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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 11 Composite Materials PowerPoint Presentation to accompany
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Chapter 11
Composite Materials
PowerPoint Presentation to accompany
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CO 11
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Figure 11.1a
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Figure 11.1b
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Fibers for reinforce plastic composite materials
1.Glass fibers for reinforcing plastic resins
-High strength to weight ratio
-Good dimensional stability
-Good resistance to heat, cold, moisture, and corrosion
-Good electrical insulation properties
-Ease of fabrication
-Relatively low cost
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Fibers for reinforce plastic composite materials
E-glass (electrical) most commonly used glass.
(lime-aluminum borosilicate glass with zero or low Na and K
level)
Tensile strength 500 ksi (3.4 GPa)
E = 10.5 Msi (72.3 GPa)
S-glass (high strength) higher strength to weight ratio and more
expensive. Used for military and aerospace applications.
Tensile strength 650 ksi (4.5 GPa)
E = 12.4 Msi (85.4 GPa)
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Fabrication of Glass fibers
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(a)ใยแกวทท าเปนเสนส าหรบทอ (b)ใยแกวททอเปนแผน (c)ใยแกวทมวนกนอยางตอเนอง (d)ใยแกวททอเปนผน
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(a)เสนใยททอตดตอกนเปนผน (b) แสดงผวของผนใยแกว (c) ใยแกวทตดเปนทอนๆ ท าเปนผน (d) เสนใยแกวทน าไปทอเปนผนรวมกบแผนใยแกวทท าจากใยแกวทตดเปนทอน
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Property of glass fibers
Comparing with carbon fiber and aramid fiber, Glass
fiber has lower tensile strength and tensile modulus, but More elongation. However, Cost is lowest.!
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Carbon fibers for reinforced plastics
-Light
-High strength
-Hard and high resistance to bending
Good for aerospace
Applications.
Polyacrylonitrile
Or Pitch (Precursor)
Oxidation
Reduce O2, H2, N2
in inert gas aymostphere
Crystal structure like graphite
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A tow about 6000 carbon fibers
รป แสดงภาพถายของกลมเสนใยคารบอน(tow) ประมาณ 6000 เสน
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Monomer of Kevlar (Aromatic polyamide)
Aramid fibers for reinforcing plastic resins
KEVLAR
Hydrogen bonding bonds the polymer chains together in the transverse
direction. Thus, collectively these fibers have high strength in the longitudinal direction and weak strength in the transverse direction Kevlar aramid is used for high performance composite applications where
light weight, high strength and stiffness, damage resistance and resistance to fatigue
and stress rupture are important. One special interest is that Kevlar-epoxy materials is used for various parts of the space shuttle.
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Comparison of tensile properties.
รป แสดงลกษณะของ Stress – Strain
ของเสนใยเสรมแรงแบบตางๆ
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Comparison between tensile strength and stiffness
รป แสดงความสมพนธของ tensile strength จ าเพาะ(tensile
strength / density) กบ tensile
modulus จ าเพาะ (tensile
modulus /density) ของเสนใยเสรมแรงแบบตางๆ
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Fiber-reinforced-plastic composite materials
2 of the most important plastic resins for fiber-reinforce plastics
is
1. Unsaturated polyester
2. Epoxy
Polyester resins are lower in cost but are usually not as strong as
the epoxy resins.
Boat hulls, building panels, structure panels for automobile, aircraft
and appliances
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Cross sectional of a unidirectional fiberglass polyester composite
รป แสดงภาพถายตดขวางของเสนใยแกวทอยในทศทางเดยวดนของวสดผสมเสนใยแกว - พอลเอสเทอร
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• The strength of fiber glass-reinforced plastic is mainly related
to the glass content of the materials and the arrangement of the
glass fibers.
• In general, the higher the weight percent glass in the composite, the stronger the reinforced plastic is.
• Parallel stand fiber glass stronger than woven fiber glass.
• Chopped fiber glass has lower strength but isotropy.
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Fatigue properties of carbon fiber reinforced epoxy composite materials.
รป แสดงสมบตความลา (ความเคนสงสด v.s จ านวนไซเคลจนเกดการแตกหก) ส าหรบวสดผสมของเสนใยคารบอน – อพอกซทเปนการจดแบบทศทางเดยว โดยเปรยบเทยบกบสมบตความลาของวสดผสมอนๆบางชนด และดลหะผสมอะลมเนยม 2024-T3. R
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Unidirectional and multi directional laminate plies for a composite laminate
รป แสดงการประกอบของแผนลามเนตทเปนทศทางเดยวกน และหลายทศทางส าหรบวสดผสมลามเนต
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Five-layer bidirectional composite of carbon fiber-epoxy composite materials
รป แสดงภาพถายวสดผสมทประกอบดวย 5 ชนในสองทศทางของเสนใยคารบอน-อพอกซ
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Equation for elastic modulus of a lamellar continuous-fiber-plastic matrix composite.
Isostrain
Ec = EfVf + EmVm
For finding elastic
modulus of composite
materials
รป แสดงโครงสรางของวดสทประกอบดวยชนของเสนใย และเมทรกซ (matrix layer) ภายใตสภาวะความเครยดเทากน (ปรมาตรของวสดผสม Ve = area Ae x ความยาว Le)
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Isostress condition
รป แสดงโครงสรางของวดสทประกอบดวยชนของเสนใย และเมทรกซ (matrix layer) ภายใตสภาวะความเคนเทากน (ปรมาตรของวสดผสม Vc = area Ac x ความยาว Lc)
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Figure 11.16 เปนกราฟทแสดงของ tensile elastic modulus ทเปนฟงกชนกบเศษสวนของปรมาตรของเสนใยในพลาสตกเมทรกซเสรมแรงดวยเสนใยทอยในทศทางเดยวกนของวสดผสมลามเนต ภายใตสภาวะความเครยดเทากนและความเคนเทากน ส าหรบเศษสวนโดยปรมาตรเสนใยทก าหนดใหทสภาวะความเครยดเทากน คา modulus
สงกวา
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Open mold processes for fiber-reinforced plastic composite materials
Hand Lay-up process
รป แสดงวธการท าดวยมอโดยการเอาวสดผสมพลาสตกเสรมแรงดวยเสนใยวางลงไปกบแบบ (a) เทเรซนลงในแบบ
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Use of a roller to densify the laminate to remove the entrapped air
รป แสดงวธการท าดวยมอโดยการเอาวสดผสมพลาสตกเสรมแรงดวยเสนใยวางลงไปกบแบบ (b) .ใชลกกลงๆ ไปใหทวแผนลามเนต ใหหนาตามตองการ และไลอากาศออก
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Spray-up method for molding fiber-reinforced-plastic
composite materials
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This process is used to produced high-performance laminates usually of fiber-reinforce-epoxy systems.
Process: 1. lay out a long and wide thin sheet on a table.
2. pieces of the prepreg are cut out and placed on top of each other on a shape tool to form a laminate.
3. after the laminate is constructed, the tooling and the attached laminate are vacuum-bagged, removing of entrapped air from the laminate part.
4. vacuum bag enclosing the laminate and the tooling is put into an autoclave for the final curing of the epoxy resin.
(for example, carbon-fiber-epoxy composite material is usually heated at about 190deg at a pressure of about 100 psi.
5. after removed from the autoclave, the composite part is stripped from its tooling and is ready for further finishing operations.
Vacuum Bag-Autoclave Process
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Carbon-fiber-epoxy prepreg sheet being cut
รป แสดงการเตรยมแผนอพอกซเสรมเสนใยคารบอน ซงจะถกดดดวยเครองตดทควบคมดวยคอมพวเตอรทบรษท Mc.
Donal Douglas.
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Tooling
รป แสดงเครองมอเพอใชเปนแบบท าลามเนตหลายๆชนของวสดผสมพลาสตกเสรมแรงดวยเสนใยทมโครงสรางโคงๆ และมผวเรยบ
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Autoclave
รป แสดงสวนของปกเครองบน AV-8B ซงลามเนตดวยอพอกซเสรมเสนใยคารบอน และน าเขาบมในเครองออโตเคลบทโรงงานผลตเครองบนของบรษท McDonell
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Figure 11.22 แสดงกระบวนการปนเสนใยส าหรบท าวสดผสมพลาสตกเสรมดวยเสนใย เรมตนการท าใหเสนใยเปยกชมดวยพลาสตกเรซน แลวพนรอบแกน(mandrel) โดยเสนใยจะออกมาจากหวลอหมน(Carriage) เคลอนทไปมาเพอปเสนใยลงทmandrel
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Rolling of KEVLAR 49 and Epoxy Resin
รป แสดงการมวนเวนใย Kevlar 49 และอพอกซทใชท าถงบรรจมอเตอรจรวด
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• 1.Compression and Injection molding
• 2. Sheet Molding Compound (SMC)
New process for automobile parts…
Good for large amount and large dimension.
Close mold processes for fiber-reinforced
plastic composite materials
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Sheet Molding Compound (SMC)
mandrel
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Figure 11.25
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Continuous Pultrusion Process
This process is used in fabrication shape of constant dimension or
beam. Product has high strength because of large number of fiber
and longitudinal parallel direction of fibers.
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• Ease for design
• Castable
• Low cost
• Durable
• Low tensile strength
• Low ductility
Concrete; ceramic composite.
Portland+water+air+fine mat+ coarse mat
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Fabrication process of portland cement;
Lime (Cao) Silica(SiO2) Alumina (Al2O3) and Fe2O3
Heat at 1400-1650ºC in Rotary kiln Cement clinker
Cement clinker + Gypsum
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Concrete:
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Solidification of portland cement
Hydration reaction of tricalcium silicateand dicalcium silicate
2C3S + 6H2O C3S2·3H2O + 3Ca(OH)2 fast
2C2S + 4H2O C3S2·3H2O + Ca(OH)2 slow
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Figure 11.29
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Figure 11.30
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Figure 11.31
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Figure 11.32
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Reinforced and prestressed concrete
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Figure 11.34
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• Hydrocarbon materials
• Mechanical property like thermoplastic
• C 80-86%, H2 9-10%, O2 2-8%, S 0.5-7%, N
• Used with aggregates Asphalt mix
Bitumen
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Timber : Natural composite materials between
Cellulose and Lignin (polymer)
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• ไมเนอออน ตนไมทมองเหนเมลด หรอ เมลดแยกออกมา เขยวตลอดป เฟอร ตนสน ไมยาง มะมวง ฉ าฉา มะยม • ไมเนอแขง เมลดถกหอหม ผลดใบ โอก เมเปล เชอร ไมสก ประด แดง มะคา เตง ชงชง
Softwoods and Hard woods
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Annual growth rings
Only in soft woods
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Axes of symmetry for wood
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Microstructure of Softwoods
Tracheids and Lumen
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Microstructure of Hardwoods
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Figure 11.40
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Figure 11.41
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Figure 11.42
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Figure 11.43
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Figure 11.44
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Figure 11.45
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Figure 11.46a
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Figure 11.46b
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Figure 11.47a
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Figure 11.47b
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Figure EP11.6
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Figure 11.48
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Figure EP11.8
