Mechanical & Fluid Systems

Piezoelectric-Actuated Cryogenic Thermodynamic Vent Valve

Piezoceramic transducer elements with ceramic dielectric coating were successfully used in the actuator system. Lyndon B. Johnson Space Center, Houston, Texas Cryogenic fluid control valves require actuation that controls the geometric position of the orifice in a thermally stable manner. Traditional actuator devices may have various materials used in their construction that have varying CTEs (coefficients of thermal expansion) and therefore may shift (expand or contract) relative to the reference mounting points on the valve body. This leads to a lack of valve orifice control and leakage in the valve. To provide a more thermally stable control valve for cryogenic fluids, Dynamic Structures and Materials LLC (DSM LLC) provided a piezoelectric ceramic-driven actuation system on a cryogenic thermodynamic vent system (TVS) valve.

Posted in: Briefs, TSP, Mechanical Components

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Amine Swingbed Payload

This system minimizes water and air loss. Lyndon B. Johnson Space Center, Houston, Texas The amine swingbed was in development for incorporation into Orion’s environmental control and life support system to remove metabolic carbon dioxide and humidity from the crew atmosphere. The compact, low-power swingbed uses space vacuum to regenerate itself. Direction was given by NASA to develop it for a payload experiment on ISS using the most recent engineering development laboratory unit. To minimize overboard humidity and crew cabin ullage losses, a method for removing humidity upstream of the amine swingbed had to be developed, along with a means to minimize overboard ullage losses when the swingbed cycled.

Posted in: Briefs, Mechanical Components

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Decelerator System Simulation (DSS)

Lyndon B. Johnson Space Center, Houston, Texas The Crew Exploration Vehicle Parachute Assembly System (CPAS) project conducts computer simulations to verify that requirements on flight performance, parachute loads, and terminal rate of descent are met. The objective of this work was to obtain a high-fidelity simulation of Orion crew capsule flight test vehicles during parachute flight.

Posted in: Briefs, TSP, Mechanical Components

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Miniature, Multi-Functional, Self-Braking Vehicle

This vehicle is actuated by piezoelectric stacks through the fuselage walls. NASA’s Jet Propulsion Laboratory, Pasadena, California A novel, miniature, low-mass vehicle has been created that is driven by piezoelectric stacks and a resonance structure. Preliminary tests on similar mechanisms that are used to transmit electrical power across the wall showed efficiencies of the order of 90%. The transmitted mechanical power, and signals through metallic walls using the direct and indirect piezoelectric effects in similar motors, is of the order of 50%. The transmitted power is generated inside the vehicle body, and the mechanism is applicable to any robotic system that may require an ambulation of locomotion mechanism such as a rover, a miniature vehicle, a crawler, or a flying device.

Posted in: Briefs, TSP, Mechanical Components

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Pulse-Echo Probe Mounting Fixture for Blind Alignment on Pipes

This technology enables an effective, real-time, in-service health monitoring system for steam pipes.The probe and its mounting fixture are critical parts of the health monitoring of steam pipes. A high-temperature, piezoelectric transducer generates and receives ultrasonic waves, and the probe has to transmit the wave normal to the pipe surface. The mounting fixture is designed to allow for alignment of the probe even without a reference reflection, and thus enables blind alignment. In order to allow aligning of the probe normal to the surface of potential water condensation, and to secure intimate contact to the pipe surface, a novel mounting fixture was conceived and developed.

Posted in: Briefs, TSP, Mechanical Components, Mechanics

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Zero-Gravity Mobile Robot Using ON/OFF Adhesive Pads and Inchworm Mechanism

The robot has applications in military reconnaissance, and as a commercial toy. NASA’s Jet Propulsion Laboratory, Pasadena, California Inspection of the International Space Station and other manmade objects in space is difficult because of the microgravity environment. Robots are a promising approach to accomplish these inspection tasks and later repairs, but must be able to maneuver across the surfaces. Because there is no gravity, the robot is at high risk of floating away, necessitating grippers that can adhere to the surface and resist the forces and torques of inspecting and moving on the structure.

Posted in: Briefs, Mechanical Components

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Passive Mechanism for Maintaining Tension at a Spool to Within a Given Window

This innovation can be used with a vehicle, crane, winch, or boat, or for rock climbing, water skiing, and parasailing.During any winding or unwinding action, a tether may experience unexpected changes in tension. For example, the load being wound could become stuck and stop moving, causing the tension in the line to suddenly become extremely high. Alternatively, the load could slip, causing a lack of tension, or slack, in the line. Both of these scenarios can be harmful to neatly winding a spool in a tightly packed pattern. Excessive tension can cause one layer of line to become lodged in a layer below it and jammed. Too low of tension can cause the line on the spool to partially unravel and cause disorganized spooling. A novel mechanism utilizes the tension in the line and springs to hold a pulley between friction pads and a ratcheting mechanism to keep the tension at the spool within a particular window.

Posted in: Briefs, TSP, Mechanical Components, Mechanics

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