Mechanical Components

Metabolic Heat Regenerated Temperature Swing Adsorption

Liquid CO2 as a coolant will not contaminate the area as it is sublimated from the life support system for heat rejection. Two fundamental problems facing the development of a portable system to sustain life on extraterrestrial surfaces are (1) heat rejection and (2) rejection of metabolically produced CO2 to an environment with a ppCO2 of 0.4 to 0.9 kPa as is present on Mars. Portable life support systems typically use water for heat rejection via sublimation. Consequently, the water is removed from the life support system and into the surrounding environment after use. This wastes a valuable resource required for human life that is expensive to transport from Earth. Furthermore, rejecting the water vapor to the surrounding environment contaminates it, severely interfering with any search for life on extraterrestrial surfaces. A portable life support system should be able to use a variety of fluids for heat rejection, especially liquid CO2, as it can be easily acquired and cheaply stored on the surface of Mars. The use of liquid CO2 as a coolant has the advantage that it will not interfere with scientific investigations by contaminating the area as it is sublimated from the life support system for heat rejection.

Posted in: Mechanical Components, Machinery & Automation, Briefs

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Habitat Demonstration Unit (HDU) Vertical Cylinder Habitat

Modular habitats maximize floor area and are easy to join together. NASA’s Constellation Architecture Team defined an outpost scenario optimized for intensive mobility that uses small, highly mobile pressurized rovers supported by portable habitat modules that can be carried between locations of interest on the lunar surface. A compact vertical cylinder characterizes the habitat concept, where the large diameter maximizes usable flat floor area optimized for a gravity environment and allows for efficient internal layout. The module was sized to fit into payload fairings for the Constellation Ares V launch vehicle, and optimized for surface transport carried by the All-Terrain Hex-Limbed Extra- Terrestrial Explorer (ATHLETE) mobility system. Launch and other loads are carried through the barrel to a top and bottom truss that interfaces with a structural support unit (SSU). The SSU contains self-leveling feet and docking interfaces for Tri-ATHLETE grasping and heavy lift.

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

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Brushless Motors for In-Tank Fuel Pumps

The use of a brushless motor provides improvement in power usage and reduction of carbon dioxide emissions. Most automotive fuel systems use a Fuel Delivery Module (FDM) with components to filter and pump gasoline at a specified pressure and flow rate from the fuel tank to the engine. The FDM uses a reservoir assembly to maintain a fuel supply at the pump inlet and support components such as pressure regulators and/or limiters, filters, level sensor, and the electrical and hydraulic connections that pass through the tank. Current systems predominantly use passive electrical components such as brush pumps and resistive fuel level sensors that are independently connected to a voltage supply and body control module, respectively. The high flow levels of these systems require high-power pumps that may operate continuously at maximum speed conditions. Some newer systems may employ a voltage controller to modulate the pump supply voltage to discrete speeds depending on projected engine demand, and provide some improvement in power consumption.

Posted in: Mechanics, Mechanical Components, Machinery & Automation, Briefs

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Origami-Inspired Folding of Thick, Rigid Panels

Hinges are used to achieve the necessary folding. To achieve power of 250 kW or greater, a large compression ratio of stowed-to-deployed area is needed. Origami folding patterns were used to inspire the folding of a solar array to achieve synchronous deployment; however, origami models are generally created for near-zero-thickness material. Panel thickness is one of the main challenges of origami-inspired design.

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

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Temperature Considerations When Specifying LVDT Linear Position Sensors

LVDT linear position sensors offer significant mechanical life for industrial process control and factory automation systems. The LVDT linear position sensor can operate successfully over a wide range of temperatures, depending upon its design and the application in which it is operating. While the output of the LVDT linear position sensor is not immune to temperature variation, proper design and construction for environmental effects can produce a sensor that provides a relatively stable, highly linear output over a wide temperature range. Depending upon materials and construction techniques, modern LVDT linear position sensors can be built to withstand temperature extremes from -195 to +600 °C.

Posted in: Mechanics, Mechanical Components, Machinery & Automation, Briefs

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Electric Machine With Boosted Inductance to Stabilize Current Control

High-powered motors typically have very low resistance and inductance (R and L) in their windings. This makes the pulse-width modulated (PWM) control of the current very difficult, especially when the bus voltage (V) is high. These R and L values are dictated by the motor size, torque (Kt), and back-emf (Kb) constants. These constants are in turn set by the voltage and the actuation torque-speed requirements. This problem is often addressed by placing inductive chokes within the controller. This approach is undesirable in that space is taken and heat is added to the controller.

Posted in: Mechanics, Mechanical Components, Machinery & Automation, Briefs

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Positive-Buoyancy Rover for Under Ice Mobility

This floating rover operates at the ice/water interface in lakes and seas. A buoyant rover has been developed to traverse the underside of ice-covered lakes and seas. The rover operates at the ice/water interface and permits direct observation and measurement of processes affecting freeze- over and thaw events in lake and marine environments. Operating along the 2- D ice-water interface simplifies many aspects of underwater exploration, especially when compared to submersibles, which have difficulty in station-keeping and precision mobility.

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

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