CW Blog

It’s not Spring without a trip to Paris, France for the JEC World 2018 composites conference. It’s become a very big show, and thus, offers some big announcements and some developing trends. As CW’s Jeff Sloan pointed out in his Day 1 video yesterday, many companies are focused on aerospace with numerous examples of fuselage and structural panel demonstrators. A great number of exhibitors clearly favor diving into the automotive supply chain, offering materials (resins, reinforcements) and equipment for fast, high-rate production — like last year, leaf springs are again on display are numerous stands. Building/construction, marine, sport, architecture, art and more are all represented with new products and concepts. And, automation, Industry 4.0-compliant equipment, software and design tools, and 3D printing are clearly on everyone’s radar.

With aerospace booming, more planes are being built, faster. One strategy for driving down the costs of aerospace parts is to forego prepreg and use dry reinforcements that are subsequently infused in out of autoclave (OOA) processing. Porcher (Eclose-Badinières, France) introduced a new range of dry carbon fiber tows and tapes, called, for now, Porcher Dry Fiber, for automated processes like AFP. The dry tapes have no binder veil and are produced in a fast (patented) process that uses no water or solvent. Pierre-Yves Quefelec, Porcher’s global aerospace and defense head, says the tapes are functionalized with in-house binder chemistry, either thermoset or thermoplastic, to increase toughness, and can help drive costs out of part processing. The material, at technology readiness level (TRL) 9, is being qualified now in Europe for applications such as fuselage window frames.

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Editor Jeff Sloan and the CompositesWorld staff are in Paris for the JEC World 2018 composites industry trade show. The show is off to a busy and productive start. In this video Jeff runs through some highlights from Day One at the show. Stay tuned to the CW blog for more updates from Paris.

 

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The Stratolaunch mega-plane project continues to make progress. A recent video shows the aircraft performing a series of taxi tests at the Mojave, CA, US, Air and Space Port. The plane achieved a ground speed of 40 knots – or around 46 mph. This is a milestone for the craft, which previously reached speeds of around 28 mph in December.

With two fuselages connected by a single giant wing, the Stratolaunch is the world’s largest all-composites aircraft. It is powered by six Pratt & Whitney PW4056 engines and is 76m in length and is designed to carry a space launch vehicle payload of 500,000 lb. It has a wingspan of 118m, which is roughly 7m longer than the height of a Saturn V rocket or a 35 story building.

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A new white paper from Evonik Resource Efficiency GmbH (Marl, Germany), authored by Eike Langkabel, Sebastian de Nardo, and Jens Bockhoff, examines the best resin formulations for composites used in automotive part production, both structural parts and body panels. Specifically, the report takes a deep dive into the behaviour of various curatives and their effects on resin shrinkage, and compares epoxy and polyurethane formulations.

Residual stress is a significant problem in composites processing, say the authors, caused by chemical shrinkage of the matrix due to crosslinking of molecules, mismatch of thermal expansion or contraction among fibers and matrix (a cause of fiber print-through) and viscoelastic relaxation during fabrication. These phenomena are strongly coupled, and can lead to defects in the finished part like shape distortion, micro cracking, delamination, reduced mechanical strength, aging and wavy surfaces. And, for automotive composites, resin systems face conflicting demands: fast cycle times, which can produce residual stress, and Class-A surface quality, which decreases with increasing stress.

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