Mindoro Musical Instruments Gongs
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Fiber Composites by Bhala
INTRODUCTION
The concept of fiber composites is very old as it dates back to the 800 B.C when Israelites and as Egyptian pharaohs in third millennium BC used straw in bricks manufacturing as a reinforcement. Later on the Chinese used to do this as well. The papyrus is another such example where papyrus reed was placed parallel to each other and stacked on perpendicular layers and pressure was exerted on it in order to form papyrus paper. In 108 AD Chinese invented the paper, as we know it in the similar fashion. In 1930s a more advanced version of fiber composites came into being in United States where they used short glass fiber reinforcement in cement and fiber enforced composites were developed in 1940. Composites were also used in World War II when glass fiber and polyester resin composites were used to make boat hulls and radomes (radar cover). In 1950s for the first time composites were used in cars because of desirable properties. With time the research conducted on studying more characteristics and improving the manufacturing process has increased. Composites began to be used more and more in everyday commodities like bath tubs, railings, electrical goods, sports equipment cars etc. aerospace and ship industry also started using composites initially for some of the parts and later on for the whole structure. For the first time in construction they were used to build a dome structure in Benghazi in 1968. Now their application in construction has enhanced four folds.
COMPOSITES
A composite is usually made up of at least two materials out of which one is the binding material, also called matrix and the other is the reinforcement material (fiber, Kevlar and whiskers). There are many composite products with more than two raw materials. Those materials are not miscible together and are of a different nature. In composites both the matrix and reinforcement are distinguishable and holds their distinctive characteristics, which enhance the characteristics of the final product. This is unlike alloys where a combination of two metals produces an alloy that has totally different properties and makes both metals indistinguishable. Another example of a composite most widely used for construction is known as concrete that has cement as binder and gravel or steel rod as reinforced solid. In the case of fiber composites it is the reinforcement that basically determines their properties while the matrix holds the reinforcement in place and helps to transfer loads along the reinforcement. The matrix may be metallic, ceramic, or polymeric in origin. In the case when the reinforcement is a fiber it yields composites known as the fiber composites.
CLASSIFICATION OF COMPOSITES
Composites can be classified into the following categories:
âBlends
A blend is a mixture of two or more substances. These materials can be polymers, metals, or other components. There is no chemical bonding between the components in the blends rather links are created as a result of intermolecular forces that do occur. This blend can be quite homogenous in some cases. Some blends are mixed on the order of 1 millionth of a meter (molecular) while some are just homogenous to the naked eye.
âInter-penetrating networks
Inter penetrating networks is a type of composites which can produce synergistic properties which means that the material produced has better characteristics than that of the separate components. Most composites do not display properties that exceed the sum of the properties of its components.
âNanocomposites
Composites in which the fiber reinforcement is on the extremely small nano scale (1×10-9 meters) are known as nanocomposites. Clay particles are a common nanocomponent in composites that offers a selection of applications not seen in other large fiber composites.
âFiber Composites
Composites, which contain fibers as reinforcement material, are used for many applications. A common fiber-containing composite is fiberglass, which has polyester polymer matrix and glass fiber fillers for reinforcement. The glass fibers strengthen the resin and make it more impact resistant. Many boat hulls are made of fiberglass that must withstand the constant beating of waves and other hard objects in water such as wood and rocks. These are the composite, which we will be studying in detail.
CHARACTERISTICS OF FIBER COMPOSITES
The compositeâs characteristics that have made them useful and unique are:
âStrength
âStiffness
âExpense
âEnvironmental sustainability
APPLICATION OF FIBER COMPOSITES
Today with all the advancement in life, growing population and its increasing needs we have to consider how to meet those needs by producing the best and making it available for all. Fiber reinforced composites are helping to fulfill the needs of this growing population. They have been and are being studied in order to maximize their utilities in different fields. This part of the chapter will look into the various fields that fiber reinforced composites are being used and what are their environmental impacts.
COMPOSITE SHIPMENT IN US
This graph shows the US shipment of composites over the years. The figure shows the increasing demand resulted in increased shipment of composites and how itâs competing with steel and Aluminum. Fiber composites have the property of being light weight and strong which is the property that man has trying to achieve for a long time. Wherever composites are being applied they tend to increase the performance or quality four folds. More and more efforts are being put on increasing its efficiency and for looking at new ventures where this technology can be applied.
Application of fiber composites are represented by the following groups which are 70% of the total market value: automotive (23%), building and public works (21%), aeronautics (17%) and sports (11%), (JEC, 2005). North America represents 40% of the composites industry’s total market value, with 35% for Europe, 22% for the Asia-Pacific region and 3% for the rest of the world.
âFiber Composites in Construction
The very first known application of fiber composites was in construction. Straw reinforced clay bricks were used by the Egyptian Pharaohs, Israelites and Chinese centuries ago. Nowadays the construction is the field of greatest application of fiber composites. The property of composites of being strong and resistant to environmental impacts makes them good building material. Its weight helps only in case of transportation of this material as they are lightweight and can easily be transported. Its light structure may helping earthquake prone region. The fiber composites being lightweight and strong and has an ability to absorb and reduce seismic wave unlike heavy stones, bricks, mortar, granite etc. Being lightweight and fixed with nuts and bolts help in lateral movement and in case of collapse reduces threats to human life. In Gujarat, India such fiber composite houses have been installed in an earthquake prone region in order to reduce the impacts of future earthquakes. Flexible concrete is also made using fiber reinforcements that can withstand earthquakes. Foldable structures have been introduced and are available due to the fiber composites otherwise making of foldable structures out of cement and a bricks is a difficult task. As mentioned earlier, the first application of glass fiber reinforced composites was in a dome structure in Benghazi in 1968.
Today glass fiber reinforced composites are used in footbridges as well as Highway Bridge in Bulgaria. The first fully instrumented all-composite two-lane vehicle bridge, with an extensive health-monitoring system, was installed in US. Nearly four-year long continuous monitoring was carried out to demonstrate the performance of the bridge. Field monitored information was studied to evaluate the behavior and durability of composites in the harsh infrastructure environment. This evaluation showed the level of confidence in the long-term field benefits of composite materials and technology. Since the early 1990s, there has been an increase in the use of small pultruded6 structural shapes for the construction of industrial platforms, pedestrian bridges, latticed transmission towers, and for other applications. Fiber reinforced to concrete is widely used in building and construction since 1980s.
âFiber Composites in Aerospace and Military
As mentioned before, the quality of fiber composites of being lightweight and strong has been put into use in the aircraft, rockets, and other equipments used in aerospace. A new low cost resin system has been used to produce a composite elevator. It is widely used because of stiffness to density ratio and exceptional strength. The use of fiber composites in the transport has provided 15-30% weight saving thus increasing fuel efficiency and lowering maintenance and operation costs. Boeing 777 was built ten years ago, which had saved 680 kg of weight by using 20% of composites as building material. Fiber composites are easier to shape according to aerodynamic rules and are therefore being widely used in rockets and spaceships. First passenger carrying spaceship was made used fiber composites it has 24.8 m wingspan. Ballistic composites are materials with superior properties being lightweight and durable under environmental conditions, (water and chemicals) with high performance (high strength, impact and ballistic resistance, damage tolerance). Lightweight ballistic composites are used in a wide range of lightweight vehicles, watercraft and aircraft armor giving high performance and lightweight protection against bullets and fragments. They also have exceptional insulating properties in high temperature environments. They are being used in missiles, tanks, fighter planes and retractable bridges. They can receive and send radar signals. And they are not magnetic thus help in wars from being easily targeted.
âFiber Composites in Transportation
Fiber composites are being used is car industry. The reason for their increasing demand in this industry is because the strength and stiffness in combination with low weight decreases the fuel consumption. It is said to save up to 27% of the weight in most of the structures. All vehicles from train to cars as well as bicycles are now using fiber composites. They are not only being used in the exterior but a lot of car parts are also being made from composites which include radiators, ignition components, spoilers, door panels, hoods, hatchbacks, roof panels, bonnets, wing mirrors, rear light units, brake linings, ignition components. Internal parts and trim where they are the solution to lightness, freedom of shape, freedom of design, matching internal dcor and providing thermal and sound insulation. They are used to mould interior components for buses, seat squabs and bases, car door liners, back panel of seats, parcel shelves.
Composite materials are increasingly being used in the train industry, which has resulted in high performance and lower costs. Weight savings of up to 50% for structural and 75% for non-structural applications brings associated benefits of high-speed, reduced power consumption, lower inertia, less track wear and the ability to carry greater pay-loads. Composites also provide greater versatility in train design and optimization of train performance (e.g. lowering the centre of gravity to enhance stability). High stiffness from structural materials reduces (even eliminates) supporting framework, increases passenger room, carries fittings readily. The construction of composites (interchangeable panels) is easy to handle and install and offers rapid fitting. Due to fire resistant characteristics, it also allows full safety to the entire system. Components of coaches are generally made of glass fiber reinforced with polyesters/epoxies phenolic resins.
Fiber composites are being used in Formula 1 cars as new and improved materials are being introduced that are fireproof.
âFiber Composite in Medical Sciences
Fiber composites have found their way into medical sciences where they have provided new alternative in the field of science for other materials. Previously broken bones were supported with metal rods surgically, which in some cases would cause problem such as bending, corrosion etc thus causing a threat to the patient. Similarly in the case of amputees they had to use artificial limbs that were very heavy, they were a cause of sores in diabetics. Thus making movement difficult. With the introduction of composites in this field it has been found to be a new and improved replacement for metal rod for bone surgery. Polysiloxane-based7 composites with carbon fiber reinforcement have mechanical properties that are adequate from viewpoint of bone surgery requirement for load-bearing implants. They have also been studied to be more biocompatible. In the case of artificial limbs new lightweight and cheaper artificial limbs have been introduced. This has made mobility for amputees easier. It has also benefited the diabetic patients. Now amputees are also able to compete just like other athletes with artificial limbs that have shocks. In 1896 there were no Olympics for those with prosthetic limbs but in 1992 they could not only participate but were considered to be equally good as those with full limbs, Application of fiber composite in the spinal surgery is also remarkable. One of such is the spinal fusion that means surgical immobilization of the spine by joining two or more vertebrae, creating a bony union. The disk space may also be replaced by medical implants called interbody fusion devices (IBFDs) such as fusion cages, which holds the bone graft material within them. Recent study show creation of composites which can be applied for spinal fusion different types of material were tested along with polylactide8 fiber reinforced composites. The goal of the study was to create a composite material, which is much stronger in compression than cancellous9 bone or vertebrae. This material developed may also have use as a bone substitute or as a material for bone fixation devices, such as plates, pins, screws, etc., in applications where high strength is required. Recently fiber reinforced composite have made their way into dentistry. Their mechanical properties can be tailor-made to correspond the properties of tooth substance and bone, an increased interest has rose in their use in dentistry and medicine. Multiphase mono- and dimethacrylate polymers are matrices for composites made of inorganic and organic reinforcing fibers. These result in enhanced adhesive bonding properties in cementing of appliances such as dental bridges to tooth substance.
âFiber Composites in Sports goods
Another application of fiber composites is in sports goods. Nowadays wooden racquets and fishing rods are almost history. Wood is rarely being used for sports goods. In sports where the time and strength is what is required fiber composites are playing a great role. When designing sport equipment most important things to consider are strength, ductility10, density, fatigue resistance, toughness and cost.
With introduction of new materials in sports new records have be set. Initially bamboo stem was used for pole vaulting then came the aluminum and now sophisticated fiber composites are being used. These have layers of different fibers, which optimize the performance with an outer layer of high-strength carbon fiber providing high stiffness and an intermediate webbing of fibers together with an inner layer of wound-glass fiber building resistance to twisting. The glass fiber consists of 80% longitudinal and 20% radial fibers.
Cycling is not limited to the Olympics or sports but has become one of the modes of transportation. China manufactures 10 million cycles per year. Since the first cycle that was built in 1817 a lot of advancements have taken place in the bicycle. The most important of these changes are that made in the frame and tires. In addition to the carbon-fiber-reinforced composite frames, frames have recently been produced from magnesium, aluminum, titanium, and metal matrix composites. In addition, hybrid frames such as carbon-fiber-reinforced composites combined with titanium have been produced. Wheels with increased stability and rigidity for off-road bikes constructed from glass-fiber-reinforced nylon and disc wheels have been introduced. In disc wheels, discs made of aluminum alloys or carbon-fiber-reinforced composites replace the spokes in conventional wheels. Developments also include three- or five spoked wheels for rigidity and crosswind aerodynamics.
Tennis elbow is a condition in which the jerk as result of shot may lead to damaging blood capillaries in the tendons or muscles around the elbow. But with the composite racquets the sweet spot has been increased, stiffness and shape of the frame and handle has also been improved. This results in less vibration and less impact on the elbow. Similarly in golf the weight has been reduced of the clubs from 165grams to 115grams and the length has been increased from 109 to 114 cm, which has resulted in better and straighter shot.
âFiber Composites in Musical Instrument
One of the finest musical instruments is manufactured by fiber composites.
They are lightweight and have astonishing sound properties. A silent piano11 is a composite keyboard musical instrument fabricated on the basis of an acoustic piano, and a pianist can play a tune by piano tones or electronic tones. Carbon fiber and epoxy resin is being used to make guitars and violins, as it is lightweight and resistant to environmental impacts, and damage. It has resonating properties similar to that of wood and has lower construction time and cost. First fiber composite flute was made in Finland. It is a carbon fiber flute with synthetic rubber pads and titanium keys.
âFiber Composites in Household Products
Fiber Composites have also made their way in to our homes on the basis of their useful properties. Manufacturing of the fireproof core of fire resistant doors and screens, insulating and fire-resistant materials with different characteristics are being used, including a large number of materials comprised of insulators based on different silica compounds, e.g. fly ashes, which can be reinforced by fibers and produce fire resistant products with good thermal stability at high temperatures. Furniture is now being produced which is made of fiber composites. They are being used because they can easily be shaped into various beautiful and fashionable shapes. With the help of additives they can easily be colored according to our taste. Being lightweight it is preferred over heavy wooden and steel furniture.
Various appliances in our homes are made from fiber composites such as vacuum cleaners, food processor etc. Bathtub swimming pools and other toiletries are also made from fiber composites. Children swings, joyride, water slide are another application of fiber composites.
Waste management through land filling has caused great problem of leakage.
The layer of fiber composites is used to secure the landfill waste from leaching toxins into the environment. This is possible because of the strong structure of th
Article Source: http://www.earticlesonline.com/Article/Fiber-Composites/420928
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Structure of acoustic and electric guitars by Martina Meneghetti
The first guitars, although if they were not with the usual form, were born a lot of centuries ago in the Middle East. Over the centuries, this chord instrument, which used an amplification system with a sound box, underwent many transformations, until finally arriving to the instrument we know.
Of course even now there are several types, but the most common is the six-strings guitar. The guitar is composed of many pieces, starting from the top there are: the headstock together with the tuning keys used to keep tension in the strings and to change the tuning. Here we find the neck, the length can vary depending on the type of guitar, the neck is divided into frets that are used to tighten the strings and get the notes you want. Finally then we find the body with the soundboard and the bridge from where the strings branch off.
Of course in electric guitars we will not find the soundboard but a solid body (full body) that, to capture and disseminate the different sounds, uses pickups that are placed where would be the hole for the sound box. It is important to remember that in case of non-electric guitars sound quality and its uniqueness are completely dependent on the type of wood used to build the box and the type of joints inside it.
Even in electric guitars, the wood is very important because the neck is subjected to a much higher tension than acoustic guitars, it also has a metal core; a good neck must be able to withstand the tension and its change when you change your tune and must also be sliding to let the right hand slide. One of the most important part is certainly the strings, that, plucked with the fingers or the plectrum, emit the characteristic sound of these musical instruments.
The strings are stretched in different ways to obtain different notes. The most common tuning is re-mi-sol-la-mi. This tuning, in which the interval between two adjacent strings is right one fourth (except that between the second and third string, a distance of a major third) has established itself for its ease in forming chords. In guitars with more strings such as those with seven or eight strings, more low note are added to obtain a sound more dark and powerful, characteristic of metal music.
The power of the sound of the electric guitar is given mainly by the type of pickup installed that characterize the power and the type of sound that will be expressed through the use of amplifiers that can alter the sound in different ways. The most common amplifiers are the combo and those constituted by a surface plus a speaker.
The technical description still does not do justice to the emotions and feeling you get playing these instruments. In conclusion when you play you discover a part of you that you did not know it existed.
By Martina Meneghetti with support from luci discoteca for any information, please visit supporto microfono or for more info visit strumenti musicali mixer
Article Source: http://www.earticlesonline.com/Article/Structure-of-acoustic-and-electric-guitars/637921
