A comprehensive collection of news and information about composites.
Posted by: Sara Black26. February 2015
Semi-structural composite panels are playing a big role in the design and construction of the San Francisco Museum of Modern Art.
Sitting here looking out at the snow is making me think of warmer places. Warmer places brings to mind Florida – and the first time I went to Florida to cover a trade show, ACMA’s (then CFA’s) Composite 2001 in Tampa. That was when I met Bill Kreysler of Kreysler and Assoc., and nervously attended a meeting of the ACMA’s Architectural Division. My knowledge of composites was still very rudimentary at that point, and I hadn’t thought much about the use of composites in architecture, but Composites Technology magazine had run a story on fiberglass architectural decorative elements in 1996, and another in October 2000, about the use of composites to seismically upgrade the Marin County, CA, US, government building designed by Frank Lloyd Wright.
That 2001 Division meeting sparked an enduring interest in composites for architecture and civil construction, for me, and led to many conversations with Kreysler and others, which in turn resulted in some great articles over the ensuing years — articles on bridges, buildings, Denver’s giant bear sculpture, and later, fire safety, building code changes and architectural facades and building elements being embraced worldwide. The picture above shows Kreysler’s façade for the San Francisco Museum of Modern Art that’s currently under construction.
It is gratifying to look back over the past 14 years and see just how far this market sector has come. In addition to generating great story topics, ACMA and the Architectural Div. have made important progress in ensuring the inclusion of composites in building codes. I don’t believe I’ll soon have a repeat of the telephone call to a New York-based architect, at least 10 years ago, for a story. When I asked his view on composites usage in commercial buildings, he replied, “I’ll never use composites in a building.”
This topic has already been covered extensively by several CW writers, including my colleague Ginger Gardiner, who posted an interesting blog a couple of months ago about an event at the University of Southern California’s School of Architecture. She also visited and reviewed the ACMA Architectural Div.’s exhibit at the 2014 American Institute of Architects’ (AIA) national meeting, a “Composites Pavilion” in the exhibit hall that provided information for architects and designers about composite materials. That event was the springboard for the introduction of some really significant new products, including the new foundation wall system from Epitome. The group will mount another, larger Composites Pavilion at the 2015 AIA conference.
Ashland Performance Materials has been instrumental in helping to promote the growth of architectural composites, including development of a Web site called Compositebuild.com. The site is an informational hub that seeks to connect architects and builders to composites, and offers educational pages, case studies and links to composite firms and best practices. Another resource showcasing the reach of composites into architectural design is a blog called Composites and Architecture, an inspiring and visually stunning site built by Kreysler and Assoc. with input from contributors around the world. It shows how composites are currently being used in buildings as well as in artistic design.
The point of all this is this: Composites have made great strides in buildings and architecture because of the hard work of some industry champions to get the word out. It’s all about increasing awareness, offering education, explaining the technology, overcoming prejudices, discussing total lifecycle costs and increasing interest level in a community so that material and fabrication costs can come down as demand increases. The fact that recent building code changes allow use of composites means that architects and designers need to get up to speed on our materials and how they can be applied, to great benefit. As I wrote in my February 2013 architectural article, a well-known architect (who happens to be a neighbor of mine) said, “Architects are always intrigued by new materials. If they can perform and meet code and provide some unusual capability, then it’s worthwhile, despite added cost.”
Good to write about a hot composites trend on a very cold, snowy day.
Posted by: Ginger Gardiner18. February 2015
This blog comes from my discussions with Steve Savoie, a manufacturing and tooling engineer who spoke at last year’s International Boatbuilders Exhibition (IBEX). Steve has a background in both aerospace and marine composites, and specializes in process development, tooling design and equipment utilization. For example, his session at IBEX discussed temporary oven design and cheap ways to set up aerospace-quality data loggers and temperature control systems (watch for a blog on that coming soon). We were discussing a project using A&P Technology’s (Cincinnati, OH, US) QISO material, and he commented what a great material it is for tooling, but that a lot of people don’t seem aware of it for that end use. Not being an expert on tooling myself, I asked Steve to explain what QISO offers for composite tooling and why.
QISO was introduced by A&P several years ago. Its weave pattern features 0°/±60° carbon fiber tows braided to yield a single layer of fabric that is balanced, symmetrical and quasi-isotropic. This offers real benefits for layup of complex tooling geometry. The bias yarns are two over, two under, alternating over and under the axial yarns with equal amounts of material by weight in each direction. A&P also notes that in testing, QISO has demonstrated reduced interlaminar stresses vs. more traditional laminates (e.g., 0°/±45°/90°) because all QISO plies feature the same architecture — i.e., you don’t have a large stiffness in the 0°, which then drops off in the ±45° directions.
QISO carbon fiber fabric is balanced, symmetric and quasi-isotropic, all in one layer.
SOURCE: A&P Technology.
According to Savoie, QISO enables material savings by not having to cut and orient each individual ply to create a quasi-isotropic layup, as is typically done with conventional weaves. Since the braided fabric is quasi-isotropic itself, this step is removed from the fabricator. This is significant when one considers the typical waste involved when cutting fabric on a 45° angle for a typical eight-ply layup for quasi-isotropic tooling skins.
QISO enables multi-ply tooling layups with less labor and waste.
SOURCE: A&P Technology.
Being freed from the typical eight-ply tooling laminate also opens the possibility of unique layups such as six- or even nine-ply constructions, for example. By tailoring the mold tool sheet thickness (and cost), the tooling designer can place the fabric only where it is needed to maintain tool stiffness and geometry.
Another noteworthy attribute of QISO quasi-isotropic fabric is that it is a balanced, symmetric weave, which obviates the need to ensure the weave architecture is symmetrical across the neutral axis of the laminate. Better said, the cured tooling will not “potato chip”.
Editor’s note: A balanced fabric or laminate has equal numbers of plus- and minus-angled plies. A symmetric fabric or laminate has ply orientations that are symmetric about the mid-plane (neutral axis). Quoting from Abaris Training’s textbook on advanced composite fabrication and repair: “Laminate symmetry is necessary to maintain dimensional stability through processing.”
Savoie’s example of potato chipping is when a single ply of an asymmetric weave such as a five-harness satin is processed through an elevated cure cycle. Upon returning to room temperature the thermal stress of the matrix typically cups opposing points on one axis up and the perpendicular axis down. To counteract this effect, one typically has to make sure the weave architecture is layed up to produce symmetry about the neutral axis. This process is often termed “paper up, paper down,” which refers to the release paper side of prepregged fabric, and making sure asymmetric fabrics are flipped upside down on the other side of the mid-plane. This is not necessary with QISO because the fabric itself is symmetric.
Symmetric QISO Asymmetric woven
Because QISO is symmetric, it alleviates issues with warping due to thermal stresses.
SOURCE: A&P Technology.
QISO also provides a cost-effective solution for backing structure (egg crate) on elevated-cure composite tooling. Savoie says the material lays down fast right off the roll, and the heavy weight version bulks up quickly. In addition, he says its price per pound is very attractive. The width of the sheet is easily augmented with an additional strip of fabric, making sure to stagger joint placement for additional plies. Similar to the tooling shell, the backing structure laminate is symmetric and quasi-isotropic so that adding or reducing the thickness of the sheet is as easy as adding more plies or laying up less. QISO is offered in a variety of standard widths including 36, 52 and 59 inches and also in a range of standard areal weights including 272 g/m2 (gsm), 532 gsm and 1150 gsm. Fabric widths and weights can also be customized.
As with any other new fabric to a shop, Savoie advises doing an infusion rate study with the tooling resin selected for the application. These infused flat sheets (typically 0.25-inch thick) are well suited for waterjet cutting, which makes them an economical alternative to purchasing processed sheet stock. A&P is also working with TenCate Advanced Composites (Morgan Hill, CA, US) to offer QISO fabrics as standard prepregs.
While the focus here is on tooling applications, QISO has and continues to be used for a variety of structural composites (see Editor’s Picks at right).
Steve Savoie consults in the greater New England area and can be reached at CBNFBR@gwi.net.
Posted by: Sara Black11. February 2015
The American Composites Manufacturers Association (ACMA, Arlington, VA, US) has published a new manual under the banner of the American National Standards Institute (ANSI, Washington, DC, US). “FRP Composites Grating Manual for Pultruded and Molded Grating and Stair Treads” is intended to educate engineers, designers and end-users about the properties, performance and uses of fiber-reinforced polymer (FRP) grating. Greater knowledge of the performance benefits of FRP will increase awareness of the material and enable engineers to design and use FRP with confidence, says ACMA. FRP grating is used in many industries, from walkways in industrial plants to flooring on ships to decorative grids on commercial and residential buildings. It is more durable and corrosion resistant than steel, which can rust and corrode in extreme environments.
Aldred D’Souza, P.E., the director of engineering/design at Fibergrate Composite Structures Inc. (Dallas, TX, US) and the chair of ACMA’s Fiberglass Grating Manufacturers Council, says, “The successful completion of the FRP Composites Grating Manual marks a major milestone in the advancement of the Industry. This new standard should increase the awareness of FRP grating and its suitability in a wide range of markets beyond wastewater treatment plants, waterparks and chemical plants. As FRP gratings become more mainstream because of this wider acceptance, market expansion for composites is evident.” Other members of the Fiberglass Grating Manufacturers Council who also participated in development of the publication include Strongwell (Bristol, VA, US), Delta Composites LLC (Spring, TX, US), Seasafe Inc. (Lafayette, LA, US), Creative Pultrusions Inc. (Alum Bank, PA, US), Owens Corning (Toledo, OH, US), Interplastic Corp. (St. Paul, MN, US), Precisioneering Ltd. (Scarborough, Ontario, Canada), and ChinaGrate (Nantong, Jiangsu Province, China).
The new publication is not a design manual nor requirement, but a voluntary consensus standard. Approval of an American National Standard requires review by ANSI and assurance that the requirements for due process, consensus and other criteria for approval have been met by the standards developer, in this case, ACMA. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by “directly and materially affected interests.” The use of American National Standards is completely voluntary; their existence does not in any respect preclude anyone, whether he or she has approved the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards, emphasizes ACMA in the standard’s Preface.
The FRP Composites Grating Manual has three sections:
The new FRP Composites Grating Manual (print and digital versions) can be found at the ACMA Education Hub. The manual costs $50 for ACMA members and $75 for nonmembers for a hard copy. A digital download (PDF) version costs $40 for members and $60 for nonmembers.
To learn more about ACMA’s Fiberglass Grating Manufacturers Council, contact John Busel at email@example.com.
The X4 is one of three new Airbus Helicopters in development at Donauwörth.
SOURCE: Airbus Helicopters and AINonline.
Airbus Helicopters (Marignane, France.), a division of Airbus Group, claims to be the world’s No. 1 helicopter manufacturer, with 46% market share in the civil and parapublic (e.g., search and rescue, medical transport, law enforcement) sectors. The company employs more than 23,000 people worldwide and its in-service fleet includes 12,000 helicopters (roughly 1/3 of the world’s civil and parapublic fleet) operated by more than 3,000 customers in approximately 150 countries. Its subsidiary, Airbus Helicopter Germany (Donauwörth, Germany) plays a key role in the company but also in the composites and rotorcraft industries. Donauwörth has become a center for production of large carbon fiber reinforced plastic (CFRP) structures, including the entire tail boom and fenestron (tail rotor shroud) for the EC 145 T2 and large unitized parts for the new soon to be revealed X4. Aviation Week reported that the site has also prototyped composite rotor blades produced with levels of automation reaching 80%. Indeed, Airbus has outlined automation and reproducibility as key needs and opportunities for composites in future rotorcraft. This blog gives an overview of composites in rotorcraft seen through the lens of this German hub of innovation and expertise
Donauwörth history and capabilities
Donauwörth was originally established in 1946 as the engineering company Waggon- und Maschinenbau GmbH Donauwörth (WMD) in the Swabia region of Bavaria. It began helicopter production as part of MBB (Messerschmitt-Bölkow-Blohm GmbH) in 1978, functioning as the manufacturing arm for designs developed at the Ottobrunn headquarters. MBB was taken over by Deutsche Aerospace AG (DASA) in 1989 and its helicopter division merged with that of Aerospatiale (Paris, France) in 1992 to form Eurocopter with headquarters in Marignane, France. Eurocopter was renamed Airbus Helicopter during the 2013 reorganization of EADS into Airbus Group.
Donauwörth has a long history in composites, including MBB’s significant development work in the 1980s and 90s and Aerospatiale’s use of composites in its glass fiber composite Starflex rotor system, first flown in the Ecureuil civilian helicopter in 1974 and in the Dauphin’s fenestron enclosed tail rotor, introduced in 1972 and which went all-composite in 1982. As part of MBB, DASA and then EADS Germany, Donauwörth collaborated with various Airbus and EADS divisions (in fact, EADS Innovation Works in Ottobrunn evolved from the MBB Central Lab) and notably developed an expertise in aircraft doors, including production for the Airbus A320 family, the A330 family and A380 aircraft.
Donauwörth now builds the EC 135 T2 and T3 variants, the EC145 C2 and T2 variants, and the EC635 and EC645 military versions of the 135 and 145, respectively. Airframer.net adds military helicopter components to its production, including main rotors for the Tiger and fuselage sections for the NH90. Donauwörth facilities include a composites center, a blade and mechanical center and the 30,000 m2 Systemhaus helicopter development center opened in 2013. Employment is listed as 5413.
Composites in Airbus Helicopters
According to the book Composites Materials: Design and Applications, by Daniel Gay, by the end of the 1980s, composites were used not only in blades and hubs but comprised over 50% of the remaining rotorcraft structure. This structure became all-composite carbon fiber/epoxy during the 1990s.
SOURCE: Composite Materials: Design and Applications by Daniel Gay.
Composites use in Airbus Helicopters is shown in the slides below from a 2013 American Eurocopter presentation by Thomas Sippel titled “AEC Considerations in Rotorcraft Composites Development” and a 2014 presentation titled, “Composites in Aerospace, Future Challenges, Needs and Opportunities” by Dr. Christian Weimer, head of operations for composite technologies at Airbus Group Innovation Works, previously head of Eurocopter’s Institute for Composite Materials (Institut für Verbundwerkstoffe GmbH).
Airbus Helicopters partners in composites production include subsidiaries in Canada and Australia as well as Tier 1 supplier Aerrnova.
Composite rotor hubs
A helicopter rotor system is the rotating part which generates lift. It includes a mast, hub, and rotor blades. Notably, composites have performed in this flight critical structure for over 40 years, via the Starflex (glass fiber composite) bearingless main rotor hub which Aerospatiale pioneered and Eurocopter inherited, and the more recent Spheriflex (carbon fiber composite) system. Airbus Helicopters touts these as key safety technologies used across their product line, featuring a fail-safe design “through the application of composite materials.” This is because any damage evolves very slowly and is visible. They also reportedly ensure very fast response to pitch changes, excellent maneuverability and stability and are practically maintenance-free. The last benefit is because these systems replaced the old style bearings with laminated self-lubricating bearings and used the inherent flexibility of laminated composites for movement instead of mechanical hinges. According to Daniel Gay, the Starflex hub is made from a balanced glass fiber/epoxy layup of over 300 plies. Second Line of Defense shows a slideshow of the manufacturing steps for the Starflex (scroll to bottom of the page). The Ecureuil (EC130) also used glass fiber composites in the tail-rotor, formed by two blades attached to a composite beam. The latter, being both torsional and flexible, allowed this hinge system to be replaced as well.
Starflex bearingless rotor hub and production of the NH90 military helicopter.
Source: Airbus Helicopters.
New models and composites
According to Dr. Weimer, Airbus Helicopters definitely sees the use of composites in rotorcraft continuing to increase. Composites in the EC135 were credited with quiet operation (fenestron) and increased safety thanks to an energy-absorbing fuselage. It is hard to imagine surpassing the NH90’s reported 85% composite structure, yet Airbus indeed targets an increase should it proceed with a future heavy transport helicopter. Meanwhile, the composites content in civil rotorcraft is similar to that in commercial fixed-wing aircraft, averaging 50%. The EC175 (first deliveries were in Dec 2014) actually dropped in composites usage vs. the EC135. This is because aluminum was chosen for the airframe, perhaps because of cost or perhaps because this clean-sheet design was developed with its Chinese partner, Avicopter, which produces the main fuselage and is also creating its own variant of the rotorcraft, the Z-15/AC352 for the Chinese domestic market. The EC175 will compete in the new super-medium segment, initially against the AgustaWestland AW189, already in service, and eventually the Bell Helicopter 525 Relentless, still in development.
Source: Dr. Christian Weimer, Airbus Group.
Launched in 2014, the EC145 T2 is described as basically a new helicopter, even though it is a derivative of the long-running Bk115 that predates Eurocopter. Enhancements over its C2 predecessor include improved engines, new avionics and the largest shrouded Fenestron tail rotor (1.1m wide) that Airbus Helicopters has ever produced. Wolfgang Schoder, chief executive at Donauwörth, sites the new three-piece carbon fiber tail boom as one of the EC145’s key manufacturing advances. Designed and developed at Airbus Helicopters’ composite center of excellence in Donauwörth, the tail boom is a mostly monocoque structure, and not only saves ≈30kg vs. the previous all-metal design, but is stronger because it removes the usual stress point at the boom-vertical fin junction and is more able to cope with dynamic loads. Production was projected to ramp from 20 in 2014 to 50 in 2015 to possibly as high as 70 with a backlog of over 100 aircraft.
The new X4 helicopter will reportedly feature Blue Edge technology, part of Airbus Helicopters' Bluecopter program, which has also produced Blue Pulse technology.
SOURCE: Airbus Helicopters.
The X4 medium twin-engine helicopter is the next new development, designed to replace the long-running AS365 Dauphin/EC155 and the military version AS565 Panther. Scheduled to be unveiled unveiled on March 3 at the 2015 Heli-Expo show in Orlando, carbon fiber cockpit structures were shown to journalists in summer 2014, about the same time that fuselage components were delivered to the Systemhaus research facility. First flight for the X4 is scheduled for late 2015 with service entry in 2017. Another interesting aspect of the X4 is its use of Airbus Helicopters’ Blue Edge technology to reduce noise. The double arrow shape interrupts blade-vortex interactions (BVI) which occur when a blade impacts a vortex created at the blade tip. A five-blade Blue Edge main rotor has been flying since July 2007 on an EC155 testbed, demonstrating noise reductions of 3 to 4 dB.
The company has also developed a Blue Pulse technology which uses an active control system to reduce noise and vibration. The technologies, both developed within Airbus Helicopters’ Bluecopter program, were not developed to be used together. Piezoelectric actuators move the flap modules on the trailing edge of each rotor blade 15 to 40 times per second in order to completely neutralize the “slap noise” typically heard during descent. Blue Pulse technology has been flying since 2005, showing a noise reduction of up to 5 dB, and development of a production-ready system continues using an EC145.
Meanwhile, images have already made the rounds on the internet of what appears to be a heavily modified EC135 operating from Donauwörth. With a five-blade main rotor, wider-chord blades and the trademark kinked “Blue Edge” blades, speculation is that this is a testbed for the X9 development, currently scheduled to hit the market by 2018-2019.
Needs and opportunities in helicopter composites
Dr. Christian Weimer’s 2014 presentation also outlined what Airbus sees as the future needs and opportunities for composites in rotorcraft. These include:
All-composite aircraft doors
Donauwörth’s long history in composites R&D extends beyond rotorcraft. Airbus Helicopters reports that 1,300 of its personnel work in development, production, and maintenance of fixed-wing aircraft components. Donauwörth has over 20 years of experience and produces more than 4,000 passenger and cargo doors per year for various Airbus aircraft. Upon receipt of the competitive contract to develop and produce the all-composite doors for the A350 XWB wide body aircraft, Schoder remarked that it demonstrated Donauwörth’s innovative strength and international competitiveness in carbon fiber technology. “The development and manufacture of aircraft components is another mainstay of Eurocopter’s activities in Germany, which complements our helicopter production.” He also said it confirmed Donauwörth’s decision to focus away from traditional metal structures to new manufacturing technologies based on composites. Benefits of the all-composite design reportedly include parts reduction, the application of advanced mechanical systems, additional safety features and equipment that is easier to maintain. A new building at Donauwörth was designed to enable automated production methods and quality control at high production rates.
Awarded in 2010, Donauwörth’s contract is for all A350 doors, each shipset including four pairs of passenger doors, two cargo doors and one baggage door. Korean Air Aerospace Division is a program partner, reportedly producing three of the doors, including the cargo doors.
According to an article by RTM press manufacturer WICKERT (Landau in Pfalz, Germany), it supplied a composite press system to Donauwörth, specifically developed for the production of the A350 XWB doors. The WKP 2500 S composite press for resin transfer molding (RTM) A350 door elements features integration of the injector, heating and cooling and press shuttle into the press control system. The press, which has one fixed upper arm and one fixed lower arm, features a 1200mm installation height, 2500 kN closing pressure, 2400 x 1800 mm mounting plates and 1000 mm piston stroke. Fully automatic mounting is carried out via shuttle which also handles return transport after processing. Cycle time at the Donauwörth production facility is reportedly 6 hours per aircraft door.
Wickert exhibited a complete A350 inner core door frame (left) at Composites Europe 2013 (Sep 17-18, Messe Stuttgart, Germany), manufactured using RTM with the WKP 2500 S Composite Press (right). SOURCE: Wickert
When asked if Donauwörth will get involved with further fixed-wing projects beyond the A350 doors, Schoder replied the door production comes out of the facility’s past and is an important business, but not its core. He said he had no intention to extend that cooperation or grow that partnership with Airbus Toulouse. And yet, it’s obvious the facility has developed the ability to supply large, high-quality, primary structure assemblies meeting full-rate production requirements, a feat which is still a struggle for some suppliers.
Posted by: Jeff Sloan3. February 2015
Learjet 85 workers in Mexico had helped develop the out-of-autoclave processes used to fabricate the plane's fuselage.
Bombardier (Montreal, Quebec, Canada), disappointingly but not surprisingly, announced in mid-January that it is pausing the development of the composites-intensive Learjet 85 business jet and laying off 1,000 employees in Wichita, KS, US, and Querétaro, Mexico, who were working on the program. As a result, the company will record a pre-tax special charge in the fourth quarter of 2014 of approximately $1.4 billion, mainly related to the impairment of the Learjet 85 development costs. Bombardier pointed to the sluggish business jet market as the reason for the action.
“Bombardier constantly monitors its product strategy and development priorities,” says Pierre Beaudoin, president and CEO, Bombardier. “Given the weakness of the market, we made the difficult decision to pause the Learjet 85 program at this time. We will focus our resources on our two other clean-sheet aircraft programs under development, CSeries and Global 7000/8000, for which we see tremendous market potential. Both programs are progressing well.”
The question that remains is whether or not the Learjet 85 program has been simply paused, or whether it’s permanently discontinued. Official statements from Bombardier leave open the option of resurrecting the program. It’s possible, however, that the company is simply cutting its losses and moving on.
Whether or not the program survives, there’s no argument that Bombardier was unusually ambitious in the application of composites to the aircraft — particularly an aircraft of its relatively small size. Carbon fiber wingskins and spars for the plane were being fabricated in Belfast, Northern Ireland, using an in-autoclave resin transfer infusion process (RTI). More significantly, the fuselage was being infused out-of-autoclave (OOA) in Querétaro at an altitude of more than 6,000 ft. Fabricating a fuselage OOA is unusual by itself. Doing so at 6,000 ft, where available vacuum pressure is 20% less than at sea level, had tested Bombardier severely.
Still, when Bombardier’s Pierre Harter reported on the Learjet 85’s composites work at SAMPE 2013, it sounded like many of the technical hurdles has been cleared. Indeed, the process had been tuned to the point where Bombardier had void content of <1% in the fuselage structure. Such progress, it is hoped, can be applied elsewhere if it doesn’t live on in the Learjet 85.