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ENGR-45_Lec-28_Composites.ppt 1 Bruce Mayer, PE Engineering-45: Materials of Engineering Bruce Mayer, PE Registered Electrical & Mechanical Engineer Engineering 45 Composite Materials

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ENGR-45_Lec-28_Composites.ppt 2 Bruce Mayer, PE Engineering-45: Materials of Engineering Learning Goals – Composites List The CLASSES and TYPES of Composites When to Use Composites Instead of Metals, Ceramics, or Polymers How to Estimate Composite Stiffness & Strength Examine some Typical Applications

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ENGR-45_Lec-28_Composites.ppt 3 Bruce Mayer, PE Engineering-45: Materials of Engineering Terms & Classifications Composite MultiPhase Material with Significant Proportions of Each Phase Phase Components –MATRIX –DISPERSED Phase Matrix The CONTINUOUS Phase The Matrix Function –transfer stress to other phase(s) –Protect other phase(s) from the (corrosive) Environment 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. 47.

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ENGR-45_Lec-28_Composites.ppt 4 Bruce Mayer, PE Engineering-45: Materials of Engineering Terms & Classifications cont.1 Composite Classifications MMC Metal Matrix Composite CMC Ceramic Matrix Comp. PMC Polymer Matrix Comp. Dispersed Phase (DP) Function = To Enhance the Matrix Properities –MMC: increase σ y, TS/σ u, creep resistance –CMC: increase K c (fracture toughness) –PMC: increase E, σ y, TS/σ u, creep resistance Classes: Particle, fiber, structural

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ENGR-45_Lec-28_Composites.ppt 5 Bruce Mayer, PE Engineering-45: Materials of Engineering Composite Taxonomy Composites PARTICLE ReinforcedFIBER ReinforcedSTRUCTURAL LARGE Particle DISPERSION Strengthened Continous (Aligned) DIScontinous (Short) Laminates Sandwich Panels Aligned Randomly Oriented

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ENGR-45_Lec-28_Composites.ppt 6 Bruce Mayer, PE Engineering-45: Materials of Engineering Composite Survey – Particle-I 60 Adapted from Fig , Callister 7e. (Fig is copyright United States Steel Corporation, 1971.) -Spheroidite steel matrix: ferrite ( ) (ductile) particles: cementite (Fe 3 C) (brittle) m Adapted from Fig. 16.4, Callister 7e. (Fig is courtesy Carboloy Systems, Department, General Electric Company.) -WC/Co cemented carbide matrix: cobalt (ductile) particles: WC (brittle, hard) V m : 10-15vol%! 600 m Adapted from Fig. 16.5, Callister 7e. (Fig is courtesy Goodyear Tire and Rubber Company.) -Automobile tires matrix: rubber (compliant) particles: C (stiffer) 0.75 m Particle-reinforced Fiber-reinforcedStructural Examples

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ENGR-45_Lec-28_Composites.ppt 7 Bruce Mayer, PE Engineering-45: Materials of Engineering ReInforced ConCrete Concrete is a PARTICLE ReInforced Composite Matrix = PortLand Cement –3CaO-SiO 2 + 2CaO-SiO 2 Dispersed Phases –Sand+Gravel Aggregate –60%-80% by Vol Steel ReInforcing Bars (Rebar) A type of FIBER Reinforcement Improves Tensile & Shear Strength

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ENGR-45_Lec-28_Composites.ppt 8 Bruce Mayer, PE Engineering-45: Materials of Engineering More ReInforced Concrete Concrete gravel + SAND + cement Why sand and gravel? Sand packs into gravel VOIDS Reinforced concrete - Reinforce with steel reBAR or reMESH Increases TENSILE strength - even if Concrete matrix is cracked PreStressed concrete - reMesh under tension during setting of concrete. Tension release puts concrete under COMPRESSIVE Stress Concrete is much stronger under compression.

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ENGR-45_Lec-28_Composites.ppt 9 Bruce Mayer, PE Engineering-45: Materials of Engineering Composite Survey – Particle-II Composite Material Elastic Modulus, E c Two Rule of Mixtures Approximations Data: Cu matrix w/tungsten particles vol% tungsten E(GPa) lower limit: 1 E c V m E m V p E p cmm upper limit: E VE V p E p (Cu) (W) rule of mixtures Particle-reinforced Fiber-reinforcedStructural Rule-of-Mixtures Applies to Other Properties Electrical conductivity, σ elect : Replace E by σ elect Thermal conductivity, k: Replace E by k. Springs in PARALLEL Springs in SERIES

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ENGR-45_Lec-28_Composites.ppt 10 Bruce Mayer, PE Engineering-45: Materials of Engineering Composite Survey: Fiber-I Fibers very strong Provide significant strength improvement compared to pure matrix-material Example: fiber-glass Continuous glass filaments in a polymer matrix Strength due to fibers Polymer simply holds them in place

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ENGR-45_Lec-28_Composites.ppt 11 Bruce Mayer, PE Engineering-45: Materials of Engineering Fiber Materials Whiskers - Thin single crystals - large length to diameter ratio graphite, SiN, SiC high crystal perfection – extremely strong, strongest known very expensive Traditional Fibers polycrystalline or amorphous Generally polymers or ceramics Ex: Al 2 O 3, Aramid, E-glass, Boron, UHMWPE

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ENGR-45_Lec-28_Composites.ppt 12 Bruce Mayer, PE Engineering-45: Materials of Engineering Composite Survey: Fiber-II Fiber Materials Whiskers - Thin single crystals with large length to diameter ratio –graphite, SiN, SiC –high crystal perfection – extremely strong, strongest physical form known –very expensive to produce Particle-reinforced Fiber-reinforcedStructural – Fibers polycrystalline or amorphous generally polymers or ceramics Ex: Al 2 O 3, Aramid, E-glass, Boron, UHMWPE – Wires Metal – steel, Mo, W

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ENGR-45_Lec-28_Composites.ppt 13 Bruce Mayer, PE Engineering-45: Materials of Engineering aligned continuous aligned random discontinuous Adapted from Fig. 16.8, Callister 7e. Fiber Alignment

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ENGR-45_Lec-28_Composites.ppt 14 Bruce Mayer, PE Engineering-45: Materials of Engineering ISOstress & ISOstrain isoSTRAIN Tensile strength and elastic modulus when fibers are parallel to the direction of stress isoSTRESS Tensile strength and elastic modulus when fibers are perpendicular to the direction of stress

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ENGR-45_Lec-28_Composites.ppt 15 Bruce Mayer, PE Engineering-45: Materials of Engineering Composite Survey – Fiber-I ALIGNED, CONTINUOUS Fibers Examples Fiber-reinforced Particle-reinforcedStructural Metal: (Ni 3 Al)- (Mo) by eutectic solidification. From W. Funk and E. Blank, Creep deformation of Ni 3 Al-Mo in-situ composites", Metall. Trans. A Vol. 19(4), pp , Used with permission. matrix: (Mo) (ductile) fibers: (Ni 3 Al) (brittle) 2 m Glass w/SiC fibers formed by glass slurry E glass = 76GPa; E SiC = 400GPa. (a) (b) From F.L. Matthews and R.L. Rawlings, Composite Materials; Engineering and Science, Reprint ed., CRC Press, Boca Raton, FL, (a) Fig. 4.22, p. 145 (photo by J. Davies); (b) Fig , p. 349 (micrograph by H.S. Kim, P.S. Rodgers, and R.D. Rawlings). Used with permission of CRC Press, Boca Raton, FL.

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ENGR-45_Lec-28_Composites.ppt 16 Bruce Mayer, PE Engineering-45: Materials of Engineering Composite Survey – Fiber-II DISCONTINUOUS, RANDOM, 2D (Planer) Fibers Fiber-reinforced Particle-reinforcedStructural Example: Carbon-Carbon Process: fiber/pitch, then burn out at up to 2500C. Uses: disk brakes, gas turbine exhaust flaps, rocket nose cones. Other variations: Discontinuous, random 3D Discontinuous, 1D –Fully Aligned Adapted from F.L. Matthews and R.L. Rawlings, Composite Materials; Engineering and Science, Reprint ed., CRC Press, Boca Raton, FL, (a) Fig. 4.24(a), p. 151; (b) Fig. 4.24(b) p (Courtesy I.J. Davies) Reproduced with permission of CRC Press, Boca Raton, FL. (b) view onto plane C fibers: very stiff verystrong C matrix: less stiff less strong (a) fibers lie in plane

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ENGR-45_Lec-28_Composites.ppt 17 Bruce Mayer, PE Engineering-45: Materials of Engineering Composite Survey – Fiber-III CRITICAL fiber length for effective stiffening & strengthening: Fiber-reinforced Particle-reinforcedStructural fiber diameter shear strength of fiber-matrix interface fiber strength in tension

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ENGR-45_Lec-28_Composites.ppt 18 Bruce Mayer, PE Engineering-45: Materials of Engineering Fiber Lengths cont. Example: FiberGlass Need Fiber Lengh > 15mm Reason for length Criteria examine Extreme cases Very Short Fiber has very little hold-in force and would PULL-OUT (Fiber PULLS OUT before Fracture) Very Long Fiber would take almost all the axial load (Fiber FRACTURES before PullOut) Shorter, thicker fiber:Longer, thinner fiber: Poorer fiber efficiency Better fiber efficiency Adapted from Fig. 16.7, Callister 6e.

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ENGR-45_Lec-28_Composites.ppt 19 Bruce Mayer, PE Engineering-45: Materials of Engineering Composite Survey – Fiber-IV Estimate E c and TS Valid for LONG Fiber Condition: Fiber-reinforced Particle-reinforcedStructural The Elastic Modulus in Fiber Direction efficiency factor Typical Values for K: Aligned 1D: K = 1 (anisotropic) Random 2D: K = 3/8 2D isotropy) Random 3D: K = 1/5 (3D isotropy) TS in fiber direction (1D, Aligned) by VOLUME Weighted Average

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ENGR-45_Lec-28_Composites.ppt 20 Bruce Mayer, PE Engineering-45: Materials of Engineering Composite Survey – Structural Stacked and bonded fiber-reinforced sheets Orthogonal stacking sequence: e.g., 0°/90° benefit: balanced, in-plane stiffness Sandwich panels low density, honeycomb core benefit: small weight, large bending stiffness Structural Fiber-reinforcedParticle-reinforced honeycomb adhesive layer face sheet Similar to Composite Beam Lab Exercise

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ENGR-45_Lec-28_Composites.ppt 21 Bruce Mayer, PE Engineering-45: Materials of Engineering Composite Benefits Ceramic Matrix Composites Better FRACTURE TOUGHNESS fiber-reinf un-reinf particle-reinf Force Benddisplacement Metal Matrix Composites Improved CREEP RESISTANCE

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ENGR-45_Lec-28_Composites.ppt 22 Bruce Mayer, PE Engineering-45: Materials of Engineering Composite Benefits cont.1 Polymer Matrix Composites Better E:ρ (Stiffness:Weight) ratio E(GPa) G=3E8 K=E Density, [Mg/m 3 ] metal/ metal alloys polymers PMCs ceramics

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ENGR-45_Lec-28_Composites.ppt 23 Bruce Mayer, PE Engineering-45: Materials of Engineering Specific Strength The PRIMARY Motivation for the Use of Composites Hi-Strength, Hi-Stiffness & Lo-Weight Thus Two Important Metrics Specific STRENGTH Similarly The Specific STIFFNESS Now Specific Weight Where –ρ Density in kg/m 3 –g Acceleration of Gravity (9.81 m/s 2 )

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ENGR-45_Lec-28_Composites.ppt 24 Bruce Mayer, PE Engineering-45: Materials of Engineering Specific Strength cont.1 Now Determine Units for S σ and S E by Way of Examples For 7075 Al in the Heat treated State – u = 83 ksi – = lb/in 3 For Kevlar-49 (Aramid Fiber) –E = 131 GPa –ρ = 1444 kg/m 3 Find Now Specific Stiffness

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ENGR-45_Lec-28_Composites.ppt 25 Bruce Mayer, PE Engineering-45: Materials of Engineering

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ENGR-45_Lec-28_Composites.ppt 26 Bruce Mayer, PE Engineering-45: Materials of Engineering S σ vs S E Comparison The High DENSITY of Metal Reduces S σ and S E The Low STRENGTH & STIFFNESS of most Polymers Reduces S σ and S E

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ENGR-45_Lec-28_Composites.ppt 27 Bruce Mayer, PE Engineering-45: Materials of Engineering Summary – Composite Matls Composites Classified by: The Matrix Material –Ceramic (CMC) –Metal (MMC) –PolyMer (PMC) ReInforcement Geometry –Particles –Fibers –Layers

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ENGR-45_Lec-28_Composites.ppt 28 Bruce Mayer, PE Engineering-45: Materials of Engineering Summary – Composites cont.1 Composites enhance matrix properties: MMC: enhance y, TS, creep performance CMC: enhance K c PMC: enhance E, y, TS, creep resistance Particle ReInforced Elastic modulus can be estimated by the Rule of Mixtures Properties are isotropic

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ENGR-45_Lec-28_Composites.ppt 29 Bruce Mayer, PE Engineering-45: Materials of Engineering Summary – Composites cont.2 Fiber ReInforced: Elastic modulus and TS can be estimated along fiber direction By Rule of Mixtures Properties can be isotropic or anisotropic Structural: Based on build-up of sandwiches in layered form –Plys –HoneyCombs

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ENGR-45_Lec-28_Composites.ppt 30 Bruce Mayer, PE Engineering-45: Materials of Engineering WhiteBoard Work Prob Given IsoStrain, Longitudinal Loading for a Continuous Fiber Composite: Then Show Where –F Force –E Elastic Modulus –V Volume fraction –Sub-f fiber –Sub-m matrix –Sub-c composite

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ENGR-45_Lec-28_Composites.ppt 31 Bruce Mayer, PE Engineering-45: Materials of Engineering Bruce Mayer, PE Licensed Electrical & Mechanical Engineer Chabot Engineering Appendix E-glass

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ENGR-45_Lec-28_Composites.ppt 32 Bruce Mayer, PE Engineering-45: Materials of Engineering E Glass - BackGround eID=764 eID=764 Background E-Glass or electrical grade glass was originally developed for stand off insulators for electrical wiring. It was later found to have excellent fibre forming capabilities and is now used almost exclusively as the reinforcing phase in the material commonly known as fibreglass.

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ENGR-45_Lec-28_Composites.ppt 33 Bruce Mayer, PE Engineering-45: Materials of Engineering E Glass - Composition Composition E-Glass is a low alkali glass with a typical nominal composition of SiO 2 54wt%, Al 2 O 3 14wt%, CaO+MgO 22wt%, B 2 O 3 10wt% and Na 2 O+K 2 O less then 2wt%. Some other materials may also be present at impurity levels.

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ENGR-45_Lec-28_Composites.ppt 34 Bruce Mayer, PE Engineering-45: Materials of Engineering E Glass – Key Properties Properties that have made E-glass so popular in fibreglass and other glass fibre reinforced composite include: Low cost High production rates High strength, (see table on next slide) High stiffness Relatively low density Non-flammable Resistant to heat Good chemical resistance Relatively insensitive to moisture Able to maintain strength properties over a wide range of conditions Good electrical insulation

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ENGR-45_Lec-28_Composites.ppt 35 Bruce Mayer, PE Engineering-45: Materials of Engineering E Glass – Fibre Strength Table 1. Comparison of typical properties for some common fibres.

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ENGR-45_Lec-28_Composites.ppt 36 Bruce Mayer, PE Engineering-45: Materials of Engineering E Glass – Use in Composites The use of E-Glass as the reinforcement material in polymer matrix composites is extremely common. Optimal strength properties are gained when straight, continuous fibres are aligned parallel in a single direction. To promote strength in other directions, laminate structures can be constructed, with continuous fibres aligned in other directions. Such structures are used in storage tanks and the like. Random direction matts and woven fabrics are also commonly used for the production of composite panels, surfboards and other similar devices.

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