MEMs

Composite Material Fire Safety Training Course

AFRL scientists and engineers, working cooperatively with experts from academia and the firefighting community, have developed a Composite Material Fire Safety training program designed to improve the safety and effectiveness of Air Force, Department of Defense (DoD), and civilian firefighters. The team created the program to educate firefighters on the methodologies they need to rapidly and safely extinguish composite materials fires.

Posted in: Briefs, Materials
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Automated Material Deposition Chamber

AFRL materials scientists have acquired an automated deposition chamber (see figure on next page) that enables them to simultaneously or sequentially deposit solid-lubricant coatings onto target objectives from any of three deposition sources. The chamber also incorporates AFRLinvented technology entailing a hybrid, magnetron-assisted, pulsed-laser deposition (PLD) process. The scientists acquired the chamber to study protective solid-lubricant coatings capable of resisting wear and corrosion in (relatively) large friction components, including gears and bearings, and preventing static friction in microelectromechanical systems devices such as switches and connectors.

Posted in: Briefs, Materials
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AFRL Finding Ways to Decrease Unmanned Air Vehicle Costs

In support of the Aeronautical Systems Center's (ASC) Global Hawk Systems Group, AFRL has undertaken a program to study manufacturing tolerances for laminar flow on aircraft wings. On the drawing board, air vehicle designs have perfectly smooth aerodynamic surfaces, yet it is nearly impossible for manufacturers to fabricate those surfaces without some imperfections. Any surface imperfection, no matter how slight, can affect the properties of the boundary layer— the air flowing nearest an air vehicle's body during flight. In turn, this airflow dramatically impacts the amount of drag an air vehicle experiences. When the boundary layer is smooth, or laminar, drag is minimal; as the boundary layer becomes more turbulent, drag increases. Nonetheless, decreasing the amount of surface imperfection is not always a practical solution, because as the manufacturing processes become more stringent, they also become increasingly expensive and time-consuming endeavors. It is therefore vitally important to determine the relationship between the height, shape, and location of surface imperfections and the resulting performance degradation.

Posted in: Briefs, Mechanical Components
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Adaptable Miniature Initiation System Technology

The ever-changing nature of warfare presents constant challenges to weapon system designers, who must carefully consider various perspectives of mutual importance. Specifically, designers must address constraints associated with newly developed aircraft, such as the F-22 and F-35, which carry their stores internally and thus have size limitations on their payloads. Weapons designers must also recognize the weight of political pressures that fuel concerns about a given weapon's potential to cause collateral damage to civilian populations. At the same time, they must respond adequately to warfighter demand for the flexibility to employ the most effective weapon against a given target.

Posted in: Briefs, Electronics & Computers
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Rapid Model Fabrication for Responsive Aerodynamic Experimental Research

Technicians machine traditional metal wind tunnel models in a process that can span months. Although these models are highly precise, the meticulously slow manufacturing process precludes a quick assessment regarding a new design's feasibility and thus impedes the ever-increasing need to help today's warfighter address constantly changing warfare threats. In support of the Integrated Rapid Aerodynamics Assessment program, AFRL has been exploring the impact of rapid prototyping (RP) technology in meeting this escalating need. According to AFRL's Mr. Gary Dale, an originator of this experimental research effort, "We were looking for a way to quickly generate experimental data that we could use to verify computational fluid dynamics (CFD) results. The CFD researchers were generating solutions in a matter of days or even hours, and they wanted to verify their solutions with [wind tunnel] experimental data." By producing a model in days—or possibly hours, depending upon model complexity—RP technology enables this concurrent study of air vehicle concepts via computer simulation and wind tunnel results.

Posted in: Briefs, Manufacturing & Prototyping
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Unified Flow Solver

A variety of gas flow problems are characterized by the presence of rarefied and continuum domains. In a rarefied domain, the mean free path of gas molecules is comparable to (or larger than) a characteristic scale of the system. The rarefied domains are best described by particle models such as Direct Simulation Monte Carlo (DSMC); or, they involve solution of the Boltzmann kinetic equation for the particle distribution function. The continuum flows are best described by Euler or Navier-Stokes equations in terms of average flow velocity, gas density, and temperature and are solved by computational fluid dynamics (CFD) codes. The development of hybrid solvers combining kinetic and continuum models has been an important area of research over the last decade. Potential applications of such solvers range from high-altitude flight to gas flow in microsystems.

Posted in: Briefs, Software
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Super-High-Strength Aluminum Alloy

AFRL researchers developed a superhigh- strength aluminum alloy that engineers can use to improve the capability and performance of aerospace components—cryogenic rocket engine components, in particular. They created an aluminum alloy with specific strength and ductility characteristics surpassing those of the alpha titanium alloy currently used in rocket engine turbopumps. The aluminum alloy also demonstrates less sensitivity to hydrogen embrittlement, is lighter weight, and is potentially less costly to manufacture than the titanium alloy.

Posted in: Briefs, Materials
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Recent Advances in Insensitive Munitions

AFRL scientists from the High Explosives Research and Development facility successfully developed, demonstrated, and transitioned a nextgeneration melt-castable explosive formulation. The new formulation, MNX-795, exhibits significantly improved insensitive munitions (IM) characteristics—a requirement for the formulation's intended use in the MK- 84 bomb.

Posted in: Briefs, Materials
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Geopolymers

The use of ceramics in an ancient culture is one measure of that society's overall technical sophistication. Combining the study of ancient ceramics with modern science and technology has led to the creation of new ceramics with superior properties. Victor Glukhovsky, a scientist working in the Ukraine half a century ago, researched differences in the durability of ancient cements and more modern concretes. His work ultimately led to the synthesis of various aluminosilicate binders from clays, feldspars, volcanic ashes, and slags. These binders exhibited properties superior to those of the cementitious materials in common use at that time. Decades after Glukhovsky's discoveries, Ukrainian builders continued to employ aluminosilicate binders in construction applications, confirming their outstanding durability.

Posted in: Briefs, Materials
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Composites Affordability Initiative

AFRL and Boeing have developed an innovative structural inspection technique for testing bonded structures. This technique provides materials engineers a first-time, validated, nondestructive capability to test for weak adhesive bonds and determine the minimum strength of adhesively bonded aerospace structures. The new method will enable aircraft designers to use bonded structures in a wider range of applications, and industry analysts predict it will provide both a 25% reduction in fabrication and assembly time and a 75% reduction in life-cycle costs.

Posted in: Briefs, Materials
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