1 | P a g e

10/31/2011

Navid, Sam | ENGR 190W

Professor John Stupar

BOEING 787

DREAMLINER

COMPOSITE MATERIALS AND THEIR EFFICACY IN

AERONAUTICS

Figure 1. Boeing 787 DreamLiner Fuselage

2 | P a g e

ABSTRACT

Composite Materials remain fairly new to the realm of commercial aircrafts but have showed

their long term strength and stability in military aircraft and application of use in other products. The

advantage in strength to weight when compared to their substitute aluminum is staggering; with nearly

half the weight and twice the strength it is no wonder why composites are widely being implemented.

The dangers, however, are clear; respiratory problems from the onset of construction to later years in

life, danger to the environment due to non-recyclability and most important the insurance that the

composite material was properly constructed using techniques garnished only in the past years. With

the different molding methods available, it is no wonder why composite materials are being produced

on a mass scale. The low cost of materials makes the use of composites more viable, the high cost for

engineered composite materials are a drawback but only on the factor of cost- their performance

numbers eclipse their competing materials specifications. The efficacy of Composites in Aeronautics is

unparalleled; the strong lightweight materials are building massive superstructures such as the Boeing

787, which is 80% composite, on a large scale and in quick time frames. The purpose of this research

proposal is to investigate the efficacy of composite materials in the aeronautical industry.

3 | P a g e

Table of Contents

Abstract ......................................................................................................................................................... 2

List of Illustrations ......................................................................................................................................... 4

Composite Materials ..................................................................................................................................... 5

Mechanics of Composite Materials .............................................................................................................. 6

Composition of Materials ............................................................................................................................. 7

Categories of Fiber-Reinforced Materials ..................................................................................................... 8

Molding Methods .......................................................................................................................................... 9

Disadvantages and Failures ......................................................................................................................... 10

Ethical Dilemma and Efficacy ...................................................................................................................... 11

Summary ..................................................................................................................................................... 13

Bibliography ................................................................................................................................................ 14

Addendum .................................................................................................................................................. 16

About the Author ........................................................................................................................................ 23

Readability Analysis .................................................................................................................................... 24

4 | P a g e

List of Illustrations

Figure 1. Boeing 787 DreamLiner Fuselage………………………………………………………………………………………………1

Figure 2. Boeing 787 DreamLiner in Hangar…………………………………………………………………………………………….2

Figure 3. Carbon Fiber/Kevlar Weave pre-impregnated............................................................................... 6

Figure 4. Lockheed Martin F22 Raptor with Full AfterBurner’s .................................................................... 7

Figure 5. Composite Material Variation ........................................................................................................ 8

Figure 6. Boeing 787 Autoclave .................................................................................................................... 9

Figure 7. Boeing’s Carbon Roll Tip Application ........................................................................................... 10

Figure 8. Space Shuttle Colombia Carbon-Carbon Crack ............................................................................ 10

Figure 9. Composite’s Being dumped at Landfill ........................................................................................ 11

Figure 10. Modes of Fiber Deposition in Lung Airways .............................................................................. 12

Figure 11. Boeing 787’ ................................................................................................................................ 13

5 | P a g e

Composite Materials

Thomas Gray once said “Ignorance is Bliss,” but does trusting one’s life to a Composite Material

prove more naïve than ignorant? We live in a world where there is more than 1 cubic foot of Composite

Material that (in this case concrete) exists per person. Composite Materials are synthetic or naturally

occurring materials made from two or more constituent materials with significantly different properties

which remain distinct at the microscopic level. There are two categories of constituent materials; where

one material acts as a matrix and the other a resin reinforcement material. The reinforcement is

stronger, stiffer and forms a backbone while the matrix keeps the reinforcement set in place. For the

purpose of this research proposal I will focus on Composite Materials for aircraft due to the immense

popularity in construction and rising criticism of their longevity and usability in real life practice.

Engineers have looked at the unique stresses that aerofoil’s encounter during flight and from

the data they gathered have sought after a material that could withstand “Extreme changes in

temperature, external forces,

and water or chemical erosion

[9]. Composites are being chosen

over conventional materials such

as Aluminum because of their

specific strength, or strength to

weight ratio. Composites used in

the aerospace industry have a

specific strength of 785kN*m/kg

whereas an aluminum alloy has

222kN*m/kg” [9]. What this

means is that for a one pound

structure, a composite based

piece could withstand nearly 4

times the induced load than the aluminum piece. Of course, these numbers are coarse and baseless

without a practical application; however they serve to prove the advancements in strength where

panels need not be as heavy because of the support provided. In the case of aircraft construction,

special precautions must be taken to ensure a lightweight structure is produced that could provide

strong insulation that protects the passengers from the external environment. For this very reason, it is

Figure 2. Boeing 787 DreamLiner in Hangar

6 | P a g e

important to incorporate Composite Materials that can withstand flexure and high heat; “An aircraft

made of pure metal could fail catastrophically if a small crack appeared in the skin of the airplane. On

the other hand, aircraft integrating reinforced composite materials such as fiberglass, graphite, and

other hybrids will be stronger and less likely to break up at stress points in situations involving

turbulence” [9]. The first step in producing composite structures for aircraft is selecting the variety of

materials that could be layered up, molded and finally procured for use.

Mechanics of Composite Materials

Composites have revolutionized a number of industries, especially the aviation industry, in

which the development of higher quality composites allows companies to build bigger and better

aircraft. Composite Materials are made in layers or plies with a woven web of reinforcement that lays

sandwiched between a plastic or binding resin. Resin’s are not all the same; it is of utmost importance

that epoxy resin, that when cured is transparent, is used as the structural matrix material. Epoxy has a

very low viscosity allowing the liquid to fully coat the individual fibers. The coating process is critical to

keeping the matrix protected from the elements,

most importantly UV radiation that causes the

resin and fibers to degrade. The physical property

of composite materials are “anisotropic, meaning

they are different depending on the direction of

the applied load), important in the development

of stiff panels that require special orientation to

deflect wind and applied structural loads” [4].

The aerospace industry primarily uses Carbon

Reinforced Plastic (CRP) as the main material for

fuselage and wing portions. The world’s largest commercial aircraft, the Airbus A380, has 16% of its total

airframe made from CRP’s. It is not a traditional method of construction to employ Carbon Fiber and

Plastic Reinforcement in aircraft design as of late, due to the constraint of cost and testing to meet the

stated requirements of stress and flexure.

Composition of Materials

Figure 1. Carbon Fiber/Kevlar Weave pre-impregnated

7 | P a g e

Aircraft structures are fundamentally unidirectional. This means that one dimension, often the

length, is much larger than the others - width or height. For example, the span of the wing and tail spars

is longer than their width and depth; the fuselage ribs have a much larger chord length than height

and/or width; a whole wing has a span that is larger than its chords or thickness; and the fuselage is

much longer than it is wide or high. For Carbon Reinforced Plastic’s to be used effectively, they must be

interwoven by special looms that create tight symmetric weaves; it is these weaves of Carbon, Kevlar

and most contentiously used Polypropylene that create a matrix that is then covered by a thick coat of

epoxy resin.

Epoxy resin is a two part product that uses a chemical reaction to bond two polymers of

reagents. In the case of thermoset polymers, these agents are specially formulated to react when

introduced to heat as they first require a press to mould the weaves of fibers into the given shape. After

the epoxy is poured and the mould shaped, the tub, or mold with composite weaves and resin, is placed

into an oven or vacuum press where high heat and high pressure to procure the final product. “Instead

of plywood or sheet metal which allows single curvature only, the composite designer uses cloth where

the fibers are laid in two directions embedded in resin. This has the advantage of freedom of shape as a

double curvature

construction method;

which provides

optimum aerodynamic

shapes that improve

aircraft efficiency” [5].

The designer of the

aircraft must take this

into consideration when

using CPR’s in the

construction process;

fibers are used in the

desired direction exactly

where and in the

amount required. Significant weight reduction can be received if adequate CPR’s are used where

needed, improving efficiency, fuel consumption and lowering the overall cost of construction. The U.S.

Figure 2. Lockheed Martin F22 Raptor with Full AfterBurner’s

8 | P a g e

Military has been using Composites in their aircraft for the past 40 years. Their longevity and strengths

are visible, most notably is the Lockheed Martin made F-22 Raptor that is 25% Composite, “The high

performance capabilities of the F-22 requires the significant use of composite materials, which are both

stronger and lighter weight than traditional materials, and offer better protection against corrosion” [3].

The fibers used are embedded in resin to hold them in place and provide the required support against

buckling. Today there are a variety of composite materials that fit the needs of strong lightweight

construction. Glass, Kevlar, Carbon and Carbon-carbon are the main raw materials being used for the

process. The composites are constructed in thin layers that sandwich the fibers in a uni-directional

pattern often separated by a lightweight core to achieve the required stiffness.

Categories of Fiber-Reinforced Composite Materials

The two categories composite materials can exist under are short fiber reinforced materials and long

fiber continuously reinforced materials. “The

aerospace industry exclusively uses woven

continuous fibers” as shown in Figure (a) [6]. This

form of weaving is widely available for

production purposes, thus giving an advantage

over the short reinforced fibers. Most important,

however, is the strength gains by long fiber

strands; better ability to intertwine and lock than

their counterpart made of flakes/chips that are

assorted at random. Designing for a desired strength is done easily with long continuous fibers which

retain their constant material properties over a greater length for proper calculation. The most

important of these constants are the Young Modulus and Poisson ratio. Respectively, the Young

Modulus refers to the stiffness of the elastic material and the Poisson ratio pertains to the axial strain.

With these two constants in place, manufacturing an already complex material becomes easier for

engineers to produce.

Figure 3. Composite Material Variation

9 | P a g e

Molding Methods

The accepted procedure for material combining varies because of the vast array of molding

techniques. The “melding” event cures the Carbon Reinforced Plastics are “combined, compacted and

processed,” if the material is a thermoset polymeric it requires additional heat to solidify the

polymerase. Of the many molding methods, three stand out as the most commonly used; the vacuum

bag, pressure bag and autoclave method. The vacuum bag technique involves a polyurethane bag being

placed over the material after being lain in their respective upper and lower mold states. The air is

evacuated out via a nipple, causing the material matrix to be pressed into the resin. “A “platen” is placed

inside the bag for the material being pressed to lie upon” to prevent deformation of the intended piece.

Commercially created composites for floors and vehicle door panels are created this way [1]. Pressure

bag molding is very simple in principle and widely used to create pieces that are not of aerospace grade;

the reason being that the procedure only involved the two mould pieces being pressed together via a

clamp, high heat and resin. The outsourcing of labor in countries other than the U.S. heavily rely on this

method because it requires very little skill and has a low cost.

The method used exclusively by the aerospace industry is the autoclave technique. An autoclave

is a large oven that can accept composite

structures of full scale size (wings, fuselage,

wing box etc). The oven operates at

pressures above atmospheric, ensuring that

the resin is fully compacted into the weave

grain for maximum structural efficiency. The

intense heat within the autoclave forces the

polymers to bond fully too.

From an engineering standpoint,

this method is very attractive and supported by

Boeing because it allows new developments to be created in rapid succession. A quality mold is needed

to meet very strict quality control to prevent the coated fiber’s from being too “dry” or “wet” from the

process. The effect of a too dry mold is the inadequacy of proper strength and therefore the entire piece

must be destroyed; whereas a too wet mold is feasibly strong though it weighs significantly more than a

properly made piece that needs no further smoothing.

Figure 4. Boeing 787 Autoclave

10 | P a g e

Disadvantages and Failure

The methods used to apply Carbon Fiber and weaves of fibers alike are similar; but there are more

efficient ways to making a stronger piece. In the figure to the right, Boeing is using a “Carbon-Roll Tip to

apply bundles of pre-impregnated” weaves with resin to a fuselage mockup [1]. This may not seem like a

disadvantage at first; however,

when compared to the first

methods of carbon construction

and their primitive mechanisms

of application it is clear to see

the deficiency in understanding

property materials.

Composites can fail on

both the macro and microscopic

levels. Tension failures usually

occur on the macroscopic level

due to buckling; where physical

assessment can determine if the piece had fractured. Tension failures are much harder to spot as they

happen on the microscopic level; beginning the progress of degradation unknowing to the users of the

particular piece. Most composites are

“brittle and have little to no reserve

strength” beyond the initial onset of

breakage [6]. Failure of Composite

Materials commonly occurs in the form of

delaminating of the matrix; where

individual fibers can be pulled out of the

matrix making an extremely unstable

structure. However, the most common

type of failure is brittle failure caused by

compression; the most widely used example

of this failure is the” breakage of Space Shuttle Colombia’s carbon-carbon composite tile that suffered a

Figure 5. Space Shuttle Colombia Carbon-Carbon Crack

Figure 6 . Boeing’s Carbon Roll Tip Application

11 | P a g e

catastrophic failure as is re-entered Earth’s atmosphere” [1]. It is because of this very fine line between

failure and a working piece that Carbon Composites have only recently been incorporated into use by

the civilian population. Placing trust in a material that can break without the onset of yielding and worse

without warning has been a challenge for engineers. To aid in the process of quality control the CPR’s

can be subjected to “ultrasonic, thermo-graphic and X-ray radiation” [12]. These individual tests are

important in ensuring that no loose matrix fibers exist or worse, fine hair line cracks. The difficulty of this

process is that the entire Carbon Panel must be tested and ran along the surface with the testing

material; whereas an aluminum panel would only need x-ray photography in the welds to ensure a solid

connection. As one can perceive, the use of x-ray photography on the regular to check for panel integrity

can lead to health risks of over exposure to x-rays.

Ethical Dilemma and Efficacy

Composite Materials have the greatest value when it comes to lightweight and strong structure

construction. The more an aircraft weighs-the more fuel it burns; so a weight reduction of any number is

important to aeronautical engineers. However, despite the low weight and high strength yields

“composites have not been a miracle solution for aircraft structures” [2]. The primary reason composites

have not been adopted fully is because they are labor intensive and often require complex fabricating

machines to ensure proper construction. The complex construction methods make repairs near

impossible and increase the amount of waste that is sent to landfills; carbon materials are currently not

recyclable because their binding

agents are heavily embedded

between the weaves.

Waste and difficulty of

serviceability are not the only

ethical dilemmas that come to

mind when constructing

composites; health and safety do.

In the unprocessed form,

thermoset resins pose great health

risk because of the volatile organic

Figure 7. Composite’s Being dumped at Landfill

12 | P a g e

compounds given off into the atmosphere unscented [13]. Resins can cause radical skin damage and

allergic reactions; potentially fatal if one is allergic to the material and has a possible allergic reaction;

the solvent’s in resin remain hazardous in the construction and disposal stage. Fibers are inherently

benign, but carbon and glass fibers in particular do cause serious respiratory irritation. Unless the molds

for composite materials are constructed perfectly, they would regularly require sanding to meet the

smooth aerofoil requirement. The problem of respiratory infection begins in this stage, though it may

not have immediate negative effects on one’s health. The resins are active chemicals that not only cause

allergies but “chemicals that attack our body (especially eyes and lungs) and they have the unfortunate

property of being cumulatively

damaging” and there

symptoms are evident years

after handling [5].

The common ailments

related to Carbon Fiber and

Composite Exposure is

adherence of particulate

matter to the lungs and

passageway. From Figure 8 we

can see the different modes of

fiber deposition; I will discuss

the two common types. The airway region in the “human lung consists of a series of branching

capillaries called bronchioles”; in larger airways, fibers with greater terminal velocity are deposited by

impaction against the inside walls of airways [10]. The smaller the airway the slower the air velocity

becomes, hence sedimentation becomes the primary form of damage.

The efficacy of composite materials in the real world is apparent; their lightweight and specific

weight ratio makes them ideal for aircraft components. Cost and manufacturing equipment are distinct

barriers to overcome when constructing composites; of course the companies that produce them are

not too restricted in those terms. Unless the molds are designed well they require delicate sanding, this

sanding coupled with the toxic properties of resin pose serious health risks for specialists who handle

the construction process. Protection of masks, filters and ventilation are all important to ensure safety,

though the risk exists and life threatening symptoms occur years after the onset of contact. Backed by

Figure 8. Modes of Fiber Deposition in Lung Airways

13 | P a g e

large corporations, only these specialists can be trusted to come up with reliable and undeniably strong

structures that can handle the required loads.

Summary

Composite Materials remain fairly new to the realm of commercial aircrafts but have showed

their long term strength and stability in military aircraft and application of use in other products. The

advantage in strength to weight when compared to their substitute aluminum is staggering; with nearly

half the weight and twice the strength it is no wonder why CRP’s are widely being implemented. The

dangers, however, are clear; respiratory problems from the onset of construction to later years in life,

danger to the environment due to non-recyclability and most important the insurance that the CRP

panel was properly constructed using techniques garnished only in the past years. With the different

molding methods available, it is no wonder why composite materials are being produced on a mass

scale. The low cost of materials makes the use of composites more viable, the high cost for engineered

CPR’s are a drawback but only on the factor of cost- their performance numbers eclipse their competing

materials specifications. The efficacy of Composites in Aeronautics is unparalleled; the strong

lightweight materials are building massive superstructures such as the Boeing 787 on a large scale and in

quick time frames. Composite Materials are here to stay for their inherent benefits to the aeronautical

industry.

Figure 9. Boeing 787’

14 | P a g e

Bibliography

[1] Composite material - Wikipedia, the free encyclopedia. (2011, October 25). Wikipedia, the

free encyclopedia. Retrieved October 26, 2011, from http://en.wikipedia.org/wiki/Composite_

[2] Day, D. (2009, July 23). Composites and Advanced Materials. Centennial of Flight. Retrieved October 28, 2011, from http://www.centennialofflight.gov/essay/Evolution_of_Technology/composites/Tech40.htm

[3] "F-22 Materials and Processes." GlobalSecurity.org - Reliable Security Information. N.p., 7 July 2011. Web. 28 Oct. 2011. <http://www.globalsecurity.org/military/systems/aircraft/f-22-mp.htm>.

Figure 1. Boeing: Multimedia - Image Gallery - 787 Dreamliner. (2011, July 19). The Boeing

Company. Retrieved October 26, 2011, from

http://www.boeing.com/companyoffices/gallery/images/commercial/787/k63211-1.html

Figure 2. Boeing: Commercial Airplanes - 787 Home. (2010, September 10). The Boeing

Company. Retrieved October 26, 2011, from http://www.boeing.com/commercial/787family

Figure 3. Composite material - Wikipedia, the free encyclopedia. (2011, October 25). Wikipedia,

the free encyclopedia. Retrieved October 26, 2011, from

http://en.wikipedia.org/wiki/Composite_

Figure 4. "F-22 Materials and Processes." GlobalSecurity.org - Reliable Security Information. N.p., 7 July 2011. Web. 28 Oct. 2011. <http://www.globalsecurity.org/military/systems/aircraft/f-22-mp.htm>.

Figure 5. Composite material - Wikipedia, the free encyclopedia. (2011, October 25). Wikipedia,

the free encyclopedia. Retrieved October 26, 2011, from

http://en.wikipedia.org/wiki/Composite_

Figure 6. Batey, A. (2010, September 7). Boeing's billion dollar gamble: Inside the world's biggest

building, where the new 787 Dreamliner plane is built | Mail Online. Home | Mail Online.

Retrieved October 26, 2011, from http://www.dailymail.co.uk/home/moslive/article-

1308128/Boeings-billion-dollar-gamble-Inside-worlds-biggest-building-new-787-Dreamliner-

plane-built.html

Figure 7. Cohen, A. (2010, December 7). Airbus starts making first composite barrel for A350

XWB | Boeing and Aerospace News - seattlepi.com. Blogs - seattlepi.com. Retrieved October 26,

2011, from http://blog.seattlepi.com/aerospace/2010/12/07/airbus-starts-making-first-

composite-barrel-for-a350-xwb/

15 | P a g e

Figure 8. Space Shuttle Columbia disaster - Wikipedia, the free encyclopedia. (2011, October 25).

Wikipedia, the free encyclopedia. Retrieved October 26, 2011, from

http://en.wikipedia.org/wiki/Space_Shuttle

Figure 9. Hjelmar, J. (1995, September 12). Landfill Sites: Selection, Types, Techniques |

SchoolWorkHelper. School Work Helper. Retrieved October 26, 2011, from

http://schoolworkhelper.net/2011/06/landfill-sites-selection-types-techniques/

Figure 10. Tech Report. (2006, September 10). FAA. Retrieved October 26, 2011, from

www.tc.faa.gov/its/worldpac/techrpt/ar98-34.pdf

Figure 11. Boeing: Commercial Airplanes - 787 Home. (2010, September 10). The Boeing

Company. Retrieved October 26, 2011, from http://www.boeing.com/commercial/787family

[4] Griffis, B. (2008, March 28). Composites. MatWeb. Retrieved October 24, 2011, from www.matweb.com/reference/composites.aspx Bob Griffis

[5] Heintz, C. (2009, August 13). Data. Zenith Air. Retrieved October 24, 2011, from www.zenithair.com/kit-data/ht-85-12.html Chris Heintz

[6] Lomborg, B. (2001). The skeptical environmentalist: measuring the real state of the world. New York: Cambridge University Press.

[7] Matthews, F. L., & Rawlings, R. D. (1999). Composite materials: engineering and science. Boca Raton, Fla.: CRC Press ;.

[8] McGraw-Hill encyclopedia of science & technology: an international reference work in twenty volumes including an index. (9th ed.). (2002). New York: McGraw-Hill.

[9] Smith, S. (2003, September 2). What are Composite Materials. WiseGeek. Retrieved October 24, 2011, from www.wisegeek.com/what-are-composite-materials.htm

[10] Space Shuttle Columbia disaster - Wikipedia, the free encyclopedia. (2011, October 25).

Wikipedia, the free encyclopedia. Retrieved October 26, 2011, from

http://en.wikipedia.org/wiki/Space_Shuttle

[11] Tech Report. (2006, September 10). FAA. Retrieved October 26, 2011, from

www.tc.faa.gov/its/worldpac/techrpt/ar98-34.pdf

[12] Waterman, P. (2007, March 1). Defining Composites. DeskEngineer. Retrieved October 24, 2011, from www.deskeng.com/articles/aaaedt.htm

[13] Wermen, Banks. "About Composites – Learn about Plastic and Composite Materials." About Composites – Learn about Plastic and Composite Materials. N.p., 12 Aug. 2010. Web. 31 Oct. 2011. <http://composite.about.com/>.

16 | P a g e

17 | P a g e

18 | P a g e

19 | P a g e

20 | P a g e

21 | P a g e

22 | P a g e

23 | P a g e

About the Author

Sam Navid was born in Northridge, California on April 6 1990. He is the youngest in the family of

4. Having his three older siblings attend UC Berkeley and UCLA studying political put great pressure on

Sam to perform well early in life. His father, a Mechanical Engineer, had always pushed him towards the

field of engineering.

Life wasn’t always this simple however. Sam attended CastleBay Elementary just a few blocks

from his home, classes were never an issue until his 3rd grade teacher who consistently and without fail

gave “red” cards for misconduct, though Sam did nothing to deserve them. Following Castlebay he

attended Nobel Middle School where he met his friend and his passion for Mountain Biking. Sam soon

entered Mammoth Mountain’s DH CycloCross Series; he didn’t win, but it was an eye opening

experience to the world of extreme sports for him.

High school proved to be an uneventful time until Senior Year came around and I joined the

Senior Leadership Committee. I was the formal chair and in charge of planning that year’s Prom at the

Ronald Reagan Presidential Library.

Sam had his hopes set on UC Berkeley after graduating with high honors but found himself

accepted to UC Irvine instead. He was happy with the turn of events that lead him there because within

his first week he had tried out for UCI’s T&F team and had made it. Currently a part of the Ski &

Snowboard Club on Campus, Sam’s passion for extreme sport’s continue.

His favorite type of movie’s to watch are Zombie movies as they will, and I quote “better

prepare me for the impending apocalypse.” Sam’s humorous side is clear to see; unfortunately he

cannot enjoy watching movies anymore because he leads an adult life. Sam is currently in his senior

year at UC Irvine and work’s at BroadCom as an Intern.

24 | P a g e

Readability Analysis