Mechanical & Fluid Systems

Aluminum Gas Tungsten Arc Orbital Tube Welding

Orbital tube butt welding could be performed on aluminum tubes. NASA’s Jet Propulsion Laboratory, Pasadena, California JPL has been hand-welding aluminum tubing for decades in support of flight programs and ground support equipment, including thermal plates and shrouds. This hand-welding process is time-consuming, cumbersome, difficult, and unreliable in terms of repeatability and success, which leads to leaks, rework, and cost increase. Socket-style meltdown welds are difficult to inspect via traditional nondestructive evaluation (NDE) methods (radiography) since by design, there is always an inherent highstress point in the joint.

Posted in: Briefs, TSP, Mechanical Components, Welding, Aluminum


Use of Eccentric Bushings to Precision-Locate Multiple Parts on a Large Mating Structure

Lyndon B. Johnson Space Center, Houston, Texas Cups/cones are being used to provide a shear load transfer capability on a large separation interface that uses multiple discreet retention and release (R&R) devices (such as frangible nuts, separation nuts, separation bolts, etc.). To both provide good shear load-sharing among all R&Rs and to prevent relative motion between the mating structures, the cups/cones must be designed with minimal (and sometimes zero) radial clearance. This tight fit requires that the cup and the cone on the mating structures are precisely located to each other.

Posted in: Briefs, Mechanical Components, Fastening, Parts


Effective Packing of Large Panels via Scrolling and Origami Folding

The packing mechanism employs an origami configuration that may have sport and military applications. NASA’s Jet Propulsion Laboratory, Pasadena, California There is a need for large mirrors that can be launched to various bodies in the solar system in a packed form and unfolded to provide the required dimensions. The solution to the need for foldable panels that can be made as mirrors or other structures including antennas, etc. has been conceived using an origami configuration that is folded in two dimensions. The foldable panel configuration, if made as a mirror, allows supporting rover operation in craters and caves that are shadowed and inaccessible to direct sunlight. The benefits of its use include providing light to the solar cells of the rover, providing a heating source using sunlight, and illuminating the area of operation where the rover is located.

Posted in: Briefs, TSP, Mechanical Components, Antennas, Solar energy, Spacecraft


Six-Degree-of-Freedom Control With Only Eight Thrusters

Even as few as eight thrusters can provide six-degree-of-freedom control of a spacecraft and do so without undesired coupling between torque and translational force generation functions. NASA’s Jet Propulsion Laboratory, Pasadena, California Typical spacecraft thruster configurations are often unable to provide full six-degree-of-freedom control and may have unwanted interaction between their attitude control and trajectory control functions, have undesirably high instantaneous electrical power demands, and use more thrusters than desirable. These last two potential problems gain increased significance if a spacecraft is required to have especially small size and mass, and have very low cost.

Posted in: Briefs, TSP, Mechanical Components, Attitude control, Spacecraft


Precise Direct Control of Pressure or Vacuum Using a Digitally Controlled Actuator

A closed/semi-open pressure or vacuum system uses an electric screw mechanical actuator that can be digitally controlled and monitored, and which receives feedback directly from an external or internal source. This innovation can adjust for media temperature changes, expansion, and contraction in a constant volume and pressure system. This is done by extending or retracting a leak-free, high-pressure, or vacuum-sealed piston that is controlling pressure or vacuum.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Sensors and actuators, Pistons


Irreversible Entropy Production Rate in High-Pressure Turbulent Reactive Flows

NASA’s Jet Propulsion Laboratory, Pasadena, California To model high-pressure reactive flows, the most promising methodology is large eddy simulation (LES) in which one solves the large scales of the problem and models the small scales. There is currently no guidance as to the relative importance of small scales originating from different phenomena.

Posted in: Briefs, Mechanical Components, Simulation and modeling


Piezoelectric Actuator for a 2-inch Isolation Cryogenic Valve

Lyndon B. Johnson Space Center, Houston, Texas This project is focused on the development of a high-force, high-speed piezoelectric actuator for control of a 2-inch (≈5-cm) isolation valve application in a cryogenic vacuum environment. The piezo motor actuators on the two cryogenic isolation valves were successfully tested at NASA MSFC at 300 to 400 psi (≈2.07 to 2.76 MPa) flow pressure. The testing did not expose the piezo elements to temperatures below 0 °C. Iceramic piezo material has not failed under cryogenic testing to the date of this reporting.

Posted in: Briefs, TSP, Mechanical Components, Sensors and actuators, Ceramics, Parts


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