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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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The application of procedures for designing and evaluating structural integrity of various construction techniques is discussed. The fatigue performance improvement of the following conditions is described: (1) conical fasteners, (2) hole preparation, (3) interference fit, and (4) interference protection. The application of fatigue tests to determine fail-safe conditions is analyzed.
A conceptual design was developed for an MLI system which will meet the design constraints of an ILRV used for 7- to 30-day missions. The ten tasks are briefly described: (1) material survey and procurement, material property tests, and selection of composites to be considered; (2) definition of environmental parameters and tooling requirements, and thermal and structural design verification test definition; (3) definition of tanks and associated hardware to be used, and definition of MLI concepts to be considered; (4) thermal analyses, including purge, evacuation, and reentry repressurization analyses; (5) structural analyses (6) thermal degradation tests of composite and structural tests of fastener; (7) selection of MLI materials and system; (8) definition of a conceptual MLI system design; (9) evaluation of nondestructive inspection techniques and definition of procedures for repair of damaged areas; and (10) preparation of preliminary specifications.
Labor costs and techniques associated with the refurbishment of representative TPS and their attach concepts suitable for space shuttle application have been identified on the basis of experimental tests. Ablative and reusable surface insulation TPS configurations were designed, fabricated, and tested on a full-scale mockup. The TPS attachment methods investigated included pi-strap, multiple mechanical fasteners, key/keyway, and direct bond concepts. Techniques for performing installation, inspection, repair and replacement of TPS components were studied by examining a variety of shop procedures. Major problem areas associated with these procedures and the designs to which they were applied were analyzed for several significant parameters such as handling, gaskets between joints, repair techniques, ablator plugs, etc. Results of time and motion studies of specific maintenance tasks, simulating operational procedures, were obtained. Using these data, refurbishment labor cost projections were generated for a representative Space Shuttle orbiter.
A prototype all carbon triode ultrahigh vacuum gage was fabricated and tested. The gage exhibited a sensitivity of 3.7 per torr for nitrogen and an X-ray background approximately 0.1 as large as would be expected of a metal gage of the same design. The gage made from these materials, showed good sensitivity and durability. A practical technique was developed for bonding carbon components together without metal fasteners. The bond is made with a cross-linked phenolic resin which is converted to vitreous carbon by a careful pyrolysis procedure. The resulting bonds are strong, electrically conductive, and can withstand repeated excursions to 2500 K in vacuum. Measurements of adsorption and outgassing characteristics of four refractory carbons have confirmed that such materials are suitable for use in ultrahigh vacuum and that some are superior refractory metals in man respects.
Analysis, design, fabrication, and test activities were conducted to develop additional technology needed for application of filament-wound fiberglass struts to cryogenic flight tankage. It was conclusively verified that monocoque cylinder or ogive struts are optimum or near-optimum for the range of lengths and loads studied, that a higher strength-to-weight ratio can be achieved for fiberglass struts than for any metallic struts, and that integrally-wrapped metallic end fittings can be used to achieve axial load transfer without reliance on bond strength or mechanical fasteners.
An advanced composite shear web design concept has been developed for the Space Shuttle Orbiter main engine thrust beam structure. Various web concepts were synthesized by a computer-aided adaptive random search procedure. A practical concept is identified having a titanium-clad, boron/epoxy plate with vertical boron/epoxy reinforced stiffeners. Baseline composite and titanium shear resistant designs are compared; the composite concept is 28% lighter than the titanium web. Element test results show the metal cladding effectively reinforces critical composite load transfer and fastener hole areas making the composite web concept practical for other shear structure applications.-
An improved manufacturing process has been developed for TD-NiCr that provides sheet of improved quality, better gage control, and reproducible properties. A standard manufacturing process has been developed for the alternate alloy, DS-NiCr, produced by pack-chromizing Ni-2ThO2 sheet. Extension of forming and joining technology for TD-NiCr is in process. Formability criteria are being established for basic sheet forming processes related to the manufacture of Shuttle TPS panels. They include brake forming, corrugation forming, joggling, dimpling, and beading. Joining processes applicable to TPS panels are being optimized with emphasis on establishment of joint efficiencies. Resistance spot welding (fusion and solid state), resistance seam welding, solid-state diffusion welding, and brazing are included in the joining programs. Development of improved manufacturing technology for TD-NiCr fasteners is also being accomplished. Mechanical and physical properties of TD-NiCr are being characterized to provide design-allowable data.
Device consists of helical heating coil inside cylinder and affixed at one end. Piston is fastened at other end and is free to move axially through cylinder. Electrical power extends coil when applied to conductors. Bimetallic stirrer may also be made in vane form.
Axial tension and compression are transmitted between end fittings and fiberglass tube without depending on glass-to-metal bonding, conventional fasteners or combination of these things. Joint design significantly reduces both structural weight of strut and its cross-sectional area.
Ends of metal tube are fastened to axles which are supported on bearings so tube can rotate about its long axis while subjected to invariant bending moment that stresses it along longitudinal axis of rotation. Heat absorbed leads to expansion of metal, which unbalances internal forces and generates rotational moment in tube.
An advanced composite shear web design concept was developed for the Space Shuttle orbiter main engine thrust beam structure. Various web concepts were synthesized by a computer-aided adaptive random search procedure. A practical concept is identified having a titanium-clad + or - 45 deg boron/epoxy web plate with vertical boron/epoxy reinforced aluminum stiffeners. The boron-epoxy laminate contributes to the strength and stiffness efficiency of the basic web section. The titanium-cladding functions to protect the polymeric laminate parts from damaging environments and is chem-milled to provide reinforcement in selected areas. Detailed design drawings are presented for both boron/epoxy reinforced and all-metal shear webs. The weight saving offered is 24% relative to all-metal construction at an attractive cost per pound of weight saved, based on the detailed designs. Small scale element tests substantiate the boron/epoxy reinforced design details in critical areas. The results show that the titanium-cladding reliably reinforces the web laminate in critical edge load transfer and stiffener fastener hole areas.
The development of a unique closed-pore ceramic foam insulation (CPI) produced from low cost fly ash cenospheres is reported for space shuttle external thermal protection. Two basic design approaches were developed: bonded and mechanically fastened. A description of the concepts is presented in addition to fabrication and test results.
This paper gives some examples of projects underway. The projects are grouped according to the primary parameter being studied: loads, configuration, environment, or material. Significant topics include the effect of truncated loads, the effect of proof-tests, interference fasteners, accelerated and real-time tests for supersonic aircraft materials, crack-growth rates in built-up structures, and a model method by which material can be selected for a particular set of operating conditions.
Modular line block comprises matched modular elements machined to accept fluid lines of different diameters. Modules can support different fluid-line configurations. Top and bottom surfaces are machined to accept dovetail strip used for holding modules together. End modules have holes drilled through to accept fastening screws.
Auger-shaped single-point fastener attaches rigid surface insulation tiles to orbiter shuttle spacecraft. Method can be used to bond wide variety of materials, including insulation, elastomers, and fibrous materials. Since insulation is attached at only one point, insulation and structure are free to form without inducing bond separation.
For compacting concretes in building, vibrating beams are used. The vibrations are generated by inertial vibrators, and the beam is normally displaced by the operator by means of a handle that is elastically fastened to the beam by means of rubber pads. Considered are vibrations transmitted to the operator, taking into account the beam's shock vibration motions. The steady state motion of a dynamic beam pattern is studied, and results of experimental tests with existing equipment are presented.
Research was begun into the dynamic characteristics of wires, including the self-damping properties. A series of wire insulator fastenings, with and without dampers, was also developed.
Electromechanical vibration inducers with high reliability and low noise level were created to study premature operating losses in their support bearings. An investigation was also made of the feasibility of developing stable synchronous operation of two vibrational inducers, rigidily fastened to a solid body with and without flexible suspension.