1. OOA and Recent Developments
in ACM
-A review
Submitted to
Prof. Wang Rumin
Department of Applied Chemistry
School of Science,
NPU, Xi’an, China
Prepared by
Shameel Farhan
PhD Student
(Carbon foam core sandwich structures)
Student ID 2013410005
CIRTM: co-injection RTM
Crystic VI: vacuum infusion (Scott Bader)
DRDF: double RIFT diaphragm forming (University of Warwick)
LRI: liquid resin infusion
MVI modified vacuum infusion (Airbus)
* Quickstep * use of liquids for enhanced heat transfer in infusion
RFI: resin film infusion
RIFT: resin infusion under flexible tooling (ACMC Plymouth)
RIRM: resin injection recirculation moulding
SCRIMP Seeman Composites Resin Infusion Molding Process (TPI)
VAIM: vacuum-assisted injection moulding
VAP vacuum assisted processing (patented by EADS)
VARI: vacuum assisted resin injection system (Lotus Cars)
VARIM: vacuum assisted resin injection moulding
V(A)RTM: vacuum (-assisted) resin transfer moulding
VIM: vacuum infusion moulding.
VIMP: vacuum infusion moulding process
VM/RTM Light: a hybrid RIFT/RTM (Plastech)
VIP: vacuum infusion process
OOA
Is it a game changer for all
applications in the
industry?
OOA-BMI
Quiet revolution

2. Out-Of-Autoclave (OOA)
OOA actually mean “never in the autoclave”, or “autoclave never needed” or
technically “outside of the autoclave.” Speeding up the production process while
at the same time achieving “autoclave material performance and overall quality”
without autoclave.
There are several out of autoclave technologies in current use including resin
transfer molding RTM), Same Qualified Resin Transfer Molding (SQRTM),
vacuum-assisted resin transfer molding (VARTM), and balanced pressure fluid
molding. The most advanced of these processes can produce high-tech net shape
aircraft components.
The Quickstep™ Process (balanced pressure molding) changes the way
advanced composites are manufactured by using a unique fluid-based technology
for curing the composite materials. It is an OOA process. It works by trapping
the laminate between a free floating rigid (or semi-rigid) mold that floats in a
Heat Transfer Fluid (HTF). The mold and laminate are separated from the
circulating HTF by a flexible membrane or bladder. The HTF can then be
rapidly heated and then cooled to cure the laminate.
Fig.1 Schematic of Quickstep™ Process
Benefits of Quickstep™ Process
 Lower capital costs – typically around two-thirds of the cost of an
equivalent capacity autoclave
 Lower energy consumption for heating/cooling of the laminate
 Eliminates the need for compressed air or nitrogen use
 Only 1 to 4 psi operating pressures on parts

3.  No oven size restrictions
 Reduction in cure cycle times from 50-90% compared with autoclave and
oven using commercial prepregs
 Very accurate part temperature control
 Enhanced repeatability in cure cycles – evenly distributed heat-up and
cool-down
 Rapid heating aids full resin flow through and between laminate layers
for improved inter-laminar properties and improved surface quality
 Limited exotherm (when the material generate its own heat from the
chemical reaction) even in laminates that are 2 inches thick
 Quickstep’s unique ability to halt and then recommence the cure reaction
at any point in the cycle makes it possible to co-cure, join and bond one
composite part to another
 Ability to form entire integrated components without secondary bonds or
fasteners
 Reduces end product weight and part count
 No complex backing structure, resulting in lower costs per mold
 No need to delay the commencement of curing while waiting for other
parts, as occurs with large batch autoclaves
 Lower development costs due to faster iteration of experiments
 Curing of conventional autoclave or oven-style pre-pregs, including
phenolics
 Low pressure processing allows for the use of lighter weight cores
 Cured honeycomb structures have less print-through of the honeycomb
cell patterns, but with improved adherence at the bond points
 Low resin viscosity improves surface wetting of foam cores
OOA-BMIs
The development of OOA bismaleimide (BMI) systems has been a “quiet
revolution” in OOA processing development. Or it needs to be a goal for
everyone. Cytec developed OOA-BMI in 2011. For 17 years, Maverick Corp.
(Blue Ash, Ohio) has produced polyimide resins, which they sell to prepreggers
like Renegade Materials Corp. (Dayton, Ohio). Maverick and Renegade, in fact,
have worked closely together since 2008 and were recently joined by Akron
Polymer Systems (Akron, Ohio) and NASA Glenn (Cleveland, Ohio) as partners
in an OOA Materials for High-Temperature Composite Applications project.
The effort benefits from a recently awarded Third Frontier Grant from the U.S.
state of Ohio. The team’s contribution and Ohio’s matching funds will total $2
million over two years, during which BMI and polyimide systems will be
developed for service temperatures of 400°F to 700°F (204°C to 371°C). Dr.
Robert Gray, Maverick president and director of product development, reports

4. that polyimides enable service temperatures between 400°F/204°C and
700°F/371°C and cost $100/lb to $250/lb, while BMI resins provide up to
350°F/177°C hot/wet performance and cost $70/lb to $100/lb. But processing
BMI resins is a little easier because, unlike polyimides, they do not form reaction
byproducts, such as water and alcohol, during cure. Gray believes that most
fabricators are limited to processing only BMI materials for high-temperature
applications. However, Gray plans to reduce the complexity of processing
polyimides by moving away from very low viscosity resins toward systems of
greater molecular weight, formulated for VBO-curing prepregs. Military
applications for polyimide composites include stator vanes leading into the
compressor in jet engines, exhaust flaps in back of the engines, and outer bypass
ducts. Polyimide structures also can handle extreme environments in and around
commercial aircraft engines. Maverick and Renegade have identified many
structural applications for polyimides, including UAV and low-observable
applications. By offering more affordably processed OOA polyimides,
Maverick’s program could help aircraft designers cut weight by reducing the
need for insulation and shielding, especially on launch vehicles and other space
platforms where weight is super critical. Currently, PMR-15 (supplied by Cytec
as CYCOM 2237), the industry-standard polyimide, requires autoclave cure at
200 psi/13.8 bar. Gray explains, “Very few composites manufacturers have
large, high-temperature autoclaves. If we can process polyimides OOA, we
could dramatically expand the high-temp composite parts supplier base and
broaden the use of these lightweight materials. “But what is the driver for an
OOA BMI? According to industry consultant Jeff Hendrix, most BMI and
polyimide parts that require performance above ~275˚F/~135˚C are used in
engines, and don’t typically need to be large. These parts fit into current
autoclaves, and most, in fact, are compression molded. “It’s not the upper use
temperature that drives selection of BMIs, but the superior notched properties at
even lower temperatures that makes them attractive to many programs,”
AFRL’s Russell agrees, noting that “5250-4 BMI [produced by Cytec] was used
heavily in the JSF [program], even where no elevated service temperature was
needed, simply because it was able to deliver higher stiffness-to-weight and
strength-to-weight ratios due to its hot/wet performance, which means lighter
structures. “Russell also sees the need for higher temperature performance in
future programs. Thus, OOA BMIs are of interest to us.” Russell says that
NASA has an interest because the use of BMI in the nose-cone of its launch
vehicles could eliminate costly, heavy insulation materials.

5. No more autoclaves?
Bombardier’s LearJet has taken a major step by pursuing an all-composite OOA
fuselage, but most manufacturers of large commercial structures will probably
wait and see. Ostermeier sees military aerospace moving toward OOA faster
than commercial aircraft, and if NASA does produce out-of-autoclave launch-
vehicle sections reliably, he predicts that it could change composites
manufacturing quite a bit. Hendrix maintains his skepticism, “I believe OOA has
a bright future, but people should be careful because they think it is so much
cheaper. “For Hahn, however, the issue is OOA’s utility in real-world production
vs. R&D programs, where the driver for decision-making often is a program
deadline. “The OOA materials we are looking at right now cost the same as the
autoclave primary structure materials in use,” she notes. “But if they allow us to
complete tooling in six weeks, and then proceed to prototyping and production
much more quickly, it could win in trade studies for an application.” Offering
weight, cost and process advantages, these “hot zone” resins is moving down the
thermometer and into OOA. Although autoclave cure isn’t going away,
designers of composite aero structures continue to beat the drum for matrix
resins that can be processed OOA by a number of means. Yet they’re also
searching for superior resin performance, particularly in terms of damage
tolerance. This quest has put the spotlight on BMI and benzoxazine resin
systems. Each offers an attractive alternative to established epoxies.
Fig. 2 Bombardier’s LearJet all-composite OOA fuselage
BMI excels in high-temperature applications. However, much of its use on the F-
35 Lightning II Joint Strike Fighter is due to its superior hot/wet performance at
more moderate temperatures, which enables damage-tolerant structures at lower
mass than can be achieved with epoxy. At a cost now comparable to high-
performance epoxies, BMI is encroaching on epoxy’s recent gains in the OOA
prepreg market. At a cost and performance level between standard epoxies and
BMI, benzoxazine is increasingly viewed as a way to attack the cost of
composite structures throughout the supply chain, not only because of its room-
temperature stability and processing advantages, but because it also satisfies

6. complex structural demands and meets supply, surface finish and health and
safety requirements.
OOA BMI: Drivers and difficulties
Until now to date, four such systems are commercially available (see Table 1).
Dr. James K. Sutter, materials lead for large-scale composite structures at NASA
Glenn Research Center (Cleveland, Ohio), has evaluated many OOA BMI
systems, and presented the results at recent SAMPE Tech conferences and High
Temple Workshops. “When I surveyed the industry with regard to BMI
development in 2011, only three companies responded that they had an OOA
system to meet our challenging requirements,” he reports. One was Stratton
Composite Solutions (Marietta, Ga.), whose BMI-1 resin is now used in resin
transfer molding (RTM) and vacuum-assisted RTM (VARTM) more than in
prepreg. The company is developing a BMI foam for high-temperature tooling
board. The other two suppliers, TenCate Advanced Composites (Nijverdal, The
Netherlands, and Morgan Hill, Calif.) and Renegade Materials Corp.
(Springsboro, Ohio), have since made significant product improvements as
they’ve worked with NASA.
Fig. 3 Future OOA-cured composite structure for AresV.

7. “OOA BMI is attractive because it enables affordable, lightweight tooling with
excellent machinability and durability,” says Sutter. “The same tools made from
Invar would be at least three times heavier and more costly, while epoxies
cannot meet the temperatures or durability required.” NASA is also interested in
the ability to make very large composite launch vehicle structures with higher
service temperatures. Sutter explains, “For every 50°C [90°F] increase in Tg we
can take out 1,000 lb [454 kg] in thermal protective system (TPS)
weight.”According to Chris Ridgard, associate technical fellow at advanced
materials supplier Cytec Aerospace Materials (Tempe, Ariz.), the use of BMI is
being driven not just by tooling and applications where service temperatures
exceed 350°F/177°C, but also by the increasing use of composites in structures
that need improved hot/wet and open-hole compression (OHC) performance at
moderate temperatures, such as 80°C to 120°C (176°F to 248°F). Ridgard
details, “Most of the BMI structures on the F-35 use it because it outperforms
epoxy and enables stronger, lighter weight parts.” Stratton Composite’s owner,
Bob Stratton, also touts BMI’s better resistance to fluid ingress and gives
supporting data for its superior strength retention: “BMI can offer a room-
temperature OHC of 52 ksi (359 MPa) and at 220°F (104°C) it is still 49 ksi (338
MPa), where a typical structural epoxy goes from 40 ksi to 30 ksi (276 MPa to
207 MPa) or below at the same temperatures.”Previously, BMI was thought to
be too expensive. “But now,” Stratton asserts, “BMI can be processed at the
same cost as high-temperature epoxy resins.” NASA’s Sutter quotes $75/lb for
carbon fiber/BMI prepreg, compared to $70/lb for intermediate-modulus (IM)
carbon fiber/epoxy prepreg. Stratton cites BMI’s long cycle times on programs
such as the U.S. F-22 jet fighter, an F-35 predecessor, as a significant cost issue
that is now being addressed. “Cytec materials used on the F-22 required a 13-
hour autoclave cycle because they had a six-hour cure,” he recalls. “However,
we have demonstrated a cycle time of less than 3.5 hours using the OOA
Quickstep process.”
OOA- BMI for tooling
Cytec’s Industrial Materials business has released a new OOA BMI tooling
system, HTM520, that features a standard 375°F/190°C cure and post cure
options at higher temperatures, with good machinability. Having withstood more
than 200 thermal cycles between 20°C/68°F and 177°C/350°F with no micro
cracking during tests, it also offers what is expected to be a long service life.
Ridgard discusses the difficulties in developing an OOA BMI system. “If you
look at why BMIs don’t process as well out of autoclave, you see two factors,”
he points out. “First, OOA epoxy prepregs have been designed with evacuation

8. channels” — less than 100 percent impregnation provides dry fiber paths — “so
that you can edge breathe the laminate, whereas BMIs tend to flow too much and
close off such evacuation channels. Second, the high levels of vacuum used in
the production of aircraft structures tend to volatize some of the resin
components; thus, the volatiles in the resin must be controlled because there is
no autoclave or RTM pressure to push them back into solution.” Ridgard says
Cytec has achieved the necessary control of flow and volatiles in its HTM520
system, which also results in better cured-ply thickness control. “If you push the
viscosity up, the system is more stable so that resin does not flow all over the
place. The tighter rein on thickness can also result in significantly reduced
shimming and assembly costs for structures.” Ridgard says it would not surprise

9. him to see a flow-controlled structural BMI based on HTM520 used with an
autoclave because it gives that much better part accuracy, which is critical for
most aerospace structures. But what about applications beyond tooling? Cytec’s
BMI product manager, Mark Ostermeier, answers, “Cytec has a strong interest in
using similar materials for structural applications. There has been huge growth in
OOA epoxy materials, which are moving toward higher cure and service
temperatures.” That said, Cytec has seen mixed industry interest, with some
requesting BMI performance using vacuum-bag only processing while others
want only significantly improved notched properties.
Fig. 4 OOA-cured tool made from Cytec Aerospace Materials’HTM520 BMI
tooling prepreg.
“These could go hand-in-hand,” Ostermeier allows, “but there is no specific
program demanding such a product.”A potential fifth source, Hexcel (Stamford,
Conn.), is working to develop an OOA BMI prepreg with thermal, mechanical
and automated-layup capabilities equivalent to its autoclave-cure M65 product,
but with enhanced toughness, targeted primarily for aerospace primary structures
but also for vacuum-bag only (VBO) tooling. “We can produce void-free OOA
parts,” claims Hexcel chemist Bob Buyny. “Now, it’s a matter of fine-tuning for
specific programs and being ready to scale up production.” Although Hexcel has
definite program targets, there are, thus far, no set timelines for qualifications.
Benzoxazine: The contender
Benzoxazine was discovered in the 1940s. Huntsman Advanced Materials
(Basel, Switzerland, and The Woodlands, Texas) began working with it in the
late 1980s, and Henkel Aerospace (Bay Point, Calif.) followed a decade later.

10. Even though benzoxazine was qualified for printed-circuit boards (PCBs) very
quickly in 2000 — it was one of the few readily available nonhalogenated
materials that met all of the performance requirements — systems for structural
composites weren’t commercialized until 2008. Huntsman sells benzoxazine
building-block components to prepreggers, resin formulators and adhesives
manufacturers, while Henkel offers a range of formulated prepregs, infusion
resins and adhesives. “This market has been slower to develop,” explains
Huntsman’s composites marketing manager, Carl Holt, “because of the
conservative nature of commercial aerospace and the extensive background
epoxies have, including material databases.” Another difficulty is that
benzoxazine can require cure temperatures higher than the 350°F/177°C
standard for aero structures. Huntsman observes that benzoxazine processing
temperatures and times can be varied widely using many different catalysts.
Through its development of proprietary catalysts, only two of Henkel’s six
benzoxazine systems — three for structural prepreg and three for structural
infusion — require a cure over 200°C/392°F. The others cure at close to
177°C/350°F.Formed by reacting phenol, formaldehyde and amine, the
chemistry of benzoxazine is unique in that its additive reaction results in ring
opening polymerization (ROP), which produces a high molecular weight
polymer and imparts near-zero cure shrinkage and two other key features: (1) it
creates a reactive site that makes benzoxazine an über-reactive polymer for
hybridizing with other resins, including epoxy, phenolic and BMI; and (2) it
enables benzoxazine to polymerize with itself (homopolymerize) to form
polybenzoxazine thermoset networks very similar to phenolic. Roger Tietze, a
senior scientist technologist for Huntsman, points out, “This is why you get
phenolic type properties without the condensation reaction which makes
phenolic so difficult to process.” David Leach, Henkel’s global composites
segment manager, explains, “The processing is basically the same as epoxy, and
you don’t have the issues with voids during cure that must be managed with
phenolics. In addition, the heat of reaction is lower than epoxies.” Henkel claims
that a 19-mm (0.75-inch) thick, 150-ply laminate can be cured with a 5°C/min
(9°F/min) ramp rate without an uncontrolled exotherm.
Between epoxy and BMI
“There is a lot of interest because of the material’s advantages,” says Holt. These
include high stiffness, excellent thermal properties (high Tg), lower moisture
absorption and better flammability resistance (high char yield) than epoxies.
Leach points out that benzoxazine also has better resistance to ultraviolet (UV)
radiation than epoxies, with cured resin showing no discoloration, chalking or

11. degradation after 95 days in outdoor exposure. Although reports from university
studies show exotic benzoxazines with Tg as high as 300°C to 350°C (572°F to
662°F), Tietze says more common formulations exhibit a glass transition
between 150°C and 250°C (302°F and 482°F). Like BMI, higher Tg systems
have increased molecular weight and crosslinking, which gives them higher
modulus and service temperature but also results in brittleness, so they need to
be toughened to prevent micro cracking. Leach explains that the benzoxazine
formulation Henkel supplied to Airtech International (Huntington Beach, Calif.)
for its Beta Prepreg tooling system is different than what Airtech offers in its
structural products. “They were looking for long tooling life at elevated
temperature, so we developed that system with a Tg of 250°C [482°F] for 200°C
[392°F] continuous service, obtained via post-cure.” However, he notes that “the
benzoxazine formulations we have now are starting to get into the BMI service
temperatures.”
That is almost unavoidable because, just like BMI, Henkel’s benzoxazine
products are targeted toward epoxy’s shortfall in hot/wet performance. Leach
says most epoxies have a maximum hot/wet service temperature of
120°C/250°F. All of Henkel’s benzoxazine products have a continuous service
temperature of 120°C or higher and claim excellent hot/wet properties.
“Traditionally, designers have been more interested in improved retention of
hot/wet properties at 250°F and below,” Leach explains, “but more are finding
hot spots that demand higher service temps with the recent trend of increased
composites in airframes. We see this as a big growth area in the future.”
Stratton claims that BMI chemistry is not inherently more expensive than
epoxies. “Perhaps that’s true,” says Leach, “but that’s not been the experience in
the industry, to date.” He notes that the amount of BMI actually flying is small
compared to epoxies. Compared to BMI, Leach again cites savings with
benzoxazine due to elimination of frozen storage and thawing, but he adds that
“there are also process cycle time and ease of layup advantages for both manual
and automated placement.”
Benzoxazine’s future
Although BMIs are clearly ahead developmentally and commercially, and some
users caution that it has not yet attained the maturity of BMI and still require
development in several areas, including OOA processing, benzoxazines are
coming on strong. Henkel has OOA benzoxazine systems for prepreg and
infusion, and Huntsman has liquid benzoxazines in commercial development.
Dave Nesbitt, president of Matrix Composites (Rockledge, Fla.), a specialist in

12. the design, development and qualification of complex integrated composite
structures, sees potential for benzoxazine. Matrix is working with several
customers to put benzoxazine composites into production, but Nesbitt, too, sees
a need for continued product development. “Benzoxazine offers a unique blend
of properties — the burn resistance and smoke toxicity benefits of phenolic but
with the strength and modulus of BMI,” he notes. “That opens a lot of doors.”
Indeed, benzoxazine is said to offer the flame, smoke and toxicity (FST)
performance of phenolic without its voids and processing difficulties. That has it
poised to push large, integrated structures into aircraft and other transportation
interiors.
However, Nesbitt cautions that those who use benzoxazine “must work through
some of its processing challenges, as with any new material.” He adds, “We
have had great success at high pressures (>100 psi) in both RTM and autoclave
environments, but benzoxazine is more challenging to process at lower pressures
typical of VARTM, infusion and VBO curing. These are manageable, though,
when appropriate measures are taken to ‘vent’ the outgassing that occurs during
cure at low pressure.” That said, Henkel presented its development of a void-free
48-ply OOA-cured laminate using its BZ prepreg and the Boeing-developed
double vacuum bag debulk (DVD) process in its “Out of Autoclave Composite
Repair” presentation at SAMPE 2013 (May 6-9, Long Beach, Calif.).“The
industry has a comfort level with BMI that is not there yet with benzoxazine,”
says Cytec’s Ridgard. “It will be cautious in developing applications to make
sure there are no hidden problems like cyanate ester showed with moisture.”
Huntsman’s Holt doesn’t entirely disagree: “It took the industry many years to
develop epoxies to meet toughened properties and cure processing
requirements.” Benzoxazine, he admits, must negotiate a similar transition, “but
there is no reason why it can’t be developed to meet all of these needs.”Indeed,
benzoxazine is demonstrating a unique and almost limitless ability to react with
other resins (e.g., epoxy, phenolic, BMI, thiol) and produce hybrid formulations
with exceptional properties
Benzoxazine + BMI?
Resin supplier Huntsman Advanced Materials (Basel, Switzerland and The
Woodlands, Texas) sees benzoxazine resins as traditional chemistry boundary
breakers that open whole new resin-system possibilities. For example, a recent
patent application describes novel benzoxazine/thiol compositions that are useful
in coatings, sealants, adhesives and many other applications.

13. “Traditionally, this cannot be achieved with epoxy,” explains Huntsman scientist
technologist Dong Wang. “This shows how benzoxazine’s chemistry is
overcoming obstacles in polymer formulation and processing.” Recently, in fact,
there has been a flurry of research activity on blends of bismaleimide (BMI) and
benzoxazine, including a 2013 Chinese patent application specifically for
composites applications that claims the blend exhibits improved thermal stability
and toughness vs. benzoxazine alone, yet it maintains the inherent machinability
of the latter.
“The ability to achieve truly unique resin properties is practically limitless,”
claims Wang, “because not only can benzoxazine react with so many polymers
but there is such a wide variety of amine and phenol monomers which can also
be combined and tailored to affect the final system performance.” Researchers in
India, for example, report modifying benzoxazine’s Tg by 149°C/88°F simply by
playing with the monomer feed ratio.
Huntsman predicts that such custom tailoring of resins will be the norm in
structural composites within 15 to 20 years.

14. Latest Composite Showcase
First Smart Carbon Fiber Bike
Canadian based company Vanhawks have introduced the world’s first carbon
fiber smart bike that allows you to connect to your smart phone via Bluetooth.
The bike, called Valour connects to iOS, Android and Pebble smart watches
through Bluetooth and tracks rider statistics in real-time including the route,
distance, speed, and time. Valour’s LED handlebar indicators are connected to
the smart phone’s GPS navigation and give riders turn-by-turn directions,
reducing the distraction of having to look at a smartphone screen. The Valour
also includes, the industry’s first sensor-driven blind spot detector, which alerts
the rider of any object in their blind spot through haptic feedback in the handle
bar grips. Onboard sensors monitor ride statistics in real-time and syncs the data
with the Vanhawks app. The route data gathered by the sensors will also let the
riders know where the safest routes are. Every Valour is connected to each other
through a mesh-network, and is alerted when one goes missing, aiding in its
recovery. The frame of the bike is developed from carbon fiber using proprietary
technology which makes internal walls to reinforce critical load bearing points in
the frame. Its carbon fiber technology, replicates the construction of human
bones, making the bike frame strong enough to withstand the toughest roads and
potholes. The Valour weighs in at just over 7kgs, making it light enough to carry
up flight of stairs without breaking a sweat.
The Vanhawks Valour is available for a limited pre-order now on Kickstarter
starting at $999. The Valour will ship in Autumn 2014.
Fig. 5 Valour smart carbon fiber bike.

15. Nike Air Jordan XX8
The Jordan Brand, a division of Nike has unveiled the Air Jordan XX8, the 28th
shoe in the Jordan range. The new basketball shoe boasts an ultra-modern stealth
design and more technological advances. This ultra-light shoe designed by
Tinker Hatfield has a load of new enhancements over the previous model. The
Air Jordan features a high-performance; stretch-synthetic shroud that provides a
sleek exterior, while a molded external heel counter is made out of carbon fiber
for lightweight support. A multi directional outsole pattern provides excellent
traction and durability for the court. Schoeller mesh, a Swiss fabric used in
premium motorcycling jackets, is used in the shroud that encompasses the shoe
to provide an extra layer of support, stability and style for the athlete.
Fig. 6 Nike Air Jordan XX8 shoes.
It will only be available in Houston on February 15, 2013, and then nationwide
on Saturday, February 16, for a suggested retail price of $250.
Human Powered Helicopter Lifts Off
Last summer a team of engineering students from the Clark School of
Engineering at the University of Maryland created a human-powered helicopter
called Gamera, they managed to get it off the ground and keep it aloft for 11
seconds. However their new model, the Gamera II managed to stay airborne for
a solid 50 seconds, smashing the world record.
The Gamera II has been improved from its predecessor in many ways. It is 105
feet across, and each of the four rotors is 42 feet long. Thanks to the weight
saving benefits of carbon fiber the entire helicopter weighs just 32 kilos, which
is over 13 kilos lighter than the previous design.

16. Luno chair made by carbon fiber string at different
positions.
The amazing Luno chair is the creation of Korean based designer Il Hoon Roh
and is the result of experiments conducted by suspending carbon fiber string at
different positions. Made from carbon fiber string woven together by hand, the
Luno (Latin for curve) chair is the result of many experiments conducted by
suspending string at various positions, the designer allowed gravity to shape the
final form resulting in smooth natural curvature. To create the curves, a
hexagonal shape was used on the surface, and carbon fiber strings were woven
from the surface to the metal base.
Fig. 7 Luno carbon fiber chair.
Zodiac Aerospace have teamed up with Hexcel to develop a
new introduce the L3, a lightweight composite aircraft seat.
The L3 is a revolutionary passenger seat dedicated for medium/short-haul
flights, offering good space to passengers and to airlines a higher density and a
lighter weight, below 4 kg per passenger. The manufacturing process of the seat,
resulting from cooperation between Zodiac Seats and Hexcel will ensure a quick
manufacturing and delivery time compared to current seats. The all-composite
seat has been manufactured using Hexcel’s carbon fiber prepreg product which
provided light weight, mechanical resistance and an aesthetic appearance. The
armrests and tray tables are manufactured from Hexcel’s HexMC compression
molding process, providing a unique look and strong resistance.

17. Fig. 8 L3 lightweight composite aircraft seat.
New Transparent Fiber Composite Materials for Future
Devices
On January 30, 2014, the US Patent & Trademark Office published a patent
application from Apple titled "Transparent Fiber Composite." Apple's invention
relates to transparent composite materials, and more particularly to relatively
transparent composites formed with fibers encapsulated in a resin. Apple has
been experimenting with composite materials since 2007 as we detailed in a
2010 patent report. This is all part in parcel of research that Apple is heavily
investing in so as to find new materials for future devices. The wearable
computer is one such category that will be able to take advantage of composite
materials such as the one found in today's patent filing.
As most fiberglass cures, the fiberglass can appear to take on a slight green hue
imparted by the resin. Colored resins can be easier to handle during the
manufacturing process. Many fiberglass objects can be painted or have a cover
lay applied to both hide the green color and provide a final finish for the
fiberglass object. It can be desirable to have low cost, high strength, relatively
clear fiber reinforced composites. Relatively clear fiberglass composites can
enable lightweight and strong housings that can include a clear window for
either displays or even camera lenses.
Apple's invention generally describes various embodiments that relate to
relatively transparent fiber reinforced composites. In one embodiment, a fiber for
the composite can be selected and an index of refraction related to the fiber can
be determined. A sizing can be selected for application to the fiber such that an
index of refraction of the sizing can be within a tolerance amount of the index of

18. refraction of the fiber. A resin can be selected for the composite such that an
index of refraction of the resin is also within the tolerance amount of the
determined index of refraction of the fiber. A transparent fiber-resin composite is
disclosed. In one embodiment, the transparent fiber-resin composite can include
a glass fiber, a sizing and a resin where the sizing and the resin are selected to
have an index of refraction similar to a determined index of refraction of the
glass fiber. In one embodiment, the glass fiber can include less than 0.1% of iron
oxide. A method of forming a transparent fiber-resin composite by injection
molding is disclosed. In one embodiment, a chopped glass fiber is selected and
the index of refraction of the glass fiber is determined. A sizing for the chopped
glass fiber is selected with an index of refraction similar to the index of
refraction of the glass fiber. The sizing is applied to the glass fiber and a resin is
selected with an index of refraction similar to the index of refraction of the glass
fiber. The glass fiber is mixed with the resin and the mixture is injection molded.
Silk fibers come on strong in composites
13 May 2014 | Cordelia Sealy
Fig. 9 SEM images of the plain weave textiles: (a) flax, (b) hemp, (c) silk A, and
(d) silk B. SEM images of cross-sections of silk rovings and fibers in (e) and (f).
Silk fibers from spiders and silk worms could prove an effective and novel
reinforcement in bio composites, according to research carried out at the
University of Oxford. Many different fibers are used as reinforcing agents in
composites, but demands for sustainable materials are spurring interest in natural
fibers. Liquid composite and compression molding are the most common

19. manufacturing process, in which reinforcement fibers are arranged in a
‘preform’, a polymer filling agent is introduced, and the two are molded or
compressed together. The more compressible the fiber reinforcement, the higher
the fiber content that can be achieved in the composite.
Darshil U. Shah and colleagues have found that silk reinforcements are far more
compressible than typical plant fibers and even glass fiber textiles [Shah, D.
U., et al., Composites: Part A 62 (2014) 1-10, DOI: 10.1016/j. Unlike plant
fibers such as flax and hemp, which typically form bundles, silk from the
silkworm Bombyx mori, for example, is created as long, smooth individual
threads. These threads or filaments, which can reach up to 1500 m, have almost
triangular-shaped cross sections that fit together much more snugly than
cylindrical plant fibers.
Textiles woven from silk fibers are much easier to compact than those woven
from hemp or flax, according to the study. Comparing silk, hemp, and flax
woven textiles in a scanning electron microscope reveals that silk has a much
tighter and more ordered weave with much less ‘fluffiness’ or loose, disordered
fibers. When it comes to making bio composites, this means that less compaction
pressure is required to achieve a particular fiber volume fraction. For a given
compaction pressure, the volume fraction of silk fibers was 10-15% higher than
the best flax reinforcement. In fact, silk composites with fiber volume fractions
of up to 60% could be produced at low compaction pressures, suggests Shah.
Silk fiber reinforcements have another benefit over plant fibers in that they can
withstand bending without breaking better than plant fibers, improving the
mechanical performance of the composite. According to the researchers, the
findings mean that silk fibers could overcome the bottleneck facing plant fiber
reinforcements and enable the manufacture of high fiber-content bio
composites.“Not only are silk reinforcements significantly more compressible
than plant fiber reinforcements, but their compactibility exceeds that of even
glass fiber textiles,” explains Shah. “Consequently, silk fiber reinforcements
offer a unique opportunity in the production of high fiber volume fraction natural
fiber composites.”Not only would silk-reinforced composites be more
sustainable because less energy is required to produce the fibers, but less
environmentally unfriendly polymer filler would be needed. Ultimately, these
composites could offer better mechanical performance too, particularly where
light-weight and high-toughness are required, as well as sustainability.

20. 3D vascular system allows for self-healing of composite
materials
22 April 2014 | Laurie Donaldson
Scientists have turned to nature to develop a 3D vascular system that permits
high-performance composite materials such as fiberglass to heal both
autonomously and repeatedly. Damage to such fiber-reinforced composites,
commonly used within engineered structures in aerospace, automotive, civil,
naval and even sporting goods due to their effective strength-to-weight ratio, can
be difficult to detect and repair using traditional approaches. The team, from the
University of Illinois at Urbana-Champaign, whose research was published in
the journal Advanced Materials [Patrick et al. Adv. Mater. (2014) DOI:
10.1002/adma.201400248], were looking to solve the problem in composites of
small cracks that become irreversible damaged by delamination, limiting the
wider deployment of such materials in industry. They demonstrated the first
repeated healing in a fiber-reinforced composite system using vasculature
patterns of micro-channels that integrate dual networks that are isolated from
each other – an epoxy resin and hardener acting as liquid healing agents
sequestered in two different micro channel networks. As fiber-composite
laminates are produced by the weaving and stacking of multiple layers, it is
comparatively easy for the structure to separate between the layers. In this new
3D vascular system, when a fracture breaks apart the separate networks, the
healing agents are automatically released into the crack plane. On coming into
contact with one another in situ, or within the material, they polymerize to form
a structural glue at the damage site and were shown to heal the material over
multiple cycles. It is important the vascular networks do not run in straight lines
to allow the healing agents to mix properly once released. Therefore the vessels
were overlapped, significantly improving their resilience and life span. The team
introduced the same process used for making laminates to stitch in a line made
from a bio-friendly polymer (termed “sacrificial fiber”) within the composite.
Once this was achieved, the system was heated to melt and evaporate the
sacrificial fibers so that hollow micro channels remained, which became the
vasculature for the self-healing system. The method therefore integrates
seamlessly with standard manufacturing processes for polymer composites and is
also highly scalable.

21. The approach could be used in structures prone to cyclic damage and are
critically important for the safety and performance of engineered systems. The
team is now continuing to explore biomimetic vasculatures through more
advanced fabrication techniques, which could lead to even more complex
vascular architectures, including multi-scale and branched networks.
A short discussion on Short Beam Shear test
method for composite materials
Dr. Donald F. Adams (Wyoming Test Fixtures (Salt Lake City, Utah) suggests
larger support and loading cylinders for the Short Beam Shear test method. The
primary attraction of the SBS method for many users is the simplicity, the small
size of the test specimen and the ease with which the test can be performed. As a
result, the SBS method is widely used. Yet it is not without its detractors. The
test method loads a beam specimen in three-point bending, as shown in Fig. 10.
The term “short beam” indicates that the support span length, s, is a low multiple
of the specimen thickness, t. The goal is to force the beam specimen to fail in a
shear mode. This can be achieved because the shear stress is independent of the
support length, whereas the flexural (bending) stresses are a linear function of
the support length. Thus, the shorter the beam, the greater the shear stress
relative to the bending stresses.
The SBS test method was first standardized by ASTM in 1965, as ASTM D
2344, and titled “Apparent Interlaminar Shear Strength of Parallel Fiber
Composites by Short-Beam Method.” The standard suggested using a support
span length-to-specimen thickness ratio, s/t, of 5 for glass-fiber-reinforced
composites and 4 for all other reinforcing fibers, including carbon, steel, boron,
aramid and so forth. The questionable distinction for glass fibers was based
primarily on some limited analytical studies that were being conducted at the
time. The use of “apparent” in the title was to acknowledge that the shear
stresses in the short beam are not only not uniform, but also are accompanied by
tensile and compressive axial stresses as well as through-the-thickness tensile
and compressive stresses. Simply put, it was well known that the SBS method
was not a “pure shear” test, as would have been desirable. Nevertheless, it was
considered a shear test. In the 2000 revision of ASTM D 2344, however, the title
was altered to “Short-Beam Strength of Polymer Matrix Composite Materials
and Their Laminates.” The word “shear” was deleted from the title and from the
definition of the strength quantity it measures. In spite of these negative
implications, the SBS test continues to be used extensively for the same reason

22. as always — it is easy to perform and can provide a good comparative
assessment of material performance, even if it does not necessarily provide
accurate quantitative data. Notably, the revised method eliminated the separate
s/t ratio for glass fiber composites. The standard now specifies that s/t = 4 be
used for all types of fiber-reinforced polymers. And although the originally
defined 0.250-inch diameter loading cylinder and 0.125-inch diameter specimen
support cylinders were retained, consistent with ASTM’s decision to require
“soft” rather than “hard” conversions from U.S. customary units to SI units, the
SI “equivalent” diameters became 6 mm and 3 mm rather than the previous 6.35
mm and 3.2 mm.The soft conversions raise an obvious question: Is it necessary
to use different cylinders if a test is being conducted per the SI version of the
standard? The strict answer, of course, is yes. But it has been clearly
demonstrated during the past decade that small changes in cylinder diameter
make little difference in the test results.
Further, these studies have demonstrated experimentally and numerically that
larger cylinder diameters are beneficial because they induce more uniform
stresses within the beam specimen. Using small-diameter cylinders introduces
high local stress concentrations. Larger cylinders spread the applied load over a
wider specimen surface area, resulting in more uniform internal stress states in
the specimen. In fact, it would be logical to size the cylinders in proportion to the
specimen thickness and, thus, the anticipated failure load. However, this has not
yet been proposed and, perhaps, is not practical. A standard loading cylinder
diameter as large as 25 mm/1 inch has been suggested.1
However, considering the
small thickness of a typical specimen, a loading cylinder diameter of 12.7
mm/0.50 inch, with a corresponding diameter of 6.35 mm/0.25 inch for the
support cylinders, is a more practical option (Fig. 1b). Note that, for the three-
point bending SBS test depicted in Fig. 1, the reaction forces at the supports are
one-half the force applied on the loading cylinder, justifying the use of smaller
support cylinders. In fact, if the test specimen is relatively thin, there isn’t
sufficient space between the support points to accommodate a large-diameter
cylinder. For example, on a typical 2.5-mm/0.10-inch thick specimen with a
support span ratio of 6, the distance between supports will be a mere 15 mm/0.60
inch, indicating that the largest support cylinder diameter can be only 15
mm/0.60 inch. Of course, it isn’t necessary to use full cylinders because it is only
the radius of the surface in contact with the specimen that is significant. These
same studies also have shown that the s/t ratio has a strong influence on the
obtained “apparent shear strength” and the failure mode. From Fig. 1a, it can be
inferred that, as s/t decreases from the value of 4, the support cylinders get closer
to being directly under the loading cylinder, and there will be more of a through-

23. the-thickness crushing of the specimen, rather than bending, thus altering the
failure mode away from shear. Correspondingly, if s/t becomes too great — that
is, if the specimen is no longer a short beam — the previously noted flexural
(axial tensile or compressive) failures will occur rather than a shear failure. Most
likely, there will be compressive failures at or near the specimen surface under
the loading point, where the stress concentrations occur. Studies indicate that an
s/t ratio in the range of 4 (the current ASTM recommendation) to 9 is
favorable.1
Therefore, standardizing a ratio of 6 or 7 would be reasonable. In
this s/t range, there is typically one large and abrupt load drop at failure, with
shear cracks visible at or near the midthickness of the specimen, typically in the
region midway between the loading and support points where the shear stress is
greatest. In summary, it is suggested that ASTM D 2344 be revised to specify
an s/t ratio of 6, a loading cylinder diameter of 12.7 mm/0.50 inch and a support
cylinder diameter of 6.35 mm/0.25 inch, as depicted in Fig. 1b. These
modifications are minor, will have relatively little influence on direct
comparisons of new results with legacy values, and will provide more consistent
shear failure modes.
Fig. 10 Short Beam Shear specimen test configurations. Source: Don Adams
A new term Melding
Melding is a combination of "melting" and "welding", where one
semi-cured part melts into another semi-cured part to form one integrated
component with no physical difference or secondary bonds.

24. MELTING + WELDING = MELDING
By using the Quickstep curing process, a section of the part can be fully
cured while another section can be left partially cured or uncured. The partially
cured or uncured sections can then be joined using the Quickstep Melding
Process. To do this, the partially cured or uncured sections are laid together and
cured simultaneously, as shown in the schematic below. A layer of pre-preg fiber
can then be used to cover the joint between the two sections, thereby melting and
chemically bonding with the part and mechanically bridging the joint.
Fig. 11 Melding.