Mechanical & Fluid Systems

Multi-Spoked Wheel Assembly

NASA Glenn researchers have developed a spoked drive mechanism for robots and other vehicles that is capable of two rotational modes. This robust ground traction (drive) assembly for remotely controlled vehicles operates smoothly not only on surfaces that are flat, but also upon surfaces that include rugged terrain, snow, mud, and sand. The assembly includes a sun gear and a braking gear. The sun gear is configured to cause rotational force to be applied to second planetary gears through a coupling of first planetary gears. The braking gear is configured to cause the assembly (or the second planetary gears) to rotate around the braking gear when an obstacle or braking force is applied.

Posted in: Briefs, Mechanical Components, Wheels, Robotics, Autonomous vehicles, Vehicle dynamics

Nanotube-Based Device Cooling System

Carbon nanotubes (CNTs) are being studied for applications in high-strength/low-weight composites and other applications. Recent research on thermal dissipation materials for high-power electronic devices is generating a lot of interest in various industries. NASA has developed a method for cooling a device, such as an electronic device, that produces extreme heat that must be dissipated. CNTs have attracted much attention due to their extraordinary mechanical and unique electronic properties. Computer chips have been subjected to higher and higher thermal loads and it is challenging to find new ways to perform heat dissipation. As a result, heat dissipation demand for computer systems is increasing dramatically. CNTs, which are known to provide high thermal conductivity and to be small and flexible, are suitable for cooling these electronic devices. One critical problem is provision of a compliant, usable composite of CNTs with a material that meets other needs for heat dissipation.

Posted in: Briefs, Mechanical Components, Electronic equipment, Electronic equipment, Thermal management, Thermal management, Composite materials, Materials properties, Nanotechnology

A Method for Accurate Load/Position Control of Rigidly Coupled Electromechanical Actuators

NASA has developed a technique designed to prevent cross-coupling in systems where two or more linear electro-mechanical actuators (EMA) are rigidly connected and are in danger of becoming cross-coupled. In such systems where the linked EMAs are commanded to achieve two distinct goals, such as position and load control, control problems often arise — especially at higher load and linear velocity levels. Both position and load control become inaccurate and in certain situations, stability of the overall system may be compromised. The NASA-developed approach mitigates the problem and achieves both accurate position following and desired load levels between the two (or more) actuators.

Posted in: Briefs, Mechanical Components, Mechanics, Positioning Equipment, Electronic control systems, Electronic equipment, Sensors and actuators, Electronic control systems, Electronic equipment, Sensors and actuators

Ultralight Self-Deployable Solar Sails

Deployment of large structures such as solar sails relies typically upon electromechanical mechanisms, mechanically expandable or inflatable booms, launch restraints, controls, and other mechanisms that drastically increase the total mass, stowage volume, and areal density. The primary performance parameter for solar sails is areal density, which determines the acceleration of the sail. Present technology allows the solar sail areal density to be around 20 g/m2, and that permits only nearby demonstration missions.

Posted in: Briefs, Mechanical Components, Mechanics, Sun and solar, Packaging, Lightweighting, Spacecraft

Ultra-Compact Heat Rejection System

Radiator panels are the baseline heat rejection approach for most space systems. This approach is sound, but requires a large amount of surface area to radiate the anticipated heat load. The large panels require support structures to hold them in place and prevent damage. These structures impact mass and cost. Additionally, it is not practical to launch, transport, integrate, and relocate large panels as monolithic units. For this reason, a foldable scissor assembly is envisioned to stow the panels compactly and extend them before system startup. The moving parts and flexible fluid connections required for this approach add complexity and potential failure modes to the system. Some mission plans also require power system mobility for exploration well beyond the base camp. For this scenario, the radiator assemblies must be retracted, stowed, and redeployed each time the system is moved. These activities require time and effort, and they expose the radiator panels and associated mechanisms to damage risk. Even when properly stowed, the relatively thin panels could be damaged during transportation.

Posted in: Briefs, Mechanical Components, Mechanics, Thermal management, Thermal management, Packaging, Radiators, Spacecraft

Transformable and Reconfigurable Entry, Descent, and Landing Systems and Methods

The Adaptable, Deployable Entry Placement Technology (ADEPT) concept is a mechanically deployable, semi-rigid aeroshell entry system capable of achieving low ballistic coefficient during entry for planetary or Earth return missions. The decelerator system offers a lighter-weight solution to current rigid, high-ballistic-coefficient aeroshells and enables missions that are currently not feasible with rigid aeroshell construct.

Posted in: Briefs, Mechanical Components, Mechanics, Body panels, Entry, descent, and landing, Lightweighting

Self-Latching Piezocomposite Actuator

Langley Research Center, Hampton, Virginia

NASA’s Langley Research Center has developed a self-latching piezocomposite actuator. The self-latching nature of this invention allows for piezo actuators that do not require constant power draw. Among other applications, the invention is well suited for use in aerodynamic control surfaces and engine inlets. The technology is a self-latching piezoelectric actuator with power-off, set-and-hold capability. Integrated into an aerodynamic control surface or engine inlet, the self-latching piezocomposite actuator may function as a trim tab, variable camber airfoil, vortex generator, or winglet with adjustable shapes. Deflections could be made in-flight, and set and maintained (latched) without a constant power draw. Current piezo actuators require constant power to control and manage their electric fields. The control device leverages the shape memory behavior (specifically, the remnant stress-strain behavior) to create a morphing actuator that changes and holds the new shape with no applied control signal.

Posted in: Briefs, Mechanical Components, Automation, Airframes, Electronic control units, Sensors and actuators, Electronic control units, Sensors and actuators

Active Response Gravity Offload and Method

Lyndon B. Johnson Space Center, Houston, Texas

To train astronauts to live and work in the weightless environment on the International Space Station, NASA employs a number of techniques and facilities that simulate microgravity. Engineers at the NASA Johnson Space Center (JSC) have developed a new system called the Active Response Gravity Offload System (ARGOS) that provides a simulated reduced gravity environment within a confined interior volume for astronauts to move about and/or equipment to be moved about as if they were in a different gravity field. Each astronaut/item is connected to an overhead crane system that senses their actions (walking or jumping, for example) and then lifts, moves, and descends them as if they had performed the action in a specified reduced gravity.

Posted in: Briefs, Mechanical Components, Automation, Education, Education and training, Automation, Test facilities

Fluid Harmonic Absorber

Marshall Space Flight Center, Alabama

NASA Marshall Space Flight Center’s Fluid Structure Coupling (FSC) technology is a highly efficient and passive method to control the way fluids and structures communicate and dictate the behavior of a system. This technology has the demonstrated potential to mitigate a multitude of different types of vibration issues, and can be applied anywhere internal or external fluids interact with physical structures. For example, in a multistory building, water from a rooftop tank or swimming pool could be used to mitigate seismic or wind-induced vibration by simply adding an FSC device that controls the way the building engages the water.

Posted in: Briefs, Mechanical Components, Automation, Water, Vibration, Vibration

Variable-Aperture Reciprocating Reed Valve

Marshall Space Flight Center, Alabama

NASA’s Marshall Space Flight Center engineers have developed a new reed valve for controlling fluid flow back and forth between two chambers. The VARR valve provides two-way flow that is proportional to flow demand. As the pressure gradient builds on one side, the reed valve responds by opening an amount that is proportionate to the gradient, or demand, allowing bidirectional flow. Some mechanical and fluid systems that rely on the controlled flow of fluids between chambers will benefit from the new design. Compared to current fixed-orifice devices, VARR may expand the performance envelope by offering a more continuous flow response in applications in which the pressure environment is constantly changing. Proportional two-way flow can enable a fine-tuned system response to pressure building on one side of the valve. In these changing gradient conditions, the reed valve is better than fixed-sized orifices, which are optimized for one flow condition and are likely to over- or under-restrict flow for all other flow gradients.

Posted in: Briefs, Mechanical Components, Automation, Computational fluid dynamics, Valves, Hydraulic systems

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