Composites are materials made from two or more components that have significantly different physical or chemical properties which remain distinct (on a macroscopic level) within the finished structure. The advantage of composite materials is that, the properties they exhibit are not simply the sum of the properties of the constituent materials.
Composites consist of reinforcement and matrix material. The reinforcement, which generally takes the form of fibers, has high tensile strength but is susceptible to breakage. In contrast, the matrix which surrounds and supports the reinforcement has a relatively low tensile strength but is extremely tough. When combined, the matrix and the reinforcement, counteract each other’s weaknesses to produce a material that is stronger, stiffer and more damage resistant than either material alone.
Advanced materials play a crucial role in reducing the environmental impact of aviation. Materials that have high strength whilst being light weight, have improved temperature capability or are more adaptive, can all help to reduce fuel burn and emissions. Properties of composites like stiffness, thermal expansion etc. can be varied continuously over a broad range of values using appropriate fiber, resin and fabrication mechanism. Fiber glass dominates the composites industry as a preferred reinforcement fiber, with a share of around 85%-90%. Other reinforcement fibers like carbon fiber and aramid fiber are sparingly used in India.
Why Textiles in Aircraft Industry?
Enhance the comfort and aesthetics properties
20-50% less weight
Reduce the total weight
Resistance to water, fuels, extremes of temperature
Provides advanced insulation
In the aerospace industry, composites are generally made of non-metallic fibers like carbon, glass or aramid, embedded in a polymeric matrix (example: plastic or epoxy); although in some cases, the matrix is a metal such as Aluminium, titanium or magnesium. For example, glass–reinforced fiber metal laminates known as glares are used in significant proportions in airframes. Ceramic composites are also being considered for some aerospace applications.
Use of carbon fiber reinforced textile materials, since the other widely used composite reinforcement fibers, glass and aramid have gained relatively limited use in the aerospace sector, owing to weight and lack of stiffness with regards to glass and to the problem of moisture absorption with respect to aramid fiber Similarly applications concentrate on the use of epoxy resin systems, as these dominate the aerospace composites sector.
Fibers and Composites
Carbon/epoxy (CFRP) – used as a primary structural and skin material.
Kevlar/epoxy – mostly used in military applications, in primary structures and amour plating.
Glass fiber – used as a structural and skin material (on amateur-built and aircraft).
Glass/phenolic (GFRP) – used in interior fittings, furnishings and structures.
Boron/epoxy – used in composite repair patches, older composite structures.
Poly-Fiber can be rejuvenated after years of weathering. Poly-Fiber is the only all-VINYL system which bonds extremely well to polyester fabrics and remains flexible when it dries and does not support combustion
A typical composite material construction for helicopter blade
One type of composite structure used in aerospace is the sandwich panel. In this structure a light weight core material such as a honeycomb is sandwiched between two laminated composite sheets known as skins. Sandwich panels are popular as they have the highest stiffness-to-weight and strength-to-weight ratios of all composites and have excellent resistance to bending and buckling.
The various textile structures used to make FRP are
1). Multi axial warp knit
2). 2-D Tri axial braid
3) 3-D braid
4) Knitted/ stitched
Final year B.Tech Textile Technology