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Plastic films lubricate workpiece so it deforms smoothly. Thin layers of plastic below top die and above bottom die ensure wire screen slides as shaped by hydroforming. Plastic layers are 0.0043 in. (0.11 m) thick. Preformed to contours of dies and final workpiece. New method of hydroforming fine-wire-mesh heat-shield screens eliminates wrinkles and marks. Prevents screen from being damaged and pores from becoming blocked.
This work is an illustrated handbook containing the rationale and procedure for the evaluation of multilayer printed wiring board construction integrity with respect to plated-through holes in accordance with the requirements of MIL-P-55110D, Printed Wiring Boards. It is intended as a practical aid for those concerned with determining the construction integrity of multilayer boards for high reliability applications. Photomicrographs of cross sectioned holes illustrate defect types, acceptable and unacceptable conditions, and methods of measurement. A procedure for specimen preparation is given, and appropriate paragraphs of the military specification are included and explained.
The NASA requirements for assuring reliable rigid printed wiring board design are prescribed. Basic considerations necessary to assure reliable rigid printed wiring board design are described and incorporated.
Buried Wire Gages operated from a Constant Temperature Anemometer System are among the special types of instrumentation to be used in the Boundary Layer Apparatus for Subsonic and Transonic flow Affected by Noise Environment (BLASTANE). These Gages are of a new type and need to be adapted for specific applications. Methods were developed to fabricate Gage inserts and mount those in the BLASTANE Instrumentation Plugs. A large number of Gages were prepared and operated from a Constant Temperature Anemometer System to derive some of the calibration constants for application to fluid-flow wall shear-stress measurements. The final stage of the calibration was defined, but could not be accomplished because of non-availability of a suitable flow simulating apparatus. This report provides a description of the Buried Wire Gage technique, an explanation of the method evolved for making proper Gages and the calibration constants, namely Temperature Coefficient of Resistance and Conduction Loss Factor.
Limitations on the spatial resolution of multisensor hot wire probes have precluded accurate measurements of Reynolds stresses very near solid surfaces in wind tunnels and in many practical aerodynamic flows. The fabrication, calibration and qualification testing of very small single horizontal and X-array hot-wire probes which are intended to be used near solid boundaries in turbulent flows where length scales are particularly small, is described. Details of the sensor fabrication procedure are reported, along with information needed to successfully operate the probes. As compared with conventional probes, manufacture of the subminiature probes is more complex, requiring special equipment and careful handling. The subminiature probes tested were more fragile and shorter lived than conventional probes; they obeyed the same calibration laws but with slightly larger experimental uncertainty. In spite of these disadvantages, measurements of mean statistical quantities and spectra demonstrate the ability of the subminiature sensors to provide the measurements in the near wall region of turbulent boundary layers that are more accurate than conventional sized probes.
Zocchi et al. (1987) discovered that when two wires are symmetrically placed along the center of a Hele-Shaw cell, symmetric but narrow fingers of dimensionless width lambda less than 0.5 develop. The value of lambda decreases as the pushing velocity increases, but at a certain critical finger width the finger suddenly undergoes a transition to the asymmetrical state. A simple theory to predict this critical finger width as a function of D, the dimensionless distance between two wires is developed by assuming that the finger opens up a negative angle at the contact point.
Sensitivity of electronic moisture sensor to low levels of moisture increased by new electrode configuration. Moisture-sensing circuit described in "Low-Cost Humidity Sensor" (NPO-16544). New twisted pair of wires takes place of flat-plate capacitor in circuit. Configuration allows for thermal expansion and contraction of polymer while maintaining nearly constant area of contact between polymer and wires.
Using three different current injection methods and a simple voltage probe, transfer impedances for Solid Rocket Motor (SRM) joints, wire meshes, aluminum foil, Thorstrand and a graphite composite motor case were measured. In all cases, the surface current distribution for the particular current injection device was calculated analytically or by finite difference methods. The results of these calculations were used to generate a geometric factor which was the ratio of total injected current to surface current density. The results were validated in several ways. For wire mesh measurements, results showed good agreement with calculated results for a 14 by 18 Al screen. SRM joint impedances were independently verified. The filiment wound case measurement results were validated only to the extent that their curve shape agrees with the expected form of transfer impedance for a homogeneous slab excited by a plane wave source.
The principal activity under the HOST effort to improve the state of the art in high temperature static strain measurement has been a contract under which a palladium-chromium (PdCr) alloy was developed. The contract effort is continuing with the goal of developing a thin film high temperature static strain gage system. In addition to this effort, researchers contracted with Battelle-Columbus Laboratories to draw the PdCr allow into wire while researchers at Lewis worked to gain experience with this alloy as a wire strain gage.
The tensile behavior of a 200-micrometer-diameter tungsten lamp (218CS-W), tungsten + 1.0 atomic percent (a/o) thoria (ST300-W), and tungsten + 0.4 a/o hafnium carbide (WHfC) wires was determined over the temperature range 1300 t0 1600 K at strain rates of 3.3 X 10 to the -2 to 3.3 X 10 to the -5/sec. Although most tests were conducted on as-drawn materials, one series of tests was undertaken on ST300-W wires in four different conditions: as-drawn and vacuum-annealed at 1535 K for 1 hr, with and without electroplating. Whereas heat treatment had no effect on tensile properties, electropolishing significantly increased both the proportional limit and ductility, but not the ultimate tensile strength. Comparison of the behavior of the three alloys indicates that the HfC-dispersed material possesses superior tensile properties. Theoretical calculations indicate that the strength/ductility advantage of WHfC is due to the resistance to recrystallization imparted by the dispersoid.
Vibration dampers constructed with multiple loops of wire rope are studied. The literature on such devices is reviewed briefly, and dynamic and static models of them are examined. Fundamental and advanced NASTRAN models for wire rope damping are considered.
The present analysis method for hot-wire data in supersonic turbulence takes sound field effects into account and yields greater accuracy in its treatment of flow variable fluctuations than existing methods despite requiring only a moderately accurate estimate of static pressure fluctuations. The method demonstrates the way in which neglecting pressure fluctuations will affect hot-wire data analysis, as well as indicating the probable direction the errors will take.
Small cup enables more than one wire to be soldered to plated through hole in printed-circuit board. Made of brass plated with silver. Inserted in eyelets or plated through holes and swaged onto boards. Used on breadboard circuits and on newly-manufactured circuit boards. Useful in modification of circuit boards, where they serve as convenient attachment points for jumper wires and leads of added components.
Power-by-wire (PBW) is a key element under subsonic transport flight systems technology with potential savings of over 10 percent in gross take-off-weight and in fuel consumption compared to today's transport aircraft. The PBW technology substitutes electrical actuation in place of centralized hydraulics, uses internal starter-motor/generators and eliminates the need for variable engine bleed air to supply cabin comfort. The application of advanced fiber optics to the electrical power system controls, to built-in-test (BITE) equipment, and to fly-by-light (FBL) flight controls provides additional benefits in lightning and high energy radio frequency (HERF) immunity over existing mechanical or even fly-by-wire controls. The program plan is reviewed and a snapshot is given of the key technologies and their benefits to all future aircraft, both civil and military.
Parallel gap resistance welding was used to attach lead wires to sputtered thin film sensors. Ranges of optimum welding parameters to produce an acceptable weld were determined. The thin film sensors were Pt13Rh/Pt thermocouples; they were mounted on substrates of MCrAlY-coated superalloys, aluminum oxide, silicon carbide and silicon nitride. The entire sensor system is designed to be used on aircraft engine parts. These sensor systems, including the thin-film-to-lead-wire connectors, were tested to 1000 C.
For technological applications of high T(sub c) superconductors, it will be necessary to overcome the inherent problem of brittleness, to develop materials with high current carrying capacity, and to devise ways of joining superconductors with other materials. These issues will be addressed in the context of superconducting films on metallic wires. These composite systems are expected to produce flexible wires with desirable properties.
Presented in this paper are the main results of the 1987 Rocket Triggered Lightning Program (RTLP) in Florida: I greater than 60 kA, DI/DT greater than 400 kA/micro-S. Optical and electrical observations from flashes triggered by grounded wire or insulating cable (200 m) rocket technique are presented. Correlation between I and DI/DT measurements are presented and discussed. These measurements were carried out with the same grounded wire rocket technique in Florida in 1985, 1987, and in France in 1986.
Hard vacuum-deposited film improves nozzle properties. Tip and bore surfaces of proposed nozzle for feeding wire for gas/tungsten arc welding coated with film of synthetic diamond. Film gives nozzle following advantages: lower friction, thermal conductivity, less wear, electrical isolation of wire from nozzle, and high resistance to corrosion.