Downloaded 50 times
Uploaded byTHEVENDRAN GUNASELAN
bonding and composite
This document provides information about bonding and composites. It discusses the different types of composites including polymer matrix composites, metal matrix composites, and ceramic matrix composites. It describes the advantages and disadvantages of composites. It also outlines various fabrication processes for composites such as laminating, pultrusion, filament winding, and adhesive bonding.
More Related Content
Similar to bonding and composite
bonding and composite
- 1. BONDING & COMPOSITES GROUPMEMBERS MATHAN RAJ A/L MANIMAREN THEVENDRAN A/L GUNASELAN
- 2. What is Composite? Bonded structure using chemical methods Combinationsof 2 or more elements – differ in composition Combinations of 2 or more elements – differ in identities & properties
- 3. Multiphase material withsignificant proportions of phases. • Continuous phase (Matrix) – to transfer stress to other phases and protect phases from environment. • Dispersed/reinforcing phase – purpose is to enhance matrix properties. • Classification : Particles, fibers, structural.
- 4. ADVANTAGE High Strength to WeightRatio Customizable Stiffness & Strength Corrosion Resistance High Fatigue Resistance Complex shape built using less mould Ease of Maintenance Absorb radar microwaves (stealth capability). Simplify and reduces inspection time.
- 5. DISADVANTAGE Manufacture & repaircure time Mechanical properties affected by temperature and moisture Difficulty, reliability issue & cost in inspection Low bearing and interlaminar strength High material cost Poor energy absorption and impact damage May require lightning strike protection
- 6. MATRIX Classification: • Metal MatrixComposite (MMC) • Ceramic Matrix Composites (CMC) • Polymer Matrix Composite (PMC)
- 7. Polymer Matrix Composite(PMC) or Fiber- Reinforced Plastics • Fibers (discontinuous and dispersed phase) + plastic matrix (continuous phase) • Properties: • Strong and stiff • High specific strength (strength to weight ratio) • High specific stiffness (stiffness to weight ratio) (Brittle and abrasive, less toughness and chemically degradable when exposed to the atmosphere)
- 8. • Percentages offibers (by volume)–10% to 60% (limited by the average distance between adjacent fibers) • Highest practical fiber content is 65% ( higher percentage can lower physical properties) *Hybrid when more than one fiber is used.
- 9. REINFORCING FIBERS • GLASS •GRAPHITE • ARAMIDS (KEVLAR) • BORON • Others • (Nylon, Silicon Carbide, Silicon Nitride, Aluminium Oxide, Sapphire, Steel, Tungsten etc.0
- 10. Fiber Size andLength • Mean diameter < 0.01mm • Oriented in longitudinal direction (strong and stiff in tension) • Small cross section (low defects exist) • Classified • Short fibers (aspect ratio 20 – 60) : Improve mechanical properties as a result of increasing the average fiber length. • Long fibers (200 – 500) : transmit load through the matrix better, commonly used in critical applications, particularly at elevated temperature.
- 12. Matrix Materials • Thermosets– Epoxy (most commonly used ~ 80% of PMC), polyester, phenolics, fluorocarbons, polyethersulfone, silicon and polyimides • Thermoplastics –Polyetheretherketone
- 13. Functions • to supportthe fibers in place, transfer stresses to them. • to protect the fibers against physical damage and the environment. • to reduce the propagation of cracks, by virtue the greater ductility and toughness.
- 14. Properties of ReinforcedPlastics • mechanical and physical properties depends on : • Type • Shape • Orientation of the reinforcing material • Length of the fibers • Volume fraction (%) of the reinforcing material
- 15. • type andamount of reinforcement effect the physical prop. and resistance (fatigue, creep and wear) • Highest stiffness and strength = fibers are aligned in the direction of the tension force • strength of the bond between the fiber and the polymer matrix
- 16. Metal Matrix Composite(MMC) • An alloy (Aluminium, Al-Lithium, Magnesium, Copper, Titanium and superalloys) • Three types of such composites 1. dispersion-strengthened - in which the matrix contains a uniform dispersion of very fine particles (10–100nm) 2. particle-reinforced – particles of sizes greater than 1μm are present 3. fibre-reinforced - fibres may be continuous through out the length of the component, or less than a micro metre in length, and present at almost any volume fraction, from 5 to75%.
- 17. • Reinforcement materials •Graphite, Boron, Alumina, SiliconCarbide, AluminiumOxide, Molybdenum, Tungsten
- 18. Advantages 1. Higher elasticmodulus 2. Resistance to elevated temperature 3. Higher toughness and ductility Disadvantage 1. Higher density thus greater difficulty in processing the parts
- 19. Ceramic Matrix Composite(CMC) Properties: 1. Strong and stiff 2. Resist high temperatures. 3. Lack toughness Matrix materials (retain strength up to 1700 oC): Silicon Carbide, Silicon Nitride, Aluminium Oxide and Mullite(Al,Si,O2) Carbon-CarbonMatrixComposites – strength up to 2500 oC (Carbon and Aluminium Oxide)
- 20. Fabrication of CompositeMaterials • Particulate • Laminar I. Hot or Cold Roll Bonding II. Explosive Bonding III. Adhesive Bonding IV. Sandwich Structures • Fiber-reinforced
- 21. Processes Designed ToCombine Fibers and Matrix • Prepregs • Sheet Molding Compounds (SMC) • Bulk Molding Compounds
- 22. Fabrication of FinalShapes from Fiber-Reinforced Composites Pultrusion • Continuous process that is used to produce simple shapes of uniform cross section eg: round, rectangular, tubular, plate, sheet and structural products. • Extremely high strengths products (reinforcement can be up to 75% of the final structure). • Crosssection – up to 1.5m wide and 0.3m thick. Reinforcing fibers
- 23. Bundles of continuous reinforcingfibers are drawn through a bath of thermoset polymer resin The material is then pulled through one or more heated dies, which further shape the product and cure the resin Upon emergence form the heated dies, the product is cooled by air or water, cut to length and then fabricated into products e.g fishing poles, ski poles
- 24. Resin-coated/ resin impregnated, high strength,continuous filaments, bundles or tape made from fibers of glass, graphite, boron, Kevlar or similar materials can be used to produce cylinders, spheres, cones and other container type shapes that have exceptional strength to weight ratios The filaments are wound over a form or mandrel, using longitudinal, circumferential, or helical patterns or combination in order to take advantage of their highly directional strength properties By adjusting the density of the filaments in various locations and selecting the orientation of the wraps, products can be designed to have strength required and lighter weight in less critical regions After winding, the part and mandrel are placed in an oven for curing, after which the product is stripped from the form The matrix (epoxy type) binds the structure together and transmits the stresses to the fibers
- 25. Final curing Involving elevatedtemperature and possibly applied pressure Multiple reinforcement sheets Passed through a resin bath, faced with non stick sheet and passed through squeeze rolls. For tubing The impregnated stock is wound around a mandrel of the desired internal diameter Pre preg sheets or reinforcement sheets saturated in resin then compressed under pressure on the order of 7MPa. Lamination and Lamination Type Processes Laminated materials can be produced as sheets Tubes rods
- 26. Lamination Type Processes Vacuum - bagmolding Air pressure holds the laminate against the mold while the resin cures. Curing generally at room temperature but moderate elevated temperature may be used Pressure bag molding A flexible membrane is positioned over the female mold cavity and pressurized to force the individual plies together and drive out entrapped air and excess resin Compression molding For large production quantities and high quality The dies are heated and curing occurs during the compression operation
- 27. Other processes Spray Molding • Nodesired properties required. • Mixing chopped fibers and catalyzed resin and spraying the combination on to a mold form. • Rollers or squeegees can be used to remove entrapped air and work the resin in to the reinforcement. • Room temperature curing, sometimes elevated temperature is used to accelerate the cure. Sheet Stamping • Thermoplastic sheets reinforced with non woven fiber–heated and press-formed. Injection Molding • Chopped or continuous fibers are placed in a mold cavity that is then closed and injected with resin
- 28. Fabrication of Fiber– Reinforced Metal Matrix Composites Continuous fiber metal matrix composites can be produced by variations of filament winding, extrusion and pultrusion. Fiber reinforced sheets can be produced by electroplating, plasma spray deposition coating or vapor deposition of metal on to a fabric or mesh, then shaped and bonded.
- 29. Fabrication of Fiber– Reinforced Ceramic Matrix Composites Common method includes chemical vapor deposition or chemical vapor infiltration of a coated fiber base. Hot pressing technique.
- 30. Secondary Process andFinishing Can be processed further with conventional equipment (sawed, drilled, routed, taped, threaded, turned, milled, sanded and sheared). Precautions should be used to prevent the formation of splinters, cracks, frayed or delaminated edges. Sharp tools, high speed sand low feeds are generally required. Quickly remove cutting debris–prevent cutters becoming clogged. Abrasive materials (in nature)–dull most conventional cutting tools. Use diamond or polycrystalline diamond tooling to achieve realistic tool life. Use abrasive slurry–smooth surface. Lasers and Water Jets as alternative cutting tools
- 31. Adhesive Bonding A varietyof joining methods can be used to provide the assembly function. Alternative joining methods include adhesive bonding, welding, brazing, soldering, and mechanical fastening. Adhesives are available in several forms: liquid, paste, solution, emulsion, powder, tape and film. • Adhesives thickness ~0.1mm. • Adhesive application may be required due to the following properties. a. strength (shear and peel) b. toughness c. resistance to various fluids and chemical. d. resistance to environmental degradation (heat, moisture) e. ability to wet the surfaces to be bonded
- 33. Design for AdhesiveBonding
- 34. Butt joint designLap joint design
- 35.