Mechanical Components

Ball Bearings Equipped for In Situ Lubrication on Demand

Operational lifetimes can be prolonged. In situ systems that provide fresh lubricants to ball/race contacts on demand have been developed to prolong the operational lives of ball bearings. These systems were originally intended to be incorporated into ball bearings in mechanisms that are required to operate in outer space for years, in conditions in which lubricants tend to deteriorate and/or evaporate. These systems may also be useful for similarly prolonging bearing lifetimes on Earth.

Posted in: Mechanical Components, Briefs

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Formation Flying of Tethered and Nontethered Spacecraft

A paper discusses the effect of the dynamic interaction taking place within a formation composed of a rigid and a deformable vehicle, and presents the concept of two or more tethered spacecraft flying in formation with one or more separated freeflying spacecraft.

Posted in: Mechanical Components, Briefs, TSP

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Fast Laser Shutters With Low Vibratory Disturbances

Opposing cantilevered piezoelectric bending actuators balance each other to minimize vibration. The figure shows a prototype vacuum-compatible, fast-acting, long-life shutter unit that generates very little vibratory disturbance during switching. This is one of a number of shutters designed to satisfy requirements specific to an experiment, to be performed aboard a spacecraft in flight, in which laser beams must be blocked rapidly and completely, without generating a vibratory disturbance large enough to adversely affect the power and frequency stability of the lasers. Commercial off-the-shelf laboratory shutter units — typically containing electromagnetcoil-driven mechanisms — were found not to satisfy the requirements because they are not vacuum-compatible, their actuators engage in uncompensated motions that generate significant vibrations, and their operational lifetimes are too short. Going beyond the initial outerspace application, the present vacuum compatible, fast-acting, long-life shutter units could also be used in terrestrial settings in which there are requirements for their special characteristics.

Posted in: Mechanical Components, Briefs, TSP

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Split-Resonator, Integrated-Post Vibratory Microgyroscope

This design is better suited to mass production. An improved design for a capacitive sensing, rocking-mode vibratory microgyroscope is more amenable to mass production, relative to a prior design. Both the improved design and the prior design call for a central post that is part of a resonator that partly resembles a cloverleaf or a flower. The prior design is such that the post has to be fabricated as a separate piece, then bonded to the rest of the resonator in the correct position and orientation. The improved design provides for fabrication of the post as an integral part of the resonator and, in so doing, makes it possible to produce a waferful of microgyroscopes, without need to fabricate, position, and attach posts.

Posted in: Mechanical Components, Briefs, TSP

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Blended Buffet-Load-Alleviation System for Fighter Airplane

Reductions in buffet loads translate to longer fatigue lives. The capability of modern fighter airplanes to sustain flight at high angles of attack and/or moderate angles of sideslip often results in immersion of part of such an airplane in unsteady, separated, vortical flow emanating from its forebody or wings. The flows from these surfaces become turbulent and separated during flight under these conditions. These flows contain significant levels of energy over a frequency band coincident with that of low-order structural vibration modes of wings, fins, and control surfaces. The unsteady pressures applied to these lifting surfaces as a result of the turbulent flows are commonly denoted buffet loads, and the resulting vibrations of the affected structures are known as buffeting. Prolonged exposure to buffet loads has resulted in fatigue of structures on several airplanes. Damage to airplanes caused by buffeting has led to redesigns of airplane structures and increased support costs for the United States Air Force and Navy as well as the armed forces of other countries. Time spent inspecting, repairing, and replacing structures adversely affects availability of aircraft for missions.

Posted in: Mechanical Components, Briefs

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Vortobots

Vortex-generating microscopic robots would move in swarms. The term “vortobots” denotes proposed swimming robots that would have dimensions as small as micrometers or even nanometers and that would move in swarms through fluids by generating and exploiting vortices in a cooperative manner. Vortobots were conceived as means of exploring confined or otherwise inaccessible fluid environments: they are expected to be especially attractive for biomedical uses like examining the interiors of blood vessels.

Posted in: Mechanical Components, Briefs, TSP

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Ultrasonic/Sonic Jackhammer

Advantages include low noise, low vibration, and low average power demand. An ultrasonic/sonic jackhammer (USJ) is the latest in a series of related devices, the first of which were reported in “Ultrasonic/Sonic Drill/Corers With Integrated Sensors” (NPO-20856), NASA Tech Briefs, Vol. 25, No. 1 (January 2003), page 38. Each of these devices cuts into a brittle material by means of hammering and chiseling actions of a tool bit excited with a combination of ultrasonic and sonic vibrations. A small-scale prototype of the USJ has been demonstrated. A fully developed, full-scale version of the USJ would be used for cutting through concrete, rocks, hard asphalt, and other materials to which conventional pneumatic jackhammers are applied, but the USJ would offer several advantages over conventional pneumatic jackhammers, as discussed below.

Posted in: Mechanical Components, Briefs, TSP

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