Mechanical & Fluid Systems

Locking Mechanism for a Flexible Composite Hinge

This compact, self-deploying and locking boom has application in deployable booms, commercial satellites, and robotic vehicles that require high-data-rate communications.Composites have excellent strength characteristics, are lightweight, and are increasingly being used in space applications. However, they are highly inflexible and require hinged joints when used as deployable structures. This is a challenge for CubeSats/SmallSats, as the hinges and actuation mechanisms get very small and require multiple custom precision parts. A method of impregnating carbon fibers with a silicone matrix has been developed, which makes the composite flexible. This also makes it self-deploying, as the strain energy in the fibers will cause it to straighten. Unfortunately, a purely flexible beam does not have the required rigidity to maintain dimensions accuracy, as it can sag.

Posted in: Briefs, Mechanical Components, Mechanics, Composite materials, Lightweight materials, Materials properties, Parts, Satellites

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Temperature-Compensating PMT Housing

Shrinking or contracting light guides is a problem when photomultiplier tubes (PMTs) are glued to the guides. If there is no way to allow movement of the PMTs, when the temperature goes down, the light guide contracts and breaks the glue joint. The PMTs cannot be left loose to rattle around inside the detector. They must be held precisely, yet gently, and allowed to move.

Posted in: Briefs, Fluid Handling, Mechanical Components, Mechanics, Optics, Thermodynamics, Adhesives and sealants

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Jet Engine Exhaust Nozzle Flow Effector

Shape memory alloy provides variable shape control of aircraft structure through actively deformable surfaces.NASA’s Langley Research Center has created novel flow effector technology for separation control and enhanced mixing. The technology allows for variable shape control of aircraft structure through actively deformable surfaces. The flow effectors are made by embedding shape memory alloy actuator material in a composite structure. When thermally actuated, the flow effector deflects into or out of the flow in a prescribed manner to enhance mixing or induce separation for a variety of applications, including aeroacoustic noise reduction, drag reduction, and flight control. NASA developed the active flow effectors for noise reduction as an alternative to fixed-configuration effectors, such as static chevrons, that cannot be optimized for airframe installation effects or variable operating conditions, and cannot be retracted for off-design or failsafe conditions.

Posted in: Briefs, Aerospace, Aviation, Mechanics, Alloys, Smart materials, Nozzles, Exhaust pipes, Jet engines

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A Structural Joint with Multi-Axis Load Carrying Capacity

The technology can be used in aerospace and automotive applications, outdoor structures, and sporting goods.NASA’s Langley Research Center has developed a composite joint connector that is more structurally efficient than joints currently on the market. Traditionally, composite joints can bear heavy loads along their length but tend to fail when stress is applied along multiple axes. This joint is designed to minimize stress concentrations, leading to overall increased structural efficiency when compared to traditional joints.

Posted in: Briefs, Joining & Assembly, Mechanics, Composite materials, Parts, Connecting rods

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Eddy-Current-Minimizing Flow Plug for Use in Flow Conditioning and Flow Metering

Innovators at NASA’s Marshall Space Flight Center have developed a suite of prototype fluid plug technologies with an array of capabilities for fluid flow metering, mixing, and conditioning. Each innovation within this suite is based upon a core technology that has no moving parts, is simple to manufacture, and provides high reliability and efficiency. Also, the base fluid plug technology can be modified with very few or no hardware changes to achieve the desired effect or combination of mixing, metering, and conditioning capabilities depending on the application.

Posted in: Briefs, Mechanical Components, Mechanics, Computational fluid dynamics, Customization, Product development, Fittings, Valves, Reliability

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Process for Forming a High-Temperature Single Crystal Preloader

Non-contacting, acoustic pressure seals and preloader superalloys prevent fluid leakage.Friction has long been a thorny problem for sealing-device designers. Traditional sealing devices rely on a contacting relationship between surfaces and sealing elements to prevent fluid leakage, but in the case of moving elements, this contact produces friction that causes wearing and eventual failure of the sealing system. Friction also consumes energy and produces harmful debris. In a new breakthrough, however, researchers at NASA’s Glenn Research Center have patented an acoustic seal that generates a pressure barrier to prevent fluid leakage from a high-pressure area. Instead of using contacting components as a seal, the patented seal employs acoustic technology to generate pressure waves that control, mitigate, or prevent fluid leakage. The result is a very low-leakage, non-contact seal that eliminates problems associated with friction. In addition, when traditional seals are needed in extremely high-temperature environments, Glenn innovators have developed new processes to enable the fabrication of single-crystal superalloys that can increase the upper limit of thermal seals to greater than 2000 °F.

Posted in: Briefs, Fluid Handling, Mechanical Components, Mechanics, Fabrication, Adhesives and sealants, Acoustics, Valves

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Compact Vibration Damper

Applications include wind tunnel models, launch vehicles, smokestacks, helicopters, wind turbines, and skyscrapers.NASA’s Langley Research Center has developed a compact tuned damper to reduce vibration occurring at a fixed frequency. Tuned dampers reduce vibration of the base structure by the dissipation of energy. The magnitude of the dissipated energy is proportional to the square of the displacement or velocity of the tuned mass, which in turn is proportional to the range of motion. The NASA damper design allows the slider mass to achieve 2× to 3× greater range of motion than that found in conventional devices. This enables 4× to 9× more effectiveness for the same size and weight; or the same effectiveness for a 4× to 9× decrease in weight. The damper is also tunable and can be adjusted in effectiveness. The damper can be made small enough for use in wind tunnel tests, or scaled up to large sizes like those used in helicopters, wind turbines, or skyscrapers.

Posted in: Briefs, Mechanical Components, Mechanics, Propellers and rotors, Dampers and shock absorbers, Wind power, Vibration, Wind tunnel tests

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