Materials

Mechanistic-Based Multiaxial- Stochastic-Strength Model for Transversely- Isotropic Brittle Materials

The methodology is applicable to a wide variety of graphite, coatings, and composite materials. A methodology has been developed and the software written to predict the probability of failure of transversely isotropic (a type of anisotropy) materials under generalized thermomechanical loading. This methodology is mechanistic in that it is based on the physical characteristics of brittle fracture, and morphological in that it considers the size, shape, and orientation distribution of strength controlling defects or flaws. On that basis, it can also account for a material’s failure modes and direction of damage initiation from loading. It is capable of predicting an anisotropic material’s probability of failure under transient and cyclic loading. This innovation can be applied to materials such as graphite, coatings, or the individual brittle constituents of composite materials.

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Bulk Metallic Glasses and Matrix Composites as Spacecraft Shielding

These materials offer combinations of high hardness, low melting temperature, low density, and formability like a plastic. Spacecraft shielding is defined as the outer layer of a satellite or spacecraft that protects it against micrometeorite and orbital debris (MMOD), radiation damage, and re-entry temperatures. There are several problems with the design and implementation of shields, particularly in the area of MMOD shielding. Spacecraft and satellites need to have the lowest possible mass due to the enormous cost per pound of putting them into orbit or deep space. However, low Earth orbit (LEO) is currently littered (and increasingly so) with orbital debris, primarily remnants of rocket upper stages, satellites, and pieces of spacecraft that have broken away or have collided with other objects. The major threat is that this debris is traveling at 8 to 18 km/s, and any piece larger than a few centimeters has the kinetic energy to potentially become a “spacecraft killer.” Large debris is tracked with radar, but the smaller debris (below a centimeter or so) is too small to track and must be mitigated by shields in the event of a collision. The International Space Station, for example, employs over 500 different shield designs into its outer skin, which are designed to protect a variety of vital components.

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Epoxies and Glass Transition Temperature

Gain a better understanding about glass transition temperature (Tg) and why it is one of many factors to consider for bonding, sealing, coating and encapsulation applications. In this paper, we explore how temperature impacts the performance of polymers, why glass transition temperature is significant, and how it is measured. Tg can be an extremely useful yardstick for determining the reliability of epoxies as it pertains to temperature.

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Bulk Metallic Glasses and Composites for Optical and Compliant Mechanisms

This innovation has uses in the aerospace, optics, bio-implants, spacecraft, and sporting equipment industries. Mechanisms are used widely in engineering applications due to their ability to translate force and movement. They are found in kinematic pairs, gears, cams, linkages, and in flexure mechanisms (also known as compliant mechanisms). Mechanisms and flexures are used widely in spacecraft design, especially in the area of optics, where precise positioning of telescope mirrors requires elastic flexing of elements. A compliant mechanism is generally defined as a flexible mechanism that uses an elastic body deformation to cause a displacement (such as positing a mirror). The mechanisms are usually constructed as a single monolithic piece of material, and contain thin struts to allow for large elastic bending with low input force. This creates the largest problem with developing precise mechanisms; they must be fabricated from a single piece of metal, but are required to have strict accuracy on their dimensions. They are generally required to have high strength, elasticity, and low coefficient of thermal expansion.

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Film-Forming, Self- Crosslinking, Aqueous Superabsorbent Coating

This air-curable material absorbs and holds liquids, vapors, and proteins for applications in healthcare, wound care, packaging, textiles, and engineering. Aqueous Superabsorbent Coating (ASC) technology is a liquid polymer solution that dries to form an absorbent film. It can absorb up to 40 g/g by weight of water, depending on the chemistry used, and can absorb water vapor from the air up to 70% by weight. Tests have demonstrated a greater absorbency of fluids containing proteins than cross-linked sodium polyacrylates (ASC 8-10g/g versus SAP 6g/g). The material can be “dried” after hydrolysis with exposure to air at moderate temperature.

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Non-Toxic, Anti-Corrosive, Crystalline Waterproofing Material

This material prevents concrete deterioration by preventing water and other corrosives from getting to the reinforcing steel. This product is an efficient concrete waterproofing solution. The crystalline, anti-corrosive material features a patented eka-molecular-sieve structure. The cement-based material works with the matrix of cement and water to create crystals that block the pores and capillaries in the concrete, making it impervious to water and corrosives. The material cures within 24 hours without any special ventilation. It continues to penetrate into the substrate as long as water is present. It will lay dormant in the substrate for years without the presence of water; however, if water attempts to enter at a future date through hairline cracks, the chemicals once again will become active and block the passage of water, creating a self-healing capability.

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Applications for Gradient Metal Alloys Fabricated Using Additive Manufacturing

A new roadmap for gradient metals that could be used in cars, optics, aircraft, and sporting goods. Recently, additive manufacturing (AM) techniques have been developed that may shift the paradigm of traditional metal production by allowing complex netshaped hardware to be built up layer-by-layer, rather than being machined from a billet. The AM process is ubiquitous with polymers due to their low melting temperatures, fast curing, and controllable viscosity, and 3D printers are widely available as commercial or consumer products. 3D printing with metals is inherently more complicated than with polymers due to their higher melting temperatures and reactivity with air, particularly when heated or molten. The process generally requires a high-power laser or other focused heat source, like an electron beam, for precise melting and deposition. Several promising metal AM techniques have been developed, including laser deposition (also called laser engineered net shaping or LENS® and laser deposition technology (LDT)), direct metal laser sintering (DMLS), and electron beam free-form (EBF). These machines typically use powders or wire feedstock that are melted and deposited using a laser or electron beam. Complex net-shape parts have been widely demonstrated using these (and other) AM techniques and the process appears to be a promising alternative to machining in some cases.

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