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Saturday, December 25, 2010

CFRP Component for BMW

Last June, BMW has announced a trio of new aero components for the M3 family, including a small rear lip spoiler, mirror caps and a new front splitter.

These components are made from carbon fibre reinforced plastic - the same super-light and super-tough material used in the M3's roof panel - the new BMW Performance parts are also coated in an ultraviolet-resistant laminate, protecting against yellowing, cracking and degradation.

Sunday, December 19, 2010

Composite Fabrication : Resin Transfer Molding (RTM)

RTM or Resin Transfer Molding is a closed mold process. In this process, matched male and female molds are being used. Before the process injection, fiber pre-form is places in the mold cavity. Then the molds are clamped. Resin mix then is injected or transferred into the cavity through injection ports at a relatively low pressure.
Schematic diagram of RTM process
Injection pressure is normally less than 690 kPa (or 100psi). The displaced air is allowed to escape through vents to avoid dry spots. Cure cycle is dependent on part thickness, type of resin system and the temperature of the mold and resin system. The part cures in the mold, normally heated by controller, and is ready for its removal from the mold when sufficient green strength is attained.

RTM offers the promise of producing low cost FRP parts with complex structures and large near net shapes. Relatively fast cycle times with good surface definition and appearance are easily achievable. The ability to consolidate parts allows the saving of considerable amount of time over conventional lay-up processes.
Example of RTM Machine
Since RTM is not limited by the size of the autoclave or by pressure, new tooling approaches can be utilized to fabricate large, complicated structures. However, the development of the RTM process has not fulfilled its full potential. For example, the RTM process is yet to be automated in operations such as preforming, reinforcement loading, demolding, and trimming. Therefore, RTM can be considered an intermediate volume molding process.

Several unresolved issues in RTM encountered by composite engineers are in the areas of process automation, preforming, tooling, mold flow analysis and resin chemistry. During the last decade, rapid advances in RTM technology development have demonstrated the potential of the RTM process for producing advanced fibre reinforced plastic and composite parts.
RTM Simulation

Product of RTM Process

Tuesday, December 14, 2010

Oscar With His CFRP Composite Legs

Carbon Fibre Reinforced Plastic (CFRP) composite legs is a product that composite researchers and designers can be proud of. Made from carbon fibre and being design for disabled person.

And who doesnt know Oscar Pistorius, gold medalist in paralympic, a double amputee, who uses carbon fibre composite legs. He is also known as the "Blade Runner" and "the fastest man on no legs". 

He is better than a normal person, thanks to fibre reinforced and composite technology. He’s already considered one of the fastest men in the world.

Oscar Pistorius with CFRP Legs

Also read :
Carbon Fiber Composite Running Legs - Composite Material Blog

Sunday, December 12, 2010

Sandwich Composite and Core Material

Sandwich composite, considered to be a class of structural composites consist of two strong outer sheets or faces separated by a layer of less dense material or core, which has lower stiffness and lower strength. The faces bear most of the in-plane loading and also any transverse bending strength. Typical face material include aluminum alloys fiber reinforced plastics titanium steel and plywood.

Structurally the core serves two functions. First it separates the faces resist deformations perpendicular to the face plane. Secondly it provides a certain degree of shear rigidity along planes which are perpendicular to the faces. Various materials and structures are utilized for cores including foamed polymers synthetic rubber inorganic cements as well as balsa wood.

Another popular core consist of a honeycomb structure-thin foil that have been formed into interlocking hexagonal cells with axes oriented perpendicular to the face planes. The material of which the honeycomb is made may be similar to the face material. Sandwich panels are found widely in a wide variety of applications they include roofs floors and wall of building and in aircraft for wing fuselage and tail plane skins.

Structural sandwich construction is one of the first forms of composite structures to have attained broad acceptance and usage. Virtually all commercial airliners and helicopters and nearly all military air and space vehicles make extensive usage of sandwich construction. In recent years, most commercial space vehicles have also adopted this technology for many components

Example of Sandwich Composite, Using Honeycomb Core

Thursday, December 9, 2010

Kaizen : From Composite Technology to Fibre Reinforced Plastic

Lately we have made some improvement to our weblog. We changed our name from CompositeTechnology.blogspot to This is we think a best name for this weblog as this resource centre only talk about plastic/polymer composite, while composite represent a wide range of material including metal matrix composite and ceramic matrix composite.
Besides that, we redesign this page to look more attractive and more visitors friendly.

Next step, we will create a Fibre Reinforced Plastic community on facebook, to discuss and share our knowledge concerning polymer composite and fibre reinforced plastic (FRP) issues. We hope to hear comments from all students, researchers and FRP engineers out there!

- Mr Joe Jeff

Monday, December 6, 2010

Laminate Structure and Classification in FRP

The last post we discuss about lamina and laminate terminology and definition. This post will talk about laminate classification. Laminates can be classified according to the fiber orientation :

• Unidirectional Laminate- The fiber angle in any ply is parallel to the fiber angle in every other ply. This is a thick lamina from a mechanics point of view.

• Cross Ply Laminate - The fiber angle in any ply is normal to at least one other ply and parallel to any other ply or plies (i.e., contains only 0 and 90E plies).

• Angle Ply Laminate - Fiber angle of any ply is not restricted to parallel and normal directions. These definitions have different consequences depending upon whether the fiber directions are defined by their fabrication direction or loading direction. For the purposes of composite design the fiber directions relative to the loading directions are relevant. For, instance if laminate is fabricated by laying up 0 and 90E plies, it can be used as cross ply or an angle ply laminate. Laminates can also be classified based on stacking sequence.

• Symmetric Laminate – In a symmetric laminate all plies above the midplane have the same angle as the ply in the equivalent position below the midplane (i.e., the midplane of the laminate is a plane of symmetry).

• Antisymmetric Laminate - All plies above the midplane have the opposite (negative) angle as the ply in the equivalent position below the midplane. (The midplane is a plane of antisymmetry)

• Asymmetric Laminate - The midplane is not a plane of symmetry or antisymmetry.

Friday, December 3, 2010

Lamina and Laminate, What Is That?

So, what is lamina? What is laminate? What is the different?
Let us talk about lamina first.

A lamina is a flat (or sometimes curved) arrangement of unidirectional (or woven) fibers suspended in a matrix material. A lamina is generally assumed to be orthotropic, and its thickness depends on the material from which it is made.

For example, a graphite/epoxy (graphite fibers suspended in an epoxy matrix) lamina may be on the order of 0.127 mm thick. For the purpose of analysis, a lamina is typically modeled as having one layer of fibers through the thickness. This is only a model and not a true representation of fiber arrangement. Both unidirectional and woven laminas are schematically shown below.

Schematic illustration of lamina composite

While a laminate is a stack of lamina, as illustrated below, oriented in a specific manner to achieve a desired result. Individual lamina is bonded together by a curing procedure that depends on the material system used. The mechanical response of a laminate is different from that of the individual lamina that forms it. The laminate’s response depends on the properties of each lamina, as well as the order in which the lamina are stacked.

Schematic of laminate composite

So, to construct a product (laminate) we have to use a several lamina with determined orientation to achieve properties that we want. Usually, lamina is not used without stacking it to create a laminate. These lamina is being hold together thanks to the resin that we choose depending on service conditon of the product.

Saturday, November 27, 2010

Pultrusion Process of Kenaf Fibre

Recently I visited an institute that doing research on Kenaf fibre / fiber. Kenaf is a natural fibre that came from hibiscus family plant. The process involve here is pultrusion. Here are some pictures during my visit there :

Kenaf Fibre
Impregnated with Polyester Resin
Into The Heated Die
Exiting The Die
The Pullers
Finish Product After Cutting Process
Suggested Application 

Wednesday, November 24, 2010

Fiberglass Grating

Typical Layers in FRP Grating
Fiberglass is one of the most lightweight materials used by man today, and there are so many applications for fiberglass gratings today.

Fiberglass grating or FRP grating is products that involve pultrusion of glass fiber. This process include of a pulling mechanism of fiberglass roving and continuous mats. The fiber then being impregnated with resin in resin bath and being pulled into a heated die to get the shape that customer need.

The main reason of using fiberglass grating instead of steel is the ability of fiberglass to withstand corrosion.  Other than that, fiberglass grating are maintenance free, long service life and non conductive.

Resin that being used to produce this fiberglass grafting usually are Vinylester and Isopthalic  Polyester.

The grating can be used in either new application or for replacing existing application which is exposed to corrosive environment. The application can be found in all type of industries such as offshore, oil and gas, power plants, waste treatment, public facilities etc. 

Example Application of Fiberglass Grating

Friday, September 10, 2010

Fibre Forms and Architecture

a. strand - a compactly associated bundle of filaments. Strands are rarely
seen commercially and are usually twisted together to give yarns.

b. yarns - a closely associated bundle of twisted filaments or strands with
the same filament diameter each between 4-13 mm.
Yarns have varying weights described by their ‘tex’ (weight in grammes
of 1000 linear metres) or denier (weight in lbs of 10,000 yards).
Typical tex range usually being between 5 and 400.

c. rovings - a loosely associated bundle of untwisted filaments or strands.
The same each filament diameter in a roving, usually between 13-24mm.
Have varying weights, i.e. tex range is usually between 300 and 4800.
Two basic types of roving:
Direct roving - filaments are gathered together directly after melting.
Assembled roving - several strands be brought together separately after
manufacture, and usually have smaller filament diameters for better
wet-out and mechanical properties.

d. Chopped strands – continous strands which are chopped into into
various lengths, i.e. 3, 6, 9, 12, 25, 50 mm.
Commonly used in moulding compounds (BMC/DMC) or reinforcing
sharp radii, etc.

e. Chopped strand mat (CSM) - a principal form of glass fibres for fibreglass.
Chopped filament strands of 50 mm length, bonded by suitable binder
which are then pressed to form a mat and wound into rolls.
Typical CSM densities between 225 to 900 gram/m2.
Due to random orientation, common glass to resin ratio range between
1:2 to 1:2.5 by weight.

f. Continous filament mat (CFM) - a continuous glass strand of swirl mat.
Designed for press moulding (cold/hot) and RTM.
Random orientation of continuous multi-filament with low binder content
Allows exceptional wetting compared to CSM, considerable stretch,
and minimises tailoring.

g. Woven roving (WR) – glass roving which are woven to form cloth type
with densities range between 150 to 900 gram/m2.
Glass to resin ratio for WR is usually taken as 1:1, i.e. higher fibre content.
Disadvantages: difficult to cut, difficult to handle (when cut), and more
difficult to mould than CSM.
Typical construction would be WR and CSM laid-up alternately.

h. Woven fabric (cloth) – a woven product of textile yarns with various
weaving styles (plain, twill, harness satin, etc.) and densities range
between 90 to 300 gram/m2.
More expensive and use for high performance applications such as
aircrafts and electrical.
i. Surfacing mat (tissue) – use for backing gelcoat and final decorative layer.
Designed for press moulding (cold/hot) and RTM.

j. Special products/hybrids – combination of various types and forms of
glass to meet individual needs, processes and end-product performance.

Friday, September 3, 2010

Sheet Moulding Compounds (SMC)

SMC is a combination of chopped glass strands and filled polyester resin, in the form of a sheet. Processing of SMC by compression or injection moulding enables the production of bodywork or structural automotive components, and electrical or electronic machine housings in large industrial volumes. The process also penetrates sectors such as sanitary ware (baths) and urban furniture (stadium and cinema seating), etc.

The prepreg contains all the components needed for moulding the final part (resin, reinforcement, filler, catalyst, low profile additives, etc.) in a malleable and non-tacky sheet. Its characteristics allow it to fill a mould under the conditions of moulding temperature and pressure employed.

SMC prepreg is made from glass strands chopped to lengths of 25 or 50mm, sandwiched between two layers of film, onto which the resin paste has already been applied. The prepreg passes through a compaction system that ensures complete strand impregnation before being wound into rolls. These are stored for a few days before moulding, to allow the prepreg to thicken to a mouldable viscosity.

The main process for moulding SMC material is Compression moulding. The film is stripped off and the material is cut into suitable pieces. These are collated into piles of material, which are called the charge. This is positioning in the mould tool. Heated moulds are used and a compression pressure is applied. The base resin being a thermosetting material cures and
hardens. The part is ejected. Any flash is trimmed by the operator.

SMC Manufacturing

Thursday, April 29, 2010

Safety & Hazard in Composite Industry

Composite materials result from combining at least two different components to yield a new material whose properties differ from the original constituents. For example, concrete is a composite made of gravel and cement. The term took on a new meaning in the early 1960s when the aerospace industry began producing and testing structural components made of resins reinforced with carbon or boron fibers. With the successful use of these lightweight, high performance materials, new terms were coined: advanced composite materials (ACM) and high performance composites. Loosely defined, advanced composite materials are high performance man-made materials consisting of a fiber reinforced matrix system. ACM can be tailored for specific applications by combining resin and fiber properties to produce the desired weight, temperature resistance, and electrical conductivity or strength characteristics. The choice of resins is diverse - epoxy, polyimide, polyurethane, bismaleimide and metals, to name a few - as are the choices for fiber reinforcement - carbon, boron, aromatic polyamide, ceramic, glass and metal. Similarly, ACM applications are almost limitless, from aircraft components, satellite reentry shields and turbine engines to prosthetic devices, fishing rods and sports goods.

Along with the increasing usage of composite materials came the concern about possible associated health risks. Occupational health personnel were already familiar with the generation of vapors during chemical manufacturing processes such as those encountered during matrix production. The unknown parameters dealt with handling the raw fibrous materials and repairing composites. The heavy use of ACM in aircraft created another problem - what happens to the resins and the fibers during a fire or explosion? Concern escalated because fibrous materials were involved, and the inevitable possible parallel with asbestos fibers arose. The scientific community began searching for the answers to these questions.

However, the advanced composite industry is only about 30 years old - still in its infancy –so research data is limited. Epidemiological studies are almost nonexistent, and until recently, animal studies were conducted using artificial exposure routes. Thus far, the limited experimental evidence suggests potential problems when machining composites and during mishap scenarios involving ACM. This chapter summarizes the most current information on advanced composite materials, including chemical and physical properties of the components, exposure issues, regulatory standards and toxicological data. The intention is to provide information that will assist the industrial hygienist, occupational medicine physician and other medical department professionals in making informed decisions about the health hazards associated with ACM.

No attempt has been made to individually identify and discuss all composite components available. Such a document would be monumental; ACM technology, particularly matrix formulations, is still developing, improving and producing new variations. Consequently, matrices are discussed as broad categories, with specific constituents addressed as necessary to alert the reader to associated hazards. The reinforcing fibers are addressed specifically, since the potential for health risk from this component is still unclear.

It is important to understand the terminology in order to read and assess toxicological data. This section will concentrate on some of the basic terms and definitions that are applicable to the composite user, especially in reading Material Safety Data Sheets, the most common source of information on materials.

Thursday, April 1, 2010

Types of Glass Fibre

E-glass (electrical): lower alkali content (<1%) and stronger.
Good tensile and compressive strength and stiffness, good electrica properties and relatively low cost, but impact resistance relatively poor.
E-glass is the most common form of fibre used in polymer composites.

C-glass (chemical): best resistance to chemical attack.
Mainly used in the form of surface tissue in the outer layer of
laminates used in chemical and water pipes and tanks.

R, S or T-glass: manufacturers trade names of equivalent fibres. R (Vetrotex,
France), S (Owen Corning, USA) and T (Nittobo, Japan)
Having higher tensile strength and modulus than E glass, with
better wet strength retention. Higher ILSS and wet out properties
are achieve through smaller filament diameter.

A-glass: Soda lime glass with high alkali content between 10-15%.
Very poor mechanical properties but high resistant to chemical attacks.

D-glass: Improved dielectric glass developed for high performance electronic applications.

Tuesday, March 30, 2010

Definition of Shelf Life

Shelf life is an arbitrary time for practical storage of a thermoset system.

Shelf life derives from the storage concept; i.e., how long can a thermoset be left on the shelf before it becomes difficult or even impossible to use in the intended application.

The term can refer to a one-can system (e.g., a phenolic molding compound must be molded within 1 year of compounding) or a two-can mix that must be set aside for a few hours before use.

Shelf life is also used to describe the storage stability of unmixed components of a thermosetting resin system if there is some threat to their reactivity as a consequence of the storage. For example, some curing agents are very hygroscopic and will lose reactivity if airborne moisture were to penetrate the storage container.

Thursday, March 25, 2010

Cleaning Solvents

Solvents such as acetone, methyl ethyl ketone and methanol are used in large quantities to clean equipment and tools. Of these, acetone is the most widely used. Many fabricators have begun to replace acetone with dibasic ester @BE). DBE is a mixture of the methyl esters of adipic, glutaric and succinic acids that is both less volatile and less flammable than acetone (Lucas 1988). Methylene chloride has been used widely for cleaning because it is an effective solvent for many cured resins, although its use has been declining due to health and safety concerns.

Solvents are used to remove uncured resins from spray equipment, rollers, brushes, tools, and finished surfaces. Typical solvents used include acetone, methanol, methyl ethyl ketone (MEK), toluene and xylene. Acetone and other similar solvents are used for general cleaning, as standard practice for most open-mold fabricators of fiberglass products. To clean the spray equipment, acetone is usually circulated through the lines after the spray operation is shut down for the day. A simple but effective method practiced by some fabricators to minimize wastes is placing the containers of solvent near the resin spray area to prevent spills and drippage for tool cleaning. Generally, the solvent is reused until the high concentration of resin contamination prevents effective cleaning. However, if the containers are left uncovered, solvent will evaporate, increasing air emissions as well as resin concentration. Methylene chloride is an effective solvent for cured resins, and has been used by plastics fabricators.

Although many other solvents have been tried, including multicomponent mixtures, these have had mixed results. The best way to minimize the need for this chemical is to clean equipment before the resin dries. Disposal of contaminated solvents represents a major hazardous waste management expense. In addition, fugitive air emissions during the curing and cleaning processes are also of concern.

Saturday, March 20, 2010

Release Agents Used in Composite Industry

A release agent is simply a coating that is applied to a surface to stop the material being moulded (usually a plastic) from sticking, i.e. it facilitates the easy release of the plastic from the mouldA lubricant, liquid, or powder (often silicone oils and waxes) used to prevent sticking of molded articles in the cavity.

Release Agent Requirements

• Guaranteed release
• Quick and easy to apply
• Low cost / part
• High quality finish
• Low defect rate
• No processing problems
• Ability to release a wide range of materials

Release Agents used in Composite Industry

i. Paste /Liquid Wax
Traditional products for open face, low temperature moulding processes, e.g. GRP. Usually carnauba wax based

ii. PVA (PolyVinylAlcohol dissolved in water)
Provides a release film; poor finish, guaranteed release

iii. Internal Mould Release Agent (IMR)
-Soaps, glycols or phosphates
-Used in pultrusion, abrasive processes or easy to release systems such as SMC

iv. Semi-Permanent Mould Release Agent (SPMRA)
-Polymer resins used extensively throughout advanced composite processes and where optimum productivity is paramount
-Lowest cost per released part

Monday, March 15, 2010

Storage and Handling of Prepregs

Prepregs should be stored as received in a cool dry place or in a refrigerator. After removal from refrigerator storage, prepreg should be allowed to reach room temperature before opening the polyethylene bag, thus preventing condensation (a full reel in its packaging can take up to 48 hours). Typically prepregs have a guaranteed shelf life at - 18 ºC of 12 months. Tack life at 23 ºC depends on the matrix, and is clearly defined on the relevant Product Data Sheet.
Prepregs are particularly low-risk in terms of handling hazards for the following reasons :

• Prepreg is covered on both sides by protective coverings, which are not removed until assembly lay-up. It should be cut to shape before removing the protective coverings and virtually no handling of the prepreg is necessary.

• Unlike wet lay-up methods of fibre reinforced composite manufacture, where dry fibre and liquid resin are used,uncured prepregs have no loose fibrous dust and are splash-free, leak-free and spillage free.

• Prepregs are volatile-free at normal room temperature.

• Prepregs have a moderate/low tack level at normal room temperature.

However, the usual precautions when handling synthetic resins should be observed, ie. always wear gloves and ensure arms are covered, thus avoiding skin contact with the product. Repeated unprotected touching of prepreg can cause an allergic reaction.
Dust from machining cured product will contain fibrous material, inhalation of which should be avoided. Provide positive dust extraction and collection from the cutting zone. Protect against fire and explosion by avoiding dust formation and ignition sources when machining cured product. Dust from products containing carbon fibre is electrically conductive.

Tuesday, March 9, 2010

Prepreg Material

Short for preimpregnated. A combination of mat, fabric, nonwoven material or roving with resin, usually cured to the B-stage, ready for molding. Can be redesignated as standard or net resin prepregs:

• Standard prepreg contains more resin than is desired in the finished part; excess resin is bled off during cure.

• Net resin prepreg contains the same resin content that is desired in the finished part; no resin bleed.

Prepreg containing a chemical thickening agent is called a mold-mat and those in sheet form are called sheet-molding compounds.

A prepreg consists of a combination of a matrix (or resin) and fibre reinforcement. It is ready to use in the component manufacturing process.
It is available in :

• UNIDIRECTIONAL (UD) form (one direction of reinforcement)

• FABRIC form (several directions of reinforcement).

Friday, January 22, 2010

Definition of Pot Life

Pot life or working life is the available time to process a reacting thermosetting formula.

Once the ambient cure temperature is reached and the crosslinking reaction begins, pot life describes the time available before the mixture becomes intractable or otherwise difficult to process.
For example, the pot life of a coating is the time during which the viscosity remains low enough to allow for easy brushing or spraying. In a molding compound, the working life represents the amount of residence time available in the molding machine before the material must be injected into the mold in order to have trouble-free molding and/or a defect-free part

Tuesday, January 19, 2010

Definition of Shelf Life

Shelf life is an arbitrary time for practical storage of a thermoset system.

Shelf life derives from the storage concept; i.e., how long can a thermoset be left on the shelf before it becomes difficult or even impossible to use in the intended application.

The term can refer to a one-can system (e.g., a phenolic molding compound must be molded within 1 year of compounding) or a two-can mix that must be set aside for a few hours before use.
Shelf life is also used to describe the storage stability of unmixed components of a thermosetting resin system if there is some threat to their reactivity as a consequence of the storage. For example, some curing agents are very hygroscopic and will lose reactivity if airborne moisture were to penetrate the storage container.