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In materials science, advanced composite materials (ACMs) are
materials Material is a substance or mixture of substances that constitutes an object. Materials can be pure or impure, living or non-living matter. Materials can be classified on the basis of their physical and chemical properties, or on their geolog ...
that are generally characterized by unusually high strength
fibres Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate ...
with unusually high
stiffness Stiffness is the extent to which an object resists deformation in response to an applied force. The complementary concept is flexibility or pliability: the more flexible an object is, the less stiff it is. Calculations The stiffness, k, of a ...
, or
modulus of elasticity An elastic modulus (also known as modulus of elasticity) is the unit of measurement of an object's or substance's resistance to being deformed elastically (i.e., non-permanently) when a stress is applied to it. The elastic modulus of an object is ...
characteristics, compared to other materials, while bound together by weaker
matrices Matrix most commonly refers to: * ''The Matrix'' (franchise), an American media franchise ** ''The Matrix'', a 1999 science-fiction action film ** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchis ...
. These are termed "advanced composite materials" in comparison to the
composite material A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...
s commonly in use such as
reinforced concrete Reinforced concrete (RC), also called reinforced cement concrete (RCC) and ferroconcrete, is a composite material in which concrete's relatively low ultimate tensile strength, tensile strength and ductility are compensated for by the inclusion ...
, or even
concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...
itself. The high strength fibers are also low
density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematicall ...
while occupying a large fraction of the
volume Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). ...
. Advanced composites exhibit desirable
physical Physical may refer to: * Physical examination, a regular overall check-up with a doctor * ''Physical'' (Olivia Newton-John album), 1981 ** "Physical" (Olivia Newton-John song) * ''Physical'' (Gabe Gurnsey album) * "Physical" (Alcazar song) (2004) * ...
and
chemical properties A chemical property is any of a material's properties that becomes evident during, or after, a chemical reaction; that is, any quality that can be established only by changing a substance's chemical identity.William L. Masterton, Cecile N. Hurley, ...
that include light weight coupled with high stiffness ( elasticity), and strength along the direction of the reinforcing fiber, dimensional stability, temperature and chemical resistance, flex performance, and relatively easy processing. Advanced composites are replacing metal components in many uses, particularly in the
aerospace industry Aerospace is a term used to collectively refer to the atmosphere and outer space. Aerospace activity is very diverse, with a multitude of commercial, industrial and military applications. Aerospace engineering consists of aeronautics and astron ...
. Composites are classified according to their matrix phase. These classifications are polymer matrix composites (PMCs),
ceramic matrix composite In materials science, ceramic matrix composites (CMCs) are a subgroup of composite materials and a subgroup of ceramics. They consist of ceramic fibers embedded in a ceramic matrix. The fibers and the matrix both can consist of any ceramic mate ...
s (CMCs), and
metal matrix composite In materials science, a metal matrix composite (MMC) is a composite material with fibers or particles dispersed in a metallic matrix, such as copper, aluminum, or steel. The secondary phase is typically a ceramic (such as alumina or silicon carb ...
s (MMCs). Also, materials within these categories are often called "advanced" if they combine the properties of high (axial,
longitudinal Longitudinal is a geometric term of location which may refer to: * Longitude ** Line of longitude, also called a meridian * Longitudinal engine, an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicle, ...
) strength values and high (
axial Axial may refer to: * one of the anatomical directions describing relationships in an animal body * In geometry: :* a geometric term of location :* an axis of rotation * In chemistry, referring to an axial bond * a type of modal frame, in music * ...
, longitudinal) stiffness values, with low weight, corrosion resistance, and in some cases special
electrical Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described ...
properties. Advanced composite materials have broad, proven applications, in the
aircraft An aircraft is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or by using the Lift (force), dynamic lift of an airfoil, or in ...
, aerospace, and
sports equipment Sports equipment, sporting equipment, also called sporting goods, are the tools, materials, apparel, and gear used to compete in a sport and varies depending on the sport. The equipment ranges from balls, nets, and protective gear like helmets. ...
sectors. Even more specifically ACMs are very attractive for aircraft and aerospace structural parts. ACMs have been developing for NASA's '' Advanced Space Transportation Program'', armor protection for ''
Army aviation An army aviation unit is an aviation-related unit of a nation's army, sometimes described as an air corps. These units are generally separate from a nation's dedicated air force, and usually comprise helicopters and light support fixed-wing air ...
'' and the ''
Federal Aviation Administration The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic ...
'' of the USA, and high-temperature shafting for the ''
Comanche helicopter The Comanche or Nʉmʉnʉʉ ( com, Nʉmʉnʉʉ, "the people") are a Native American tribe from the Southern Plains of the present-day United States. Comanche people today belong to the federally recognized Comanche Nation, headquartered in Law ...
''. Additionally, ACMs have a decades long history in military and government aerospace industries. However, much of the technology is new and not presented formally in secondary or
undergraduate education Undergraduate education is education conducted after secondary education and before postgraduate education. It typically includes all postsecondary programs up to the level of a bachelor's degree. For example, in the United States, an entry-le ...
, and the technology of advanced composites manufacture is continually evolving. Public domain content from a U.S. government department
Materials created by the federal government
are generally part of the public domain and may be used, reproduced and distributed without permission.


Overview and historical perspective

Manufacturing ACMs is a multibillion-dollar industry worldwide. Composite products range from
skateboard A skateboard is a type of sports equipment used for skateboarding. They are usually made of a specially designed 7-8 ply maple plywood deck and polyurethane wheels attached to the underside by a pair of skateboarding trucks. The skateboarder ...
s to components of the
Space Shuttle The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program n ...
. The industry can be generally divided into two basic segments, industrial composites and advanced composites. Several of the composites manufacturing processes are common to both segments. The two basic segments are described below.


Industrial composites

The industrial composites industry has been in place for over 40 years in the U.S. This large industry utilizes various
resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on nat ...
systems including
polyester Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include natura ...
,
epoxy Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also co ...
, and other specialty resins. These materials, along with a
catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
or curing agent and some type of fiber reinforcement (typically glass fibers) are used in the production of a wide spectrum of industrial components and consumer goods: boats, piping, auto bodies, and a variety of other parts and components.


Advanced composites

The Advanced composites industry, or Advanced composite materials industry, is characterized by the use of expensive, high-performance resin systems and high-strength, high-stiffness fiber reinforcement. The aerospace industry, including
military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is typically authorized and maintained by a sovereign state, with its members identifiable by their distinct ...
and
commercial aircraft An airliner is a type of aircraft for transporting passengers and air cargo. Such aircraft are most often operated by airlines. Although the definition of an airliner can vary from country to country, an airliner is typically defined as an ai ...
of all types, is the major customer for advanced composites. These materials have also been adopted for use by the
sporting goods Sports equipment, sporting equipment, also called sporting goods, are the tools, materials, apparel, and gear used to compete in a sport and varies depending on the sport. The equipment ranges from balls, nets, and protective gear like helmets. ...
suppliers who sell high-performance equipment to the
golf Golf is a club-and-ball sport in which players use various clubs to hit balls into a series of holes on a course in as few strokes as possible. Golf, unlike most ball games, cannot and does not use a standardized playing area, and coping wi ...
,
tennis Tennis is a racket sport that is played either individually against a single opponent (singles) or between two teams of two players each (doubles). Each player uses a tennis racket that is strung with cord to strike a hollow rubber ball cov ...
,
fishing Fishing is the activity of trying to catch fish. Fish are often caught as wildlife from the natural environment, but may also be caught from fish stocking, stocked bodies of water such as fish pond, ponds, canals, park wetlands and reservoirs. ...
, and
archery Archery is the sport, practice, or skill of using a bow to shoot arrows.Paterson ''Encyclopaedia of Archery'' p. 17 The word comes from the Latin ''arcus'', meaning bow. Historically, archery has been used for hunting and combat. In ...
markets; as well as in the swimming pool industry with Composite wall structures. While aerospace is the predominant market for advanced composites today, the industrial and automotive markets will increasingly see the use of advanced composites toward the year 2000(Its now 2019 this is out of date). At present, both manual and automated processes are employed in making advanced-composite parts. As automated processes become more predominant, the costs of advanced composites are expected to decline to the point at which these materials will be used widely in electronic, machinery, and surface transportation equipment. Suppliers of advanced composite materials tend to be larger companies capable of doing the
research and development Research and development (R&D or R+D), known in Europe as research and technological development (RTD), is the set of innovative activities undertaken by corporations or governments in developing new services or products, and improving existi ...
necessary to provide the high-performance resin systems used in this segment of the industry. End-users also tend to be large, and many are in the aircraft and aerospace businesses.


Limitations

Despite their strength and low weight, composites have not been a miracle solution for aircraft structures. Composites are typically difficult to inspect for flaws. Some of them absorb moisture. Most importantly, they can be prohibitively expensive, primarily because they are labor-intensive and often require complex and expensive fabrication machines. Aluminium, by contrast, is easy and inexpensive to manufacture and repair, for example in a minor collision an aluminium component can often be hammered back into its original shape, whereas a crunched fiberglass component will likely have to be completely replaced. Public domain content (see above reference) Aluminium has a relatively high fracture toughness, allowing it to undergo large amounts of
plastic deformation In engineering, deformation refers to the change in size or shape of an object. ''Displacements'' are the ''absolute'' change in position of a point on the object. Deflection is the relative change in external displacements on an object. Strain ...
before failure. Composites, on the other hand, are less damage tolerant and undergo much less plastic deformation before failure. An airplane made entirely from aluminium can be repaired almost anywhere. This is not the case for composite materials, particularly as they use different and more exotic materials. Because of this, composites will probably always be used more in military aircraft, which are constantly being maintained, than in commercial aircraft, which have to require less maintenance. Aluminium still remains a remarkably useful material for aircraft structures and metallurgists have worked hard to develop better aluminium alloys, for example aluminium-lithium alloys.


See also

*
Composite material A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...
*
NASA Advanced Space Transportation Program The Advanced Space Transportation Program (ASTP) is a NASA program to intentionally advance current space transportation system technologies, and innovate novel technologies, through intense research efforts that are intended to culminate in reg ...


External links

*Buckland, Peter G
Advanced composite materials with application to bridges
September 30, 1991. *Oak Ridge National Laboratory

Vol. 33, No. 3, 2000. *Worldwide Composites Search Engin

Large database of companies involved in composite materials.


References

: : {{DEFAULTSORT:Advanced composite materials (science and engineering) Composite materials Materials science Ceramic materials Fibre-reinforced polymers