A comprehensive collection of news and information about composites.
GS Caltex, a little-known South Korean petrochemicals company based in Seoul, made a name for itself this week when it was reported to be in talks with electric car specialist Tesla Motors Inc. over the potential supply of long fiber-reinforced thermoplastics for use in Tesla vehicles. GS Caltex calls the material long carbon fiber-reinforced thermoplastic (CLFT). Properties of the material (fiber length, resin type, etc.) are unknown as yet.
Whether and to what extent Tesla employs CLFT in its vehicles, this news raises an interesting question that’s come up in the last few months as the automotive industry wrestles with the challenge of integrating composite materials into new vehicles. The question is this: If use of continuous carbon fiber in cars is too expensive, and if manufacturing processes are too slow, might long fiber-reinforced thermoplastics provide the stepping stone automakers need to start the migration to composites?
There’s much to like in long-fiber technology. First, the primary manufacturing process in which it’s used is injection or compression molding, both of which the automotive industry understands and has familiarity with. Second, several machinery suppliers, like Engel, Arburg and KraussMaffei, are working on injection technologies designed to minimize fiber shear, thus elongating fiber length in finished parts. This increases part strength and durability.
Third, there is at least some research that shows that even chopped carbon fiber provides a substantial fraction of the strength supplied by continuous carbon fiber. George Husman, chief technology officer at Zoltek (St. Louis, Mo., USA), reported at SAMPE Tech in Seattle last spring on research he’s done that shows just 0.7 mm of carbon fiber length provides 70 percent of theoretical modulus of continuous carbon fiber.
Such data require substantiation, but if it’s valid then it wouldn’t be hard to see that a long fiber-reinforced thermoplastic might easily find several homes in a car — at least in semi-structural parts, if not fully structural parts.
CW will investigate this further. Look for a more complete report soon.
For the past 100 years, protection for ground-based armored fighting vehicles and their occupants has basically mean more armor. Weapons’ ability to penetrate armor, however, has advanced faster than armor’s ability to withstand that assault. As a result, achieving even incremental improvements in crew survivability has required significant increases in vehicle mass and cost.
Increasingly heavy, less mobile and more expensive armored vehicles hinder rapid deployment and maneuverability in often challenging environments. Moreover, larger vehicles are limited to roads and require more logistical support. They are also more expensive to design, develop, field and replace. The U.S. military is now seeking innovative and disruptive solutions to ensure the operational viability of the next generation of armored fighting vehicles.
DARPA has created the Ground X-Vehicle Technology (GXV-T) program to disrupt the current trends in mechanized warfare. GXV-T seeks to investigate revolutionary ground-vehicle technologies that would simultaneously improve vehicle mobility and survivability through new approaches including detection avoidance and evasion of engagement and targeted hits.
GXV-T’s technical goals include the following improvements relative to today’s armored fighting vehicles:
“GXV-T’s goal is not just to improve or replace one particular vehicle—it’s about breaking the ‘more armor’ paradigm and revolutionizing protection for all armored fighting vehicles,” said Kevin Massey, DARPA program manager. “Inspired by how X-plane programs have improved aircraft capabilities over the past 60 years, we plan to pursue groundbreaking fundamental research and development to help make future armored fighting vehicles significantly more mobile, effective, safe and affordable.”
To familiarize potential participants with the technical objectives of GXV-T, DARPA has scheduled a Proposers' Day on Friday, September 5, 2014, at DARPA’s offices in Arlington, Va. Advance registration is required through the registration website: http://www.sa-meetings.com/GXV-T. Space is limited and registration closes Friday, August 22, 2014 at 5:00 PM Eastern Time or when capacity is reached, whichever comes first. DARPA reserves the right to limit the number of attendees from any individual organization.
The DARPA Special Notice document announcing the Proposers’ Day and describing the specific capabilities sought is available at http://go.usa.gov/Edsh. For more information, please email DARPA-SNemail@example.com.
DARPA aims to develop GXV-T technologies over 24 months after initial contract awards, which are currently planned on or before April 2015. The GXV-T program plans to pursue research, development, design and testing and evaluation of major subsystem capabilities in multiple technology areas with the goal of integrating these capabilities into future ground X-vehicle demonstrators.
The GXV-T program provides the following four technical areas as examples where advanced technologies could be developed that would meet the program’s objectives:
Radically Enhanced Mobility – Ability to traverse diverse off-road terrain, including slopes and various elevations; advanced suspensions and novel track/wheel configurations; extreme speed; rapid omnidirectional movement changes in three dimensions.
Survivability through Agility – Autonomously avoid incoming threats without harming occupants through technologies such as agile motion (dodging) and active repositioning of armor.
Crew Augmentation – Improved physical and electronically assisted situational awareness for crew and passengers; semi-autonomous driver assistance and automation of key crew functions similar to capabilities found in modern commercial airplane cockpits.
Signature Management – Reduction of detectable signatures, including visible, infrared (IR), acoustic and electromagnetic (EM).
It’s one thing to manufacture and sell a composites-related product — it’s another to truly understand how that product will behave during processing and cure. Multiaxial fabric maker Formax (Narborough, Leicester, U.K.) is involved in a multi-year endeavor to simulate, in partnership with several research and university entities, the behavior of dry fabrics during molding. Tom James, Formax’s director of innovation and leader of the modeling effort, says that the simulation research was spurred by customers interested in high-volume production and parts with complex shapes, who want to reduce their risks before any tools are cut — ultimately, the automotive industry.
James breaks down composites simulation into three major areas: 1) simulating drape, or how dry fabric will conform to the tool, or potentially wrinkle; 2) simulating flow of resin through a fabric in a tool, a problem that many have tackled, and 3) simulating how a finished part performs in service, a fairly well-understood exercise. It’s the first item that Formax is tackling, along with colleagues at the University of Nottingham through a Knowledge Transfer Partnership, the University of Cambridge and the Warwick Manufacturing Group (Coventry, U.K.). He explains that modeling dry fabric movement is very difficult because it is the “most non-linear” problem out there, i.e., no factor is directly related to another in a one to one fashion. “The material is non-linear, the material deformations are large and the loads and boundary conditions change during forming.”
The group is investigating a variety of codes that include Abaqus from Dassault Systèmes (Waltham, Mass.), PamForm’s FE multi-physics solver from ESI Group (Rungis, Cedex, France), as well as several different finite element analysis (FEA) non-linear crash analysis codes that the group has adapted to dry materials. Formax does not yet own its own software license, and participates in the knowledge transfer group strictly on a non-commercial, research and development basis for now, James explains.
“We realized that we had to be very knowledgeable about our own fabrics. We wanted to be prepared if a customer came to us and said ‘We’d like a quadraxial fabric, and please send us all the data about it so that we perform our computer analysis,’” he says. That meant creating a data base, for all of Formax’s many fabric styles, of the key material input parameters, shown in the table below — a task James describes as “time-consuming and expensive.” Each fabric was (or is being) lab tested using industry-accepted methods to generate th e material characteristics, in each fiber direction, and then those properties were physically validated using a double hemisphere (lozenge) tool in the Formax lab. The model results for a particular fabric are tweaked slightly if required to more closely match the tested reality. Eventually this testing/validation step may be eliminated, says James, but “we’re not there yet.”
To better illustrate what James and the partner group are undertaking, he cites a hypothetical structural automotive part, such as a B-pillar. The auto OEM’s engineers would design the part, and a tool, and would then come to Formax for a carbon fiber multiaxial, for example, a 0/±45/90, with a desired areal weight. Then, Formax would enter that fabric’s properties into PamForm (or another code) and create a “base” fabric simulation, which would show their customer how that fabric would behave in the mold — how would the fibers orient within the mold shape, the friction generated, locking angle, wrinkle or bridge formation, would the fabric “ladder” along the edge, and what stresses would be created. It would also illustrate the fabric’s permeability within the mold, to help define mold fill and process cycle time.
From that base condition, the computer simulations give Formax the ability to improve or optimize the fabric for that customer’s hypothetical B-pillar, says James: “We can run hundreds of simulations, changing just one thing each time, to improve fabric shear modulus, or bending stiffness, for example.” Take stitch length: in a carbon fiber multiaxial, the properties of the carbon fiber itself dominate. But, he says, the stitches are modeled as another fabric element, less stiff than the carbon. The stitches create friction between the carbon tows, causing local compression forces that affect drapability. Formax could change stitch length or style, from pillar to tricot, for example, to optimized the fabric to the mold and application. “This modeling has forced us to think about different stitch styles, and to do things we might not have tried otherwise,” adds James.
“Lots of companies offer a fabric with ‘high drape,’ but often they can’t give quantitative information to truly define fabric behavior,” concludes James. “As more high-volume automotive parts develop, we will have the capability to optimize and customize fabrics through simulation.”
Click here to view a PDF of Formax's fabric data input parameters to model simulation codes.
Posted by: Ginger Gardiner4. August 2014
Front end for the new ICx intercity trains of Deutsche Bahn (German Railways) featuring composites. SOURCE: Voith.
“Future rolling stock and infrastructure in the UK is at a materials crossroad,” noted Justin Cunningham, editor of Engineering Materials magazine, in a recent blog “Is rail industry set to lightweight with composites?” He related that the national trade association, Composites UK (Herts), held an event to introduce composites to the rail industry for consideration on future projects such as High Speed 2, the high speed rail project to begin construction in 2017, initially extending from London to Birmingham (Phase 1) and then branching to both Manchester and Leeds (Phase 2).
Cunningham relates, “There is genuine interest from the [UK] rail sector to lightweight, increase efficiency and better exploit materials technology. It knows it is behind the technology curve compared to other industries and wants to see improvement on the new projects now coming through. Indeed, Chinese trains and rail infrastructure have seen composites applied to great benefit.” But he is unsure when and how the UK rail industry will move forward with composites.
Voith Turbo has no such hesitation. A division of the global engineering company Voith GmbH (Heidenheim/Brenz, Germany), it has announced it will introduce a lateral energy absorber made of glass fiber reinforced plastics (GFRP) and aluminum at this year’s InnoTrans, International Trade Fair for Transport Technology (Sep. 23-26, Berlin, Germany). Offering a potential 60 percent weight reduction vs. standard steel absorbers, this new GFRP energy absorber was developed as part of the crash energy handling design of Voith Turbo’s new Galea vehicle head and front end systems.
New GFRP energy absorber offers 60 percent weight reduction vs. standard steel absorbers. SOURCE: Voith.
Train front ends must bear extreme loads when impacts occur. Voith’s new GFRP energy absorber comprises a fiber composite crash tube with an aluminum bearing and an anti-climber plate to provide excellent corrosion resistance and longevity. The system also complies with fire protection requirements according to the standard EN 45545-2:2013, class R7/HL3. With a total weight on only 70 to 95 kg (154 to 209 lb), it offers a constant energy absorption behavior at an outstanding energy to weight ratio, saving up to 600 kg (1,323 lb) per vehicle when equipped with four absorbers.
Other benefits include reduced size and mounting space required. In the case of a crash, the fiber composite crash tube defibrates (i.e. separates into its fibrous components), and thus can be easily deflected below the vehicle underframe. This allows mounting space behind the absorber to be reduced to 30 cm (≈ 1 ft). The absorber can also be adapted to the customer’s requirements, for force levels between 600 and 1600 kN at a maximum consumption length of 1000 mm (3.3 ft).
Galea integrated crash structure for rail vehicles offers maximum energy absorption at minimum weight. SOURCE: Voith.
Meanwhile, Voith’s Galea vehicle head, designed for intercity railway transportation, is comprised mostly of GFRP, making it a lightweight solution compared with steel front ends. It not only significantly reduces the vehicle’s fuel consumption, but also minimizes the axle load and thus the wear of train and tracks. Alternatively, the load capacity of the train can be increased. Galea’s modular and flexible concept makes it a standard platform for all types of exterior designs, minimizing mounting and replacement times and, accordingly, the train’s downtimes.
Voith will also showcase the front nose of the new ICx high speed trains of Deutsche Bahn (German Railways). From 2016 on, these will gradually replace first the current Intercity/Eurocity trains and later the ICE1 and ICE2 vehicles. New developments in aerodynamics and optimization of interior space have realized savings in weight and energy consumption.
Voith explains that composites offer not only weight savings, but also the forming of complex geometries and free-form surfaces which help with innovative aerodynamic surfaces as well as specific geometries in an easy and cost-saving way.
The compact CFRP adapter coupler can be carried and fitted by one person alone. SOURCE: Voith.
Finally, carbon fiber reinforced plastics (CFRP) will be featured in Voith adapter couplers, used whenever a train needs to be towed. Legal requirements demand that every train has one on board. Versus steel, the CFRP adapter coupler cuts weight by nearly 50 percent, weighing only 23 kg (51 lb), and enabling it to be carried and mounted by only one person. This saves significant time and improves safety since adapter couplers are mostly used in emergency situations and must be fitted by train personnel on short notice. Furthermore, CFRP requires considerably less material thickness vs. steel to achieve the same strength characteristics, a definite benefit in the usually restricted mounting space between the vehicle front and the structure to which it is being attached.
Posted by: Jeff Sloan23. July 2014
Although several years behind schedule and many billions of dollars over budget, the composites-intensive F-35 Lightning II fighter jet is expected to be a core of the U.S. and its allies' fighting arsenal for many years to come.
The Soviet Union tested its first nuclear weapon on Aug. 29, 1949, about five to 10 years before the United States expected it would. The test effectively ended the U.S. monopoly on fission-based nuclear weaponry and launched the decades-long arms race that became the hallmark of the Cold War.
The natural tendency for the Americans was to attempt to regain the upper hand, either by building more fission weapons in effort to stay ahead of the Soviets, or build a bigger weapon. The bigger weapon would be a thermonuclear or fusion-based bomb, which until 1949 existed on the drawing board only as a conceptual weapon. A thermonuclear bomb, fueled by hydrogen, would be orders of magnitude more powerful and destructive than the uranium- and plutonium-based bombs dropped on Japan at the end of World War II, but would require a significant technical effort to develop and test. President Harry Truman faced a simple question: Whether or not to try and make a thermonuclear weapon, or just build more weapons based on the “old” fission technology.
Robert Oppenheimer, physicist and “father” of the atomic bomb developed in the Manhattan Project, actually opposed development of a thermonuclear weapon. It was, he argued, not a battlefield weapon, but a tool used only for destruction of entire cities and regions. It would be, in short, too costly to develop and too destructive to apply. However, faced with the prospect that the Soviets would certainly not show similar restraint, Truman had no choice but to authorize a thermonuclear weapon development program. The U.S. successfully tested its first hydrogen bomb in 1954, followed by the first Soviet hydrogen bomb test in 1955.
There are, today, shades of some of the same “race” logic at work with the F-35 Lightning II Joint Strike Fighter, being built by Lockheed Martin for sale to the U.S. and several partner countries. The composites-intensive F-35, as has been well documented, is about seven years behind schedule and billions of dollars over budget. This has prompted calls for the program’s end, which seems unlikely given that the F-35 and its variants are in testing and early production. The argument has also been made that many of the current jet fighters in the U.S. arsenal can do what the F-35 can do.
Indeed, the U.S. and its allies have relied on fourth-generation fighters like the Boeing F/A-18E/F Super Hornet, the Eurofighter Typhoon, the Dassault Rafale and the Lockheed Martin F-22 Raptor for about 20 years. These planes have served well and continue to perform — and might be adequate for the foreseeable future. The problem is that, like it or not, other countries that may or may not be antagonistic to the U.S. and its allies are developing fifth-generation fighters on par with the F-35. These include the Russian Sukhoi PAK FA and the Chinese Chengdu J-20, so keeping up with the competition seems to demand a fighter like the F-35.
But is fighter jet development done at any cost? Had the U.S. Congress known up front what the true cost of the F-35 would be, it likely would not have authorized it. And it would be nice to think that the U.S. and its allies had gotten so good at airplane development that cost and time overruns were the exception, not the rule. But the F-35 is a complex system, and complex systems invite unpredictability.
There is hope, however, in the fighter jet development world for creativity, speed and efficiency. Witness in particular the recently debuted Scorpion, an all-composite, tandem-seat, twin tail tactical jet fighter, self-funded and developed by Textron Airland LLC (Wichita, Kan.), a joint venture between Textron and Airland Enterprises. The plane went from concept to first flight in just two years, was designed and produced in secret and demonstrates clearly the potential for efficient and on-time fighter development. Scorpion is not an F-35 replacement, but it does prove what’s possible and might be more a harbinger of what’s to come.
The Textron Airland LLC Scorpion fighter, which was introduced in July 2014, was self-funded and evolved from concept to first flight in just two years.