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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

FCC in Viking articulated boom

The application requirements and manufacturing techniques for the flat conductor cable used in the Viking Lander Articulated Boom Unit are described. The Viking Boom is a 3-axis device utilized to position a soil sampler and provide digging forces. This application imposed severe restrictions on size, weight, materials, and choice of manufacturing processes. The final cable assembly design resulted in a combination of collated cable and flexible circuits assembled by resistance welding techniques.

Hawkins, E. S.↗
NASA NTRS1973

Development of a lightweight body-mounted solar cell array with a high power to weight ratio.

Three lightweight solar cell arrays have been fabricated with a high power-to-weight ratio. These arrays incorporate resistance welded interconnections, improved antireflection coating on the solar cell and lightweight substrates. Two of the substrates were constructed of magnesium with different structural geometry, while the third substrate was conventional aluminum honeycomb. All arrays utilized thin solar cells having a titanium-palladium-silver contact system and an antireflection coating of titanium oxide. The cells were welded with silver plated molybdenum interconnections. The two arrays having magnesium substrates exhibited a power/weight of 70.4 W/kg (32 W/lb.) and 81 W/kg (36.8 W/lb.), while the conventional array demonstrated a power/weight of 45.2 W/kg (20.6 W/lb.).

Somberg, H.↗
NASA NTRS1976

Flexible, FEP-Teflon covered solar cell module development

Techniques and equipment were developed for the large scale, low-cost fabrication of lightweight, roll-up and fold-up, FEP-Teflon encapsulated solar cell modules. Modules were fabricated by interconnecting solderless single-crystal silicon solar cells and heat laminating them at approximately 300 C between layers of optically clear FEP and to a loadbearing Kapton substrate sheet. Modules were fabricated from both conventional and wraparound contact solar cells. A heat seal technique was developed for mechanically interconnecting modules into an array. The electrical interconnections for both roll-up and fold-up arrays were also developed. The use of parallel-gap resistance welding, ultrasonic bonding, and thermocompression bonding processes for attaching interconnects to solar cells were investigated. Parallel-gap welding was found to be best suited for interconnecting the solderless solar cells into modules. Details of the fabrication equipment, fabrication processes, module and interconnect designs, environmental test equipment, and test results are presented.

Rauschenbach, H. S.↗
NASA NTRS1977

Low thermal flux glass-fiber tubing for cryogenic service

This paper describes analytical techniques, fabrication development, and test results for composite tubing that has many applications in aerospace and commercial cryogenic installations. Metal liner fabrication is discussed in detail with attention given to resistance-welded liners, fusion-welded liners, chem-milled tubing liners, joining tube liners and end fittings, heat treatment and leak checks. Composite overwrapping, a second method of tubing fabrication, is also discussed. Test programs and analytical correlation are considered along with composite tubing advantages such as minimum weight, thermal efficiency and safety and reliability.

Hall, C. A.↗
NASA NTRS1977

A hermetic sealing process for large irregularly shaped hybrid microcircuit enclosures

A system for sealing vacuum baked hybrids in a dry inert atmosphere using an overlapping spot resistance weld is described. A unique electrode configuration and fixturing that permits sealing of large and irregularly shaped gold plated Kovar packages to the hermeticity requirements of MIL-STD-883 was discussed. Metallurgical considerations and comparisons to laser sealing were made. Problems encountered during the development and optimization of the process were highlighted. Solutions to plating, fixturing, warpage, weld splatter and cracked bead problems are presented.

Stahler, M. R.↗
NASA NTRS1979

High temperature - low mass solar blanket

Interconnect materials and designs for use with ultrathin silicon solar cells are discussed, as well as the results of an investigation of the applicability of parallel-gap resistance welding for interconnecting these cells. Data relating contact pull strength and cell electrical degradation to variations in welding parameters such as time, voltage and pressure are presented. Methods for bonding ultrathin cells to flexible substances and for bonding thin (75 micrometers) covers to these cells are described. Also, factors influencing fabrication yield and approaches for increasing yield are discussed. The results of vacuum thermal cycling and thermal soak tests on prototype ultrathin cell test coupons and one solar module blanket are presented.

Mesch, H. G.↗
NASA NTRS1979

High temperature, low mass solar blanket development

This paper presents methods of incorporating ultrathin silicon solar cells into photovoltaic blankets for space applications. This type of cell has the highest power-to-mass ratio and best performance under space radiation of any silicon solar cell. Interconnect materials and designs, and the results of the investigation of the applicability of parallel-gap resistance welding for interconnecting ultrathin cells are discussed. Data relating contact pull strength and cell electrical degradation to welding parameters such as time, voltage, and pressure are presented. Methods for bonding ultrathin cells to flexible substrates and for bonding thin covers to these cells are described, and the results of vacuum thermal cycling and thermal soak tests on prototype ultrathin cell test coupons are included.

Mesch, H. G.↗
NASA NTRS1982

Blanket technology

It was concluded that systems requirements would force a reassessment of the conventional approach to interconnecting cells into blanket or array modules. Defense applications (hardening) were identified as the key requirement that would force a movement away from the standard method (solder) of forming array circuits. The panel also agreed that requirements associated with the impending NASA Space Station and in-bound missions would lead to alternative interconnecting approaches. It was concluded that the diverse requirements of future space missions (high temperature and extended thermal cycling) might not be met by one approach, such as parallel-gap resistance welding. The panel suggested that other options such as high temperature solders and brazing be considered for the various mission requirements that were anticipated. The panel agreed that blanket technology was potentially suitable for in-orbit annealing to temperatures of 200 C provided that conventional soldered connecting techniques were replaced by "welding".

Scott-Monck, J.↗
NASA NTRS1985

Clamp Secures Material to Cylinder Base

Two-part clamp assembled around pipe or post, ends not free. Resistance welding clamp to post and locking ring to lower part of clamp permanently fixes clamp in place, preventing thermal cycling from loosening clamp.

Tam, Y. S.↗
NASA NTRS1990

Compact Pinch Welder

Compact resistance-welding pinch gun lets one operator do jobs formerly needing two workers. Light in weight and produces repeatable, high-quality weld joints. Welding-electrode head rotates for easy positioning. Lever at top of handle activates spring to pinch electrodes together at preset welding force. Button at bottom of handle activates welding current. Cables supply electrical power.

Starck, Thomas F.↗
NASA NTRS1992

High temperature solder device for flat cables

A high temperature solder device for flat cables includes a microwelder, an anvil which acts as a heat sink and supports a flexible flat ribbon cable that is to be connected to a multiple pin connector. The microwelder is made from a modified commercially available resistance welding machine such as the Split Tip Electrode microwelder by Weltek, which consists of two separate electrode halves with a removable dielectric spacer in between. The microwelder is not used to weld the items together, but to provide a controlled compressive force on, and energy pulse to, a solder preform placed between a pin of the connector and a conductor of the flexible flat ribbon cable. When the microwelder is operated, an electric pulse will flow down one electrode, through the solder preform and back up the other electrode. This pulse of electrical energy will cause the solder preform to heat up and melt, joining the pin and conductor.

Haehner, Carl L.↗
NASA NTRS1994

Metafusion: A breakthrough in metallurgy

The Metafuse Process is a patented development in the field of thin film coatings utilizing cold fusion which results in a true inter-dispersion of dissimilar materials along a gradual transition gradient through a boundary of several hundred atomic layers. The process is performed at ambient temperatures and pressures requiring relatively little energy and creating little or no heat. The process permits a remarkable range of material combinations and joining of materials which are normally incompatible. Initial applications include titanium carbide into and onto the copper resistance welding electrodes and tungsten carbide onto the cutting edges of tool steel blades. The process is achieved through application of an RF signal of low power and is based on the theory of vacancy fusion.

Joseph, Adrian A.↗
NASA NTRS1959

Compressive Strength of Stainless-Steel Sandwiches at Elevated Temperatures

Experimental results are presented from crippling tests of stainless-steel sandwich specimens in the temperature range from 80 F to 1,200 F. The specimens included resistance-welded 17-7 PH stainless-steel sandwiches with single-corrugated cores, type 301 stainless-steel sandwiches with double-corrugated cores, and brazed 17-7 PH stainless-steel sandwiches with honeycomb cores. The experimental strengths are compared with predicted buckling and crippling strengths. The crippling strengths were predicted from the calculated maximum strength of the individual plate elements of the sandwiches and from a correlation procedure which gives the elevated-temperature crippling strength when the experimental room-temperature crippling strengths are known. Photographs of some of the tested specimens are included to show the modes of failure.

Mathauser, Eldon E.↗
NASA NTRS2007

Development of Probabilistic Structural Analysis Integrated with Manufacturing Processes

An effort has been initiated to integrate manufacturing process simulations with probabilistic structural analyses in order to capture the important impacts of manufacturing uncertainties on component stress levels and life. Two physics-based manufacturing process models (one for powdered metal forging and the other for annular deformation resistance welding) have been linked to the NESSUS structural analysis code. This paper describes the methodology developed to perform this integration including several examples. Although this effort is still underway, particularly for full integration of a probabilistic analysis, the progress to date has been encouraging and a software interface that implements the methodology has been developed. The purpose of this paper is to report this preliminary development.

Pai, Shantaram S.↗
NASA NTRS1972

Weld-brazing - a new joining process

A joining process designated weld brazing which combines resistance spot welding and brazing has been developed. Resistance spot welding is used to position and align the parts as well as to establish a suitable faying surface gap for brazing. Fabrication is then completed by capillary flow of the braze alloy into the joint. The process has been used successfully to fabricate Ti-6Al-4V titanium alloy joints using 3003 aluminum braze alloy. Test results obtained on single overlap and hat-stiffened structural specimens show that weld brazed joints are superior in tensile shear, stress rupture, fatigue, and buckling than joint fabricated by spotwelding or brazing. Another attractive feature of the process is that the brazed joints is hermetically sealed by the braze material.

Bales, T. T.↗
NASA NTRS1973

Development of the weld-braze joining process

A joining process, designated weld-brazing, was developed which combines resistance spot welding and brazing. Resistance spot welding is used to position and aline the parts, as well as to establish a suitable faying-surface gap for brazing. Fabrication is then completed at elevated temperature by capillary flow of the braze alloy into the joint. The process was used successfully to fabricate Ti-6Al-4V alloy joints by using 3003 aluminum braze alloy and should be applicable to other metal-braze systems. Test results obtained on single-overlap and hat-stiffened panel specimens show that weld-brazed joints were superior in tensile shear, stress rupture, fatigue, and buckling compared with joints fabricated by conventional means. Another attractive feature of the process is that the brazed joint is hermetically sealed by the braze material, which may eliminate many of the sealing problems encountered with riveted or spot welded structures. The relative ease of fabrication associated with the weld-brazing process may make it cost effective over conventional joining techniques.

Bales, T. T.↗
NASA NTRS1972

Development of dispersion-strengthened Ni-Cr-ThOz alloys for the space shuttle thermal protection system

Manufacturing processes were developed for TD-NiCr providing small sheet (45 x 90 cm), and larger sheet (60 x 150 cm) and foil. The alternate alloy, DS-NiCr, was produced by pack-chromizing Ni-ThO2 sheet. Formability criteria are being established for basic sheet forming processes, which are brake forming, corrugation forming, joggling, dimpling, and beading. Resistance spot welding (fusion and solid state), resistance seam welding, solid state diffusion welding, and brazing are included in the joining programs. Major emphasis is centered on an Al-modified Ni-Cr-ThO2 alloy development. These alloys, containing 3 to 5% Al, form the protective Al2O3 scale. This enhances oxidation resistance under reentry conditions. Both TD-NiCrAl and DS-NiCrAl alloys are included. A tentative composition of Ni-16Cr-3.5Al-2ThO2 was selected based on oxidation resistance and fabricability.

Blankenship, C. P.↗