16-11-2012, 02:14 PM
Engineering Applications of Composites Materials
Engineering Applications.pdf (Size: 2.69 MB / Downloads: 420)
Introduction:
Composites are one of the most widely used materials because of their adaptability to different situations and the relative ease of combination with other materials to serve specific purposes and exhibit desirable properties.
In surface transportation, reinforced plastics are the kind of composites used because of their huge size. They provide ample scope and receptiveness to design changes, materials and processes. The strength-weight ratio is higher than other materials. Their stiffness and cost effectiveness offered, apart from easy availability of raw materials, make them the obvious choice for applications in surface transportation.
In heavy transport vehicles, the composites are used in processing of component parts with cost-effectiveness. Good reproductivity and resilience handling by semi-skilled workers are the basic requirements of a good composite material. While the costs of achieving advanced composites may not justify the savings obtained in terms of weight vis-a-vis vehicle production, carbon fibers reinforced epoxies have been used in racing cars and recently for the safety of cars.
Polyester resin with suitable fillers and reinforcements were the first applications of composites in road transportation. The choice was dictated by properties like low cost, ease in designing and production of functional parts etc. Using a variety of reinforcements, polyester has continued to be used in improving the system and other applications.
Application of Composites in Aircraft Industry
The use of fibre reinforced composites has become increasingly attractive alternative to the conventional metals for many aircraft components mainly due to their increased strength, durability, corrosion resistance, resistance to fatigue and damage tolerance characteristics. Composites also provide greater flexibility because the material can be tailored to meet the design requirements and they also offer significant weight advantages. Carefully designed individual composite parts, at present, are about 20-30% lighter than their conventional metal counterparts. Although all-composite airplanes are now available in the world market, yet advances in the practical use of composite materials should enable further reduction in the structural weight of airplane. The composite materials used in aircraft industry are generally reinforced fibres or filaments embedded in a resin matrix. The most common fibres are carbon, aramid, glass and their hybrid. The resin matrix is generally an epoxy based system requiring curing temperatures between 120° and 180°C (250° and 350°F).
The first structural composite aircraft components, which were introduced during 1950-60, were made from glass fibre reinforced plastics. These components included the fin and the rudder of Grumman E-2A, helicopter canopies, frames, radomes, fairings, rotor blades, etc. Due to high strength and stiffness combined with low density, composites like Boron Fibre Reinforced Plastics (BFRP) and Carbon Fibre Reinforced Plastics (CFRP) .were preferred instead of aluminium for high performance aircraft structures. For lightly loaded structures, Aramid Fibre Reinforced Plastics (AFRP) which possess low density, have been used.