Textile composites are fiber-reinforced composite materials. The form of textile fabric being used as reinforcement are: woven , knitted , braided. Textile-reinforced composite materials (TRCM) are part of the general class of engineering materials called composite materials. There are two categories of constituent materials:
- Matrix: Matrix holds the reinforcements in an orderly pattern.
- Reinforcement: Used to provide strength.
Two or more chemically distinct material Which when combined Have improved properties Over the individual material. For example : wood, bamboo, bricks.
Classification of composite materials
MATRIX MATERIAL
- Polymer matrix composite : Epoxides , polyester , nylon
- Ceramic matrix composite : siC , glass ceramics etc.
- Metal matrix composite : Aluminium alloys , magnesium alloys , titanium.
REINFORCEMENT MATERIAL
- Fibre – short or long fibers (S glass , R glass , carbon fibre)
- Yarn
- Fabric composite: woven , knitted, braided.
Polymer matrix composite material are classified on the basis of resin into two categories: thermoplastic and thermoset.
1) thermoplastic composite : this is a type of Composite materials with Thermoplastic resin like polyester , HDPE etc.
Advantages of thermoplastic matrix
- Unlimited shelf life at room temperature
- Ease of processing
- Ease of handling
- Reformabale
- High impact energy absorption
- Excellent fracture resistance.
- Thermo-set composite : In this composite Thermoset polyester like Epoxy , unsaturated polyester And vinyl-ester are used as resin.
Application
Automotive , naval , Aeronautical and aerospace.
Advantages of thermoset matrix
- Thermal stability
- Chemical resistance
- Low creep and stress relaxation
- Low viscosity
- Large database
Overall the properties of the composite are determined by
- The properties of the fibre.
- The properties of the resin.
- The ratio of fibre to resin in the composite (Fibre Volume Fraction).
- The geometry and orientation of the fibres in the composite.
The production methods of textile composites are more attractive over Conventional unidirectional Laminate composite because of their high production rate. Yarn interlacing which improves structural stability and damage tolerance makes textile composite attractive. Textile composites are used typically because of their high strength-to-weight and stiffness-to-weight ratios. This family of materials, at the centre of the cost and performance spectra, offers significant opportunities for new applications of polymer composites. They are manufactured from woven fabrics are formed of arrangement of fibers and matrix. Composite materials are selected over modern metallic material Due to their:
- High strength.
- Light weight.
- Long life.
- Net shape manufacturing.
- Design flexibility.
Mechanical behavior
Bishop and Curtis16 were amongst the first to demonstrate the potential advantages of woven fabrics for aerospace applications. Glass-reinforced woven fabrics give rise naturally to composites with lower mechanical properties because of the much lower value of the glass fibre modulus compared to carbon. the mechanical properties of woven fabric-reinforced composites are directed by the type of fiber used.
Mechanical behavior of braided reinforcement
2d braided reinforcement will be considered primarily , since it lends itself to direct comparison with laminated composites with a 0/±q construction. The strengths of braided reinforced composites are lower than their pre pegged counterparts.
Mechanical behavior of knitted reinforcement
The tensile and compressive properties of the knitted fabrics are poor , but they are more likely to be chosen for their processability and energy-absorbing characteristics than their basic in-plane properties.
Advantages of reinforcing fibre
- E-glass and S-glass : high strength and low cost
- aramid : high strength and low density
- HS carbon : high strength and stiffness
- UHM carbon : very high stiffness
Disadvantages of reinforcing fibre
- E-glass and S-glass : low stiffness and fatigue
- aramid : high moisture absorption
- HS carbon : high cost
- UHM carbon : low strength and high cost
Composite manufacturing process
1. Hand lay up method
Any sorts of products can be made because we have to only lay the reinforcing fabric and pour the matrix.
Advantages:
- Tooling cost is low
- Versatile products can hand laid
Disadvantages:
- Longer curing cycles
- Time consuming
- Highly labor demanding
- No control over orientation of fibres
- Large void content
2. Spray method
As in hand lay up we are supposed to do hand laying instead of this we can spray with the help of spray gun both chopped fibre and resin. The following process is as follows :
- Chopped fibre and resin is sprayed on mold.
- These combination is then cured.
- This process is slowly substituted by resin transfer molding.
Advantages:
- Any material can be used as a mold.
- It is a continuous process.
- Respraying is used for correction of errors.
Disadvantages:
- Process is unfriendly to environment.
- Inconsistency in fibre and matrix distribution.
- Slow process.
- Smooth finish can only be obtained on one side.
3. Open mold spray up chopping method
In this method roving or fibre are chopped first and then mixed with matrix material. The operator has to control both chopping and spraying because the process is more operated operator dependent than hand lay up. Here chopper fun feeds the glass roving and resin. The resin saturated is deposited on mold. The laminate is then rolled to thoroughly saturate the glass strand and compact the chop.
4. Sheet molding method :
Advantages:
- Higher throughput
- Inexpensive
- Reliability
Disadvantages:
- Higher volume fractions are not possible
- Only simple boards can be made
Reference:
- Prof. Apurba Das , textile engineering ,IIT DELHI ( taken out from their nptel lectures )
- Hand book of technical textile , edited by A R Horrocks and S C Anand , woodhead publishing limited.
- Image reference : https://www.sciencedirect.com/topics/materials-science/textile-composite