Special Coverage

NASA Supercomputer Simulations Reveal 'Noisy' Aerodynamics
Robotic Gripper Cleans Up Space Debris
Soft Robot “Walks” on Any Terrain
Defense Advanced Research Projects Agency
Using Microwaves to Produce High-Quality Graphene
Transducer-Actuator Systems for On-Machine Measurements and Automatic Part Alignment
Wide-Area Surveillance Using HD LWIR Uncooled Sensors
Heavy Lift Wing in Ground (WIG) Cargo Flying Boat
Technique Provides Security for Multi-Robot Systems
Bringing New Vision to Laser Material Processing Systems
NASA Tests Lasers’ Ability to Transmit Data from Space

Laser Anemometer Measures Flow in a Centrifugal Compressor

Detailed measurements of complex flow fields within the NASA Low Speed Centrifugal Compressor (LSCC) have been acquired. The measurement data provide insight into the fundamental physics of flow in centrifugal compressors, and can be used to assess computational fluid dynamics codes and to develop flow-physics models. The resultant benefit is better predictive computational tools and shorter design cycle times.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Computational fluid dynamics, Measurements, Compressors, Test equipment and instrumentation

Magnetostrictive Inertial-Reaction Linear Motors

Linear-translation motors containing inertial-reaction masses driven by magnetostrictive actuator elements are undergoing development. These motors could be used to make fine position adjustments in diverse scientific and industrial instruments that operate at temperatures ranging from near absolute zero to room temperature; for example, they could be used to drive translation stages in scanning tunneling microscopes that operate at liquid-helium temperature (4 K), or to move cryogenic-temperature optical elements that must be located at long but precise distances from each other (as in interferometers). [These motors should not be confused with proposed magnetostrictive motors that would move in "inchworm" fashion and would be used for similar purposes, described in "Magnetostrictive Actuators for Cryogenic Applications," NASA Tech Briefs, Vol. 20, No. 3 (March 1996), page 84.]

Posted in: Briefs, Mechanical Components, Mechanics, Optics, Sensors and actuators, Optics, Sensors and actuators, Electric motors, Test equipment and instrumentation, Industrial vehicles and equipment

Pulse-tube Refrigerator Unit

Pulse-tube Refrigerators can be operated over a wide range of temperatures. These units can be used in numerous space and commercial refrigeration applications, including food refrigerator/freezers, laboratory freezers, and freeze dryers. Pulse-tube Refrigerators can also be used to cool detectors and electronic devices.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Cooling, Refrigerants

Device for High-Pressure Fused Deposition of Engineering Polymers From Feed Rods

A more versatile delivery system for fused deposition has recently been developed. This system uses a very stiff, precise, and compact actuator to drive a small piston/cylinder extruder that has a heated nozzle. Because feed rods are used as the feed material, this newly developed delivery system does not have the materials limitations of conventional delivery systems.

Posted in: Briefs, TSP, Materials, Sensors and actuators, Sensors and actuators, Extrusion, Materials properties, Nozzles, Pistons

Plasma Window Technology for Propagating Particle Beams and Radiation from Vacuum to Atmosphere

Plasma windows can separate vacuum and atmosphere, or regions of high and low vacuums, in a way which facilitates transmission of various particle beams and/or radiation from low- to high-pressure regions. In a prototype device, a stabilized plasma arc was properly configured to function as a nonsolid plasma window. Since charged particles can be focused by these arcs, focusing of such beams is a secondary function of this device.

Posted in: Briefs, Electronics & Computers, Windows and windshields, Waveguides, Waveguides, Gases

Bounceless Switch/Monostable Multivibrator

A circuit has been designed to debounce a mechanical switch, which is used to activate a digital circuit. Contacts tend to make and break connections several times until the switch contacts settle out. The repetitive activity plays havoc with digital circuits because more than one state condition could be activated by the switch as it bounces around between state conditions.

Posted in: Briefs, TSP, Electronics & Computers, Integrated circuits, Switches, Integrated circuits, Switches, Vibration, Vibration

Advanced Cryogenic Insulation System for Graphite/Organic Resin Composite Cryogenic-Tank Structures

Engineers at Rockwell International Corporation's Space System Division have developed a new method of insulating composite structural material that will stand up to the harsh environment of space. The new liquid-hydrogen cryogenic tankage proposed for advanced launch systems — such as the Reusable Launch Vehicle and the X-33 — will be made from a graphite/epoxy material. Although this composite material will produce a lighter-weight cryogenic insulation tank, current cryogenic insulation materials did not endure rigorous stress testing.

Posted in: Briefs, Materials, Containers, Composite materials, Graphite, Insulation, Resins, Lightweighting, Spacecraft

Deflection of Stretched Circular Membrane Under Pressure

Equations have been derived to describe the deflection of a circular membrane under both in-plane and transverse loads. More specifically, the equations describe the radial (in-plane) and perpendicular-to-the-plane deflections for the case of a circular membrane that has been stretched at its periphery with a uniform preload to keep it taut, then clamped rigidly at its periphery, and then subjected to differential pressure.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Mathematical models, Test procedures

Impedance-Based Cable Tester

The figure illustrates the major functional blocks of an impedance-based cable-testing apparatus that can locate an open or short circuit in a cable. There is no need to disconnect the cable from all other equipment in preparation for a test – an advantage in a system in which cable connections are located in places that are not readily accessible.

Posted in: Briefs, TSP, Electronics & Computers, Electric cables, Electric cables, Product development, Non-destructive tests, Test equipment and instrumentation

Controlled-Orientation Short-Fiber Composite Bodies

A technique for depositing materials into position using a positive-displacement extruder to build up a body has been developed. This technique also includes a process to prepare composite materials through a solid free-body forming process containing directionally aligned short-fiber reinforcement and ceramic-particulate reinforcement (of which at least a portion is derived from an alkoxide precursor).

Posted in: Briefs, TSP, Manufacturing & Prototyping, Forming, Composite materials, Fibers

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