COMPOSITES. Chapter 4

Transcription

1 COMPOSITES Chapter 4 1

2 Introduction A Composite material is a material system composed of two or more macro constituents that differ in shape and chemical composition and which are insoluble in each other. The history of composite materials dates back to early 20th century. In 1940, fiber glass was first used to reinforce epoxy. Applications: Aerospace industry Sporting Goods Industry Automotive Industry Home Appliance Industry 2

3 Combination of two or more individual materials Design goal Obtain a more desirable combination of properties (principle of combined action) e.g., low density and high strength 3

4 Ancient Mud bricks making Making bricks with straw The earliest man made composite materials were straw and mud combined to form bricks for building construction. Ancient brick making was documented by Egyptian tomb paintings. 4

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13 Composites 13

14 Classification of composites 14

15 Composites consist of: 1. Combination of two or more materials Composite = matrix + fiber (filler): Matrix: material component that surrounds the fiber. Usually a ductile, or tough, material w/ low density Strength usually = 1/10 (or less) than that of fiber Examples include: thermoplastic or thermoset Thermoset most common (epoxy, pheneolic) Serves to hold the fiber (filler) in a favorable orientation. Fiber also known as reinforcing material aka Filler: Materials that are strong with low densities Examples include glass, carbon or particles. 2. Designed to display a combination of the best characteristics of each material i.e. fiberglass acquires strength from glass and flexibility from the polymer. 3. Matrix and filler bonded together (adhesive) or mechanically locked together!

16 Terminology/Classification Composite: -- Multiphase material that is artificially made. Phase types: -- Matrix - is continuous -- Dispersed - is discontinuous and surrounded by matrix Adapted from Fig. 16.1(a), Callister & Rethwisch 8e. 16

17 Composite Structural Organization: the design variations

18 Terminology/Classification Matrix phase: -- Purposes are to: - transfer stress to dispersed phase - protect dispersed phase from environment -- Types: MMC, CMC, PMC metal ceramic polymer woven fibers cross section view 0.5mm Dispersed phase: -- Purpose: MMC: increase y (yield stress) CMC: increase K ic (Fracture Toughness) PMC: increase E, y,. -- Types: particle, fiber, structural 0.5mm Reprinted with permission from D. Hull and T.W. Clyne, An Introduction to Composite Materials, 2nd ed., Cambridge University Press, New York, 1996, Fig. 3.6, p

19 Matrix Composites Matrix Materials: Polymer Matrix Composites PMC There are two basic categories of polymer matrices: Thermoplastics Thermoset plastics Roughly 95% of the composite market uses thermosetting plastics Thermosetting plastics are polymerized in two ways: By adding a catalyst to the resin causing the resin to cure, basically one must measure and mix two parts of the resin and apply it before the resin cures By heating the resin to it s cure temperature 19

20 Common thermosetting plastics: Phenolic (phenols): good electrical properties, often used in circuit board applications Epoxies: low solvent emission (fumes) upon curing, low shrink rate upon polymerization which produces a relatively residual stress free bond with the reinforcement, it is the matrix material that produces the highest strength and stiffness, often used in aerospace applications Polyester (Polyester resin): most commonly used resin, slightly weaker than epoxy but about half the price, produces emission when curing, used in everything from boats to piping to Corvette bodies (combat ships). 20

21 The reinforcement in a polymer matrix composite provides strength and stiffness that are lacking in the matrix. The continuous reinforcing fibers of advanced composites are responsible for their high strength and stiffness. The most important fibers in current use are glass, graphite, and aramid (Kevlar). 21

22 Sanchez, Clément, et al. "Applications of advanced hybrid organic inorganic nanomaterials: from laboratory to market." Chemical Society Reviews 40.2 (2011):

23 carbon fiber composite car parts 23

24 Matrix Composites Matrix Materials: Metal Matrix Composites MMC 24

25 Source: Basics of Metal Matrix Composites, Karl Ulrich Kainer 25

26 Source: Basics of Metal Matrix Composites, Karl Ulrich Kainer 26

27 MMC Applications 27

28 Applications of MMC in Automotive: Some automotive disc brakes use MMCs. Early Lotus Elise models used aluminum MMC rotors, but they have less than optimal heat properties and Lotus has since switched back to cast iron. Modern high performance sport cars, such as those built by Porsche, use rotors made of carbon fiber within a silicon carbide matrix because of its high specific heat and thermal conductivity. 3M sells a preformed aluminum matrix insert for strengthening cast aluminum disc brake calipers, allowing them to weigh as much as 50% less while increasing stiffness. Ford offers a Metal Matrix Composite (MMC) driveshaft upgrade. The MMC driveshaft is made of an aluminum matrix reinforced with boron carbide. Honda has used aluminum metal matrix composite cylinder liners in some of their engines, including the B21A1, H22A and H23A, F20C and F22C, and the C32B used in the NSX. Toyota has since used metal matrix composites in the Yamaha designed 2ZZ GE engine which is used in the later Lotus Lotus Elise S2 versions as well as Toyota car models, including the eponymous Toyota Matrix. Porsche also uses MMCs to reinforce the engine's cylinder sleeves in the Boxster and

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32 Light Weight Metal Matrix Composite Brake Drum 32

33 Matrix Composites Matrix Materials: Metal Matrix Composites MMC 33

34 GE tests GE9X engine with ceramic matrix composites. Ground testing is underway on a GEnx engine that contains lightweight, heatresistant ceramic matrix composite (CMC) components. 34

35 Composite Survey Composites Particle-reinforced Fiber-reinforced Structural Largeparticle Dispersionstrengthened Continuous (aligned) Discontinuous (short) Laminates Sandwich panels Aligned Randomly oriented Adapted from Fig. 16.2, Callister 7e.

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37 Composite Benefits CMCs: Increased toughness Force particle-reinf fiber-reinf un-reinf Bend displacement 10 3 E(GPa) 10 2 PMCs: Increased E/ 10 1 PMCs ceramics metal/ metal alloys.1 G=3E/8 polymers.01 K=E Density, [mg/m 3 ] MMCs: Increased creep resistance Al ss (s -1 ) Al w/sic whiskers (MPa) Adapted from T.G. Nieh, "Creep rupture of a silicon-carbide reinforced aluminum composite", Metall. Trans. A Vol. 15(1), pp , Used with permission.

38 Particle-reinforced Fiber-reinforced Structural Examples: - Spheroidite steel matrix: ferrite ( ) (ductile) 60 m particles: cementite (Fe 3 C) (brittle) Adapted from Fig , Callister & Rethwisch 8e. (Fig is copyright United States Steel Corporation, 1971.) - WC/Co cemented carbide - Automobile tire rubber matrix: cobalt (ductile, tough) : matrix: rubber (compliant) 600 m 0.75 m particles: WC (brittle, hard) particles: carbon black (stiff) Adapted from Fig. 16.4, Callister & Rethwisch 8e. (Fig is courtesy Carboloy Systems, Department, General Electric Company.) Adapted from Fig. 16.5, Callister & Rethwisch 8e. (Fig is courtesy Goodyear Tire and Rubber Company.) 38

39 Particle-reinforced Fiber-reinforced Structural Classification: Particle Reinforced Concrete gravel + sand + cement + water - Why sand and gravel? Sand fills voids between gravel particles` Reinforced concrete Reinforce with steel rebar or remesh - increases strength - even if cement matrix is cracked Pre-stressed concrete - Rebar/remesh placed under tension during setting of concrete - Release of tension after setting places concrete in a state of compression - To fracture concrete, applied tensile stress must exceed this compressive stress Post-tensioning tighten nuts to place concrete under compression nut threaded rod 39

40 Particle-reinforced Fiber-reinforced Structural Classification: Fiber Reinforced Fibers very strong in tension Provide significant strength improvement to the composite Ex: fiber-glass - continuous glass filaments in a polymer matrix Glass fibers strength and stiffness Polymer matrix holds fibers in place protects fiber surfaces transfers load to fibers 40

41 Particle-reinforced Fiber-reinforced Structural Classification: Fiber Reinforced (v) Critical fiber length for effective stiffening & strengthening: fiber ultimate tensile strength fiber length 2 f d c fiber diameter shear strength of fiber-matrix interface Ex: For fiberglass, common fiber length > 15 mm needed For longer fibers, stress transference from matrix is more efficient Short, thick fibers: fiber length 2 f d c Long, thin fibers: fiber length 2 f d c Low fiber efficiency High fiber efficiency 41

42 Benefits of Long Fiber Reinforced 42

43 Composite Production Methods Pultrusion* Continuous fibers pulled through resin tank to impregnate fibers with thermosetting resin Impregnated fibers pass through steel die that preforms to the desired shape Preformed stock passes through a curing die that is precision machined to impart final shape heated to initiate curing of the resin matrix *The term is a portmanteau word, combining "pull" and "extrusion". Fig , Callister & Rethwisch 8e.

44 Filament Winding Continuous reinforcing fibers are accurately positioned in a predetermined pattern to form a hollow (usually cylindrical) shape Fibers are fed through a resin bath to impregnate with thermosetting resin Impregnated fibers are continuously wound (typically automatically) onto a mandrel After appropriate number of layers added, curing is carried out either in an oven or at room temperature The mandrel is removed to give the final product Adapted from Fig , Callister & Rethwisch 8e. [Fig is from N. L. Hancox, (Editor), Fibre Composite Hybrid Materials, The Macmillan Company, New York, 1981.]

45 Pipe Fiber Reinforce Plastic Pipe 45

46 Particle-reinforced Fiber-reinforced Structural Classification: Structural Laminates - -- stacked and bonded fiber-reinforced sheets - stacking sequence: e.g., 0º/90º - benefit: balanced in-plane stiffness Sandwich panels -- honeycomb core between two facing sheets - benefits: low density, large bending stiffness face sheet adhesive layer honeycomb Adapted from Fig , Callister & Rethwisch 8e. Adapted from Fig , Callister & Rethwisch 8e. (Fig is from Engineered Materials Handbook, Vol. 1, Composites, ASM International, Materials Park, OH, 1987.) 46

47 Special Issue: Composites for Ultralight Vehicles Jenna Owen University of Texas at Austin ElectroPhen, 2008

48 Introduction Ultralight Strategy Materials Advanced Composites Hypercar Conclusion

49 Current model and disadvantages Steel model has been seen for almost a century. Cars are very heavy due to the weight of the steel. Current vehicles are not energy efficient. 85% of energy input is lost 1% of energy is used to move the passengers

50 Ultralight Strategy Mass decompounding is the key to an efficient vehicle design. Every 10% of weight reduction translates to a 7% increase in fuel economy.

51 Materials Light Steel (25-30% lighter) Hydroform tubing used to create the autobody. Laser welding allows thin steel to be welded to thicker steel. Aluminum (40% lighter) New types of alloys and production techniques tested Advanced Composites (50-67% lighter)

52 Advanced Composites Composition Polymers embedded into a matrix of plastic Composed of carbon, aramid, or similar fibers Composites durable, fatigue resistant, and reduce noise and vibrations. Design Materials formed into one unit or shell Aerodynamic drag reduced by 40-50% Rolling resistance reduced by 50%

53 Advanced Composites Safety Materials are 20 times as stiff, 4 times as tough, and can handle temperatures twice as high. Composites can absorb 5 times more energy than an equivalent amount of steel. Cost Advanced composites are expensive 1-2 orders of magnitude fewer parts Simple assembly and few tools required

54 Hypercar Incorporates ultralight technology along with a hybrid electric drive system Travels miles per gallon Sundance Channel, 2008

55 Conclusion Ultralight technology will increase the energy efficiency of future vehicles. Advanced composites create light, safe, durable, and superefficient vehicles.

56 Advanced Composite Technology Manufacturing 56

57 Projects: 1. Simulation of Injection Molding with Moldex 3D 2. The Future use of composites materials in transport. 3. Use of Shape memory alloys for Solar tracking system. 57

58 Literature Reviews: IUG Library: 58

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61 Instructions for writing academic research Documentation ( Scientific paper, Research Proposal, technical Report) 1. Abstract 2. Motivation Research Goals 3. State of the art Literature Reviews 4. Background Title of Research Project Ex: The Solar panel tracking system Ex: Shape memory alloys 5. Methodology 6. Design and testing 7. Conclusion 8. References 61