Materials & Coatings

Oriented Nanofibers Embedded in a Polymer Matrix

Lyndon B. Johnson Space Center, Houston, Texas

A method of forming a composite of embedded nanofibers in a polymer matrix with a high degree of alignment has been created using a nanofiber continuous fiber (NCF) system. This innovation incorporates nanofibers in a plastic matrix forming agglomerates, and then uniformly distributes them by exposing the agglomerates to hydrodynamic stresses that force the agglomerates to break apart. In combination, or additionally, elongational flow is used to achieve small diameters and alignment.

Posted in: Briefs, Materials, Forming, Composite materials, Fibers, Nanomaterials, Polymers

Low-Scatter Starshade Edges

This technology has applications in flexible optical masks, apertures, and encoders where sharp edges and material robustness are important.

A starshade occulter is a large space structure whose shape is specially designed to produce a diffraction pattern in starlight that can aid a telescope in direct imaging of exoplanets. The diffraction pattern produces extremely high-contrast dark regions in the starshade’s shadow on the order of 10-9 or 10-10. To do so, the edge shape of the structure must be held to extremely tight tolerances. In addition, potentially obscuring glint light from the Sun must be minimized to prevent loss of contrast.

Posted in: Briefs, Materials, Imaging and visualization, Optics, Spacecraft

Processing and Damage Tolerance of Continuous Carbon Fiber Composites Containing Puncture-Self-Healing Thermoplastic Matrix

Langley Research Center, Hampton, Virginia

The initiation and propagation of damage ultimately results in failure of aircraft structural components. Often, impact damage is difficult to identify in-service, and hence design of continuous carbon fiber reinforced polymer (CFRP) composite structure involves up to a 50% knockdown in the undamaged failure strength allowable. If damage is identified in a composite structure, the vehicle must be grounded for structural repair. This involves the grinding away of damaged regions and drilled holes to secure patches. By providing a polymer matrix with the ability to self-heal after impact damage is incurred, vehicle safety is greatly improved by increasing the design allowable for strength, resulting in more efficient CFRP structure.

Posted in: Briefs, Materials, Aircraft structures, Composite materials, Fibers, Materials properties, Polymers, Thermoplastics

Advanced Supported Liquid Membranes for CO‚2 Control in EVA Applications

This sorbent can be used in the capture of CO2 from coal-fired power plants and other power generation facilities.

Lyndon B. Johnson Space Center, Houston, Texas

NASA has a clear need to develop new technology in support of its future goals, including missions beyond low-Earth orbit, the possible development of lunar outposts, and the eventual exploration of Mars. As these missions develop, it is anticipated that crewmembers will spend extended time outside the spacecraft and established habitats, requiring new, robust, lightweight life support systems for extravehicular activities (EVAs). One area that is critical to life support systems is the control of CO2, and new spacesuits must be able to accommodate longer EVAs without increasing the size or weight of the current portable life support system (PLSS).

Posted in: Briefs, Materials, Carbon dioxide, Materials properties, Spacecraft

Low-Density Titanium-Based Bulk Metallic Glasses with High Glass-Forming Ability

These materials can be used in gears, bearings, latches, inserts, and sheet metal.

Ti-based bulk metallic glasses (BMGs) and matrix composites (BMGMCs) are a subset of the class of materials known synonymously as amorphous metals, liquid metals, and glassy metals, described by their majority element (in atomic percent) being that of titanium. BMGs are non-crystalline metal alloys based in a wide variety of elemental systems, including zirconium, iron, nickel, hafnium, gold, platinum, palladium, and silver, among others. The vast majority of commercially utilized BMGs are based in Zr-Ti-Cu-Ni-Be or Zr-Cu-Ni-Al due to their relatively low-cost elements and large glass-forming ability (GFA), typically greater than 1 cm. BMGs have long been considered to be a material without a clear application, as the density of BMGs fits squarely between two common, highperformance crystalline alloys that BMGs are usually thought to be replacements for: steel (density = 7.8 g/cm3) and titanium (density = 4.5 g/cm3). For example, Zr-based BMGs generally fit into the range of 6 to 6.5 g/cm3, which makes them difficult to use as direct replacements for conventional materials.

Posted in: Briefs, Materials, Alloys, Glass, Materials properties

Thermal Management Coating (TMC)

The coating uses micro-encapsulated phase-change material.

Marshall Space Flight Center, Alabama

An experimental study was conducted in conjunction with the research and development program at the NASA Marshall Space Flight Center (MSFC) on thermal protection systems (TPS) for aerospace applications, a new concept for reusable TPS material. The new system uses a micro-encapsulated phase-change material rather than an ablative material to dissipate the heat produced during supersonic flight. This new material absorbs energy as it goes through a phase change during the heating portion of the flight profile and then the energy is released as the material cools. This new TPS consists of micro-encapsulated phasechange material and a resin system to adhere the coating to the structure. The technology has been successfully tested in the hot gas tunnel (aero-thermal heating). The figure shows the test results.

Posted in: Briefs, Materials, Thermal management, Coatings, colorants, and finishes, Materials properties

AeroHeating Tools (AHT) Suite

Lyndon B. Johnson Space Center, Houston, Texas

This suite of computer programs, called “tools,” is used to calculate local flow angles over damage sites in the Shuttle Orbiter Thermal Protection System (TPS). It provides a quick and easy way to compute cross flow angles over points of interest on the Shuttle Orbiter TPS.

Posted in: Briefs, Materials, Computer software and hardware, Thermal management, Spacecraft

EXOS Software

Lyndon B. Johnson Space Center, Houston, Texas

An improved version of EXOS software allows for the modeling of fabrics, mixtures, and porous materials, and also provides the ability to accept hex mesh geometries. The code employs a novel numerical method, a hybrid particle finite element approach, as well as particles and elements in tandem, each modeling distinct aspects of the physics. Ellipsoidal particles are used to model contact-impact and volumetric thermomechanical response (Euler parameters provide a singularity-free description of particle rotations). Elements are used to model “strength” effects; namely, tensile inter-particle forces and elastic-plastic deviatoric deformation.

Posted in: Briefs, TSP, Electronics & Computers, Coatings & Adhesives, Materials, Software, Computer simulation, Finite element analysis, Tensile Strength

Scientists Print in 4D

Scientists at the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Harvard John A. Paulson School of Engineering and Applied Sciences have brought a fourth dimension to their microscale 3D printing technology.

Posted in: News, Manufacturing & Prototyping, Materials

Beetle-Inspired Patterning Prevents Frost

Taking a page from the beetle's playbook, Virginia Tech biomedical engineers created a way to control condensation and frost growth on airplane parts, condenser coils, and windshields.

Posted in: News, Coatings & Adhesives, Composites, Materials, Metals

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