New Material For Aircraft Wings Could Save Billions

Source:

http://www.sciencedaily.com/releases/2007/09/070926094727.htm

Science Daily — Building aircraft wings with a special aluminium fibre combination makes them nearly immune to metal fatigue. The application of this technology, partly developed at Delft University of Technology, will lead to substantial savings.

The unusual qualities of this special material (called CentrAl, an abbreviation of Central Reinforced Aluminium) can make a significant contribution to the development of truly energy-efficient, 'green' aircraft. Lower fuel consumption and reduction of maintenance costs could lead to worldwide savings as high as $100 billion.
Fatigue is a phenomenon that affects materials after long-term exposure to cyclic loading. As a result of varying loads, fractures eventually occur. The new, high-quality CentrAl aluminium constructions are stronger than the carbon fibre reinforced plastic (CFRP) constructions that have recently been used in aircraft wings such as the Boeing 787. By using CentrAl wing constructions, the weight can be reduced by another 20 per cent compared to CFRP constructions. Furthermore, using CentrAl results in considerably lower manufacturing and maintenance costs.
The CentrAl concept comprises a central layer of fibre metal laminate (FML), sandwiched between one or more thick layers of high-quality aluminium. This creates a robust construction material which is not only exceptionally strong, but also insensitive to fatigue. The CentrAl technique allows for simple repairs to be carried out immediately, as is the case in aluminium constructions, -- but not the case when using CFRP constructions.
This patented new concept is one of the results of an intensive collaboration between the company GTM Advanced Structures, founded in The Hague in 2004 and specialising in new aircraft materials and constructions, the American aluminium company Alcoa, and the Faculty of Aerospace Engineering of Delft University of Technology.
During a conference in Delft (Conference on Damage Tolerance of Aircraft Structures: 25-28 September 2007), GTM and Alcoa have presented the new concept to international experts in the field of metal fatigue and damage sensitivity of aircraft constructions. The US Air Force, Alcoa and GTM will also shed new light on the fact that the new CentrAl materials create possibilities for so-called 'Carefree structures'.
These are aircraft constructions that are less sensitive to damage caused, for example, by fatigue, hail storms, other weather phenomena, trucks that collide with the aircraft and corrosion. Carefree aircraft constructions will be characterised by significantly reduced maintenance costs.
Note: This story has been adapted from a news release issued by Delft University of Technology.

Fausto Intilla

www.oloscience.com

Bridge Strengthening Research

Source:

http://www.sciencedaily.com/releases/2007/09/070914163132.htm

Science Daily — These days, a drive across a bridge is not always a pleasure cruise. Mindful of the war on terrorism, it can often be a cautious experience.

In one scenario, someone sets off a series of bombs to weaken the cables and the key structural connections of a major city bridge, all during rush hour. Not easy to do, but now thinkable. This summer, the possibility of sabotage was quickly examined—then dismissed—when the I35W bridge in Minneapolis tragically collapsed into the Mississippi River.
As authorities monitor and stand guard over bridges, the Homeland Security Science & Technology Directorate is looking to scientists and engineers for the security technologies of tomorrow. What if, for instance, we could one day not only guard bridges but fortify them? Like Superman’s blue suit, what if the cables and connections on bridges could be shielded with protective sleeves or covers, making them nearly impossible for the villains to penetrate?
This is the goal of the Directorate's bridge-strengthening research. Through a partnership with the U.S. Army Corps of Engineers’ Engineer Research and Development Center, the Directorate’s Infrastructure and Geophysical Division is testing current bridge designs and investigating advances in steel and reinforced concrete to explore whether such shields could work.
The first step is to determine which bridges and materials are most vulnerable, says Stanley Woodson, who oversees the project at the Center’s Geotech and Structures Lab. A major focus, he says, are the cables and the support columns—or towers—that are used in the cable-stayed design of bridges. Unlike the cables of a suspension bridge, which are attached from tower to tower, the cables in a cable-stayed bridge are connected directly to accessible points along the horizontal bridge deck.
"In controlled experiments, Woodson’s team has been re-creating the forces holding up these bridges and blowing up samples of their cables using various kinds of explosives," say Dr. Mary Ellen Hynes, director of the research. "They then use sophisticated software to analyze the impact and results."
“We tension the cables just like a real bridge,” Woodson explains. “We want to see just how they’d react in an actual terrorist event.”
The next step will be more complicated, says Woodson: Determining what material would suffice for another layer of protection, and what form it should take. “We’re looking at the practical as well as the innovative,” he says, recognizing the potential for high costs.
By the end of 2008, Woodson and his team will be imitating concrete bridge towers and subjecting them to the same explosive testing.
Note: This story has been adapted from a news release issued by Department of Homeland Security.

Fausto Intilla

www.oloscience.com

Skyray 48 Takes Flight

Source:

http://www.sciencedaily.com/releases/2007/09/070919174711.htm

Science Daily — Calm excitement filled the ground control station. Engineers stared intently at their computer screens as the pilot, sitting next to them, flexed his fingers on the controls. Ground crew tending the aircraft finished putting away their equipment. Preparations for the first flight of the unmanned X-48B Blended Wing Body research aircraft were complete.

Years of research, design, construction, wind tunnel and ground tests coalesced into this one moment of time.
Radios crackled. "Tower, Skyray 48 in position, lakebed runway 23, request clearance for takeoff..."
"Skyray 48 roger, main base winds 220 at 6, report airborne, lakebed 23..."
"Wilco"
"Five, four, three, two, one, brakes..."
Quickly, the manta ray-shaped aircraft rolled down the dry lakebed runway trailing a plume of dust as it picked up speed, its three small jet engines whining.
With an excitement that only comes with an aircraft's first flight, the triangular red, white and blue X-48B leapt into the air, obviously wanting to fly.
"Skyray 48's airborne," Boeing pilot Norm Howell called, matter-of-factly. And with that, years of toil blossomed into the sweet fruit of success on July 20, 2007 at NASA's Dryden Flight Research Center on Edwards AFB, Calif.
One of the latest cutting-edge experimental aircraft, or X-Planes, the X-48B BWB is a collaborative effort of the Boeing Co., NASA's Fundamental Aeronautics Program, and the Air Force Research Laboratory. The 21-foot wingspan, 500-pound, remotely piloted plane is designed to demonstrate the viability of the blended wing shape. And demonstrate it has.
After completion of six flights, the X-48B team began a four-week maintenance and modification period during which removable leading edges with extended slats are being replaced with slatless leading edges in order to mimic a slats-retracted configuration. The change requires a software update to the flight control software. In addition, the team is removing and replacing all of the aircraft's flight control actuators for maintenance purposes.
NASA is interested in the potential benefits of the aircraft - increased volume for carrying capacity, efficient aerodynamics for reduced fuel burn, and, possibly, significant reductions in noise due to propulsion integration options. In these initial flights, the principal focus is to validate prior research on the aerodynamic performance and controllability of the shape, including comparisons of flight test data with the extensive database gathered in the wind tunnels at NASA's Langley Research Center in Virginia.
The Subsonic Fixed-Wing Project, part of NASA's Fundamental Aeronautics Program, has long supported the development of the blended wing body concept. It has participated in numerous collaborations with Boeing, as well as several wind tunnel tests for different speed regimes. The team is focused on researching the low-speed characteristics of the design and expanding its flight envelope beyond the limits of current capabilities.
In addition to hosting the X-48B flight test and research activities, NASA Dryden is providing engineering and technical support -- expertise garnered from years of operating cutting-edge air vehicles. NASA assists with the hardware and software validation and verification process, the integration and testing of the aircraft systems, and the pilot's ground control station. NASA's range group provides critical telemetry and command and control communications during the flight, while the flight operations group provides a T-34 chase aircraft and essential flight scheduling. Photo and video support complete the effort.
The composite-skinned, 8.5 percent scale vehicle can to fly up to 10,000 feet and 120 knots in its low-speed configuration. The aircraft is flown remotely from a ground control station by a pilot using conventional aircraft controls and instrumentation, while looking at a monitor fed by a forward-looking camera on the aircraft.
Up to 25 flights are planned to gather data in these low-speed flight regimes. Then, the X-48B may be used to test the aircraft's low-noise and handling characteristics at transonic speeds.
Two X-48B research vehicles were built by Cranfield Aerospace Ltd., in England, in accordance with Boeing specifications. The vehicle that flew on July 20, known as Ship 2, was also used for ground and taxi testing. Ship 1, a duplicate, was used for the wind tunnel tests. Ship 1 is available for use as a backup during the flight test program.
So far, so good as the Skyray 48 team works through the late summer heat of the Mojave Desert as they continue blazing a trail with this futuristic aircraft design.
Note: This story has been adapted from a news release issued by National Aeronautics And Space Administration.

Fausto Intilla

www.oloscience.com

Near-Infrared LIDAR Helps Pilots

Source:

http://www.sciencedaily.com/releases/2007/08/070823120237.htm

Science Daily — Airline pilots will have more advance warning of potentially hazardous atmospheric conditions ¡V such as icing ¡V using a new near-infrared Light Detection and Ranging (LIDAR) system developed by scientists at RL Associates in Chester, Pa. The system, now in a prototype testing phase, will also provide better images in foggy, rainy or extremely hazy conditions, making it easier for pilots to take off and land in those conditions, thereby potentially reducing flight delays.
Right now, other experimental systems use visible green light to detect the different types of particles in the atmosphere. Most commercial planes, however, don't have this kind of system, and flights are grounded rather than risk a foggy landing or misidentifying clouds of icy particles. The RL Associates LIDAR system, which could be quickly commercially deployed, is slated for testing in approximately 18 months.
LIDAR exploits the same basic principle as radar, using light waves instead of radio waves. Lasers use light at wavelengths much smaller than radio waves, so they are much better at detecting very small objects. LIDAR already is frequently used in atmospheric physics ¡V but not on commercial planes ¡V to measure the densities of various particles in the middle and upper atmospheres. According to Mary Ludwig of RL Associates, the system uses a laser light beam that is polarized, or has its electric field pointing in a specific direction. The system beams the polarized infrared light out, and then records the amount of polarization that returns to the sensors. Rain and fog return a less polarized signal, and metal and people return a more polarized signal. The data is then processed to form an image of the ground, or could be translated into verbal commands if needed.
The system can better detect different types of particles in the atmosphere, such as ice, supercooled liquid or just regular water vapor. It can also identify the difference between water vapor and other kinds of substances, such as metal or the human body. Ludwig says the RL Associates system is the first of its kind to use near-infrared. The system also employs a "range-gated detector" that is only turned on for very short periods of time when the return signal is expected. This leads to a vastly improved signal-to-noise ratio, resulting in better images, particularly in obscuring conditions such as fog or haze.
Article: FThG4, "Near-Infrared LIDAR System for Hazard Detection and Mitigation Onboard Aircraft"
Note: This story has been adapted from a news release issued by Optical Society of America.

Fausto Intilla
www.oloscience.com

Spark-free, Fuel-efficient Engines On The Way

Source:

http://www.sciencedaily.com/releases/2007/07/070723175256.htm

Science Daily — In an advance that could help curb global demand for oil, MIT researchers have demonstrated how ordinary spark-ignition automobile engines can, under certain driving conditions, move into a spark-free operating mode that is more fuel-efficient and just as clean.The mode-switching capability could appear in production models within a few years, improving fuel economy by several miles per gallon in millions of new cars each year.

Over time, that change could cut oil demand in the United States alone by a million barrels a day. Currently, the U.S. consumes more than 20 million barrels of oil a day.The MIT team presented their latest results on July 23 at the Japan Society of Automotive Engineers (JSAE)/Society of Automotive Engineers (SAE) 2007 International Fuel and Lubricants Meeting.Many researchers are studying a new way of operating an internal combustion engine known as "homogeneous charge compression ignition" (HCCI). Switching a spark-ignition (SI) engine to HCCI mode pushes up its fuel efficiency.In an HCCI engine, fuel and air are mixed together and injected into the cylinder. The piston compresses the mixture until spontaneous combustion occurs. The engine thus combines fuel-and-air premixing (as in an SI engine) with spontaneous ignition (as in a diesel engine). The result is the HCCI's distinctive feature: combustion occurs simultaneously at many locations throughout the combustion chamber.That behavior has advantages. In both SI and diesel engines, the fuel must burn hot to ensure that the flame spreads rapidly through the combustion chamber before a new "charge" enters. In an HCCI engine, there is no need for a quickly spreading flame because combustion occurs throughout the combustion chamber. As a result, combustion temperatures can be lower, so emissions of nitrogen pollutants are negligible. The fuel is spread in low concentrations throughout the cylinder, so the soot emissions from fuel-rich regions in diesels are not present. Perhaps most important, the HCCI engine is not locked into having just enough air to burn the available fuel, as is the SI engine. When the fuel coming into an SI engine is reduced to cut power, the incoming air must also be constrained--a major source of wasted energy. However, it is difficult to control exactly when ignition occurs in an HCCI engine. And if it does not begin when the piston is positioned for the power stroke, the engine will not run right."It's like when you push a kid on a swing," said Professor William H. Green, Jr., of the Department of Chemical Engineering. "You have to push when the swing is all the way back and about to go. If you push at the wrong time, the kid will twist around and not go anywhere. The same thing happens to your engine."According to Green, ignition timing in an HCCI engine depends on two factors: the temperature of the mixture and the detailed chemistry of the fuel. Both are hard to predict and control. So while the HCCI engine performs well under controlled conditions in the laboratory, it is difficult to predict at this time what will happen in the real world.Green, along with Professor Wai K. Cheng of the Department of Mechanical Engineering, and colleagues in MIT's Sloan Automotive Laboratory and MIT's Laboratory for Energy and the Environment have been working to find the answer.A large part of their research has utilized an engine modified to run in either HCCI or SI operating mode. For the past two years, Morgan Andreae (MIT PhD 2006) and graduate student John Angelos of chemical engineering have been studying the engine's behavior as the inlet temperature and type of fuel are changed. Not surprisingly, the range of conditions suitable for HCCI operation is far smaller than the range for SI mode. Variations in temperature had a noticeable but not overwhelming effect on when the HCCI mode worked. Fuel composition had a greater impact, but it was not as much of a showstopper as the researchers expected. Using the results of their engine tests as a guide, the researchers developed an inexpensive technique that should enable a single engine to run in SI mode but switch to HCCI mode whenever possible. A simple temperature sensor determines whether the upcoming cycle should be in SI or HCCI mode (assuming a constant fuel).To estimate potential fuel savings from the mode-switching scheme, Andreae determined when an SI engine would switch into HCCI mode under simulated urban driving conditions. Over the course of the simulated trip, HCCI mode operates about 40 percent of the time.The researchers estimate that the increase in fuel efficiency would be a few miles per gallon. "That may not seem like an impressive improvement," said Green. "But if all the cars in the US today improved that much, it might be worth a million barrels of oil per day--and that's a lot."This research was supported by Ford Motor Company and the Ford-MIT Alliance, with additional support from BP.

Note: This story has been adapted from a news release issued by Massachusetts Institute of Technology.

Fausto Intilla

www.oloscience.com

Full-time Sensors Can Detect Bridge Defects

Source:

http://www.sciencedaily.com/releases/2007/08/070811213550.htm

Science Daily — Networks of small, permanently mounted sensors could soon check continuously for the formation of structural defects in I-beams and other critical structural supports of bridges and highway overpasses, giving structural engineers a better chance of heading off catastrophic failures.A Sandia National Laboratories team is developing and evaluating a family of such sensors for use on a variety of safety-critical structures.

Full-time monitoring sensors already have been tested and proven by Sandia for use on aircraft structures.Over time, the stresses on a bridge caused by traffic, weather, and construction can result in the formation of tiny cracks in the steel and concrete structures of bridges. Exposure to wind, rain, and other elements can cause corrosion that can become a structural concern as well. Like nerve endings in a human body, permanently mounted, or in-situ sensors offer levels of vigilance and sensitivity to problems that periodic checkups cannot, says Dennis Roach, who leads the Sandia team.Structural health monitoring (SHM) techniques, as they are called, are gaining acceptance in the commercial aviation sector as a reliable and inexpensive way to alert safety engineers to the first stages of defect formation and give them the earliest possible warning that maintenance is needed. With sensors continually checking for the first signs of wear and tear, engineers can detect cracks sooner, do the right maintenance at the right time, and possibly prevent massive failures, he says.Where flaws formSandia’s SHM work is an extension of its decades of research in non-destructive inspection (NDI) technologies currently used in manual inspections of commercial aircraft — to scan for small cracks in the airframe, for example. The SHM sensors being developed or evaluated at Sandia can find fatigue damage, hidden cracks, erosion, impact damage, and corrosion, among other defects commonly encountered in bridges.The Sandia team already has developed or evaluated several types of inexpensive, reliable sensors that could potentially be mounted on important infrastructure, typically where flaws are expected to form. “If I usually get fatigue damage in a particular area, that’s where I am going to install a sensor,” Roach says.One promising SHM sensor, a Comparative Vacuum Monitoring (CVM) sensor, is a thin, self-adhesive rubber patch, ranging from dime- to credit-card-sized, that detects cracks in the underlying material. The rubber is laser-etched with rows of tiny, interconnected channels or galleries, to which an air pressure is applied. Any propagating crack under the sensor breaches the galleries and the resulting change in pressure is monitored.The CVM sensors — manufactured by Structural Monitoring Systems, Inc. (SMS) — are inexpensive, reliable, durable, and easy to apply, says Roach. More important, they provide equal or better sensitivity than is achievable with conventional inspection methods and can be placed in difficult to access locations, he says.Some other sensors being considered include flexible eddy current arrays, piezoelectric transducers that can interrogate materials over long distances, embedded fiber optics, and conducting paint whose resistance changes when cracks form underneath.Smart structures possible“When we set out to do NDI, in the back of our minds we knew that eventually we wanted to create smart structures that ‘phone home’ when repairs are needed or when the remaining fatigue life drops below acceptable levels,” Roach says. “This is a huge step in the evolution of NDI.”“These sensors have been tested and shown to detect defects and fatigue in metal structures where safety is of utmost concern,” says Roger Hartman, manager of Sandia’s Infrastructure Assurance and NDI Department. By combining networks of sensors of various types with other advanced materials work Sandia has done, such as using composite materials to repair damage to a highway bridge or watching for the first signs of fatigue using computerized prognostics and health management algorithms, “you begin to evolve a system approach to making important infrastructure elements safer and more reliable,” Hartman says. Ultimately, a structural engineer might plug a laptop or diagnostic station into a central port on a bridge to download structural health data. Eventually “smart structures” fitted with many sensors and augmented with PHM algorithms could self-diagnose and signal engineers that repairs are needed or that they will be needed in a defined time downstream.Sandia already is investigating applying SHM to a variety of structures. In addition to bridges and aircraft, SHM techniques could be used to monitor the structural well-being of spacecraft, weapons, rail cars, oil recovery equipment, pipelines, buildings, armored vehicles, ships, wind turbines, nuclear power plants, and fuel tanks in hydrogen vehicles, Roach says. “There is widespread recognition that SHM’s time has come, an opinion you would not have heard from many people a few years ago,” he says.Sandia is a National Nuclear Security Administration laboratory.

Note: This story has been adapted from a news release issued by Sandia National Laboratories.

Fausto Intilla

www.oloscience.com