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Technique for gauging coating thickness during prepreg processing of carbon fibers developed. Technique based on measurement of capacitance of cylindrical condenser through which bundle of prepregged fibers passed axially. Empirical results indicate capacitance linearly related to thickness of polymer coat on fibers in bundle. Capacitive transducer used successfully to measure thickness of polymer coats on several test bundles of fibers under static conditions.

Attachment to standard wire-stripping tool catches bits of insulation as they are removed from electrical wire and retains them for proper disposal. Prevents insulation particles from falling at random, contaminating electronic equipment and soiling workspace. Commercial tool modified by attaching small collection box to one of the jaws.

Resin-powder dispenser used at NASA's Langley Research Center for processing of composite-material prepregs. Dispenser evenly distributes powder (resin polymer and other matrix materials in powder form) onto wet uncured prepregs. Provides versatility in distribution of solid resin in prepreg operation. Used wherever there is requirement for even, continuous distribution of small amount of powder.

Award-winning Melt Modulation(TM) system produces single or multiple fibers of any variety of single-crystal materials in continuous or discrete lengths. Developed specifically to produce research quantities of fibers for strong, lightweight composite materials that withstand high temperatures in aerospace applications. Also used to grow such single-crystal materials as high-temperature superconductors and fiber-optic materials. Modifications enable system to apply conformal coats to fibers as they are being grown, producing fibers for greater number of composites in which coatings provide thermal and chemical compatibility between fiber and matrix materials.

Automated variable-polarity plasma arc (VPPA) welding apparatus operates under electronic supervision by welding analysis and control system. System performs all major monitoring and controlling functions. It acquires, analyzes, and displays weld-quality data in real time and adjusts process parameters accordingly. Also records pertinent data for use in post-weld analysis and documentation of quality. System includes optoelectronic sensors and data processors that provide feedback control of welding process.

ROCKFILL is software that calculates key robot weld information. Its easy-to-use menu system enables robot operator to estimate better number of passes, amount of wire, arc time, and amount of heat put into particular weld. Designed to operate on work-cell personal computer of robot and requires no documentation or training. Written in C language.

Fabrics used in curved composite-material structures prevented from skewing during composite layup by weaving them in modified process in which warp and fill yarns bonded together at their points of contact. (Bonding concept may prove similarly beneficial for braided and knitted fabrics.) In modified weaving process, adhesives prevent excessive shifting of warp and fill yarns with respect to each other.

Precise drill press equipped with rotary-indexing microscope. Microscope and drill exchange places when turret rotated. Microscope axis first aligned over future hole, then rotated out of way so drill axis assumes its precise position. New procedure takes less time to locate drilling positions and produces more accurate results. Apparatus adapted to such other machine tools as milling and measuring machines.

Method of manufacturing gears with precisely shaped teeth involves computerized inspection of gear-tooth surfaces followed by adjustments of machine-tool settings to minimize deviations between real and theoretical versions of surfaces. Thus, iterated cycles of cutting gear teeth, inspection, and adjustments help increase and/or maintain precision of subsequently manufactured gears.

Attachment for articulated borescope provides views into small, normally inaccessible spaces. Simple small round mirror on extension arm welded to borescope head. Tilted at angle to axis of borescope head, mirror provides views sideways to borescope head. Disassembly of turbopump blades not necessary to enable fluorescent-penetrant-dye inspection. Attachment used to inspect difficult-to-reach internal parts of other assemblies. Also used for inspection with ordinary white light.

Proposed fastener includes metal loops and hooks repeatedly put together and pulled apart like Velcro (or equivalent) plastic fastener. Strip of hooks stamped from sheet of metal, and tip of each hook bent at right angle to root. Many such strips arrayed in parallel to form hook half of fastener. Each hook twists and bends as loop pulled away.

Proposed metal hook-and-loop fastener engaged and disengaged many hundreds of times without breaking. Fastener opens by mechanical action. Translation moves hooks out of loops or pushes loops away from hooks. Hooks not required to flex and, therefore, do not fail by fatigue. Lifetime much greater than that of other metal hook-and-loop fasteners, depending on flexure for disengagement such as article, "Hook-and-Loop Metal Fastener" (MSC-21586).

Improved technique for consolidation of powders into dense articles developed. Peripheral bands used in consolidation, forging, and rolling operations. Facilitates consolidation of dispersion-hardened aluminous powders and composite mixtures for processing to such useful wrought articles as plates and sheets. Potential use in production of plates and sheets and perhaps other objects from "hard" powders, particularly from powders, objects made from which have propensity to crack when mechanically worked to other forms.

Two separate areas heated inductively for adhesive bonding in single operation. "E" heating head developed to satisfy need for fast-acting and reliable induction heating device. Used in attaching "high-hat" stiffeners to aircraft panels. Incorporates principles and circuitry of toroid joining gun. Width and length configured to provide variously sized heat zones, depending on bonding requirements. Lightweight, portable and provides rapid, reliable heating of dual areas in any environment. Well suited for flight-line and depot maintenance, and battlefield repair. Also useful in automotive assembly lines to strengthen automobile panels.

Windows having compound (three-dimensional) curvatures designed and fabricated for installation on research turbines and compressors to enable use of intersecting laser beams to measure flows in these machines. Design objectives include nonperturbation of flow, adequate strength, and minimal optical error.

Partly embedded fixture is simpler and sturdier than other types of outlets for optical fibers embedded in solid structures. No need to align coupling prism and lenses. Fixture includes base, tube bent at 45 degree angle, and ceramic ferrule.

New method of fabricating fin-cooled tank requires half as many arc-welding passes and features more efficient transfer of heat. Fins integral parts of tank structure. Requires only one welding pass per fin, and pass done on unobstructed inside of tank. With inside welding, fins longer and more closely spaced. Method proposed to build tank with 256 fins. Holds water in which radioisotope heat source immersed before use. Water absorbs bremsstrahlung radiation from isotope, and fins dissipate heat generated by absorption.

United States Air Force is investigating method of repairing aircraft by use of adhesive bonding with induction heating to cure adhesive. Fast-acting and reliable induction heating device that is lightweight, portable, and easy to use needed for such applications. Newly developed flexible heating head lightweight and conforms to complex, curved surfaces. Incorporates principles and circuitry of toroid joining gun described in "Toroid Joining Gun for Fittings and Couplings" (LAR-14278). Concentrates heat in local area through induction heating. Flexible heating head contains tank circuit, connected via cable to source of power.

In improved method of fabrication of precise, lightweight antenna reflectors for millimeter wavelengths, required precise contours of reflecting surfaces obtained by computer numberically controlled machining of surface layers bonded to lightweight, rigid structures. Achievable precision greater than that of older, more-expensive fabrication method involving multiple steps of low- and high-temperature molding, in which some accuracy lost at each step.

Improved technique of investment slip casting developed for making precise ceramic wind-tunnel models. Needed in wind-tunnel experiments to verify predictions of aerothermodynamical computer codes. Ceramic materials used because of their low heat conductivities and ability to survive high temperatures. Present improved slip-casting technique enables casting of highly detailed models from aqueous or nonaqueous solutions. Wet shell molds peeled off models to ensure precise and undamaged details. Used at NASA Langley Research Center to form superconducting ceramic components from nonaqueous slip solutions. Technique has many more applications when ceramic materials developed further for such high-strength/ temperature components as engine parts.

Balloon catheter similar to that used in such medical procedures as angioplasty and heart surgery protects small orifices against contamination and blockage by chips generated in machining operations. Includes small, inflatable balloon at end of thin, flexible tube. Contains additional features adapting it to anticontamination service: balloon larger to fit wider channel it must block; made of polyurethane (rather than latex), which does not fragment if bursts; material made thicker to resist abrasion better; and kink-resistant axial wire helps catheter negotiate tight bends.

Modification of powder-injection ports enables lengthy, high-temperature deposition operations. Graphite inserts prevent clogging of ports through which copper powder injected into vacuum plasma spray (VPS) gun. Graphite liners eliminate need to spend production time refurbishing VPS gun, reducing cost of production and increasing productivity. Concept also applied to other material systems used for net-shape fabrication via VPS.

Compact motor drive positions guide for welding filler wire. Drive part of automated wire feeder in partly or fully automated welding system. Drive unit contains three parallel subunits. Rotations of lead screws in three subunits coordinated to obtain desired motions in three degrees of freedom. Suitable for both variable-polarity plasma arc welding and gas/tungsten arc welding.

Robotic tube-booking subsystem proposed for use in automated manufacturing cell described in "Robotic Processing of Rocket-Engine Nozzles" (MFS-29927). Includes electric or pneumatic end effector that inspects gaps under guidance of control processor connected to robotic vision subsystem. After inspecting each gap, end effector books tubes in vicinity, then reinspects to ensure attainment of desired gap. Makes entire tube-gap area brazeable, without damage to tubes, with consistent results. In addition, robotic booking takes less time and costs less than manual booking.

Automated manufacturing cell containing computer-controlled robotic processing system developed to implement some important related steps in fabrication of rocket-engine nozzles. Performs several tedious and repetitive fabrication, measurement, adjustment, and inspection processes and subprocesses now performed manually. Offers advantages of reduced processing time, greater consistency, excellent collection of data, objective inspections, greater productivity, and simplified fixturing. Also affords flexibility: by making suitable changes in hardware and software, possible to modify process and subprocesses. Flexibility makes work cell adaptable to fabrication of heat exchangers and other items structured similarly to rocket nozzles.

Bolted structural joint satisfies competing requirements to accommodate tolerances yet fits snugly to sustain reversing shear loads. Inner and outer eccentric bushings fit in shear block. Frictional force generated by bolt tension prevents rotation of bushings after assembly.

Prototype robotic tool changer for automated welding system eliminates need for most manual tool setups and attendant problems: operates rapidly, always chooses designated tool, maneuvers tip of welding torch or other tool in correct position, and reliably connects water, gas, welding wire, high-voltage electrical signals, and ground. Also loads tools other than those for welding. Intended for use in robotic work cell producing all good parts, no rejects. In production, robot welds part, tests for flaws, and reworks as necessary before releasing it.

Proposed optical system integrated into plasma arc welding torch provides image of leading edge of weld pool and welding-arc-initiation point. Welding torch aligned better with joint. System includes coherent bundle of optical fibers and transparent cup.

Welds of better quality made, and/or heat input reduced. Improved shapes devised for abutting edges of metal pieces to be joined by plasma arc welding in keyhole mode, in which gas jet maintains molten hole ("keyhole") completely through thickness of weld joint. Edges of metal pieces to be welded together machined to provide required combination gap and shaped, thin sections. Shapes and dimensions chosen to optimize weld in various respects; e.g., to enhance penetration of keyhole or reduce heat input to produce joint of given thickness.

Inert-gas diffuser provides protective gas cover for weld bead as it cools. Follows welding torch, maintaining continuous flow of argon over newly formed joint and prevents it from oxidizing. Helps to ensure welds of consistently high quality. Devised for plasma arc keyhole welding of plates of 0.25-in. or greater thickness, also used in tungsten/inert-gas and other plasma or arc welding processes.

Conventional silicon micromachining techniques produce micrometer-sized rectangular apertures. Used to define source and detector openings for measurements of images and scattered light in visible, ultraviolet, and soft x-ray wavelength regions, and as general-purpose optical slits or slit arrays. Rectangular microscopic apertures replace circular pinholes made by puncturing foils with needles or by drilling foils with intense, highly-focused laser beams. Precise photolithography yields apertures of superior geometry.

Floating skimmer, when connected to wet/dry vacuum cleaner and placed on surface of liquid in emulsion cleaning tank, draws off floating emulsified residue. Eliminates need for tedious operation.

Continuous fiber web receives powder coat first on one side, then on other. Vibrating helical screw mechanism in powder feeder provides even flow of powder to form powder curtain that descends onto moving web. Small amount of powder that falls to side or through web recovered easily. Powder-curtain feeder part of apparatus similar to one described in "System Applies Polymer Powder to Filament Tow" (LAR-14231).

Sound-deadening bags placed on hammered workpieces. Useful in many workshop situations. Fabricated easily and inexpensively. Bags filled with particles of sand, metal shot, plastic, or glass, then sewn or molded shut. Tailored to fit special configurations of some workpieces. Devices used to deaden print rollers and to reduce vibrations in main-injector inlet manifold of rocket engine.

Forming shoe pounds edge of newly inserted plate workpiece. After many passes of shoe and advances of plate, thick land builds up at edge. Workpiece heated to enable metal to flow without strain hardening. Proposed upset-forming process replaces relatively expensive, time-consuming, and wasteful process in which integral weld lands created by machining metal away from plates everywhere except at lands.

Prototype computer-based feedback control system developed for use in gas/tungsten arc welding. Beyond improving welding technician's moment-to-moment general control of welding process, control system designed to assist technician in selecting appropriate welding-process parameters, and provide better automatic voltage control. Modular for ease of reconfiguration and upgrading. Modularity also reflected in software. Includes rack-mounted computer, based on VME bus, containing Intel 80286 and 80386 processors.

High-temperature electrostatic levitator provides independent control of levitation and heating of sample in vacuum. Does not cause electromagnetic stirring in molten sample (such stirring causes early nucleation in undercooling). Maintenance of levitating force entails control of electrostatic field and electrical charge on sample.

Captive bolt installed, removed, and reinstalled easily, even with heavily gloved hands depriving technicians of feeling of engagement of threads. Has two threads with different diameters but same pitch. Engages either housing or mating part. Useful in construction in environments where visibility, tactility, and/or maneuverability poor.

Panels bent permanently without cracking. In restraint age forming, panel wrapped onto mandrel having necessary curved contour, restrained on mandrel clamps and vacuum, and heat treated. When panel released after end of heat treatment, retains contour of mandrel except for small springback. Process repeatable: panels subsequently processed under same mechanical and thermal conditions on same contour emerge with same final contour.

Crushable washers proposed for use in protecting composite-material (matrix/fiber) panels against overloads applied by nut-and-bolt fasteners. Intended for use at drilled holes, where strengths of composite panels reduced by exposure of ends of fibers. Washer consists of metal skin filled with microcapsules of epoxy resin and hardener. Alternatively, filled with fibers collapsing under given load. Crushing action simultaneously fractures microcapsules (if used), releasing components of epoxy. These components mix and fill bolthole and fiber-reinforcement interstices. Epoxy then hardens, locking fasteners in place.

Computer programs developed for use in controlling automated welding system described in MFS-28578. Together with control computer, computer input and output devices and control sensors and actuators, provide flexible capability for planning and implementation of schemes for automated welding of specific workpieces. Developed according to macro- and task-level programming schemes, which increases productivity and consistency by reducing amount of "teaching" of system by technician. System provides for three-dimensional mathematical modeling of workpieces, work cells, robots, and positioners.

Electroform welding used to join variety of parts without addition of detrimental heat. Technique developed so large and/or complexly shaped parts joined without degrading properties of materials. Commercial uses include joining dissimilar alloys. Beneficial for suppression of distortion or maintenance of close tolerances in precise components.

Technique shows promise for fabrication of novel electronic, optoelectronic, and electro-optical devices. Experiments demonstrated feasibility of growing microscopic single-crystal CoSi2 structures beneath surfaces of Si substrates.

Report presents results of empirical evaluation of theorectical equation that predicts ultimate tensile strength of butt weld as function of some properties of welded metal and of geometry of weld.

Vacuum plasma spraying successful in depositing tenacious copper coat on flanges and other selected areas of titanium valve housing. Oxidation and concomitant brittleness eliminated.

Explosive forming, wax filling, and any one of welding, diffusion bonding, or brazing used in method of manufacturing large, complicated shell-and-liner vessels or structures. Method conceived for manufacture of film-cooled rocket nozzles but applicable to joining large coaxial shells and liners in general.

Robotic system positions brazing-foil preforms accurately and tack-welds them in place in or on large workpieces in preparation for brazing. Automates time-consuming, skill-dependent, labor-intensive brazing-foil-application procedure. Robotically attached preforms satisfies specifications better and more consistently than manually installed preforms do. Specially developed software controls system.

Simple plug devices prevent debris from entering internal passages of hardware assembly while it is being machined. Devices replace paraffin-wax seals on orifices.

Techniques for mass production of tunneling electrodes developed from silicon-micromachining, lithographic patterning, and related microfabrication processes. Tunneling electrodes named because electrons travel between them by quantum-mechanical tunneling; tunneling electrodes integral parts of tunneling transducer/sensors, which act in conjunction with feedback circuitry to stabilize tunneling currents by maintaining electrode separations of order of 10 Angstrom. Essential parts of scanning tunneling microscopes and related instruments, and used as force and position transducers in novel microscopic accelerometers and infrared detectors.

Fully automated variable-polarity plasma arc VPPA welding system developed at Marshall Space Flight Center. System eliminates defects caused by human error. Integrates many sensors with mathematical model of the weld and computer-controlled welding equipment. Sensors provide real-time information on geometry of weld bead, location of weld joint, and wire-feed entry. Mathematical model relates geometry of weld to critical parameters of welding process.