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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 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Material cutting, shaping, and forming: A compilation

Information is presented concerning cutting, shaping, and forming of materials, and the equipment and techniques required for utilizing these materials. The use of molds, electrical fields, and mechanical devices are related to forming materials. Material cutting methods by devices including borers and slicers are presented along with chemical techniques. Shaping and fabrication techniques are described for tubing, honeycomb panels, and ceramic structures. The characteristics of the materials are described. Patent information is included.

Source record↗
NASA NTRS1974

Design, fabrication, and test of lightweight shell structure, phase 2

A cylindrical shell skirt structure 4.57 m (180 in.) in diameter and 3.66 m (144 in.) high was subjected to a design and analysis study using a wide variety of structural materials and concepts. The design loading of 1225.8 N/cm (700 lb/in.) axial compression and 245.2 N/cm (140 lb/in.) torsion is representative of that expected on a typical space tug skirt section. Structural concepts evaluated included honeycomb sandwich, truss, isogrid, and skin/stringer/frame. The materials considered included a wide variety of structural metals as well as glass, graphite, and boron-reinforced composites. The most unique characteristic of the candidate designs is that they involve the use of very thin-gage material. Fabrication and structural test of small panels and components representative of many of the candidate designs served to demonstrate proposed fabrication techniques and to verify design and analysis methods.

Source record↗
NASA NTRS1975

Design, fabrication and test of lightweight shell structure

A cylindrical shell structure 3.66 m (144 in.) high by 4.57 m (180 in.) diameter was designed using a wide variety of materials and structural concepts to withstand design ultimate combined loading 1225.8 N/cm (700 lb/in.) axial compression and 245.2 N/cm (140 lb/in.) torsion. The overall cylinder geometry and design loading are representative of that expected on a high performance space tug vehicle. The relatively low design load level results in designs that use thin gage metals and fibrous-composite laminates. Fabrication and structural tests of small panels and components representative of many of the candidate designs served to demonstrate proposed fabrication techniques and to verify design and analysis methods. Three of the designs evaluated, honeycomb sandwich with aluminum faceskins, honeycomb sandwich with graphite/epoxy faceskins, and aluminum truss with fiber-glass meteoroid protection layers, were selected for further evaluation.

Lager, J. R.↗
NASA NTRS1981

Techniques for thermal sensitivity analysis

Techniques for computing the sensitivity of temperatures to changes in design variables needed for designing thermal protection systems are considered. It is shown that the choice of the most efficient technique depends on the ratio of number of temperature constraints to the number of design variables, as well as on the thermal analysis method employed. The analysis is specialized to the case of a structure modeled by finite elements, and an example of an insulation panel is used to demonstrate the techniques.

Haftka, R. T.↗
NASA NTRS1981

The design of a microstrip antenna array for a UHF space telemetry link

An array of microstrip antenna panels was designed for use on a small instrumented satellite as part of a 400-MHz telemetry link between that satellite and NASA's shuttle spacecraft. A roughly omnidirectional phi-plane pattern was desired. The 1.4-wavelength diameter of the satellite and the various ports and structures on its surface presented strong constraints on the antenna array design. Eight antennas, each one a quarter-wavelength panel with one radiating and one shorted edge, were chosen. A phi-plane pattern ripple of 4.4 dB and a gain of at least 0.1 dB relative to a half-wavelength dipole were realized. The design technique used for the individual antenna panels included the study of feed-point location for impedance matching and the effect of losses in the dielectric. A superposition method was used to synthesize the radiation patterns for different numbers and different excitations of antennas on the satellite.

Post, R. E.↗
NASA NTRS1980

Screening of high temperature adhesives for large area bonding

High temperature-resistant adhesive systems were screened for processability, mechanical and physical properties, operational capability at 589 K (600 F), and the ability to produce large area bonds of high quality in fabricating Space Shuttle components. The adhesives consisted primarily of polyimide systems, including FM34B-18, NR-150B2 (DuPont), PMR-15, LARC-13, LARC-160, Thermid 600, and AI-1130L (AMOCA). The processing studies included preparation of polyimide resins, fabrication of film adhesives, development of lay-up and cure procedures, fabrication of honeycomb sandwich panels, and fabrication of mid-plane bonded panels in joints up to 30.5 cm (12 in.) wide. The screening program included tests for tack and drape properties, reticulation and filleting characteristics, ability to produce void-free or low porosity bonds in mid-plane bonded panels, out-time stability, lap shear strength, climbing drum peel strength, and glass transition temperature (Tg). This paper describes the processing methods developed and the test results.

Stenersen, A. A.↗
NASA NTRS1983

Extended Vortex Lattice Method

Extended NASA Langley Vortex Lattice Method computer program VLM, estimates subsonic aerodynamic characteristics of up to four complex planforms. Planforms include wings with variable-sweep outer panels, wings with several changes in dihedral angle across span, wings with winglets, and wing (or wings) in conjunctions with tail and/or canard. VLM written in FORTRAN IV.

Lamar, J. E.↗
NASA NTRS1984

The NASA welding assessment program

The potential cost and performance advantages of welding was understood but ignored by solar panel manufacturers in the U.S. Although NASA, DOD and COMSAT have supported welding development efforts, soldering remains the only U.S. space qualified method for interconnecting solar cells. The reason is that no U.S. satellite prime contractor found it necessary, due to mission requirements, to abandon the space proven soldering process. It appears that the proposed NASA space station program will provide an array requirement, a 10 year operation in a low Earth orbital environment, that mandates welding. The status of welding technology in the U.S. is assessed.

Scott-Monck, J.↗
NASA NTRS1985

Steady and unsteady incompressible free-wake analysis

The flows around highly sweptback wings and bodies of revolution at high angle of attack are described, and inviscid model approximations and mathematical formulation of the problem are given to steady and unsteady incompressible flows. A general presentation of the methods of solution is given, with emphasis on current computational techniques. Detailed descriptions of the nonlinear vortex-lattice and vortex-panel techniques are presented to show how the boundary conditions are enforced using iteration. Typical numerical results are compared with the available experimental data.

Kandil, O. A.↗
NASA NTRS1997

Use of the Aromascan(TM) Instrument for Nonsubjective Evaluation of Rodent Spaceflight Hardware

This report describes the verification and utilization of the AromaScan(TM) (Hollis, NH) instrument for the ground-based evaluation of odor containment by various spaceflight habitats developed at NASA's Ames Research Center (ARC). The AromaScan(TM) instrument is an electronic odor detection system consisting of 32 polymer sensors that respond differentially to 10 different chemical groups present in an air sample. The AromaScan(TM) system also includes neural network software for constructing a database of known odors, against which an unknown odor can be compared. At present, the standard method for characterizing rodent odor containment during the development and testing of spaceflight hardware is the use of a human odor assessment panel. However, this can be a very time consuming and costly process, and the results are inherently subjective. The AromaScan(TM) system should produce more consistent and objective results, as well as a cost savings in the long term. To test and verify the AromaScan(TM) instrument, daily air samples will be collected from the exhaust port of rodent habitats, during experiment development tests, then injected into the instrument and used to create a database of recognizable odors. Human sniff tests will be performed in conjunction with the AromaScan(TM) analysis, and the results will be correlated. We will then teach the neural network to differentiate between an acceptable and an unacceptable odor profile, as defined by the human sniff test, and to be able to accurately identify an odor that would not pass a sniff panel. The results of our efforts will be to verify that the AromaScan(TM) system is a valuable alternative to human sniff panel assessments for the early iterative process of designing and testing rodent waste filters for spaceflight. Acceptance by a human panel will remain one of the final criteria for successful rodent habitat development.

Scribner, K. A.↗
NASA NTRS2010

Process Improvement Through Tool Integration in Aero-Mechanical Design

Emerging capabilities in commercial design tools promise to significantly improve the multi-disciplinary and inter-disciplinary design and analysis coverage for aerospace mechanical engineers. This paper explores the analysis process for two example problems of a wing and flap mechanical drive system and an aircraft landing gear door panel. The examples begin with the design solid models and include various analysis disciplines such as structural stress and aerodynamic loads. Analytical methods include CFD, multi-body dynamics with flexible bodies and structural analysis. Elements of analysis data management, data visualization and collaboration are also included.

Integrated design and analysis↗
NASA NTRS2020

Bayesian Statistical Models for Community Annoyance Survey Data

This paper demonstrates the use of two Bayesian statistical models to analyze single-event sonic boom exposure and human annoyance data from community response surveys. Each model is fit to data from a NASA pilot study.Unlike many community noise surveys, this study used a panel sample to collect multiple observations per participant instead of a single observation. Thus, a multilevel (also known as hierarchical or mixed-effects) model is used to account for the within-subject correlation in the panel sample data. This paper describes a multilevel logistic regression model and a multilevel ordinal regression model. The paper also proposes a method for calculating a summary dose-response curve from the multilevel models that represents the population. The two models’ summary dose-response curves are visually similar. However, their estimates differ when calculating the noise dose at a fixed percent highly annoyed.

Musical instruments↗
NASA NTRS1940

An Investigation of Sheet-stiffener Panels Subjected to Compression Loads with Particular Reference to Torsionally Weak Stiffeners

A total of 183 panel specimens of 24ST aluminum alloy with nominal thickness of 0.020, and 0.040 inch with extruded bulb-angle sections of 12 shapes spaced 4 and 5 inches as stiffeners were tested to obtain the buckling stress and the amplitude of the maximum wave when buckled. Bulb angles from 3 to 27 1/2 inches long were tested as pin-end columns. The experimental data are presented as stress-strain and column curves and in tabular form. Some comparisons with theoretical results are presented. Analytical methods are developed that make it possible for the designer to predict with reasonable accuracy the buckling stress and the maximum-wave amplitude of the sheet in stiffened-panel combinations. The scope of the tests was insufficient to formulate general design criteria but the results are presented as a guide for design and an indication of the type of theoretical and experimental work that is needed.

LOADS - COLUMNS↗
NASA NTRS2007

Protective Skins for Aerogel Monoliths

A method of imparting relatively hard protective outer skins to aerogel monoliths has been developed. Even more than aerogel beads, aerogel monoliths are attractive as thermal-insulation materials, but the commercial utilization of aerogel monoliths in thermal-insulation panels has been inhibited by their fragility and the consequent difficulty of handling them. Therefore, there is a need to afford sufficient protection to aerogel monoliths to facilitate handling, without compromising the attractive bulk properties (low density, high porosity, low thermal conductivity, high surface area, and low permittivity) of aerogel materials. The present method was devised to satisfy this need. The essence of the present method is to coat an aerogel monolith with an outer polymeric skin, by painting or spraying. Apparently, the reason spraying and painting were not attempted until now is that it is well known in the aerogel industry that aerogels collapse in contact with liquids. In the present method, one prevents such collapse through the proper choice of coating liquid and process conditions: In particular, one uses a viscous polymer precursor liquid and (a) carefully controls the amount of liquid applied and/or (b) causes the liquid to become cured to the desired hard polymeric layer rapidly enough that there is not sufficient time for the liquid to percolate into the aerogel bulk. The method has been demonstrated by use of isocyanates, which, upon exposure to atmospheric moisture, become cured to polyurethane/polyurea-type coats. The method has also been demonstrated by use of commercial epoxy resins. The method could also be implemented by use of a variety of other resins, including polyimide precursors (for forming high-temperature-resistant protective skins) or perfluorinated monomers (for forming coats that impart hydrophobicity and some increase in strength).

Leventis, Nicholas↗
NASA NTRS1934

The torsional stiffness of thin duralumin shells subjected to large torques

This report gives a simple method of estimating the torsional stiffness of thin shells, such as box beams or stressed-skin wings under large torque loads. A general efficiency chart for shells in torsion is established, based on the assumption that the efficiency of the web sheet in resisting deformation decreases linearly with the average stress. The chart is used to calculate the torsional deflections of eight box beams, a test wing panel, and a complete wing; the results of the calculations are shown in comparison with the test results. The agreement is probably as good as might be expected considering the empirical nature of the method and the well-known dispersion between results of tests on thin sheet-metal structures.

Kuhn, Paul↗
NASA NTRS1996

Optimal Design of Grid-Stiffened Composite Panels Using Global and Local Buckling Analysis

A design strategy for optimal design of composite grid-stiffened panels subjected to global and local buckling constraints is developed using a discrete optimizer. An improved smeared stiffener theory is used for the global buckling analysis. Local buckling of skin segments is assessed using a Rayleigh-Ritz method that accounts for material anisotropy and transverse shear flexibility. The local buckling of stiffener segments is also assessed. Design variables are the axial and transverse stiffener spacing, stiffener height and thickness, skin laminate, and stiffening configuration. The design optimization process is adapted to identify the lightest-weight stiffening configuration and pattern for grid stiffened composite panels given the overall panel dimensions, design in-plane loads, material properties, and boundary conditions of the grid-stiffened panel.

Ambur, Damodar R.↗
DOE OSTI2024

Additive Manufacturing for Large Displacement Unmanned Underwater Vehicles (LDUUVs)

Oak Ridge National Laboratory partnered with Anduril Industries to develop the process for adapting large format additive manufacturing for the production of underwater vehicles. This research started by defining and selecting a polymer for the vehicle panels. Coatings were tested at 9000PSI to ensure proper bonding to the 3D printed panels, then tensile tested to understand the mechanical properties. A vehicle panel fairing set was design optimized for the 3D printing process and then 3D printed. Additional work optimized coatings and tested additional reinforcements methods such as fiber weave and z-casting with fiber rods and resin. Finally, a full vehicle was constructed and successfully tested in open water by Anduril.

36 MATERIALS SCIENCE↗
NASA NTRS1974

Space shuttle orbiter mechanical refrigeration system

A radiator/condenser was designed which is efficient in both condensation (refrigeration) and liquid phase (radiator) operating modes, including switchover from the refrigeration mode to the radiator mode and vice versa. A method for predicting the pressure drop of a condensing two-phase flow in zero-gravity was developed along with a method for predicting the flow regime which would prevail along the condensation path. The hybrid refrigeration system was assembled with the two radiator/condenser panels installed in a space environment simulator. The system was tested under both atmospheric and vacuum conditions. Results of the tests are presented.

Williams, J. L.↗