Tech Exchange

Lightning Strike Protection for Composite Aircraft

NASA’s work in advanced aeronautics includes growing interest in environmentally responsive aircraft, one component of which involves use of composites to significantly reduce weight and, hence, fuel consumption. The new Boeing 787 aircraft is one recent example, and there has been a strong move toward composites in new general aviation and business jet aircraft. One disadvantage of this new direction is that the aircraft are far more vulnerable to lightning strikes. The energy deposited in a typical lightning strike involves tens of KV and 10,000-200,000 amperes, occurring in a fraction of a second. Without some type of shielding, or conductive path, the electrically insulated carbon fiber/ epoxy composites can be damaged, particularly at the entry and exit points for the strike. The aircraft instrumentation can also be damaged in such an event and extra shielding is often necessary for composite aircraft.What are the Challenges? Improved means are needed to identify when a plane is in fact struck by lightning, and both onboard and ground-based NDE methods are needed to assess the level of damage that occurred. Perhaps more importantly, means to eliminate or mitigate damage must be engineered in a cost-effective manner, ideally as a single “outer” shield that will protect the aircraft from both structural damage as well as shield instruments without additional internal hardware requirements.What is NASA Doing? Lightning damage detection/diagnosis technologies do not exist today for our modern fleet of aircraft, so one element of NASA’s program is to explore how this can be best accomplished both during flight and after the fact. Onboard current sensors will be used to measure the intensity and location of the lightning current during a strike. Simulations of lightning-arc events in the laboratory (see photo) with various test panels will provide baseline data for model development. The voltage/current measurements from such tests will be correlated against statistical data sets to estimate the level of damage expected on the composite and eventually to evaluate the safety risks associated with continuing the flight profile after a lightning strike has occurred. Since the aircraft fuselage and wing structure can be very complex, it will be important to develop physics-based models of the lightning strike event. This code would allow designers to consider different material solutions for test and evaluation and eventually should allow good correlation between the model and observed lightning strike effects in the field.What Applications Does NASA Envision? NASA intends this information and model to be made available to composite aircraft developers as a tool in their design efforts. Similar issues are faced in the wind turbine industry where the blades can be composites. There may also be applications in the electric power industry related to arc events in very high-voltage environments. What are NASA’s Needs? NASA is interested in collaborating with industry or university groups in several areas. On-board sensors for measurement of lightning strike intensity, location, and current flow during the event.Conductive paint technology or other “coating” concepts for composites to facilitate current flow, hence mitigate or eliminate structural damage, and/or remove any need for additional internal shielding of electronics.Physics-based models of complex composite structures/actual aircraft that can be adapted to include model lightning strike events to quantify electrical, mechanical, and thermal parameters to indicate damage. More Information For more information, contact Mr. George Szatkowski at 757-864-6194 or email nasa@techbriefs.com.

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Shape-Memory Alloys Replace Traditional Electromagnet Actuators

Shape Memory Alloys (SMAs) are metals that “remember” their original shapes. SMA technology can provide the same mechanical movement and required forces of an electromagnetic actuator, but in a more compact form, while removing the need for motors, gearing, or springs. This SMA technology has shown a reduction in weight of up to 50%, a reduction in the space required of up 70%, and a cost reduction of up to 30% compared to traditional electromagnetic actuators. The technology can deliver mechanical movement as well as electrical connectivity, it is intrinsically safe, can be made into a flat but flexible actuator, and can operate around curvatures. Examples of applications are compact and low-weight linear electromechanical actuators; active Bowden cable devices; and temperature-dependent shape-changing actuation, displacement, or reversible surface modification. The technology could be used by the white goods, automation, medical devices, transportation, consumer goods, and leisure goods industries. Get the complete report on this technology at: www.techbriefs.com/tow/200906b.html Email: nasatech@yet2.com Phone: 781-972-0600

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Mechanical Mounting/Connection/Release System

The internal mechanism of the connector part of this system works to maintain positioning repeatability and rigidity, and compensates for wear over time, while both the connector and receiver are tapered in two planes to assure repeatable positioning. Together, the two form a rigid connection that can be unlocked and removed in a single plane, with no access to the side faces required for release. The principles of engaging, securing, and releasing the connector of this mount from the receiver remain the same at any scale — from applications in heavy equipment attachments, to medical devices and prostheses, to the scale of nano-machines. Applications include situations where one piece of equipment must be attached rigidly to another in a single direction; for example, attaching down-hole tools for drilling or laparoscopic operating tools where attachment and release can take place in one plane only, with no access to releases on the side. Areas of application include securing shipping containers and in microgravity where applications of side force cause unwanted rotational reaction. Get the complete report on this technology at: www.techbriefs.com/tow/200906a.html Email: nasatech@yet2.com Phone: 781-972-0600

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High-Temperature Brine Viscosifier

A company seeks to increase the viscosity of brine solutions containing both mono and multivalent salts. Targeted brines may contain up to 80% weight of salt. Viscosity must stay the same up to 150°C. The thickened brine should have a yield value of the order of 1Pa (or higher) and a shear thinning behavior. The overall rheology profile should be comparable to xanthan gum solution in fresh water. The aim of the viscosity increase is to suspend solid particles. Respond to this TechNeed at: www.techbriefs.com/tn/200905d.html Email: nasatech@yet2.com Phone: 781-972-0600

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3D and/or Flock Printing Technology

A company seeks a printing capability and/or technology that creates a physical 3D texture that is tactile and soft (but not rubbery) in nature onto a flat or curved plastic surface made of polyethylene, polypropylene, or polyester material. This 3D printing enhances the product experience for the consumer by providing a more tactile surface that can increase grip, provide a pleasant texture/feeling, and/or present a less plain/sterile surface. Materials should be FDA food-safe, as well as safe when in contact with skin. Respond to this TechNeed at: www.techbriefs.com/tn/200905c.html Email: nasatech@yet2.com Phone: 781-972-0600

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Modular Electronic Air Sterilization Technology for Airborne Bacteria, Molds, and Viruses

This technology sterilizes air, eliminating odors, preventing infections, and extending the shelf life of food. The scalable system results in 100% removal of microorganisms with one passthrough of air. The technology has optimized UV exposure with a specialized lamp construction and array formation. The system can be modularized according to the required volume flows, and can react to changes via its proprietary microchip technology. It can be used in conjunction with HEPA filters to remove all unwanted bodies within an air stream. The underlying technology deals with the variation in atmospheric conditions. The system is made up of a series of highly developed tubular modules that include a unique internal intelligent microchip that understands changes in the humidity and temperature of the atmosphere and adapts the optimized UV exposure and flow in the unit (or series of units) to apply the minimum power required to achieve full sterilization. Get the complete report on this technology at: www.techbriefs.com/tow/200905b.html Email: nasatech@yet2.com Phone: 781-972-0600

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Single-Motion Extension Mechanism for Poles

Originally developed and marketed as an extension pole for painting, light bulb changing, and similar operations, the single-motion extension principle in this technology is adaptable to any rod or pole that must be extended and retracted to a compact length. It applies to extendable antennae; tent poles; emergency equipment such as stretchers, cots, or IV poles; tools; robotic arms; or surgical instruments that must extend and retract once in the body. The internal mechanism uses a metal tape similar to that in a retractable tape measure that pushes on the extending tube. The mechanism may be hand-operated or motorized, but either way, a single motion extends the pole. The internal, contained mechanism of the extension pole provides a singlemotion extension to about three times the collapsed length of the assembly. The assembly can be fabricated in a variety of materials in a variety of tensile and compression strengths in multiple segments. The assembly can scale up to greater lengths or be miniaturized to suit the application. Get the complete report on this technology at: www.techbriefs.com/tow/200905a.html Email: nasatech@yet2.com Phone: 781-972-0600

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