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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 343 records · Page 19

All sources NASA NTRS DOE OSTI

NASA NTRS1974

Conical isogrid adapter structural test results. Appendix C: Cylindrical isogrid structures

Analysis techniques and data for evaluating the load carrying capabilities of cylindrical isogrid structures subjected to compression and body bending loads are presented. Structural tests were conducted on a 120-inch diameter by 37-inch long cylindrical adapter. Photographs and drawings of the flanged isogrid adapter structure are included. The subjects considered are: (1) summary of the test data resulting from structural analysis, (2) techniques for predicting local and general instability, (3) a method for predicting extended local instability, (4) the effects of basic parameter and constant variations in extended local stability analysis, and (5) evaluation of effective skin width and compression buckling of skin panels on the basis of test data.

Source record↗

NASA NTRS1975

Dip molding to form intricately-shaped medical elastomer devices

Preshaped mandrel mounted on rotating mechanism is partically immersed in tank filled with liquid elastomer. While mandrel rotates, elastomer film forms om mandrel surface due to surface tension and capillary behavior of liquid. Devices with well-defined flanges can be made using process.

Broyles, H. F.↗

NASA NTRS1974

Titanium honeycomb acoustic lining structural and thermal test report

The results are presented of static, fatigue and thermal testing of titanium honeycomb acoustic panels representing the acoustic tailpipe for the Pratt and Whitney Aircraft JT8D Refan engine which is being studied for use on the Boeing 727-200 airplane. Test specimens represented the engine and tailpipe flange joints, the rail to which the thrust reverser is attached and shear specimens of the tailpipe honeycomb. Specimens were made in four different batches with variations in configuration, materials and processes in each. Static strength of all test specimens exceeded the design ultimate load requirements. Fatigue test results confirmed that aluminum brazed titanium, as used in the Refan tailpipe design, meets the fatigue durability objectives. Quality of welding was found to be critical to life, with substandard welding failing prematurely, whereas welding within the process specification exceeded the panel skin life. Initial fatigue testing used short grip length bolts which failed prematurely. These were replaced with longer bolts and subsequent testing demonstrated the required life. Thermal tests indicate that perforated skin acoustic honeycomb has approximately twice the heat transfer of solid skin honeycomb.

Joynes, D.↗

NASA NTRS1975

Lightweight thermally efficient composite feedlines for the space tug cryogenic propulsion system

Six liquid hydrogen feedline design concepts were developed for the cryogenic space tug. The feedlines include composite and all-metal vacuum jacketed and nonvacuum jacketed concepts, and incorporate the latest technological developments in the areas of thermally efficient vacuum jacket end closures and standoffs, radiation shields in the vacuum annulus, thermal coatings, and lightweight dissimilar metal flanged joints. The feedline design concepts are evaluated on the basis of thermal performance, weight, cost, reliability, and reusability. Design concepts were proved in a subscale test program. Detail design was completed on the most promising composite feedline concept and an all-metal feedline. Three full scale curved composite feedlines and one all-metal feedline assembly were fabricated and subjected to a test program representative of flight hardware qualification. The test results show that composite feedline technology is fully developed. Composite feedlines are ready for space vehicle application and offer significant reduction in weights over the conventional all-metal feedlines presently used.

Spond, D. E.↗

NASA NTRS1974

A separable fluid connector system effectiveness evaluation technique

An analytical technique is presented for evaluating the relationship among existing numerous separable fluid connector designs to find that configuration which is best (optimal). The data utilized in this research was acquired from approximately 900 flanges designed for six sub-systems of the S-1B stage of the Saturn 1B Space Vehicle. The method is general enough to be useful in optimizing design and systematizing decision-making in a variety of related technical fields.

Prasthofer, W. P.↗

NASA NTRS1975

Isogrid structures

Test results and related structural instability analyses are presented for a 10-foot-diameter, 37-inch-long cylinder, and a 10-foot-diameter, 40-inch-long, 45-degree conical frustum. Both structures are based upon flanged isogrids and are fabricated in 2024-T851 aluminum. Peak edge load intensities at failure were 1,654 lb/in for the cylinder and 1,457 lb/in at the small diameter of the frustum. General instability cylindrical-monocoque-structure equivalent knockdown factors for both were in good agreement (gamma = 0.48). Design analysis is also derived for estimating critical cylinder instability edge loads from the performance of two tandem isogrid members. Evaluation is made of effective skin contributing to isogrid load-carrying cross-section.

Slysh, P.↗

NASA NTRS1976

Rotary broaches

Tool is used for counterboring or backspot facing recesses for boltheads or nuts in difficult-to-reach locations, such as near webs, bosses, or flanges. Two versions of tool have been designed, one for roughing out and another for finishing.

Libertone, C.↗

NASA NTRS1976

Method of making hollow elastomeric bodies

Annular elastomeric bodies having intricate shapes are cast by dipping a heated, rotating mandrel into a solution of the elastomer, permitting the elastomer to creep into sharp recesses, drying the coated mandrel and repeating the operation until the desired thickness has been achieved. A bladder for a heart assist pump in which a cylindrical body terminating in flat, sharp horizontal flanges fabricated by this procedure has been subjected to over 2,500 hours of simulated life conditions with no visible signs of degradation.

Broyles, H. F.↗

NASA NTRS1978

Alinement tool for X-ray image intensifiers

Gage consists of upper plate and lower plate connected by aluminum post marked with metric scale. Upper plate is identical to calibration plate except for post flange. Lower plate is made of aluminum and is grooved for x-y coordinates and pattern of concentric rings that aid in recognition and measurement of nonlinearity. X-y coordinates on upper and lower plates match exactly. Gage indicates amount and direction of skew in images.

Rasmussen, D.↗

NASA NTRS1977

Problems Associated with Attaching Strain Gages to Titanium Alloy Ti-61-4V

Weldable strain gages have shown excellent high temperature characteristics for supersonic cruise aircraft application. The spotwelding attachment method, however, has resulted in serious reductions in the fatigue life of titanium alloy (Ti-6Al-4V) fatigue specimens. The reduction is so severe that the use of weldable strain gages on operational aircraft must be prohibited. The cause of the fatigue problem is thought to be a combination of the microstructure changes in the material caused by spotwelding and the presence of the flange of the stain gage. Brazing, plating, and plasma spraying were investigated as substitutes for spotwelding. The attachment of a flangeless gage by plasma spraying provided the most improvement in the fatigue life of the titanium.

Jenkins, J. M.↗

NASA NTRS1976

The high-power X-band planetary radar at Goldstone - Design, development, and early results

Selected critical microwave components for a 400-kW very-long-pulse (several hours) X-band radar system are discussed from theoretical and practical viewpoints. Included are the special-sized waveguide and flanges, hybrid power combiner, couplers, switches, polarizer, rotary joints, feedhorn, and radome. The system is installed on the National Aeronautics and Space Administration/Jet Propulsion Laboratory 64-m-diam reflector antenna at Goldstone, CA.

Hartop, R.↗

NASA NTRS1977

Design, fabrication and test of a lightweight shell structure, phase 3

Progress is reported in the construction of lightweight orthogrid shells. Graphite/epoxy panels are being used in the fabrication. The shell structure is diagramed in detail. Panel laminates, and panel stiffener flanges are described while illustrations delineate panel assembly procedures.

Source record↗

NASA NTRS1977

Stress analysis of pressure vessel assembly

A radome assembly capable of withstanding large hydrostatic pressures was designed with a sapphire hemisperical dome and a plastic housing. These two parts were connected with a stainless steel flange ring. A finite-element stress analysis of this assembly was accomplished and an experimental load test was performed to verify the predicted stresses.

Eppink, R. T.↗

NASA NTRS1977

Far-field multimodal acoustic radiation directivity

Approximate equations for the far field acoustic radiation patterns in the forward quadrant from a flanged circular duct were compared with exact equations for both single and multimodal excitations. The single mode comparison showed good agreement between the exact and approximate equations for the principal lobes of higher radial order modes. For lower and especially for zero radial order modes, there was some error in the angular location and decibel level of principal lobe peak pressure obtained from the approximate equation. Some agreement of sidelobes was also observed although the approximate equation was not intended to simulate the sidelobes. The multimodal approximate summation equations consisting only of a simple function of directivity angle and an acoustic power biasing function were checked against the exact equations for several distributions of modal power and showed excellent agreement with exact equations for all cases. Although many modes contribute to the final level and shape of the directivity curve, the major contributions appear to come from the higher radial order modes.

Saule, A. V.↗

NASA NTRS1978

Reflex feed system for dual frequency antenna with frequency cutoff means

A reflex feed system is described for a dual frequency antenna such as one which transmits and receives both S and X band signals. The dichroic plate, normally employed for directing X band radiation away from the X band horn, is replaced by a flange about the opening of the X band horn.

Hartop, R. W.↗

NASA NTRS1978

An evaluation of the sandwich beam in four-point bending as a compressive test method for composites

The experimental phase of the study included compressive tests on HTS/PMR-15 graphite/polyimide, 2024-T3 aluminum alloy, and 5052 aluminum honeycomb at room temperature, and tensile tests on graphite/polyimide at room temperature, -157 C, and 316 C. Elastic properties and strength data are presented for three laminates. The room temperature elastic properties were generally found to differ in tension and compression with Young's modulus values differing by as much as twenty-six percent. The effect of temperature on modulus and strength was shown to be laminate dependent. A three-dimensional finite element analysis predicted an essentially uniform, uniaxial compressive stress state in the top flange test section of the sandwich beam. In conclusion, the sandwich beam can be used to obtain accurate, reliable Young's modulus and Poisson's ratio data for advanced composites; however, the ultimate compressive stress for some laminates may be influenced by the specimen geometry.

Shuart, M. J.↗

NASA NTRS1978

Development of flightweight static face seals for 75.84 MPa /11 000 psi/ pressure and cryogenic temperatures

The development of a static seal configuration to meet the lightweight low-leakage requirements of the Space Shuttle Main Engine (pressure carrying capability of up to 75.84 MPa) is discussed. The design features, fabrication methods, lab testing, and performance of seal are examined. Flange and bolt details of the joint assembly are considered with attention to an ultrasonic technique for measuring preload in the bolts. Methods used for leak testing in the laboratory and in the field are described; the practicality of the procedures is considered. Attention is directed to hydrogen-environment embrittlement and its influence on seal and joint design.

Daniels, C. M.↗

NASA NTRS1979

A reflected-wave ruby maser with K-band tuning range and large instantaneous bandwidth

A novel maser concept is outlined and a unique design described which permits wide bandwidth and waveguide tuning range by employing four stages cascaded via cryogenically cooled circulators. Theoretical considerations for gain, bandwidth, gain ripple, and noise temperature are included. Operated on a closed-cycle helium refrigerator with a superconducting persistence-mode magnet, the four-stage amplifier is tunable from 18.3 to 26.6 GHz with 30 dB of net gain and achieves 240 MHz of 3-dB bandwidth near the center of this band. The measured noise temperature is 13 + or - 2 K referred to the room-temperature input flange. Applications are foreseen utilizing cooled parametric downconverters and upconverters with this amplifier at IF to extend the low-noise performance up to millimeter frequencies and down to L-band for radio astronomy and planetary spacecraft communications.

Moore, C. R.↗