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A composite material (also called a composition material or shortened to composite, which is the common name) is a
material Material is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance, a material with a definite chemical composition * Matter, anything that has mass and t ...

material
which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or physical properties and are merged to create a material with properties unlike the individual elements. Within the finished structure, the individual elements remain separate and distinct, distinguishing composites from
mixture In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds composed of atoms, ...

mixture
s and
solid solution A solid solution describes a family of materials which have a range of compositions (e.g. AxB1−x) and a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word "solution" is used to desc ...

solid solution
s. Typical
engineered
engineered
composite materials include: *
Reinforced concrete Reinforced concrete (RC), also called reinforced cement concrete (RCC), is a 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 ...
and
masonry Masonry is the building of structures from individual units, which are often laid in and bound together by mortar Mortar may refer to: * Mortar (weapon), an indirect-fire infantry weapon * Mortar (masonry), a material used to fill the gaps betwee ...

masonry
*
Composite wood Engineered wood, also called mass timber, composite wood, man-made wood, or manufactured board, includes a range of derivative wood products which are manufactured by binding or fixing the strands, particles, fibres, or wood veneer, veneers or b ...
such as
plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer In woodworking, veneer refers to thin slices of wood and sometimes bark, usually thinner than 3 mm (1/8 inch), that typically are glued onto core panels (typic ...

plywood
*
Reinforced plastic Fibre-reinforced plastic (FRP) (also called fiber-reinforced polymer, or fiber-reinforced plastic) is a composite material made of a polymer matrix reinforced with fibres. The fibres are usually glass fibre, glass (in fibreglass), Carbon fibers, car ...
s, such as fibre-reinforced polymer or
fiberglass Fiberglass (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American Englis ...
*
Ceramic matrix composites File:CMCLagerhuelsen.jpg, CMC shaft sleeves 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 o ...
( composite ceramic and metal matrices) *
Metal matrix compositesA metal matrix composite (MMC) is 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 consti ...
*and other
advanced composite materials ''Advanced Composite Materials'' is a bimonthly Peer review, peer-review scientific journal that was established in 1991. It is published by Taylor & Francis on behalf of the Japan Society for Composite Materials and the Korean Society for Composit ...
There are various reasons where new material can be favoured. Typical examples include materials which are less expensive, lighter, stronger or more durable when compared with common materials. More recently researchers have also begun to actively include sensing, actuation, computation and communication into composites, which are known as robotic materials. Composite materials are generally used for
building A building, or edifice, is a structure with a roof and walls standing more or less permanently in one place, such as a house A house is a single-unit residential building, which may range in complexity from a rudimentary hut to a complex st ...

building
s,
bridge A bridge is a structure A structure is an arrangement and organization of interrelated elements in a material object or system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to ...

bridge
s, and
structure A structure is an arrangement and organization of interrelated elements in a material object or system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A ...

structure
s such as
boat hulls A hull is the watertight body of a ship or boat. The hull may open at the top (such as a dinghy), or it may be fully or partially covered with a deck. Atop the deck may be a deckhouse and other superstructures, such as a funnel, derrick, or Mast ( ...
,
swimming pool panels Swimming is the self-propulsion of a person through water, usually for recreation, sport, exercise, or survival. Locomotion is achieved through coordinated movement of the limbs and the body. Humans can hold their breath underwater and undertak ...
,
racing car Auto racing (also known as car racing, motor racing, or automobile racing) is a motorsport Motorsport, motorsports or motor sport is a global term used to encompass the group of competitive Sports, sporting events which primarily involve ...

racing car
bodies,
shower A shower is a place in which a person bathes under a spray of typically Water heating, warm or hot water. Indoors, there is a drain in the floor. Most showers have temperature, spray pressure and adjustable showerhead nozzle. The simplest s ...

shower
stalls,
bathtub A bathtub, also known simply as a bath or tub, is a container for holding water in which a person or animal may bathe. Most modern bathtubs are made of thermoformed Thermoforming is a manufacturing process where a plastic sheet is heated to a ...

bathtub
s,
storage tanks in Karlsruhe MiRO Storage tanks are containers that hold liquids, compressed gases (gas tank; or in U.S.A "pressure vessel", which is not typically labeled or regulated as a storage tank) or mediums used for the short- or long-term storage of he ...
,
imitation Imitation (from Latin ''imitatio'', "a copying, imitation") is an advanced behavior whereby an individual observes and replicates another's behavior. Imitation is also a form of social learning that leads to the "development of traditions, and ...

imitation
granite Granite () is a coarse-grained (phaneritic A phanerite is an igneous rock Igneous rock (derived from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Lat ...

granite
and
cultured marbleEngineered stone is a composite material made of crushed stone bound together by an adhesive, (most commonly polymer resin, with some newer versions using cement mix). This category includes engineered quartz, polymer concrete and engineered marble s ...
sink A sink – also known by other names including sinker, washbowl, hand basin, wash basin, and simply basin – is a bowl-shaped used for washing , , and other purposes. Sinks have s (faucets) that supply hot and cold water and may include a sp ...

sink
s and countertops. They are also being increasingly used in general automotive applications. The most advanced examples perform routinely on
spacecraft File:Space Shuttle Columbia launching.jpg, 275px, The US Space Shuttle flew 135 times from 1981 to 2011, supporting Spacelab, ''Mir'', the Hubble Space Telescope, and the ISS. (''Columbia'' STS-1, maiden launch, which had a white external tank, ...

spacecraft
and
aircraft An aircraft is a vehicle or machine that is able to fly Flies are insect Insects or Insecta (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Lat ...

aircraft
in demanding environments.


History

The earliest composite materials were made from
straw Straw is an agricultural consisting of the dry s of plants after the and have been removed. It makes up about half of the yield of cereal crops such as , s, , and . It has a number of different uses, including , and , and . Straw i ...

straw
and
mud Mud is soil File:Stagnogley.JPG, Surface-water-Gley soil, gley developed in glacial till, Northern Ireland. Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Earth's body of soil, called ...

mud
combined to form
brick A brick is a type of block used to build walls, pavements and other elements in masonry Masonry is the building of structures from individual units, which are often laid in and bound together by mortar Mortar may refer to: * Mortar (weap ...

brick
s for
building A building, or edifice, is a structure with a roof and walls standing more or less permanently in one place, such as a house A house is a single-unit residential building, which may range in complexity from a rudimentary hut to a complex st ...

building
construction Construction is a general term meaning the and to form , , or ,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and comes from ''constructio'' (from ''com-' ...

construction
. Ancient
brick-making A brickworks, also known as a brick factory, is a factory A factory, manufacturing plant or a production plant is an industrial site, often a complex consisting of several buildings filled with machinery A machine is a man-made device ...
was documented by
Egyptian tomb paintings
Egyptian tomb paintings
.
Wattle and daub Wattle and daub is a composite material, composite building method used for making walls and buildings, in which a woven lattice of wooden strips called wattle (construction), wattle is daubed with a sticky material usually made of some combinatio ...

Wattle and daub
is one of the oldest composite materials, at over 6000 years old. Concrete is also a composite material, and is used more than any other synthetic material in the world. , about 7.5 billion cubic metres of concrete are made each year—more than one cubic metre for every person on Earth. * Woody
plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration, can later be released to fuel ...

plant
s, both true
wood Wood is a porous and fibrous structural tissue found in the stems and roots of tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and leaves in most species. ...

wood
from
trees In botany Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), organiz ...

trees
and such plants as palms and
bamboo Bamboos are a diverse group of evergreen perennial plant, perennial flowering plants in the subfamily (biology), subfamily Bambusoideae of the grass family ''Poaceae''. The origin of the word "bamboo" is uncertain, but it probably comes from t ...

bamboo
, yield natural composites that were used prehistorically by mankind and are still used widely in construction and scaffolding. *
Plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer In woodworking, veneer refers to thin slices of wood and sometimes bark, usually thinner than 3 mm (1/8 inch), that typically are glued onto core panels (typic ...

Plywood
, 3400 BC, by the Ancient Mesopotamians; gluing wood at different angles gives better properties than natural wood. *
Cartonnage Cartonnage is a type of material used in ancient Egyptian funerary masks from the First Intermediate Period to the Roman Empire, Roman era. It was made of layers of linen or papyrus covered with plaster. Some of the Fayum mummy portraits are also p ...
, layers of linen or papyrus soaked in plaster dates to the
First Intermediate Period of Egypt The First Intermediate Period, described as a 'dark period' in ancient Egypt Ancient Egypt was a civilization of Ancient history, ancient North Africa, concentrated along the lower reaches of the Nile, Nile River, situated in the place t ...
c. 2181–2055 BC and was used for
death mask A death mask is a likeness (typically in wax or plaster cast) of a person's face after their death, usually made by taking a cast or impression from the corpse. Death masks may be mementos of the dead, or be used for creation of portraits. It i ...
s. * Cob mud bricks, or mud walls, (using mud (clay) with straw or gravel as a binder) have been used for thousands of years. *
Concrete Concrete is a composed of fine and coarse bonded together with a fluid (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most widely used building material. Its ...

Concrete
was described by
Vitruvius Vitruvius (; c. 80–70 BC – after c. 15 BC) was a Roman architect and engineer during the 1st century BC, known for his multi-volume work entitled ''De architectura (''On architecture'', published as ''Ten Books on Architecture'') i ...

Vitruvius
, writing around 25 BC in his , distinguished types of aggregate appropriate for the preparation of
lime mortar Lime mortar is composed of lime and an aggregate such as sand, mixed with water. The Ancient Indians were the first to use lime mortars, which they used to plaster the Temples. In addition, the Egyptians also incorporated various limes into th ...
s. For ''structural mortars'', he recommended ''
pozzolana Pozzolana or pozzuolana ( , ), also known as pozzolanic ash ( la, pulvis puteolanus), is a natural silica, siliceous or siliceous-Aluminium oxide, aluminous material which reacts with calcium hydroxide in the presence of water at room temperature (c ...
'', which were volcanic sands from the sandlike beds of
Pozzuoli Pozzuoli (; ; ) is a city and ''comune The (; plural: ) is a local administrative division of Italy Italy ( it, Italia ), officially the Italian Republic ( it, Repubblica Italiana, links=no ), is a country consisting of a Norther ...
brownish-yellow-gray in colour near
Naples Naples (; it, Napoli ; nap, Napule ), from grc, Νεάπολις, Neápolis, lit=new city. is the regional capital of and the third-largest city of , after and , with a population of 967,069 within the city's administrative limits as of ...

Naples
and reddish-brown at
Rome , established_title = Founded , established_date = 753 BC , founder = King Romulus Romulus was the legendary founder and first king of Rome , established_title = Founded , established_date = 753 BC , fo ...

Rome
. Vitruvius specifies a ratio of 1 part lime to 3 parts pozzolana for cements used in buildings and a 1:2 ratio of lime to pulvis Puteolanus for underwater work, essentially the same ratio mixed today for concrete used at sea. Natural cement-stones, after burning, produced cements used in concretes from post-Roman times into the 20th century, with some properties superior to manufactured
Portland cement Portland cement is the most common type of in general use around the world as a basic ingredient of , , , and non-specialty . It was developed from other types of in England in the early 19th century by , and is usually made from . It is a f ...

Portland cement
. *
Papier-mâché papier-mâché masks, Haiti Papier-mâché (, ; , literally "paper-mash") is a composite material consisting of paper pieces or pulp, sometimes reinforced with textiles, bound with an adhesive, such as glue, starch, or wallpaper adhesive, wallp ...
, a composite of paper and glue, has been used for hundreds of years. * The first artificial fibre reinforced plastic was a combination of fiber glass and
bakelite Bakelite ( ; sometimes spelled Baekelite) or polyoxybenzylmethylenglycolanhydride was the first plastic made from synthetic components. It is a thermosetting polymer, thermosetting phenol formaldehyde resin, formed from a condensation reaction of ...

bakelite
, performed in 1935 by Al Simison and Arthur D Little in Owens Corning Company * One of the most common and familiar composite is
fibreglass Fiberglass (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American English ...
, in which small glass fibre are embedded within a polymeric material (normally an epoxy or polyester). The glass fibre is relatively strong and stiff (but also brittle), whereas the polymer is ductile (but also weak and flexible). Thus the resulting fibreglass is relatively stiff, strong, flexible, and ductile.


Examples


Composite materials

Concrete Concrete is a composed of fine and coarse bonded together with a fluid (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most widely used building material. Its ...

Concrete
is the most common artificial composite material of all and typically consists of loose stones (aggregate) held with a matrix of
cement A cement is a , a substance used for construction that s, hardens, and adheres to other s to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel () together. Cement mixed with fine aggregate produces for ...
. Concrete is an inexpensive material, and will not compress or shatter even under quite a large compressive force. However, concrete cannot survive tensile loading (i.e., if stretched it will quickly break apart). Therefore, to give concrete the ability to resist being stretched, steel bars, which can resist high stretching (tensile) forces, are often added to concrete to form
reinforced concrete Reinforced concrete (RC), also called reinforced cement concrete (RCC), is a 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 ...
. Fibre-reinforced polymers include
carbon fiber reinforced polymer Carbon fiber reinforced polymer (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Curr ...
and
glass-reinforced plastic Fiberglass (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American English ...
. If classified by matrix then there are thermoplastic composites, short fibre thermoplastics, long fibre thermoplastics or long fibre-reinforced thermoplastics. There are numerous
thermoset A thermosetting polymer, resin, or plastic, often called a thermoset, is a polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecule File:Pentacene on Ni(111) STM.jpg, ...

thermoset
composites, including paper composite panels. Many advanced
thermoset polymer matrixA thermoset polymer matrix is a synthetic polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy im ...
systems usually incorporate
aramid Aramid fibers are a class of heat-resistant and strong synthetic fiber Synthetic fiber or synthetic fibre (in British English; American and British English spelling differences#-re, -er, see spelling differences) are fibers made by humans throu ...
fibre Fiber or fibre (from la, fibra, links=no) is a natural Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of space and time and their contents, including ...

fibre
and
carbon fibre Carbon fiber reinforced polymer (American English), Carbon fibre reinforced polymer (English in the Commonwealth of Nations, Commonwealth English), or carbon fiber reinforced plastic, or carbon fiber reinforced thermoplastic (CFRP, CRP, CFRTP, ...
in an
epoxy resin Epoxy is the family of basic components or Curing (chemistry), 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 functiona ...

epoxy resin
matrix. Shape memory polymer composites are high-performance composites, formulated using fibre or fabric reinforcements and shape memory polymer resin as the matrix. Since a shape memory polymer resin is used as the matrix, these composites have the ability to be easily manipulated into various configurations when they are heated above their activation temperatures and will exhibit high strength and stiffness at lower temperatures. They can also be reheated and reshaped repeatedly without losing their material properties. These composites are ideal for applications such as lightweight, rigid, deployable structures; rapid manufacturing; and dynamic reinforcement. High strain composites are another type of high-performance composites that are designed to perform in a high deformation setting and are often used in deployable systems where structural flexing is advantageous. Although high strain composites exhibit many similarities to shape memory polymers, their performance is generally dependent on the fibre layout as opposed to the resin content of the matrix. Composites can also use metal fibres reinforcing other metals, as in
metal matrix compositeA metal matrix composite (MMC) is composite material with at least two constituent parts, one being a metal necessarily, the other material may be a different metal or another material, such as a ceramic or organic compound. When at least three mate ...
s (MMC) or
ceramic matrix composites File:CMCLagerhuelsen.jpg, CMC shaft sleeves 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 o ...
(CMC), which includes
bone A bone is a rigid tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa dubit ...
(
hydroxyapatite Hydroxyapatite, also called hydroxylapatite (HA), is a naturally occurring mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a ...
reinforced with
collagen Collagen () is the main structural protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowder ...

collagen
fibres),
cermet A cermet is a 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 hav ...
(ceramic and metal) and
concrete Concrete is a composite material A composite material (also called a composition material or shortened to composite, which is the common name) is a material Material is a substance Substance may refer to: * Substance (Jainism), a ter ...

concrete
. Ceramic matrix composites are built primarily for
fracture toughness In materials science, fracture toughness is the critical stress intensity factor of a sharp crack where propagation of the crack suddenly becomes rapid and unlimited. A component's thickness affects the constraint conditions at the tip of a cra ...

fracture toughness
, not for strength. Another class of composite materials involve woven fabric composite consisting of longitudinal and transverse laced yarns. Woven fabric composites are flexible as they are in form of fabric. Organic matrix/ceramic aggregate composites include
asphalt concrete Asphalt concrete (commonly called asphalt, blacktop, or pavement in North America, and tarmac, bitumen macadam, or rolled asphalt in the United Kingdom and the Republic of Ireland) is a composite material commonly used to surface road surface, r ...
,
polymer concrete Polymer concrete is a type of concrete that uses polymer to replace lime (material), lime-type cements as a Binder (material), binder. In some cases the polymer is used in addition to portland cement to form Polymer Cement Concrete (PCC) or Polymer ...
, mastic asphalt, mastic roller hybrid,
dental composite Dental composite resins (better referred to as "resin-based composites" or simply "filled resins") are dental cements made of synthetic resins. Synthetic resins evolved as restorative materials since they were insoluble, of good tooth-like appeara ...
,
syntactic foam 300px, Syntactic foam, shown by scanning electron microscopy, consisting of glass microspheres within a matrix of epoxy resin. Syntactic foams are composite materials synthesized by filling a metal, polymer, or ceramic matrix with hollow sphe ...
and
mother of pearl Nacre ( also ), also known as mother of pearl, is an organicinorganic composite material A composite material (also called a composition material or shortened to composite, which is the common name) is a material Material is a substanc ...

mother of pearl
.
Chobham armour type to be protected by Chobham armour Image:Challenger1MBT.JPEG, 300px, The British Army's Challenger 1 was the second main battle tank to use Chobham armour Chobham armour is the informal name of a composite armour developed in the 1960s at the ...
is a special type of
composite armour Composite armour is a type of vehicle armour Military vehicle A military vehicle is a type of vehicle A vehicle (from la, vehiculum) is a machine that transport Transport (commonly used in the U.K.), or transportation (used in ...
used in military applications. Additionally, thermoplastic composite materials can be formulated with specific metal powders resulting in materials with a density range from 2 g/cm3 to 11 g/cm3 (same density as lead). The most common name for this type of material is "high gravity compound" (HGC), although "lead replacement" is also used. These materials can be used in place of traditional materials such as aluminium, stainless steel, brass, bronze, copper, lead, and even tungsten in weighting, balancing (for example, modifying the centre of gravity of a tennis
racquet A racket or racquet is a sports implement consisting of a handled frame with an open hoop across which a network of strings or catgut is stretched tightly. It is used for striking a ball A ball is a round object (usually spherical, but ca ...
), vibration damping, and radiation shielding applications. High density composites are an economically viable option when certain materials are deemed hazardous and are banned (such as lead) or when secondary operations costs (such as machining, finishing, or coating) are a factor. There have been several studies indicating that interleaving stiff and brittle epoxy based
carbon fiber reinforced polymer Carbon fiber reinforced polymer (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Curr ...
laminates with flexible thermoplastic laminates can help to make highly toughened composites that show improved impact resistance. Another interesting aspect of such interleaved composites is that they are able to have shape memory behaviour without needing any shape memory polymers or shape memory alloys e.g. balsa plies interleaved with hot glue, aluminium plies interleaves with acrylic polymers or Polyvinyl chloride, PVC and
carbon fiber reinforced polymer Carbon fiber reinforced polymer (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Curr ...
laminates interleaved with polystyrene. A sandwich-structured composite is a special class of composite material that is fabricated by attaching two thin but stiff skins to a lightweight but thick core. The core material is normally low strength material, but its higher thickness provides the sandwich composite with high bending stiffness with overall low density. Wood is a naturally occurring composite comprising cellulose fibres in a lignin and hemicellulose matrix. Engineered wood includes a wide variety of different products such as wood fibre board,
plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer In woodworking, veneer refers to thin slices of wood and sometimes bark, usually thinner than 3 mm (1/8 inch), that typically are glued onto core panels (typic ...

plywood
, oriented strand board, wood plastic composite (recycled wood fibre in polyethylene matrix), Pykrete (sawdust in ice matrix), Plastic-impregnated or Plastic-coated paper, laminated paper or textiles, Arborite, Formica (plastic) and Micarta. Other engineered laminate composites, such as Mallite, use a central core of end grain balsa wood, bonded to surface skins of light alloy or GRP. These generate low-weight, high rigidity materials. Particulate composites have particle as filler material dispersed in matrix, which may be nonmetal, such as glass, epoxy. Automobile tire is an example of particulate composite. Advanced diamond-like carbon (DLC) coated polymer composites have been reported where the coating increases the surface hydrophobicity, hardness and wear resistance. Ferromagnetic composites, including those with a polymer matrix consisting, for example, of nanocrystalline filler of Fe-based powders and polymers matrix. Amorphous and nanocrystalline powders obtained, for example, from metallic glasses can be used. Their use makes it possible to obtain ferromagnetic nanocomposites with controlled magnetic properties.


Products

Fibre-reinforced composite materials have gained popularity (despite their generally high cost) in high-performance products that need to be lightweight, yet strong enough to take harsh loading conditions such as aerospace components (empennage, tails, wings, fuselages, Propeller (aircraft), propellers), boat and scull hulls, bicycle frames and
racing car Auto racing (also known as car racing, motor racing, or automobile racing) is a motorsport Motorsport, motorsports or motor sport is a global term used to encompass the group of competitive Sports, sporting events which primarily involve ...

racing car
bodies. Other uses include fishing rods, storage tanks, swimming pool panels, and Composite baseball bat, baseball bats. The Boeing 787 and Airbus A350 structures including the wings and fuselage are composed largely of composites. Composite materials are also becoming more common in the realm of orthopedic surgery, and it is the most common hockey stick material. Carbon composite is a key material in today's launch vehicles and heat shields for the re-entry phase of
spacecraft File:Space Shuttle Columbia launching.jpg, 275px, The US Space Shuttle flew 135 times from 1981 to 2011, supporting Spacelab, ''Mir'', the Hubble Space Telescope, and the ISS. (''Columbia'' STS-1, maiden launch, which had a white external tank, ...

spacecraft
. It is widely used in solar panel substrates, antenna reflectors and yokes of spacecraft. It is also used in payload adapters, inter-stage structures and heat shields of launch vehicles. Furthermore, disk brake systems of airplanes and racing cars are using carbon/carbon material, and the Ceramic Matrix Composite, composite material with
carbon fibre Carbon fiber reinforced polymer (American English), Carbon fibre reinforced polymer (English in the Commonwealth of Nations, Commonwealth English), or carbon fiber reinforced plastic, or carbon fiber reinforced thermoplastic (CFRP, CRP, CFRTP, ...
s and silicon carbide matrix has been introduced in luxury vehicles and sports cars. In 2006, a fibre-reinforced composite pool panel was introduced for in-ground swimming pools, residential as well as commercial, as a non-corrosive alternative to galvanized steel. In 2007, an all-composite military Humvee was introduced by TPI Composites Inc and Armor Holdings Inc, the first all-composite military vehicle. By using composites the vehicle is lighter, allowing higher payloads. In 2008, carbon fibre and DuPont Kevlar (five times stronger than steel) were combined with enhanced thermoset resins to make military transit cases by ECS Composites creating 30-percent lighter cases with high strength. Pipes and fittings for various purpose like transportation of potable water, fire-fighting, irrigation, seawater, desalinated water, chemical and industrial waste, and sewage are now manufactured in glass reinforced plastics. Composite materials used in tensile structures for facade application provides the advantage of being translucent. The woven base cloth combined with the appropriate coating allows better light transmission. This provides a very comfortable level of illumination compared to the full brightness of outside. The wings of wind turbines, in growing sizes in the order of 50 m length are fabricated in composites since several years. Two-lower-leg-amputees run on carbon-composite spring-like artificial feet as quick as non-amputee athletes. High pressure gas cylinders typically about 7–9 litre volume x 300 bar pressure for firemen are nowadays constructed from carbon composite. Type-4-cylinders include metal only as boss that carries the thread to screw in the valve. On 5 September 2019, HMD Global unveiled the Nokia 6.2 and Nokia 7.2 which are claimed to be using polymer composite for the frames.


Overview

Composite materials are created from individual materials. These individual materials are known as constituent materials, and there are two main categories of it. One is the Matrix (composite), matrix (Binder (material), binder) and the other Reinforcement (composite), reinforcement. A portion of each kind is needed at least. The reinforcement receives support from the matrix as the matrix surrounds the reinforcement and maintains its relative positions. The properties of the matrix are improved as the reinforcements impart their exceptional physical and mechanical properties. The mechanical properties become unavailable from the individual constituent materials by synergism. At the same time, the designer of the product or structure receives options to choose an optimum combination from the variety of matrix and strengthening materials. To shape the engineered composites, it must be formed. The reinforcement is placed onto the mould surface or into the Molding (process), mould cavity. Before or after this, the matrix can be introduced to the reinforcement. The matrix undergoes a melding event which sets the part shape necessarily. This melding event can happen in several ways, depending upon the matrix nature, such as solidification from the melted state for a thermoplastic polymer matrix composite or chemical polymerization for a
thermoset polymer matrixA thermoset polymer matrix is a synthetic polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy im ...
. According to the requirements of end-item design, various methods of moulding can be used. The natures of the chosen matrix and reinforcement are the key factors influencing the methodology. The gross quantity of material to be made is another main factor. To support high capital investments for rapid and automated manufacturing technology, vast quantities can be used. Cheaper capital investments but higher labour and tooling expenses at a correspondingly slower rate assists the small production quantities. Many commercially produced composites use a polymer matrix material often called a resin solution. There are many different polymers available depending upon the starting raw ingredients. There are several broad categories, each with numerous variations. The most common are known as polyester, vinyl ester resin, vinyl ester, epoxy, Phenolic resin, phenolic, polyimide, polyamide, polypropylene, PEEK, and others. The reinforcement materials are often fibres but also commonly ground minerals. The various methods described below have been developed to reduce the resin content of the final product, or the fibre content is increased. As a rule of thumb, lay up results in a product containing 60% resin and 40% fibre, whereas vacuum infusion gives a final product with 40% resin and 60% fibre content. The strength of the product is greatly dependent on this ratio. Martin Hubbe and Lucian A Lucia consider
wood Wood is a porous and fibrous structural tissue found in the stems and roots of tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and leaves in most species. ...

wood
to be a natural composite of cellulose fibres in a Matrix (biology), matrix of lignin.


Cores in composites

Several layup designs of composite also involve a co-curing or post-curing of the prepreg with many other media, such as foam or honeycomb. Generally, this is known as a Sandwich structured composite, sandwich structure. This is a more general layup for the production of cowlings, doors, radomes or non-structural parts. Open- and closed-cell-structured foams like polyvinylchloride, polyurethane, polyethylene or polystyrene foams, Balsa, balsa wood,
syntactic foam 300px, Syntactic foam, shown by scanning electron microscopy, consisting of glass microspheres within a matrix of epoxy resin. Syntactic foams are composite materials synthesized by filling a metal, polymer, or ceramic matrix with hollow sphe ...
s, and Composite honeycomb, honeycombs are generally utilized core materials. Open- and closed-cell metal foam can also be utilized as core materials. Recently, 3D graphene structures ( also called graphene foam) have also been employed as core structures. A recent review by Khurram and Xu et al., have provided the summary of the state-of-the-art techniques for fabrication of the 3D structure of graphene, and the examples of the use of these foam like structures as a core for their respective polymer composites.


Semi-Crystalline Polymers

Although the two phases are chemically equivalent, semi-crystalline polymers can be described both quantitatively and qualitatively as composite materials. The crystalline portion has a higher elastic modulus and provides reinforcement for the less stiff, amorphous phase. Polymeric materials can range from 0% to 100% crystallinity aka volume fraction depending on molecular structure and thermal history. Different processing techniques can be employed to vary the percent crystallinity in these materials and thus the mechanical properties of these materials as described in the physical properties section. This effect is seen in a variety of places from industrial plastics like polyethylene shopping bags to spiders which can produce silks with different mechanical properties. In many cases these materials act like particle composites with randomly dispersed crystals known as spherulites. However they can also be engineered to be anisotropic and act more like fiber reinforced composites. In the case of spider silk, the properties of the material can even be dependent on the size of the crystals, independent of the volume fraction. Ironically, single component polymeric materials are some of the most easily tunable composite materials known.


Methods of fabrication

Normally, the fabrication of composite includes wetting, mixing or saturating the reinforcement with the matrix. The matrix is then induced to bind together (with heat or a chemical reaction) into a rigid structure. Usually, the operation is done in an open or closed forming mould. However, the order and ways of introducing the constituents alters considerably. Composites fabrication is achieved by a wide variety of methods, including Advanced fiber placement, advanced fibre placement (Automated fibre placement), Fiberglass spray lay-up process, fibreglass spray lay-up process, filament winding, lanxide process, Tailored fiber placement, tailored fibre placement, Tufting (composites), tufting and z-pinning.


Overview of mould

The reinforcing and matrix materials are merged, compacted, and cured (processed) within a mould to undergo a melding event. The part shape is fundamentally set after the melding event. However, under particular process conditions, it can deform. The melding event For a
thermoset polymer matrixA thermoset polymer matrix is a synthetic polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy im ...
material is a curing reaction that is caused by the possibility of extra heat or chemical reactivity such as an organic peroxide. The melding event for a thermoplastic polymeric matrix material is a solidification from the melted state. The melding event for a metal matrix material such as titanium foil is a fusing at high pressure and a temperature near the melting point. It is suitable for many moulding methods to refer to one mould piece as a "lower" mould and another mould piece as an "upper" mould. Lower and upper does not refer to the mould's configuration in space, but the different faces of the moulded panel. There is always a lower mould, and sometimes an upper mould in this convention. Part construction commences by applying materials to the lower mould. Lower mould and upper mould are more generalized descriptors than more common and specific terms such as male side, female side, a-side, b-side, tool side, bowl, hat, mandrel, etc. Continuous manufacturing utilizes a different nomenclature. Usually, the moulded product is referred to as a panel. It can be referred to as casting for certain geometries and material combinations. It can be referred to as a profile for certain continuous processes. Some of the processes are autoclave moulding, vacuum bag moulding, pressure bag moulding, resin transfer moulding and light resin transfer moulding.


Other fabrication methods

Other types of fabrication include casting, centrifugal casting, Braiding machine, braiding (onto a former), continuous casting, filament winding, press moulding, transfer moulding, pultrusion moulding and slip forming. There are also forming capabilities including Numerical control, CNC filament winding, vacuum infusion, wet lay-up, compression moulding, and thermoplastic moulding, to name a few. The practice of curing ovens and paint booths is also required for some projects.


Finishing methods

The composite parts finishing is also crucial in the final design. Many of these finishes will involve rain-erosion coatings or polyurethane coatings.


Tooling

The mould and mould inserts are referred to as "tooling." The mould/tooling can be built from different materials. Tooling materials include aluminium,
carbon fibre Carbon fiber reinforced polymer (American English), Carbon fibre reinforced polymer (English in the Commonwealth of Nations, Commonwealth English), or carbon fiber reinforced plastic, or carbon fiber reinforced thermoplastic (CFRP, CRP, CFRTP, ...
, invar, nickel, reinforced silicone rubber and steel. The tooling material selection is normally based on, but not limited to, the coefficient of thermal expansion, expected number of cycles, end item tolerance, desired or expected surface condition, cure method, glass transition temperature of the material being moulded, moulding method, matrix, cost and other various considerations.


Physical properties

Usually, the composite's physical properties are not isotropic (independent of the direction of applied force) in nature. But they are typically Anisotropy, anisotropic (different depending on the direction of the applied force or load). For instance, the composite panel's stiffness will usually depend upon the orientation of the applied forces and/or moments. The composite's strength is bounded by two loading conditions, as shown in the plot to the right.


Isostrain rule of mixtures

If both the fibres and matrix are aligned parallel to the loading direction, the deformation of both phases will be the same (assuming there is no delamination at the fibre-matrix interface). This isostrain condition provides the upper bound for composite strength, and is determined by the rule of mixtures: E_C = \sum_ V_iE_i where ''EC'' is the effective composite Young's modulus, and ''Vi'' and ''Ei'' are the volume fraction and Young's moduli, respectively, of the composite phases. For example, a composite material made up of α and β phases as shown in the figure to the right under isostrain, the Young's modulus would be as follows:E_C=V_\alpha E_\alpha+V_\beta E_\betawhere Vα and Vβ are the respective volume fractions of each phase. This can be derived by considering that in the isostrain case, \epsilon_C = \epsilon_\alpha = \epsilon_\beta = \epsilon Assuming that the composite has a uniform cross section, the stress on the composite is a weighted average between the two phases, \sigma_C = \sigma_\alpha V_\alpha + \sigma_\beta V_\beta The stresses in the individual phases are given by Hooke's Law, \sigma_\beta = E_\beta \epsilon \sigma_\alpha = E_\alpha \epsilon Combining these equations gives that the overall stress in the composite is \sigma_C = E_\alpha V_\alpha \epsilon + E_\beta V_\beta \epsilon = (E_\alpha V_\alpha + E_\beta V_\beta) \epsilon Then it can be shown that E_C = (E_\alpha V_\alpha + E_\beta V_\beta)


Isostress rule of mixtures

The lower bound is dictated by the isostress condition, in which the fibres and matrix are oriented perpendicularly to the loading direction: \sigma_C = \sigma_\alpha = \sigma_\beta = \sigma and now the strains become a weighted average \epsilon_C = \epsilon_\alpha V_\alpha + \epsilon_\beta V_\beta Rewriting Hooke's Law for the individual phases \epsilon_\beta = \frac \epsilon_\alpha = \frac This leads to \epsilon_c = V_\beta \frac + V_\alpha \frac = (\frac + \frac) \sigma From the definition of Hooke's Law \frac = \frac + \frac and in general
\frac = \sum_\frac Following the example above, if one had a composite material made up of α and β phases under isostress conditions as shown in the figure to the right, the composition Young's modulus would be:E_C=(E_\alpha E_\beta)/(V_\alpha E_\beta+V_\beta E_\alpha) The isostrain condition implies that under an applied load, both phases experience the same strain but will feel different stress. Comparatively, under isostress conditions both phases will feel the same stress but the strains will differ between each phase. A generalized equation for any loading condition between isostrain and isostress can be written as: (X_c)^n = V_m(X_m)^n + V_r(X_r)^n where X is a material property such as modulus or stress, c, m, and r stand for the properties of the composite, matrix, and reinforcement materials respectively, and n is a value between 1 and −1. The above equation can be further generalized beyond a two phase composite to an m-component system: (X_c)^n = \sum_^V_i(X_i)^n Though composite stiffness is maximized when fibres are aligned with the loading direction, so is the possibility of fibre tensile fracture, assuming the tensile strength exceeds that of the matrix. When a fibre has some angle of misorientation θ, several fracture modes are possible. For small values of θ the stress required to initiate fracture is increased by a factor of (cos θ)−2 due to the increased cross-sectional area (''A'' cos θ) of the fibre and reduced force (''F/''cos θ) experienced by the fibre, leading to a composite tensile strength of ''σparallel /''cos2 θ where ''σparallel '' is the tensile strength of the composite with fibres aligned parallel with the applied force. Intermediate angles of misorientation θ lead to matrix shear failure. Again the cross sectional area is modified but since shear stress is now the driving force for failure the area of the matrix parallel to the fibres is of interest, increasing by a factor of 1/sin θ. Similarly, the force parallel to this area again decreases (''F/''cos θ) leading to a total tensile strength of ''τmy /''sin θ cos θ where ''τmy'' is the matrix shear strength. Finally, for large values of θ (near π/2) transverse matrix failure is the most likely to occur, since the fibres no longer carry the majority of the load. Still, the tensile strength will be greater than for the purely perpendicular orientation, since the force perpendicular to the fibres will decrease by a factor of 1/sin θ and the area decreases by a factor of 1/sin θ producing a composite tensile strength of ''σperp /''sin2θ where ''σperp '' is the tensile strength of the composite with fibres align perpendicular to the applied force. The majority of commercial composites are formed with random dispersion and orientation of the strengthening fibres, in which case the composite Young's modulus will fall between the isostrain and isostress bounds. However, in applications where the strength-to-weight ratio is engineered to be as high as possible (such as in the aerospace industry), fibre alignment may be tightly controlled. Panel stiffness is also dependent on the design of the panel. For instance, the fibre reinforcement and matrix used, the method of panel build, thermoset versus thermoplastic, and type of weave. In contrast to composites, isotropic materials (for example, aluminium or steel), in standard wrought forms, possess the same stiffness typically despite the directional orientation of the applied forces and/or moments. The relationship between forces/moments and strains/curvatures for an isotropic material can be described with the following material properties: Young's Modulus, the Shear Modulus and the Poisson's ratio, in relatively simple mathematical relationships. For the anisotropic material, it needs the mathematics of a second-order tensor and up to 21 material property constants. For the special case of orthogonal isotropy, there are three distinct material property constants for each of Young's Modulus, Shear Modulus and Poisson's ratio—a total of 9 constants to express the relationship between forces/moments and strains/curvatures. Techniques that take benefit of the materials' anisotropic properties involve mortise and tenon joints (in natural composites such as wood) and Pi Joints in synthetic composites.


Mechanical Properties of Composites


Particle Reinforcement

In general, particle reinforcement is Strengthening mechanisms of materials, strengthening the composites less than fiber reinforcement. It is used to enhance the stiffness of the composites while increasing the Yield (engineering), strength and the toughness. Because of their mechanical properties, they are used in applications in which wear resistance is required. For example, hardness of Engineered cementitious composite, cement can be increased by reinforcing gravel particles, drastically. Particle reinforcement a highly advantageous method of tuning mechanical properties of materials since it is very easy implement while being low cost. The elastic modulus of particle-reinforced composites can be expressed as, E_c = V_m E_m + K_c V_p E_p where E is the elastic modulus, V is the volume fraction. The subscripts c, p and m are indicating composite, particle and matrix, respectively. K_c is a constant can be found empirically. Similarly, tensile strength of particle-reinforced composites can be expressed as, (T.S.)_c = V_m (T.S.)_m + K_s V_p (T.S.)_p where T.S. is the Ultimate tensile strength, tensile strength, and K_s is a constant (not equal to K_c) that can be found empirically.


Continuous Fiber Reinforcement

In general, continuous fiber reinforcement is implemented by incorporating a fiber as the strong phase into a weak phase, matrix. The reason for the popularity of fiber usage is materials with extraordinary strength can be obtained in their fiber form. Non-metallic fibers are usually showing a very high strength to density ratio compared to metal fibers because of the Covalent bond, covalent nature of their Chemical bond, bonds. The most famous example of this is carbon fibers that have many applications extending from sports gear to Protective gear in sports, protective equipment to SpaceX, space industries. The stress on the composite can be expressed in terms of the volume fraction of the fiber and the matrix. \sigma_c = V_f \sigma_f + V_m \sigma_m where \sigma is the stress, V is the volume fraction. The subscripts c, f and m are indicating composite, fiber and matrix, respectively. Although the stress–strain analysis, stress–strain behavior of fiber composites can only be determined by testing, there is an expected trend, three stages of the stress–strain curve. The first stage is the region of the stress–strain curve where both fiber and the matrix are Elastic Deformation, elastically deformed. This linearly elastic region can be expressed in the following form. \sigma_c - E_c \epsilon_c = \epsilon_c (V_f E_f + V_m E_m) where \sigma is the stress, \epsilon is the strain, E is the elastic modulus, and V is the volume fraction. The subscripts c, f, and m are indicating composite, fiber, and matrix, respectively. After passing the elastic region for both fiber and the matrix, the second region of the stress–strain curve] can be observed. In the second region, the fiber is still elastically deformed while the matrix is plastically deformed since the matrix is the weak phase. The instantaneous Elastic modulus, modulus can be determined using the slope of the stress–strain curve in the second region. The relationship between stress (mechanics), stress and strain can be expressed as, \sigma_c = V_f E_f \epsilon_c + V_m \sigma_m (\epsilon_c) where \sigma is the stress, \epsilon is the strain, E is the elastic modulus, and V is the volume fraction. The subscripts c, f, and m are indicating composite, fiber, and matrix, respectively. To find the modulus in the second region derivative of this equation can be used since the Slope, slope of the curve is equal to the modulus. E_c' = \frac = V_f E_f + V_m \left(\frac\right) In most cases it can be assumedE_c'= V_f E_f since the second term is much less than the first one. In reality, the derivative of stress with respect to strain is not always returning the modulus because of the Chemical bond, binding interaction between the fiber and matrix. The strength of the interaction between these two phases can result in changes in the List of materials properties, mechanical properties of the composite. The compatibility of the fiber and matrix is a measure of Stress (mechanics), internal stress. The Covalent bond, covalently bonded high strength fibers (e.g. carbon fibers) experience mostly Deformation (engineering), elastic deformation before the fracture since the Deformation (engineering), plastic deformation can happen due to Dislocation, dislocation motion. Whereas, metallic fibers have more space to plastically deform, so their composites exhibit a third stage where both fiber and the matrix are plastically deforming. Metallic fibers have Cryogenic hardening, many applications to work at Cryogenics, cryogenic temperatures that is one of the advantages of composites with Steel fibre-reinforced shotcrete, metal fibers over nonmetallic. The stress in this region of the stress–strain curve can be expressed as, \sigma_c (\epsilon_c) = V_f \sigma_f \epsilon_c + V_m \sigma_m (\epsilon_c) where \sigma is the stress, \epsilon is the strain, E is the elastic modulus, and V is the volume fraction. The subscripts c, f, and m are indicating composite, fiber, and matrix, respectively. \sigma_f (\epsilon_c) and \sigma_m (\epsilon_c) are for fiber and matrix flow stresses respectively. Just after the third region the composite exhibit Necking (engineering), necking. The necking strain of composite is happened to be between the necking strain of the fiber and the matrix just like other mechanical properties of the composites. The necking strain of the weak phase is delayed by the strong phase. The amount of the delay depends upon the volume fraction of the strong phase. Thus, the Ultimate tensile strength, tensile strength of the composite can be expressed in terms of the volume fraction. (T.S.)_c=V_f(T.S.)_f+V_m \sigma_m(\epsilon_m) where T.S. is the Ultimate tensile strength, tensile strength, \sigma is the stress, \epsilon is the strain, E is the elastic modulus, and V is the volume fraction. The subscripts c, f, and m are indicating composite, fiber, and matrix, respectively. The composite tensile strength can be expressed as (T.S.)_c=V_m(T.S.)_m for V_f is less than or equal to V_c (arbitrary critical value of volume fraction) (T.S.)_c= V_f(T.S.)_f + V_m(\sigma_m) for V_f is greater than or equal to V_c The critical value of volume fraction can be expressed as, V_c= \frac Evidently, the composite Ultimate tensile strength, tensile strength can be higher than the matrix if (T.S.)_c is greater than (T.S.)_m . Thus, the minimum volume fraction of the fiber can be expressed as, V_c= \frac Although this minimum value is very low in practice, it is very important to know since the reason for the incorporation of continuous fibers is to improve the mechanical properties of the materials/composites, and this value of volume fraction is the threshold of this improvement.


The Effect of Fiber Orientation

The change is in the fiber orientation can affect the mechanical properties of the fiber-reinforced composites especially the tensile strength. The composite tensile strength can be predicted to depending on the \theta (0° to 10° angles), the angle between the applied for, and the orientation of the fibers. (T.S.)(longitudinal fracture) = \frac where T.S. is the Ultimate tensile strength, tensile strength, \sigma is the parallel stress. Because of the misorientation, the matrix of the composite experiences a shear force. The tensile strength of composites (10° – 60° angles) due to shear failure of the matrix can be expressed as, (T.S.)(shear failure) = \frac where T.S. is the Ultimate tensile strength, tensile strength, \tau is the shear stress. If the angle \theta is even greater than (60° – 90° angles), another mode of failure, transverse mode, becomes effective. The composite transverse fracture strength can be expressed as, (T.S.)(transverse fracture) = \frac where T.S. is the Ultimate tensile strength, tensile strength, \sigma is the perpendicular stress. Thus, the angle at which the transition to fracture mode can be expressed as, \theta_c =\tan^\left(\frac\right) where \theta_c is the critical angle, \sigma is the parallel stress, and \tau is the shear stress. This critical angle is important for the design of the composite materials for certain applications.


Types of Fibers and Their Mechanical Properties

The most common types of fibers used in industry are glass fibers, carbon fibers, and kevlar due to their ease of production and availability. Their mechanical properties are very important to know, therefore the table of their mechanical properties is given below to compare them with S97 steel. The angle of fiber orientation is very important because of the anisotropy of fiber composites (please see the section "Physical Properties" for a more detailed explanation). The mechanical properties of the composites can be tested using standard mechanical testing methods by positioning the samples at various angles (the standard angles are 0°, 45°, and 90°) with respect to the orientation of fibers within the composites. In general, 0° axial alignment makes composites resistant to longitudinal bending and axial tension/compression, 90° hoop alignment is used to obtain resistance to internal/external pressure, and ± 45° is the ideal choice to obtain resistance against pure torsion.


Mechanical Properties of Fiber Composite Materials



Mechanical Properties of Aerospace Grade & Commercial Grade Carbon Fiber Composites, Fiberglass Composite, and Aluminum Alloy and Steel

This table is demonstrating one of the most important features and advantage of fiber composites over metal, that is specific strength and specific stiffness. Although the steel and the aluminum alloy have comparable strength and stiffness with fiber composites, the specific strength and Specific modulus, stiffness of composites are around higher than steel and the Aluminium alloy, aluminum alloy.


Failure

Shock, impact, or repeated cyclic stresses can provoke the laminate to separate at the interface between two layers, a condition known as delamination. Individual fibres can separate from the matrix, for example, Fiber pull-out, fibre pull-out. Composites can fail on the macroscopic or microscopic scale. Compression failures can happen at both the macro scale or at each individual reinforcing fibre in compression buckling. Tension failures can be net section failures of the part or degradation of the composite at a microscopic scale where one or more of the layers in the composite fail in tension of the matrix or failure of the bond between the matrix and fibres. Some composites are brittle and possess little reserve strength beyond the initial onset of failure while others may have large deformations and have reserve energy absorbing capacity past the onset of damage. The distinctions in fibres and matrices that are available and the
mixture In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds composed of atoms, ...

mixture
s that can be made with blends leave a very broad range of properties that can be designed into a composite structure. The most famous failure of a brittle ceramic matrix composite occurred when the carbon-carbon composite tile on the leading edge of the wing of the Space Shuttle Columbia fractured when impacted during take-off. It directed to the catastrophic break-up of the vehicle when it re-entered the Earth's atmosphere on 1 February 2003. Composites have relatively poor bearing strength compared to metals.


Testing

Composites are tested before and after construction to assist in predicting and preventing failures. Pre-construction testing may adopt finite element analysis (FEA) for ply-by-ply analysis of curved surfaces and predicting wrinkling, crimping and dimpling of composites. Materials may be tested during manufacturing and after construction by various non-destructive methods including ultrasonic, thermography, shearography and X-ray radiography, and laser bond inspection for NDT of relative bond strength integrity in a localized area.


See also

* Aluminium composite panel * American Composites Manufacturers Association * Chemical vapour infiltration * Composite (disambiguation) * Composite laminates * Epoxy granite * Hybrid material * Lay-Up process * Nanocomposites * Rule of mixtures * Scaled Composites, American aerospace company founded by Burt Rutan * Smart material *Smart Materials and Structures * Void (composites)


References


Further reading

* * * * * * Handbook of Polymer Composites for Engineers By Leonard Hollaway Published 1994 Woodhead Publishing * Madbouly, Samy, Chaoqun Zhang, and Michael R. Kessler. Bio-Based Plant Oil Polymers and Composites. William Andrew, 2015. *


External links


Composites Design and Manufacturing HUB

Distance learning course in polymers and composites

Composite Sandwich Structure of Minardi F1 Car

OptiDAT composite material database


{{DEFAULTSORT:Composite Material Composite materials, Technical fabrics, *