extended to treat the differential...
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), ROTATING BODIES, STRUCTURAL VIBRATION,...
214
214
Jul 11, 2010
07/10
by
Hannah, S. R.; Palazotto, A. N
texts
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A new trigonometric approach to the finite difference calculus was applied to the problem of beam buckling as represented by virtual work and equilibrium equations. The trigonometric functions were varied by adjusting a wavelength parameter in the approximating Fourier series. Values of the critical force obtained from the modified approach for beams with a variety of boundary conditions were compared to results using the conventional finite difference method. The trigonometric approach...
Topics: ALUMINUM ALLOYS, REUSABLE SPACECRAFT, STRUCTURAL ANALYSIS, BORON ALLOYS, MECHANICAL PROPERTIES,...
Information is given in viewgraph form on the modeling of nonlinear damping in distributed parameter systems.
Topics: NASA Technical Reports Server (NTRS), DAMPING, DISTRIBUTED PARAMETER SYSTEMS, MATHEMATICAL MODELS,...
This report is an aid to designers of structures with large area-to-mass ratios that are subject to high acoustic pressures during rocket launches. A means is provided for determining generalized modal loads using AJ-coefficients. AJ-coefficients are a measure of a vibroacoustic coupling between the structure and the acoustic field.
Topics: NASA Technical Reports Server (NTRS), ACOUSTICS, BEAMS (SUPPORTS), MODAL RESPONSE, PRESSURE...
Four different structural problems are solved to gain familiarity with the NASTRAN computer program. The problems are: (1) a simply-supported beam subjected to lateral loads, (2) a rotating filamentary composite bar under the action of centrifugal forces, (3) a missile body with aerodynamic, gravitational, and inertial forces, and (4) a square simply-supported plate with in-plane temperature changes capable of buckling the plate. Input and output data are given for each problem. The results are...
Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, STRUCTURAL ANALYSIS, BEAMS (SUPPORTS),...
89
89
Jun 13, 2011
06/11
by
Golden, Keith; Nemani, Ramakrishna; Pang, Wanlin; Votava, Pet
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The latest generation of NASA Earth Observing System (EOS) satellites has brought a new dimension to continuous monitoring of the living part of the Earth System, the biosphere. EOS data can now provide weekly global measures of vegetation productivity and ocean chlorophyll, and many related biophysical factors such as land cover changes or snowmelt rates. However, the highest economic value would come from forecasting impending conditions of the biosphere, to allow decision makers to mitigate...
Topics: STRUCTURAL DESIGN, BENDING MOMENTS, LAUNCH VEHICLES, SPACECRAFT MODULES, TRUSSES, SPACE ERECTABLE...
410
410
Jul 23, 2010
07/10
by
Dat, Rovindra; Ayyagari, Murthy; Hoag, David; Sloat, David; Anand, Yogi; Whitely, Sta
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The objective is to develop 60 GHz IMPATT diodes suitable for communications applications. The performance goals of the 60 GHz IMPATT is 1W CW output power with a conversion efficiency of 15 percent and 10-year lifetime. The final design of the 60 GHz IMPATT structure evolved from computer simulations performed at the University of Michigan. The initial doping profile, involving a hybrid double-drift (HDD) design, was derived from a drift-diffusion model that used the static velocity-field...
Topics: BEAMS (SUPPORTS), TITANIUM, TRUSSES, CONTROL THEORY, LARGE SPACE STRUCTURES, SPACE SHUTTLES,...
The functions of the Control of Flexible Structures I (COFS I) deployer and retractor assembly (DRA) are primarily to deploy and retract the Mast I beam, and secondarily to latch, unlatch, and restow the DRA mechanism. The problems associated with the diagonal folding mechanism that retracts the beam is presented, the synchronization requirements critical to the process of restowing the beam is discussed, and a proposed solution to the problem of synchronization between the mechanical systems...
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), DEPLOYMENT, FOLDING, RETRACTABLE EQUIPMENT,...
This invention relates to devices which grip cylindrical structures and more particularly to a device which has three arcuate gripping members having frictional surfaces for gripping and compressing a bi-stem. The bi-stem gripping apparatus is constructed having a pair of side gripping members, and an intermediate gripping member disposed between them. Sheets of a gum stock silicone rubber with frictional gripping surfaces are bonded to the inner region of the gripping members and provide...
Topics: NASA Technical Reports Server (NTRS), ASTRONAUTS, BEAMS (SUPPORTS), ORBITAL ASSEMBLY, SPACE...
339
339
Aug 2, 2010
08/10
by
Williams, Brian E.; Stiglich, Jacob J., Jr.; Kaplan, Richard B.; Tuffias, Robert H
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Ultramet has developed a process which promises to significantly increase the mechanical properties of powder metallurgy (PM) parts. Current PM technology uses mixed powders of various constituents prior to compaction. The homogeneity and flaw distribution in PM parts depends on the uniformity of mixing and the maintenance of uniformity during compaction. Conventional PM fabrication processes typically result in non-uniform distribution of the matrix, flaw generation due to particle-particle...
Topics: BEAMS (SUPPORTS), SPACE STATION FREEDOM, DYNAMIC MODELS, DYNAMIC STRUCTURAL ANALYSIS, FLEXIBLE...
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105
Jul 12, 2010
07/10
by
Francois, J.; Roche, J. P
texts
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The extent to which annoyance estimated by an isopsophic index is a good forecaster for annoyance perceived near airport approaches was investigated. An index of sensed annoyance is constructed, and the relationship between the annoyance index and the isopsophic index is studied.
Topics: COORDINATES, TWO DIMENSIONAL BODIES, DIFFERENTIAL EQUATIONS, MATRICES (MATHEMATICS), PROBLEM...
By using Galerkin's variational method an approximate solution is developed for a system of two differential equations with linear partial derivatives of the second order. This system of differential equations corresponds to the physical model, known in the literature as the Timoshenko Beam. The results obtained are applied to two particular cases representing respectively: the case of a beam with a rectangular section, with a constant height and a basis with a linear variation; and the case of...
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), DYNAMIC STRUCTURAL ANALYSIS, FORCED...
Nonlinear beam kinematics are developed and applied to the dynamic analysis of a pretwisted, rotating beam element. The common practice of assuming moderate rotations caused by structural deformation in geometric nonlinear analyses of rotating beams was abandoned in the present analysis. The kinematic relations that described the orientation of the cross section during deformation are simplified by systematically ignoring the extensional strain compared to unity in those relations. Open cross...
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), DEFORMATION, DYNAMIC STRUCTURAL ANALYSIS,...
The author's prior development of a general abstract representation for the design sensitivities of Green's functional for linear structural systems is extended to the case where the structural stiffness vanishes at an internal location. This situation often occurs in the optimal design of structures. Most optimality criteria require that optimally designed beams be statically determinate. For clamped-pinned beams, for example, this is possible only if the flexural stiffness vanishes at some...
Topics: NASA Technical Reports Server (NTRS), GREEN'S FUNCTIONS, LINEAR SYSTEMS, SENSITIVITY, STIFFNESS,...
A simple method of predicting the energy-absorption capability of composite subfloor beam structure was developed. The method is based upon the weighted sum of the energy-absorption capability of constituent elements of a subfloor beam. An empirical data base of energy absorption results from circular and square cross section tube specimens were used in the prediction capability. The procedure is applicable to a wide range of subfloor beam structure. The procedure was demonstrated on three...
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), DESIGN ANALYSIS, ENERGY ABSORPTION, FLOORS,...
The Composite Beam Cap Fabricator (CBCF), a part of a family of machines that was designed to develop and augment the technology of space fabrication (the automatic production of basic structural members in space is described. The major components of the CBCF are described. The mill weighs approximately 1400 pounds and its size is approximately 6 feet by 2 feet by 2 feet. It is a microprocessor under a low cost-of-concept type of contract. Consequently, all components are made of commercially...
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), COVERINGS, MILLING MACHINES, SPACE...
A curved member under axial load is analyzed using beam column theory to determine nonlinear response and the tangent stiffness associated with small displacements from the nonlinear state. Such a result is suitable for incorporation into a general nonlinear analysis using a corotational coordinate system to describe the rigid body type motion of individual members. The method is applied to buckling problems. Several examples are given to show the accuracy of the method.
Topics: NASA Technical Reports Server (NTRS), AXIAL LOADS, BEAMS (SUPPORTS), CURVES (GEOMETRY), FRAMES,...
978
978
Jul 11, 2010
07/10
by
Baker, W. E.; Kulesz, J. J.; Ricker, R. E.; Westine, P. S.; Parr, V. B.; Vargas, L. M.; Moseley, P. K
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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)...
Topics: ALUMINUM COMPOUNDS, PANELS, RIGID STRUCTURES, BEAMS (SUPPORTS), BORON COMPOUNDS, SPACE SHUTTLES,...
During the contracted period, our research was concentrated into three areas. The first was the development of an accurate and a computationally efficient method for predicting the cross-section warping functions in an arbitrary cross-section composed of isotropic and/or anisotropic materials. The second area of research was the development of a general higher-order one-dimensional theory for anisotropic beams. The third area of research was the development of an analytical model for assessing...
Topics: NASA Technical Reports Server (NTRS), COMPOSITE STRUCTURES, CROSS SECTIONS, FINITE ELEMENT METHOD,...
452
452
Jun 13, 2011
06/11
by
Nguyen, Truong X.; Ely, Jay J.; Williams, Reuben A.; Koppen, Sandra V.; Salud, Maria Theresa P
texts
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Radiated emissions in aircraft communication and navigation bands are measured from several active radio frequency identification (RFID) tags. The individual tags are different in design and operations. They may also operate in different frequency bands. The process for measuring the emissions is discussed, and includes tag interrogation, reverberation chamber testing, and instrument settings selection. The measurement results are described and compared against aircraft emission limits. In...
Topics: CERAMICS, CRACK PROPAGATION, GRAIN SIZE, STRAIN GAGES, MICROSTRUCTURE, FRACTURE STRENGTH, BEAMS...
A document describes designing, building, testing, and certifying a customized crane (Lifting Device LD) with a strong back (cradle) to facilitate the installation of long wall panels and short door panels for the GHe phase of the James Webb Space Telescope (JWST). The LD controls are variable-frequency drive controls designed to be adjustable for very slow and very-short-distance movements throughout the installation. The LD has a lift beam with an electric actuator attached at the end. The...
Topics: NASA Technical Reports Server (NTRS), CRANES, JAMES WEBB SPACE TELESCOPE, ACTUATORS,...
Mechanical device for accurate measurement of weight and changes in weight is presented. Diagram of mechanical equipment is illustrated. Construction of system is described and method of operation is analyzed.
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), EQUIPMENT SPECIFICATIONS, MECHANICAL...
It is demonstrated how with the aid of a bending test, the Weibull fracture risk function can be determined - without postulating its analytical form - by resolving an integral equation. The respective solutions for rectangular and circular section beams are given. In the first case the function is expressed as an algorithm and in the second, in the form of series. Taking into account that the cumulative fracture probability appearing in the solution to the integral equation must be continuous...
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), BRITTLE MATERIALS, FRACTURING, INTEGRAL...
The effect of actuator dynamics on the control of beam flexure during nonlinear slewing of the SCOLE model is discussed. Two aspects of physical limitations on the regulation of beam flexure are similated, i.e., (1) a one foot travel limitation of displacement of proof-mass actuators; and (2) a time delay of 0.1 secs. in application of controls. The goal was to assess the magnitude of induced errors and, comparing the results to the ideal, and to determine how much flexure there is during slew...
Topics: NASA Technical Reports Server (NTRS), ACTUATORS, BEAMS (SUPPORTS), DYNAMICAL SYSTEMS, LARGE SPACE...
Several models were built at NASA Langley and used to demonstrate the following nonlinear behavior: internal resonance in a free response, principal parametric resonance and subcritical instability in a cantilever beam-lumped mass structure, combination resonance in a parametrically excited flexible beam, autoparametric interaction in a two-degree-of-freedom system, instability of the linear solution, saturation of the excited mode, subharmonic bifurcation, and chaotic responses. A video tape...
Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), DYNAMIC STRUCTURAL ANALYSIS, FLEXIBLE...
