Solanki Utkarshsinh BRoll no: 618Final year StudentDepartment of Textile EngineeringThe M. S. University of Baroda,Kalabhavan,Vadodara.

COMPOSITES

composites

Two inherently different materials that when combined together produce a material with properties that exceed the constituent materials.

A broad definition of composite is: Two or more chemically distinct materials which when combined have improved properties over the individual materials. Composites could be natural or synthetic.

COMPOSITES

Composites are combinations of two materials in which one of the material is called the reinforcing phase, is in the form of fibers, sheets, or particles, and is embedded in the other material called the matrix phase.Typically, reinforcing materials are strong with low densities while the matrix is usually a ductile or tough material. If the composite is designed and fabricated correctly, it combines the strength of the reinforcement with the toughness of the matrix to achieve a combination of desirable properties not available in any single conventional material.

Reinforcement: fibers

GlassCarbonOrganicBoronCeramicMetallic

Matrix materialsPolymersMetalsCeramics

InterfaceBonding surface

Components of composite materials

Various Fibre characteristics

Composites – Polymer Matrix

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Polymer matrix composites (PMC) and fiber reinforced plastics (FRP) are referred to as Reinforced Plastics. Common fibers used are glass (GFRP), graphite (CFRP), boron, and aramids (Kevlar). These fibers have high specific strength (strength-to-weight ratio) and specific stiffness (stiffness-to-weight ratio)

Applications of Reinforced Plastics

Phenolic as a matrix with asbestos fibers was the first reinforced plastic developed. It was used to build an acid-resistant tank. In 1920s it was Formica, commonly used as counter top., in 1940s boats were made of fiberglass. More advanced developments started in 1970s.

Typically, although not always, consumer composites involve products that require a cosmetic finish, such as boats, recreational vehicles, bathwear, and sporting goods. In many cases, the cosmetic finish is an in-mold coating known as gel coat.

Consumer Composites

A wide variety of composites products are used in industrial applications, where corrosion resistance and performance in adverse environments is critical. Generally, premium resins such as isophthalic and vinyl ester formulations are required to meet corrosion resistance specifications, and fiberglass is almost always used as the reinforcing fiber. Industrial composite products include underground storage tanks, scrubbers, piping, fume hoods, water treatment components, pressure vessels, and a host of other products.

Industrial Composites

Applications of Reinforced PlasticsThis sector of the industry is characterized by the use of expensive, high-performance resin sycomposites stems and high strength, high stiffness fiber reinforcement. The aerospace industry, including military and commercial aircraft of all types, is the major customer for advanced composites. These materials have also been adopted for use in sporting goods, where high-performance equipment such as golf clubs, tennis rackets, fishing poles, and archery equipment, benefits from the light weight – high strength offered by advanced materials. There are a number of exotic resins and fibers used in advanced composites, however, epoxy resin and reinforcement fiber of aramid, carbon, or graphite dominates this segment of the market.

Advanced Composites

Applications of composites

Carbon Fiber Reinforced Composites

Glass Fiber Reinforced Composites

Ferrari 308 GT4

Glass Fiber Composite

Wind Blades/Wind Mills

Merits of composites•Light weight • Resistance to corrosion • High resistance to fatigue damage • Reduced machining • Tapered sections and compound contours easily accomplished• Can orientate fibers in direction of strength/stiffness needed• Possible reduced number of assemblies and reduced fastener count when consolidation is used • Absorb radar microwaves (stealth capability)• Thermal expansion close to zero reduces thermal problems in outer space applications .

Fiber Reinforced Polymer Matrix

Matrix •Transfer Load to Reinforcement•Temperature Resistance•Chemical Resistance

Reinforcement •Tensile Properties•Stiffness•Impact Resistance

1. MatrixPolyester Polyesters have good mechanical properties, electrical properties and chemical resistance. Polyesters are amenable to multiple fabrication techniques and are low cost. Vinyl EstersVinyl Esters are similar to polyester in performance. Vinyl esters have increased resistance to corrosive environments as well as a high degree of moisture resistance.Epoxy

Epoxies have improved strength and stiffness properties over polyesters. Epoxies offer excellent corrosion resistance and resistance to solvents and alkalis. Cure cycles are usually longer than polyesters, however no by-products are produced.Flexibility and improved performance is also achieved by the utilization of additives and fillers.

2.Reinforcement

Fiber TypeFiberglass(i.e

Glass)CarbonAramid   Textile StructureUnidirectional3DWoven3DBraid

Fiberglass E-glass: Alumina-calcium-

borosilicate glass (electrical applications)S-2 glass: Magnesuim aluminosilicate glass

(reinforcements)

Glass offers good mechanical, electrical, and thermal properties at a relatively low cost.

E-glass S-2 glass

Density 2.56 g/cc 2.46 g/ccTensile Strength 390 ksi 620 ksiTensile Modulus 10.5 msi 13 msiElongation 4.8% 5.3%

Introduction to REBAR

Rebar is a reinforcing steel bar or mesh of steel wires commonly used in reinforced masonry structures and reinforced concrete(RCC) to strengthen and hold the concrete in compression.

What is REBAR?

The surface of the rebar may be patterned to form better bond with the concrete. Pultruded FRP rebar is different than that of steel bars in two ways. Pultruded FRP rebar is anisotropic having high strength in the direction of fibres which improves the shear strength, dowel action and bond performance. Moreover it does not yield and is linear elastic until failure.

Introduction to rebar and its applications:

Practical applications of Pultruded Rebar:•Concrete Exposed to De-Icing Salts: Bridge decks, median barriers, approach slabs, parking structures, railroad crossings, salt storage facilities, concrete exposed to marine salts seawalls, buildings and structures near waterfronts, aquaculture operations, artificial and water breaks, floating marine docks.

•Tunnelling and Mining Applications: Soft-eye openings for tunnel boring machines (TBM's) and temporary works, rock nails, electrolytic and ore extraction tanks corrosive applications.

Features of Rebar:impervious to chloride ion and chemically inert higher tensile strengthlighter in weight than steel rebarIt also does not interfere with magnetic and radar frequencies and are electrically non-conductive and thermally stable.

•Electromagnetic Applications: MRI rooms in hospitals, airport, radio and compass calibration pads, concrete near high voltage cables, transformers and substations and cast stone elements.

PROBLEM IS STEELReinforced Concrete with Steel Rebar is the cause of the failing infrastructure

Steel rebar has been used since the early 1900’s

Steel expands 10x in volume when it rusts, and causes concrete to crack and failIron Iron Oxide

STEEL CORROSION

Epoxy Coated Steel: Corrodes

Galvanized Steel: Corrodes

Stainless Steel: Susceptible

CORROSION

Cracking with Epoxy Coated Steel,

19 Year Old Ontario Bridge, MTO 2005

Cracking with Galvanized Steel,23 Yr Old Ontario Bridge, MTO 2007

Failure with Stainless Steel,Roof of 13 Year Old

Swimming Pool Collapses, Switzerland

Rusting Stainless Steel in Bridge Install

Anthony Henday, Edmonton AB

Materials used for rebar:Glass Fibre Roving(4800 Tex), Resin(vinyl ester), Additives (Phenolex), Hardner (TBPB), Filler(calcite) materials are ued for manufacturing of Rebar.

Methods used for manufacturing rebar:Pultrusion

Pultrusion process:Pultrusion is a combination of pull and extrusion. Extrusion is pulling of material such as fibre glass and resin, through a heated die. Process begins with the fibres coming from the roving from creel. Then there is wetting by resins called as Resin Impregnation . Impregnated Fibre and Mattings are passed through preformers and guidance devices. Emerging profile is preheated and passed through heated die. Through heated dies polymerizing and curing takes place. Meanwhile pulling of the formed section.

Pultrusion machine

Pultrusion process

Test results of rebar:

SEM image of GFRP

SEM image shows the even distribution of roving in resin hence there is a proper consolidation between roving and resin . Voids in the image may enhance the poor quality of rebar and this may be caused due to material and condition used in the process of manufacturing rebar.

GFRP is more effective than the metallic TMT bars used in geo-tech and infrastructure applications. The advantages of pultrusion are as follows:1. Increased Strength 2. High Fibre Content 3. Highly Automated 4. Consistent Quality 5. High Production 6. Low Labour Required 7. Low CostTherefore, pultruded rebars are costly effective and can replaced present TMT bars.

Conclusion: