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A comprehensive collection of news and information about composites.

Posted by: Jeff Sloan

22. September 2016

Now that the composites industry has absorbed the behemouths that are the composite-intensive Boeing 787 and Airbus A350 XWB commercial aircraft programs, and now that Boeing has selected its suppliers for the 777X wing fabrication program, it's time to look ahead and think more critically about where and how composites might or might not be used in future aircraft. This is particularly important as Boeing and Airbus contemplate replacing, respectively, the 737 and the A320, and as Boeing considers replacing the 757.

The assumption for some in the industry is that the 787 and the A350 are the new standard for composites use in commercial aircraft, and that new aircraft that follow will employ the same model. However, the factors that drove material use decisions in the 787 and the A350 are different than the factors that will drive material use in a new 737, A320 or 757. Further, 787 and A350 material decisions were made a decade (or longer) ago, and the landscapes of the composites industry and the aerospace industry are much different today. 

In the meantime, manufacturers of legacy materials, like aluminum, have responded aggressively to the composites incursion and are developing new materials of their own designed to claw back the market share lost on the 787 and A350 programs. And, if you throw titanium into the mix, then the materials use picture becomes even more muddled.

It's with all of this in mind that we here at CW have developed a new webinar, designed to take a long, unbiased, practical look at the aerospace supply chain and how composites fit into the aircraft material pallette. To do this, we've asked Kevin Michaels, president of AeroDynamic Advisory, to present "Aerospace Composites in the More for Less Era," on Oct. 7 at 2 pm EDT. 

This webinar will specifically evaluate how the overall aerospace materials supply chain has evolved over the last five years, and look ahead to the materials options aircraft OEMs face as legacy aircraft like the Boeing 737 and the Airbus A320 reach maturity and possible redesign. This webinar will also look at the challenges faced by increased composites use in commercial aerospace and how competing material suppliers are responding. 

Kevin Michaels might be familiar to some of you. His company, AeroDynamic Advisory, a consulting firm focused on the global aerospace and aviation industries. He has 30 years of aviation experience and is a globally recognized expert in the aerospace manufacturing and MRO sectors. He also has significant expertise in business-to-business marketing, customer satisfaction, M&A advisory, technology assessment, cluster development and strategic planning. Kevin is a contributing columnist to Aviation Week & Space Technology and serves on the advisory board of the University of Michigan’s Aerospace Engineering Department. 

If you have a stake in aerocomposites material development, or aerocompsites fabrication, I hope you will join us for what I am sure will be an interesting and thought-provoking webinar.

Posted by: Heather Caliendo

21. September 2016

Researchers at the University of Birmingham (UK) and Harbin Institute of Technology (China) say they have developed a method of allowing composites to self-heal cracks at temperatures well below freezing. The paper, published in Royal Society Open Science, is reportedly the first to show that self-healing materials can be manipulated to operate at very low temperatures (-60°C).

The team stated that it could be applied to fiber-reinforced materials used in situations where repair or replacement is challenging such as offshore wind turbines, or even “impossible”such as aircraft and satellites during flight.

Self-healing composites have been able to restore their properties automatically and in favorable conditions, composites have shown impressive healing capability. But the researchers claim that until this paper, healing was deemed insufficient in adverse conditions, such as very low temperature.

Similarly to how some animals in the natural world maintain a constant body temperature to keep enzymes active, the new structural composite maintains its core temperature. According to researchers,  3D hollow vessels, with the purpose of delivering and releasing the healing agents, and a porous conductive element, to provide internal heating and to defrost where needed, are embedded in the composite.

Yongjing Wang, PhD student at the University of Birmingham, explained, “Both of the elements are essential. Without the heating element, the liquid would be frozen at -60°C and the chemical reaction cannot be triggered. Without the vessels, the healing liquid cannot be automatically delivered to the cracks.”

A healing efficiency of over 100% at temperatures of -60°C was obtained in a glass fiber-reinforced laminate, but the technique could be applied across a majority of self-healing composites. Tests were run using a copper foam sheet or a carbon nanotube sheet as the conductive layer. The latter of the two was able to self-heal more effectively with an average recovery of 107.7% in fracture energy and 96.22% in peak load.

The healed fiber-reinforced composite, or host material, would therefore have higher interlaminar properties – that is the bonding quality between layers. The higher those properties, the less likely it is that cracks will occur in the future.

Wang added, “Fiber-reinforced composites are popular due to them being both strong and lightweight, ideal for aircraft or satellites, but the risk of internal micro-cracks can cause catastrophic failure. These cracks are not only hard to detect, but also to repair, hence the need for the ability to self-heal.”

The group will now look to eliminate the negative effects that heating elements have on peak load by using a more advanced heating layer. Their ultimate goal, however, is to develop new healing mechanisms for more composites that can recover effectively regardless the size of faults in any condition.

Photo credit: University of Birmingham. 

Posted by: Heather Caliendo

21. September 2016

Automated Dynamics (Schenectady, NY) has installed a laser-based heating system (LHS) at UK’s University Of Sheffield and their Advanced Manufacturing Research Centre (AMRC) for use in thermoplastic composite production.

AMRC works alongside the industry to ensure development of the latest manufacturing technologies. They pride themselves on being at the forefront of new advancements, and considers composites as one of the "world’s most exciting manufacturing areas to experience growth."

Automated Dynamics’ laser heating system offers another way for researchers and educational bodies to explore an emerging technology and the associated advantages. Current hot gas heating methods have been used for automated fiber placement of thermoplastic composites, but can come with relatively slow processing rates and increased expense. Alternately, laser heating provides higher energy density and more uniform heating for faster processing rates, higher bond strength and superior surface finish. Improved process control is achieved through closed loop control of the bond zone temperature in real time. This is possible due to the millisecond response time of the LHS compared to the hot gas torch (HGT) response time of minutes. Overall, these changes translate to a 30% savings in production time and a corresponding decrease in manufacturing costs. Enabling companies to explore these methods allows for experimentation and prototyping with relatively low upfront investment, as opposed to purchasing and implementing new systems independently. In addition, testing the feasibility of new parts and processes encourages growth, innovation and expansion.

Most importantly, though, it provides the next generation of engineers and manufacturers exposure to the types of processes and technologies that will advance the composites industry.

Automated Dynamics prototype laser heating system with thermal camera temperature control.

Posted by: Ginger Gardiner

21. September 2016

Simplified production process: Inner part of ENERCON EP4 rotor blade
made with same automated winding/wrapping technique as for E-115 blades.
SOURCE: ENERCON magazine Windblatt, 01-2015

In close cooperation with its customer ENERCON (Aurich, Germany), Roth Composite Machinery (formerly EHA Composite Machinery, Steffenberg, Germany) has developed filament winding systems for the manufacture of composite rotor blade components for ENERCON wind turbines. Installed at two different ENERCON blade production plants, the automated winding systems are used to produce the shorter, inner blade sections for Enercon’s E-115, E-126 and E-141 turbines with rotor diameters of 115.6m, 127m and 141m, respectively.

A subsidiary of Roth Industries (Dautphetal-Buchenau, Germany), Roth Composite Machinery develops, designs and builds production lines for the manufacture of composites including filament winding systems, prepreg plants and coating/converting machines (finishing of web products). It excels in systems for high-quality and high-performance products for lightweight applications, and has more than 50 years of experience in the manufacture of filament winding systems. It already has similarly-sized, automated filament winding systems in use for large-scale FRP containers as well as in the aerospace industry for manufacturing rocket motor cases for the Vega and Ariane 5 launch vehicles.

Roth Composite Machinery will be exhibiting its full line of composites equipment at CAMX 2016 (Sep. 26-29, Anaheim, CA) in booth T79.
 

 Roth Composite Machinery’s unique winding and impregnation expertise The automated winding/wrapping systems feature movable platforms which enable continuous material flow and high efficiency. SOURCE: Roth Composite Machinery.


Automated Winding/Wrapping
The system developed with ENERCON exploits Roth Composite Machinery’s filament winding and impregnation expertise, alternately applying glass fiber fabrics and glass fiber rovings impregnated with epoxy resin. The reinforcement materials are impregnated and carried on movable platforms, enabling a nearly continuous material flow and high efficiency, important when manufacturing products of this size.

According to Roth Composite Machinery sales manager Dirk Fischer, his company has the unique ability to integrate two technologies into one machine concept: “It not only handles heavy mandrels — e.g., 30-80 metric tonnes — but also quickly impregnates and quickly applies both filament winding roving and woven fabrics.”

With a rail length of almost 50m, the system can produce components up to approximately 3m in diameter and 20m in length. The system builds local thickness where needed — for example, in flanges for joining the blade segments — and comprises the following: 

  • Drive stand for initiating the torque;
  • Flexible tailstock for the fixture of different mandrel lengths;
  • 3D-mandrel
  • Movable platforms for resin impregnation and material application.

Roth Composite Machinery also supported ENERCON in concept planning and development of solutions to optimize production in the further processing steps of oven cure and demolding.

ENERCON began using segmented blades with its E-101 turbine (left) and has evolved the design through its 4 MW EP4 turbines (right). SOURCE: ENERCON.

 

Segmented Blades
ENERCON’s first use of a two-piece blade was with its 3.5 MW E-101 turbines. The smaller bolt-on section near the root acted as a spoiler, capturing additional lift. The longer E-115 blades are an evolution of that original E-101 design, as shown below, and use a patented joining method comprising both cross-sectional and longitudinal bolts.


ENERCON’s original segmented blades, the E-101 (top) and E-115 (bottom), were split longitudinally. SOURCE: Navigant Research.

ENERCON used traditional construction — resin infused halves bonded together — for the 44m outer segment and filament winding of epoxy-impregnated glass fiber fabric for the 12m long inner segment.

The automated wrapping process reduces material cost and production time while providing a higher-quality product thanks to the reliability and reproducibility of the process, as well as better working ergonomics. What is produced is actually the inner

segment’s load-bearing core or blank. In a second step, a prefabricated aerodynamic trailing edge — with ENERCON’s signature integrated spoiler, increasingly flattened for the common “flat back” airfoil — is bonded onto the blank to complete the inner blade segment.

E-115 inner blade being loaded at KTA facility (left) and E-126 inner blades assembled to hub (right). SOURCE: ENERCON and Navigant Research.


The longer E-126 blades are also segmented. Though they originally used steel for the inner blade, they also now feature an inner segment made with winding/wrapping and an outer made using the classic infused half-shell construction. Blades for the newest production turbine, the 4.2 MW E-141 again are made with this hybrid composite construction.

Opened in 2013, ENERCON’s blade production facility in Haren, Germany began testing of the automated winding/wrapping method in late 2015 and use of it to produce EP4 inner blades during summer 2016.

ENERCON’s optimized production at its Haren (left) and KTA (right) production facilities. SOURCE: ENERCON Windblatt magazine (left) and ON magazine (right).


Optimized Production
In its magazine Windblatt, ENERCON reports that this segmented blade and hybrid manufacturing approach achieves process-optimized production — reducing labor costs and increasing the precision bonding needed for the thick inner section — while simplifying transport logistics via shorter sections, especially in difficult terrain and inland space-constrained (e.g. forested) sites.

However, Roth Composite Machinery’s automated winding cells are just the latest of ENERCON’s efforts to optimize its wind blade production. “Our aim is to systematically streamline our production processes and improve efficiency,” says Jost Backhaus, managing director for ENERCON’s rotor blade production (quoted from Windblatt 03-2012). In a May 2014 Windpower Monthly article by Elize de Vries, Backhaus claimed the company’s KTA Kuststofftechnologie facility in Aurich, Germany was the world’s first rotor blade plant with continuous flow production, reducing cycle time from 10 days to 7-8 days, and enabling ENERCON to jump from 4-5 blades sets/week to 7-8 weekly shipsets.
 


SOURCE: ENERCON Windblatt magazine.

Blades are moved along the production line in mobile molds, with the following steps completed at set stations:  lay glass fabrics, infuse with resin, install pre-made webs and spar boom, apply bonding agent, fold blade halves together and demold semi-finished bonded blade. While the blade is moved into the adjacent production bay, the molds returns to the beginning of the production line.

Spacing of where production occurs was also considered to optimize production logistics. “The objective here was to have short distances,” says Backhaus. Thus, fabrication of the spar webs, boom and other premade components was set up on an upper mezzanine and lowered directly into the molds by crane.

Many other production steps were automated, such as milling of the cross and longitudinal bolt holes in the blade flange for connecting the inner and outer segments. Both painting and application of adhesive to the blade shell halves and spar webs are completed robotically within mobile portals that easily accommodate variations in blade length.


Positioning robot at ENERCON’s KTA blade factory precisely places 45 layers of non-woven glass fabrics up to 45m in length into the spar mold for the E-101 rotor blades. SOURCE: ENERCON Windblatt.

Cutting and positioning of glass fabrics for the spar boom — the “backbone” of the rotor blade — are also done robotically. The machine cuts and places non-woven glass fabrics into the spar mold prior to infusion.  The fabric webs are slit to width from large supply rolls and rerolled onto special transport drums. The positioning robot rolls out the slit webs, varying 11m to 45m in length for E-101 rotor blades, positioning them precisely and repeating until 45 layers have been stacked, which takes about three hours. The robot was developed in collaboration with wi2 technologies GmbH (Barßel – Harkebrügge, Germany) and has improved quality, almost eliminating technical errors and related time-intensive rework.

Posted by: Sara Black

20. September 2016

The Chimera show truck from Svempa and Scania is a hit at car shows in Europe.

Hot-rodding might have started in the US, but it has devout adherents around the world. Fifty-one years ago, Swedish car mechanic Sven-Erik Bergendahl, nicknamed Svempa, started his tow truck business with a 1957 Plymouth sedan that he transformed into a truck, and since then, Svempa has created eye-catching and souped-up tow vehicles for car and truck shows across Europe.

In mid 1980s, Svempa and designer Jan Richter started a partnership with Swedish truck and engine manufacturer Scania to produce modified Scania trucks for shows, and the results are highly-anticipated fan successes. A recent project, dubbed Chimera, may be Bergendahl’s and Richter’s most ambitious and complex yet. Begun in early 2010, Chimera took 4 years to complete, and involves considerable composite design and materials. Richter is a friend of Ragnar Friberg, who was the source of an earlier blog about a high-end champagne flute (http://www.compositesworld.com/blog/post/not-your-average-carbon-fiber-part) and who participated in the work. The Chimera project took more than 3000 hours from first design to finish, and the vehicle is continually being optimized, says Richter. “The truck consisted of a stainless steel tubular frame with attached truck cab, front and rear axles with 4 wheels, V8 Scania engine with power train, 6 turbos, radiators, intercoolers and exhaust piping,” explains Richter. “When planning the composite body we had to take into account the heat coming from the Scania turbo-charged 16-liter V8.”

Using Richter’s drawing, Svempa workers fabricated a cardboard mockup of the bodywork, to assess aerodynamics, overall appearance and the best approach for molding the parts. They came up with five composite sections: two would cover the left and right sides of the engine, between the front and rear wheels; two would cover the left and right (front) wheels, and connect with the fifth section, at the front of the cab.

Ragnar Friberg works on the foam core ribs that shaped the composite side skirts.

Detailed measurements were taken and a series of ribs were waterjet-cut from pieces of Divinycell, Matrix MX 7-7, 25mm thick, with a density 55Kg/m3, supplied by DIAB. Friberg then “dressed” the ribs with 10mm-thick core material (same density as the 25mm) and glued the pieces to the ribs with a 30-minute cure epoxy mixed with Wacker Aerosil as a filler, which, he says, made the foam structure durable and easy to grind to final shape.

Prior to lamination, the core material was covered with an epoxy putty mixed with a thixotrope, necessary, says Friberg, to prevent the foam core from absorbing any laminating resin and becoming too heavy. The sandwich skins, inner and outer, were created with one layer of 290-g/m, 2x2 E-glass twill supplied by Hexcel, followed by a second layer of 245-g/m, 2x2 3K carbon fiber twill from AKSACA, in a hand layup process that carefully ensured the material accommodated the bodywork curves. Epoxy resin, together with a hardener that provided a 90-minute outtime, was supplied by Nils Malmgren AB. Parts were oven-cured at 60°C for 10 hours.

A view of the carbon and glass laminate.

Composite part weights totaled 41.5 kg, saving 1,500 kg compared to a production Scania truck of the same size with a steel body. Says Richter, “About 1300 hours were spent to build the truck body, not counting the paint job, and total cost was about $800,000 USD.” He adds that the goal was a contemporary, even futuristic-looking, race truck, to complement Svempas’ earlier, retro-inspired Red Pearl show truck: “Our priority was really more to display the engineering and the powerful V8 engine and turbos. The biggest challenge was setting up the frame and suspension to handle the weight of the powertrain and unsprung parts.”

The truck has now appeared at several European truck events, with very positive fan love. There are many YouTube videos related to Svempa trucks, including the Chimera: https://www.youtube.com/watch?v=zUbo0wsruew and https://www.youtube.com/watch?v=e5uTmXz2VIs. This video features the more retro-inspired Red Pearl show truck: https://www.youtube.com/watch?v=2LzwCtm6JmQ.    Check out this article about the Chimera, posted by Mack Trucks: http://www.bigmacktrucks.com/topic/36667-the-dream-truck-builder%E2%80%99s-latest-creation/.   

 

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