Textile Composites


Textilesphere- Textile Composites


Textile Composites
Composites
A composite can be defined as a material which consists of combination of properties that no single material can perform or provide. Composites are materials which have dissimilar contents but they are used to perform a task which neither of the material can perform alone. 
A composite consists of two elements namely, a Reinforcement material and Matrix (Binder). For example, consider human body where the bones act as reinforcement and the flesh acts as matrix. There are different types of composites, Metal-metal, metal-ceramic, metal-polymer, polymer-polymer etc.

TEXTILE COMPOSITES
Textile composites are made up of textile reinforcement structure and the matrix material
Reinforcement structures consists of fibers, yarn or fabrics (can be knitted, woven or non- woven) Reinforcement materials are also referred as Textile performs and they can be in various shape and size.
Matrix materials can be thermoset or thermoplastic, polymer, metal or ceramic
Textile composites can be flexible or rigid.

Types of Textile Composites
  • Textile composites are broadly classified as flexible textile composites and rigid textile composites
  • Flexible textile composites consists of conveyor belts, automotive tyres and coated fabrics
  • The main characteristics of Rigid textile composites are that thy have, high strength, high stiffness, low density, corrosion resistance and high temperature resistance

 Advantages of Textile Composites
  • They can be Anisotropic: Anisotropic material shows different properties along with different directions depending upon the orientation of fibers, yarn or fabrics
  • High strength to weight ratio than metal composites
  • It allows near net-shape manufacturing reducing cost an material waste considerably

 Applications of Composites
  • Composites replaced metals and metal alloys in the automotive industries
  • Majorly used in aerospace ( In parts of commercial aircrafts)
  • In military (Aircrafts, rocket components, missiles etc)
  • Manufacturing of electronics (Electronic boards)
  • Recreation purpose such as sporting goods

MATRIX MATERIALS

Functions of Matrix materials
  • The main function of matrix is to bind the fiber material together and hold them in particular position giving it a structural stability
  • To provide strength to the composite material
  • To protect the fiber from environment effects and handling
  • To transfer forces and stresses acting on the boundaries of the composite structure 

 Matrix materials for textile composites
  • Thermoset resins
  • Thermoplastic resins 

Thermoset Resin: The most widely used thermoset resins are Epoxy and polyester. The advantage of polyester resins are it has low costs, low viscosity and low curing temperature. The disadvantages are that it has poor strength and poor impact performance.

Advantage of Epoxy resin: It is ideal for higher temperature applications, broad range of physical and mechanical properties.

Thermoplastic Resins: Thermoplastic resins are classified commodity thermoplastic and Engineered thermoplastic 

Commodity Thermoplastic: Offers less resistance to high temperature. For example polyethylene, PVC, polypropylene.

Engineered Thermoplastics: They are temperature resistant and superior to epoxy, offer toughness and improved hot / wet resistance. Example PEEK (polyetherether ketone).

REINFORCEMENT MATERIAL
The reinforcement materials include S-glass, R-glass and wide range of carbon fibers, ceramic fibers etc. There are different forms of reinforcement materials such as long or continuous fibers, short fibers, spheres.

Classification of Textile Reinforcement Structures
They are classified under following categories:
  • Method of manufacturing (woven, knitted or braided)
  • Integration of structure (Laminated or integrated)
  • Packing density (open or solid)
  • Fiber continuity (continuous or discontinuous)
  • Direction of reinforcement

Preform:
Preform is fibrous reinforcement formed into shape before placing into mold that is, it given a pre-shape. It closely resembles final part configuration.
The multi-ply stitched fabric does not perform unless it is shaped to the nearest final configuration
They are made using rovings, chopped or woven unidirectional reinforcement material form held in place by the means of binder.
Applications: Used in corner fittings and square box to replace metal parts

Profile Preforms:
Profile preforms are fibers directly orientated in the fabric’s thickness and width directions
They strengthen load bearing structural members, provides stiffness and joins the elements
In profile preforms contains three sets of yarn in mutually perpendicular XYZ orientations and desired cross section profile
Applications: Aerospace, automotive, building / construction applications as well as certain medical products

Prepegs:
Prepegs is the textile structure that is impregnated with uncured matrix resin
Prepegs forms unidirectional and multidirectional tape, woven fabric. Fibers used for prepegs are graphite, fiber glass and aramid.
Hot melt or solvent coating process are used for prepeg fabrics
To obtain uniform thickness prepeg are calendared and is suitable for hand and machine lay up processes.

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