Mechanical & Fluid Systems

PVP-MP Method for Wrinkling Analysis of Space Membrane Structures

Distributions of stress can be predicted for taut, slack, and wrinkled areas. Parameter-Variation-Principle (PVP) based Mathematical Programming (MP) is the basis of a computational method of analyzing wrinkles in membranes. Devised for original application to lightweight membrane structures in outer space, the method can also be applied on Earth to similar structures, to diverse industrial products that include paper and textiles, and to structures made from these products.

Posted in: Mechanics, Briefs, TSP

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Vacuum Pumping Station

A proposed valve unit called a "vacuum pumping station" would be incorporated into a plumbing system that supplies a vacuum for vacuum insulated cryogenic equipment. The vacuum pumping station is intended to perform functions now performed by, and to be a simpler and more reliable alternative to, an assembly of components that include a vacuum-pump-out valve and a separate vacuum-isolation valve (with a separate actuator) used to monitor vacuum levels. The present assembly includes a leak-prone threaded connection between the pump-out and isolation valve, and leaks can also occur at other locations. The vacuum pumping station would include a vacuum-pump-out port, a thermocouple port, a thermocouple-isolation valve, a pressure-relief valve, a pressure-relief port, and a single mechanism for actuating the pump-out, isolation, and pressure-relief functions of the valve. The number of joints where leaks could develop would be only half that of the present assembly.

Posted in: Mechanics, Briefs

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Gas Generator for Inflating Structures in Outer Space

A report proposes a system that would supply gas for inflating one or more inflatable structure(s) in outer space. The system would include a small tank of helium for initial inflation, plus a catalytic hydrazine gas generator that would supply makeup gas over the long term. After initial inflation, when makeup gas was needed, liquid hydrazine from a tank would be made to pass through a catalytic bed, where it would become decomposed into a mixture of N2, H2, and a small amount of NH3. This gaseous mixture would constitute the makeup gas and would be stored in the tank that previously contained the helium. The makeup gas would be released from the tank to the structure(s) as needed. In comparison with an inflation system based only on compressed gas stored in tanks, the proposed inflation system would offer the advantage of lower mass: About 25 percent of the masses of representative previously contemplated large inflatable outer-space structures would have been contained in their inflation systems. In contrast, the mass of the proposed inflation system has been estimated to be only about 13 percent of the total mass of a representative structure.

Posted in: Machinery & Automation, Mechanics, Briefs, TSP

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Martian Landing Balls

A report describes Martian landing balls, which are under development for use in delivering scientific payloads to Mars. Martian landing balls are related to other soft-landing devices that resemble beach balls and that have been described in several previous NASA Tech Briefs articles. They are also related to the Zorb (or equivalent) — a commercial recreational device that looks like a large, transparent beach-ball/tire hybrid with a central volume that is open to the atmosphere and that accommodates a human rider. In a Mar-tian landing ball, the central volume contains a rigid cylinder that carries the payload. The cylinder is surrounded (except for small openings) by an approximately spherical airbag. In the intended use, Martian landing balls would be dropped from slowly descending solar-heated balloons. It has been estimated that a Martian landing ball with a mass of 2 kg could deliver a 10-kg payload with a landing acceleration of less than 50× normal Earth gravitation (less than about 490 m/s2). Once on the Martian surface, the airbag could be deflated; alternatively, the airbag could be kept inflated to take advantage of the wind to blow the payload to a desired location.

Posted in: Mechanics, Briefs, TSP

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Lightweight, Collapsible Hyperbaric Chamber With Airlock

Hyperbaric treatment could be provided in settings remote from major medical facilities. A lightweight, collapsible hyperbaric chamber/airlock system has been proposed as a portable unit for treating decompression sickness. Copies of the system could be stowed compactly and deployed when needed in settings in which decompression sickness is expected to occur occasionally but in which conventional heavy, rigid hyperbaric chambers are not available. Such settings include aviation, submarine operations, diving, and spaceflight.

Posted in: Mechanics, Briefs, TSP

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Reconfigurable Exploratory Robotic Vehicles

Instrumentation and mobility units could be concatenated as needed. A family of rugged, modular, reconfigurable, instrumented robotic vehicles has been proposed for use in exploration of the surfaces of Mars and other remote planets. These or similar vehicles could also be useful in such diverse terrestrial applications as exploration of volcanic craters or other hostile terrain, military reconnaissance, inspection of hazardous sites, or searching for victims of earthquakes, landslides, or avalanches. There might even be a market for simplified versions of these vehicles as toys.

Posted in: Machinery & Automation, Mechanics, Briefs, TSP

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Pressure Sensor Based on Measurement of Vibration Damping

Attributes include high resolution, wide dynamic range, compactness, and low power. A compact, low-power device measures pressure via the pressure-induced damping of oscillation of a small mechanical resonator. To achieve compactness and low mass — and thus low-power consumption — the resonator is micromachined out of silicon. In addition to the resonator, the device includes an electronic circuit that drives the oscillation and effectively measures the resonance quality factor (Q), which is inversely proportional to the rate of damping.

Posted in: Mechanics, Briefs, TSP

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