Composite material defined as a mixture of two or more than two materials (reinforcement, fillers and binder) different in composition. Composite materials are materials made from two or more than two materials with considerably differ in physical and chemical properties, that when combined, make a material with appearances different from the individual components.
In the last several decades, composite materials have increasingly supplanted metals in many structural applications involving aircraft, aerospace, military vehicles, automobiles, civil infrastructure, medical devices, and sporting equipment. The virtues of composite structure typically include reduced weight, increased performance, and fuel economy.
Composites have also revolutionized military platforms, weapons and systems. “The Army is on the cusp of revolutionizing materials that go into armament construction, making for stronger, lighter and more durable weapons, The key to this revolution is composite materials,” “Aircraft manufacturers are in a race to convert as much metal to composite as possible because the reduction in weight saves fuel and production costs are much less,” Mike Louderback, site leader at Meggitt Polymers & Composites, a business unit of Meggitt PLC. Dr. Andrew Littlefield , a mechanical engineer at the U.S. Army Armament Research, Development and Engineering Center said. Air Force Research Laboratory (ARFL) wants to develop advanced, high-temperature polymer matrix composites (PMCs) to replace titanium in military aircraft.
“Eighty percent of small parts are made of metal due to the prohibitive fabrication cost of composite parts under 20 pounds,” said Mick Maher, program manager in DARPA’s Defense Sciences Office. “Although metal parts are cheaper to make, their additional weight leads to sub-optimal performance of the system. Through TFF, we aim to develop a versatile composite material and an adaptable forming process to allow affordable fabrication of multiple part configurations from the same work cell.”
Futuristic Aircraft and Helicopters with Composites
Orbital ATK has secured a contract to produce composite components for the US Air Force’s (USAF) B-2 Spirit stealth bomber. Under the $90m contract was awarded by Northrop Grumman Orbital ATK will produce 17 hot trailing edge (HTE) composite parts over the next five years. Orbital ATK’s aerospace composites business uses proprietary production processes that are said to shorten the manufacturing cycle, and produce quality, complex components with unmatched repeatability through sophisticated robotics automation.
The B-2 Spirit stealth bomber is a key element of the US’s long-range strike arsenal and one of the most survivable aircraft in the world. The aircraft’s capabilities, including its stealth characteristics, allow it to penetrate the most sophisticated enemy defences. The B-2 is capable of all-altitude attack missions up to 50,000ft, with a range of more than 6,000nm unrefuelled and over 10,000nm with one refuelling, giving it the ability to fly to any point in the world within hours.
The United States Department of Defense’s Future Vertical Lift Program has been working to develop a new generation of improved vertical takeoff and landing (VTOL) aircraft for the U.S. Armed Forces.
According to Aviation Week, the V-280’s “major components” are its carbon fiber wing, prop rotor gearbox and composite yoke for the rotor hub. The outlet adds that the wing is the first use of large-cell carbon core composites—a sandwich of carbon-fiber skins and honeycomb. The hub yoke is laid up from composite fabrics and uses open-face tooling around the edges. The V-280 also has the first all-carbon tiltrotor blade. All of these elements helped cut overall weight and cost for the helicopter.
The use of composites has allowed V-280 to be one of the fastest military helicopters in the world, with a cruising speed of 280 knots (approx. 322 mph). The Black Hawk’s cruising speed is 150 knots (170 mph). “It carries the same payload twice as fast and has twice the range,” says Vince Tobin, vice president for advanced tiltrotor systems at Bell Helicopters.
Composites – in satellites and launch vehicles
Satellites utilize high modulus (high stiffness) carbon fibres combined with tailored resin systems for the production of structures on the satellite, including solar arrays, booms/trusses, reflectors and bus structures. Solar arrays are used to provide power to the satellite while it is in space; booms/trusses hold equipment and solar arrays to the main structure of the satellite; and reflectors are the communication disks that are used to upload and download satellite communications that enable data transmission with mobile phones, internet, HD television, military communications and analytical instruments.
The SMAP spacecraft will provide global measurements of soil moistures and indicate whether it is frozen or thawed. The six-metre-long AstroMesh® reflector, which will spin atop the spacecraft at nearly 15 revolutions per minute, provides for total global mapping every two to three days.
The reflector uses TenCate Cetex® thermoplastic composites to achieve the strength, durability and weight savings needed. ‘TenCate Cetex® thermoplastics are integral to the structure of our mesh reflectors’, states Daniel Ochoa, product development manager at Northrop Grumman’s Astro Aerospace. ‘They help to create the parabolic shape of the antenna. The material has been extensively tested as part of the unit prior to flight, and is durable and stiff, which is critical to the functioning of the antenna.’ Launch vehicles are now being developed that are either reusable or very low cost and satellite manufacturers are shifting to more rapidly deployable architectures
Air Force Wants Composites to Replace Titanium in Military Aircraft
Developing better, faster, stronger, and more sustainable aircraft requires the discovery and successful manufacturing of advanced, high-temperature materials. Additionally, the best new materials solutions meet environmental, health and safety regulations and are non-toxic alternatives to their predecessors.
Air Force Small Business Innovation/Small Business Technology Transfer (SBIR/STTR) has provided PROOF Research’s Advanced Composites Division with $750,000 to work with the Air Force Research Laboratory (ARFL) to develop advanced, high-temperature polymer matrix composites (PMCs) to replace titanium in military aircraft. Applications for these materials exist on the F135 and F110 engines; B-2, F-117 and F-22 aircraft; missile structures; and sixth-generation engines.
As a replacement for titanium structures, high-temperature PMCs offer up to a 40-percent weight savings resulting in annual fuel savings of hundreds of dollars per kilogram of titanium replaced per aircraft in addition to potential increased service life and improved fatigue resistance.
“This maturation effort supports the warfighter by providing new capabilities and performance at a reduced cost,” said Dr. Brent Volk, the AFRL researcher managing the effort. “It completes development of an advanced materials ‘toolbox’ that includes a higher temperature polyimide matrix composite, a computational process model for the material integrated into a commercial, off-the-shelf software package, validation of the process model on complex geometries, and a materials design-allowable database.”
CMCs allow for a revolutionary change in jet engine design
GE Aviation successfully tested the world’s first non-static set of light-weight, ceramic matrix composite (CMC) parts by running rotating low-pressure turbine blades in a F414 turbofan demonstrator engine designed to further validate the heat-resistant material for high-stress operation in GE’s next-generation Adaptive Engine Technology Demonstrator (AETD) program currently in development with the United States Air Force Research Lab (AFRL).
Because the rotating turbine blades made from CMCs are one-third the weight of conventional nickel alloys used in the high-stress turbine, they allow GE to reduce the size and weight of the metal disks to which the CMCs system is connected.
GE’s adaptive cycle engine will be much more durable than conventional engines because the CMC’s material temperature capability is hundreds of degrees higher than legacy nickel-based alloys currently in service in both commercial and military engines.
US Army using Composites for tougher, lighter armaments
The Army’s work with composite materials includes metal matrix, ceramic matrix and carbon-carbon composites in addition to polymer matrix, Littlefield said. For instance, carbon-carbon is used on space vehicles to withstand heat upon reentry. Heat resistance has real applicability to Army weapons systems because excessive heat is what often causes those systems to fail.
Composites for armored vehicle
Similar to the aerospace sector, composite materials are also being used in armour manufacturing to reduce weight, while still maintaining key ballistic and blast protection. Engineers claim they can now mould a vehicle shell that weighs just less than one tonne, rather than the two tonnes for steel, with similar protection properties.
Vehicles, like Supacat’s SPV400, have a fully composite armour ‘pod’ which can also be supplemented with ceramic plates if necessary.
Reducing weight through using composites means a vehicle can carry more fuel, ammunition and troops if required. Using composites will also reduce a vehicle’s overall through-life costs, while increasing its service life, mainly because composites will not rust or suffer from fatigue like metal parts.
Composites for Soldiers
The U.S. Army is developing a “third arm” device that can be attached to a soldier’s protective vest to hold a weapon. The purpose of the device is to redirect all of the weight of a weapon to the soldier’s body and lessen the weight on the soldier’s arms, freeing up his or her hands for other tasks. The prototype of the third arm weighs less than four pounds thanks to the use of carbon fiber composites. “We’re looking at a new way for the Soldier to interface with the weapon,” said Zac Wingard, a mechanical engineer for the Army Research Laboratory’s Weapons and Materials Research Directorate.
As the Army Research Laboratory explained, some soldiers are weighed down by combat gear heavier than 110 pounds. Those heavy loads may worsen as high energy weapons are developed for future warfare. The third arm could also allow soldiers to use future weapons with more recoil. Additionally, researchers plan to examine the device’s potential applications for various fighting techniques, like shoot-on-the-move, close-quarters combat, or even shooting around corners with augmented reality displays.
Composites for Weapons
Army has also started using composites in guns by replacing part of it by composites. Composites also allow tailorability in design, with different composite formulations used for different parts of a gun. In critical areas, stiffer, more expensive composites can be used, whereas in other areas, less expensive and more flexible composites can be used.
One of the biggest problems with composites is getting them to stick to the portions of a gun that must continue to be manufactured of steel, such as the barrel, Littlefield said.
The XM360 120mm cannon, part of the now-cancelled Future Combat Systems, remains one of the most mature examples of composites development. To ensure that the composite jacket fits securely over the barrel of the XM360, the steel core was first contracted by chilling it with frozen carbon dioxide, Littlefield said. Then, thermal plastic was wrapped tightly around it. Finally, as the frozen barrel warmed up, it expanded into the composite jacket.
Among crew-served weapons, the 81mm mortar tube and baseplate are now being researched for composites integration, Littlefield said. Testing should begin in about another year.
Littlefield said that metal and ceramics composites are being tested to help with excessive overheating in mortar tubes. Composites could also help reduce the weight of mortar tubes, placing less of a burden on the teams that use them. Composites could reduce the entire weapon from 90 pounds down to 50 pounds, he said. The base plate alone would go from 25 to 15 pounds.
Work is also being done to lighten the M109A6/M284 Paladin Cannon bore evacuator, using composite technology similar to that used on the M256 cannon of the Abrams tank. Composites should lighten the M284 Bore Evacuator from 200 to 78 pounds. The new composites should be ready for use in about five years and may also be used for the 155mm howitzer.
Fifth-Gen Russian Subs to Use Composites for Increased Stealth
Fifth-generation Russian submarines will use anti-sonar composite materials to hide them from enemy detection systems.“The structure and composition of these new multilayer composite materials will significantly reduce the sonar signals reflected from submarine, isolate working mechanisms from vibrations, and so on,” Valery Polovinkin, an adviser to the general director of the Krylov State Research Center, told Izvestia.
He also said that, due to the composite material’s high internal loss factor, enemy sonar would simply be unable to pick up the required level of signal while the material’s sound absorption characteristics would minimize the spread of vibrational energy.
The use of composite materials would reduce the weight of the submarine’s structures, increase its reliability and reduce operating costs since composites don’t corrode and need no paint. Composite structures would also simplify manufacturing, Polovinkin added. The new composite materials are currently being tested and the first all-composite propeller may be ready for sea trials already in 2018.
US Navy works on new composite materials
US Navy has issued a SBIR for development of a prototype radome and multi-band (at least C and Ka bands) antenna system that features an ideal mix of traditional metallic and composite materials as well as candidate advanced composites and meta-materials to allow placement on aircraft carrier mast or superstructures and protection/relocation from jet blast. The jet blast resulting from take-off and landing of VTOL aircrafts have resulted in the destruction of radomes as well as the antennas they protect from the environment.
The focussed areas are:
(1) Identify or develop methods for using advanced composite and/or meta-materials to yield significantly lighter antennas, gimbal mechanisms, and pedestals with equal or greater performance,
(2) Identify or develop advanced composite and/or meta-materials that will result in the ability to yield multi-band reflector arrays (i.e. advanced composites and meta-materials that selectively responds to multiple simultaneous set of wideband and narrowband satellite signals), and
(3) Using the knowledge gained and materials identified/developed under areas (1) and (2) to reduce large satellite antenna count and to allow mounting the lighter multi-band antennas on the aircraft carrier’s mast or upper superstructure so they are not subject to blockage or jet blast from VTOL aircraft.
The U.S. Navy has completed the limited purpose cooperative research and development agreement (CRADA) it undertook with the Swiss company Evolva to support the joint development of new composite materials.
The focus of the efforts supported by this CRADA relate to the development, validation and potential commercialization of new fire-resistant composite materials to save lives and reduce harm from fire. According to Evolva, these materials would be used on aircraft, waterborne craft, fabrics, armored vehicles, and construction materials.
These composite materials are based on a molecule that can be manufactured on an industrial scale using biotechnology and fermentation, and then polymerized and shaped/molded using standard fabrication techniques, the Swiss company explained.
Composites in Combat Engineering Systems
Combat engineering is essential in enabling forces to overcome diverse obstacles. Another promising area is the use of composites in float and fixed bridges which will bring about lighter, stronger and longer bridges. However, the use of composites is not without disadvantages. Other than cost, the use of composites poses several technical challenges.
The maintenance of composite material structures is more challenging than conventional material structures used in bridges like steel or aluminium alloys. While conventional materials can be repaired by welding, the repair is considerably more complex if a delamination occurs between the fibre and matrix in a fibre composite structure.
Furthermore, the delamination may not be visible to the operator who would not be able to sense the need for maintenance even when potentially severe damage has occurred. Hence, more experience and expertise are required to maintain composite structures. Composites are also very sensitive to flaws sustained during the manufacturing process as compared to metals. Any deviation from a tightly controlled process may lead to a compromise in the material properties of the composite.
These factors contribute to the high cost of incorporating composites in combat engineering systems. However, as more advanced composites are developed, the use of composites could be more cost effective. This could result in a trend towards the use of more composites in combat engineering systems.
Reducing Complexity: DARPA Seeks New Composite Material and Process for Manufacturing Small Parts
DARPA has launched its Tailorable Feedstock and Forming (TFF) program, which aims to reduce the time and cost burdens associated with current manufacturing design and development cycles for defense platforms. TFF aims to cut the turnaround time for part modifications and redesigns by as much as 50 percent.
Composite materials are extremely strong and lightweight, but automated systems for producing composite parts are currently cost-effective only for parts weighing 20 pounds or more. Parts weighing less than 20 pounds are usually manufactured using metals, such as aluminum, which cost less than composites but are more dense, adding weight to the system.
TFF has two main focus areas—how to make aerospace composite materials more affordable and how to process this new material into useable product form, Maher said. In current composite manufacturing, developing the tools to process materials into products takes a significant amount of time. Any design changes in the platform require redesign of the tools resulting in significant cost and schedule delays.
“Tooling processes can take six to 12 months per design cycle, significantly pushing out the timeline for production,” Maher said. “By developing flexible forming solutions to allow for multiple parts from one work cell, we believe we can shorten the tooling and production cycle for parts—which typically includes an initial design and two re-design periods—down to three years, from today’s average of about six years.”
The TFF program is seeking a tailorable short-fiber composite feedstock that is stampable and moldable and yields aerospace-grade properties. TFF also seeks technologies to create a tailorable forming work cell capable of manufacturing multiple part configurations with minimal reconfiguration costs and allowing rapid fabrication cycle time.
“If we’re successful, this program should reduce the weight of military systems by making composite parts as affordable as metal, eliminate the lengthy and costly re-tooling burden, and open new design space for small composite parts,” Maher said.
Cost and risk, especially when human life is involved, have impeded the use of advanced composites in commercial and military aircraft; however, these barriers are being overcome as both positive outcomes and user experiences increase. New applications for composite materials and structures emerge every day.
The Defense Advanced Research Projects Agency (DARPA) has awarded the University of Delaware Center for Composite Materials (UD-CCM) a $14.9 million three-year cooperative agreement for the Tailorable Feedstock and Forming (TFF) Program.
Under the leadership of director Jack Gillespie, UD-CCM seeks establish a semi-automated pilot plant to produce TuFF starting with carbon fiber precursors and ending with net-shape zero-waste formable feedstock blanks. The aim of the pilot plant is to demonstrate the feasibility and scale-up of novel technologies developed through this program with capacity to supply TuFF feedstock to designated industries for evaluation and prototype development.
The success of TuFF as a new material is expected to be transformative for complex curvature composite structures for aerospace and automotive applications in the defense and commercial sectors. “Bypassing all of the manufacturing problems associated with advanced composites, our approach will allow us for the first time to make composite parts having aerospace properties at automotive prices,”said Rob Adkinson, TuFF program manager.
PMC, CMC and MMC
Composite material is made up of fiber and matrix. The fiber provides physical strength and distributes loads in composite. The matrix material act binder. The role of the matrix is to bind the reinforcement together so that the applied stress is distributed among the reinforcement and to protect the surface of the reinforcement from being damaged from abrasion and environmental damage.
Composites are classified according to their matrix phase: Polymer matrix composites (PMC’s), Ceramic matrix composites (CMC’s) and Metal matrix composites (MMC’s). A carbon-epoxy composite consist of carbon fibers in an epoxy matrix
A polymer matrix composite (PMC) consists of a thermoset or thermoplastic resin matrix reinforced by fibers that are much stronger and stiffer than the matrix. PMCs are attractive because they are lighter, stronger, and stiffer than unreinforced polymers or conventional metals, with the additional advantage that their properties and form can be tailored to meet the needs of a specific application
Advanced composite materials comprised of carbon/graphite, aramid/Kevlar, and boron fibers, for example, along with engineered resin systems, have been used as primary structure in, for instance, the Boeing 777/787, a variety of Airbus aircraft, business jets, and military aircraft such as the U.S. Air Force F-22, F-14, and the AV-8B. Polymer composites have a high resistance to chemical corrosion and scratching. Their resilience to seawater and rust is an advantage when used in boats or other marine craft manufacture. Because the matrix decomposes at high temperatures, current PMCs are limited to service temperatures below about 300° C.
According to a new market report published by Lucintel, the future of the global composites market looks bright, with opportunities in the transportation, construction, wind energy, pipe and tank, marine, consumer goods, electrical/electronic, aerospace, and others. The global composites market is expected to reach an estimated $37.3 billion by 2021 and it is forecast to grow at a CAGR of 5.1% from 2016 to 2021. The major drivers of growth for this market are double-digit growth in wind energy and strong growth in aerospace market. Increasing urban population and high growth in the building and infrastructure development are other major drivers.
In 2015, major trends in the automotive industry are towards delivering more fuel efficient vehicles, providing a safer vehicle for the end-users, and as well as reduction in exhaust emissions. Hence Manufacturers of composite materials are coming with new and advanced manufacturing process to make improved composite materials to meet rigorous standards says Research and Markets “Composite Materials Market 2015 – Global Forecast to 2020” report.
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