Manufacturing & Prototyping

Preliminary Design of a Cryogenic Hydrogen Radiation Shield for Human Spaceflight

Liquid hydrogen is the most mass-efficient radiation shielding material.Human susceptibility to the harsh space radiation environment has been identified as a major hurdle for exploration beyond low-Earth orbit (LEO). High-energy protons and nuclei ions from Solar Energetic Particles (SEPs) and Galactic Cosmic Rays (GCRs) can result in radiation doses that are dangerous to astronaut health and even survivability if the astronauts are not adequately shielded. These high-energy particles also cause significant amounts of secondary radiation when they impinge on the spacecraft structure. Hydrogen or hydrogen-rich materials are ideal materials for radiation shielding because hydrogen does not easily break down to form a secondary radiation source.

Posted in: Briefs, Manufacturing & Prototyping, Hydrogen storage, Human factors, Radiation protection, Spacecraft

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Methods of Making and Using Tubular Solid Oxide Fuel Cells (SOFCs)

SOFCs have applications in vehicle auxiliary power units, and emergency backup power for telecom and cable repeaters.Human-occupied vehicles and autonomous vehicles such as rovers and landers may benefit from the fuel flexibility and high energy density of solid oxide fuel cells (SOFCs), compared to batteries and polymer electrolyte membrane (PEM) systems. Fuel systems greater than 1 kW are traditionally planar and exhibit high volumetric power density; however, due to large sealing areas, they have poor cycling characteristics. Recently, 250 cycles on a Tubular SOFC (T-SOFC) system (Protonex Technology Corp.) was demonstrated. Hot zones designed around T-SOFCs have a lower packing density, but significantly better cycle life and start times, making them an ideal solution. By increasing the power density of T-SOFCs, overall hot zone and system volumetric power densities can be greatly improved. Extending the methodology of freeze-casting to T-SOFCs will provide a system with the micro-structural advantages of their planar counterpart, but with the rapid thermal cycling capacity of traditional extruded SOFCs.

Posted in: Briefs, Manufacturing & Prototyping, Fuel cells, On-board energy sources, Product development

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Tool Designs for Friction Stir Welding

This repeatable, environmentally friendly, cost-effective weld method is able to weld traditionally “unweldable” alloys.Friction stir welding (FSW) is a solidstate welding process that shows promise in the aerospace industry. A new system of experimentation has been used to quickly make and screen new tool designs. After conducting a literature review, friction stir tools were designed to optimize material flow around the tool.

Posted in: Briefs, Manufacturing & Prototyping, Design processes, Technical review, Manufacturing equipment and machinery, Welding

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Novel Electrochemical Cell Designs for Simultaneous Production of Methane and Oxygen via the Electrolysis of Carbon Dioxide and Water

The two-chamber cell design allows electrolysis of water and carbon dioxide in separate chambers to minimize production of unwanted products.NASA has investigated and demonstrated the simultaneous production of methane (CH4) and oxygen (O2) via the electrolysis of carbon dioxide (CO2) and water (H2O) in one or more ionic liquids (ILs). In order to improve the likelihood of methane and oxygen production, and to reduce the likelihood of unwanted side-product formation, several innovative approaches were investigated. Research has shown thousands of options for ionic liquids that can be used in the electrochemical process; however, care must be taken to choose an ionic liquid that has high carbon dioxide solubility, limited change in viscosity due to carbon dioxide absorption, and chemical stability during the electrochemical process.

Posted in: Briefs, Manufacturing & Prototyping, Carbon dioxide, Water, Methane, Research and development, Production, Oxygen

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Metal Stamping Design Guidelines

Metal Stamping provides an economical way to produce quantities of parts that can possess many qualities, including strength, durability, wear resistance, good conductive properties, and stability. In this paper, we are sharing some ideas that can help you design a part that optimizes all the features that the metal stamping process offers.

Posted in: Briefs, TSP, Aeronautics, Manufacturing & Prototyping, Materials, Mechanical Components, Design processes, Stamping, Metals, Parts

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Pulsed Ultrasonic Stir Welding System

A solid-state weld process yields better joint quality and longer tool life.NASA’s Marshall Space Flight Center (MSFC) developed Ultrasonic Stir Welding (USW) to join large pieces of very high-strength metals such as titanium and Inconel. USW, a solid-state weld process, improves current thermal stir welding processes by adding high-power ultrasonic (HPU) energy at 20-kHz frequency. The addition of ultrasonic energy significantly reduces axial, frictional, and shear forces; increases travel rates; and reduces wear on the stir rod, which results in extended stir rod life. The USW process decouples the heating, stirring, and forging elements found in the friction stir welding process, allowing for independent control of each process element and, ultimately, greater process control and repeatability. Because of the independent control of USW process elements, closed-loop temperature control can be integrated into the system so that a constant weld nugget temperature can be maintained during welding.

Posted in: Briefs, Manufacturing & Prototyping, Adaptive control, Manufacturing equipment and machinery, Metallurgy, Productivity, Welding

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Method of Heat Treating Aluminum-Lithium Alloy to Improve Formability

This technology can be used in aerospace, recreation, transportation, and other industries where high-strength, lightweight structures are needed.NASA scientists have designed a novel heat treatment process that significantly improves the formability of high-performance aluminum-lithium (Al-Li) 2195 alloy plate stock. The heat treatment process dramatically reduces cracking and also improves the yield and range of product sizes/shapes that can be spin/stretch formed. The improved yields also provide lower costs.

Posted in: Briefs, Manufacturing & Prototyping, Forming, Heat treatment, Aluminum alloys, Lithium

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