材导module7-3-2015-201648h-print_W

1、1Advantages of GRPs1. Good balance （均衡）of properties high corrosion resistance strength and stiffnesso 20-40% fiber loading: double the strength and stiffness of the plastic resin used aloneo Continuous fiber: increase these properties fourfold creep rate, thermal expansion impact strength heat-defl

2、ection temps. (operating temps., or resistance to high temps.) dimensional stability (resistance to humidity environments)Polymer matrix composites (PMCs) and glass-reinforced plastics (GRPs)GRPs玻璃纤维增强塑料 The earliest and the most widely used fiber- resin composites Accounts for three-fourths of tota

3、l fiber- reinforced composite production Reinforcement: glass fibers in various forms Matrix: thermosetting or thermoplastic resin Production: no need for high curing temps. or pressures7.4.2 Types of compositesv Polymer matrix composites (PMCs) and glass-reinforced plastics (GRPs)v Carbon-carbon co

4、mposites碳碳复合材料 v Laminar composites叠层复合材料 v Sandwich composites夹层(芯)复合材料 v Particulate (particle) composites颗粒复合材料 v Hybrid composites混杂复合材料 Table of Contents7.1 IntroductionToday7.2 Constituents of fiber-7.4.2 Types of composites 6 typical compositesreinforced composites7.5 Composite processing7.3

5、Fiber types, structure7.5.1 Contact molding, openand propertiesmolding, and lamination7.4 Composite types,molding processesstructures & properties7.5.2 Closed molding7.5 Composite processing7.5.3 Filament winding andtape winding7.5.4 PultrusionTable of ContentsLast time7.1 Introduction7.3.2 Fiber pr

6、operties7.3.2.1 Fiber strength7.2 Constituents of fiber-7.3.2.2 Specific tensile strengthreinforced composites7.3.2.3 Specific stiffness-specific7.3 Fiber types, structuremodulusand properties7.3.2.4 Fiber loading7.3.2.5 Fiber orientation7.4 Composite types,7.4 Structure andproperties structures & p

7、ropertiesof Composite7.5 Composite processingRule of mixturesToughness and impact strength Fire ResistanceModule 7 Composite materialsJing ZhaoAdvantages overweigh disadvantages2Laminar composites叠层复合材料 Consist of layers (laminaFiber lamina 5lAminE 薄层) of at leastlaminate two different solid materia

8、lsbonded togetherMatrix Lamination allows the use of thebest properties of each layer to achieve a more useful material. Fiber-reinforced composite made up of layers of tape, fabric, or matApplications of C-C composites(continued)3. Sensor传感器 * To eliminate the need for embedding of conventional sen

9、sors in aircraft parts4. Fuel cells燃料电池 * To replace graphite electrodes石墨电极 * Light carbon composite electrode (2mm thick) with good electrical conductivity and low permeability (磁导率)Applications of C-C composites1. Aerospace & aircraft industries Nose cones （尖锥） & leading edges of space vehicles s

10、ubjected to very high temperatures (3000C)2. Auto industries Brake discs 刹车片 in racing carsCarbon-carbon composites碳碳复合材料 Characteristics1. Light weight (density: 1.3g/cm3)2. Stronger at high temps. than at low temps.3. High specific strength比强度 4. Good resistance to thermal shock耐热冲击性 5. Self-lubri

11、cating自润滑 6. Electrical properties7. Limitation: oxidation, limits the high temperature applications Solution: SiC coatingDisadvantages of GRPs1. Degree of environmental degradation Composite either component material alone Due to two-phase structures2. Residual stress & electrochemical effects Due

12、to two dissimilar materials3. Diffusion of fiber into matrix4. Thermally induced stresses Due to variation in the thermal expansion of these two materials Consequences: warping, plastic deformation, Advantages overweigh disadvantages Advantages of GRPs(continued)2. Ease of processing no need for hig

13、h curing temp. or pressures better conformability with existing metal fabrication techniques3. Low cost a multitude of (大量) uses in structural , industrial, and consumer-related products ranging in size from minute circuit boards to boat hullsSandwich (stressed-skin) composites夹层(芯)复合材料 (continued)H

14、exagonal cells Honeycomb possesses isotropic properties. It is less sensitive to temp. changes & environmental degradation than foam materials. Very light: 30% weight saving Easy to form Simple to install 100% recyclable Fabricated sandwich panel 3Aluminum honeycomb materialFace sheethoneycombSandwi

15、ch (stressed-skin) composites夹层(芯)复合材料 (continued)1. Facing materials面材 aluminum, wood, vinyl, paper, glass- reinforced plastics, stainless steel2. Core materials芯材 all families of materials in cellular form configurations构造: honeycomb蜂窝状corrugated 波纹状 waffle华夫饼状tubes管状 cones锥状 Sandwich (stressed-sk

16、in) composites夹层(芯)复合材料 Special laminar composites Function: to achieve high strength with less weight, specially a highstrength-to-weight ratio or specific strength composition1. outer surfaces or facings 5feisiN 面层 some material higher in density2. the inner material or core 芯材 some material lower

17、 in density supports the facings provide the greatest strength & stiffnessExamples of laminar composites (continued)2. Safety glass A laminated glass A layer of poly (vinyl butyral) bonded between two layers of glasspoly(vinyl butyral) (聚乙基丁缩醛) tough but weak in scratchGlassresistance brittle and da

18、ngerous contribute its toughness protect the plastic from scratching gives stiffness Safety glass with stiffness & toughness Examples of laminar composites1. Plywood 胶合板 The layers of wood bonded with a thermoset resin the longitudinal direction is at right angles in adjacent plies Isotropic propert

19、ies in the plane of each sheet3 ply5 ply三合板五合板 Grain directionLaminar composites叠层 The fiber orientation runs at different angles (e.g.:0, 45, 90 )Crossplied 交叉叠放 quasi-isotropic准各向同性的 Unidirectional单向性Anisotropic各向异性的 0 0 0 0 0 00 90+45-45-45+4590 04Occurrence of Curing1. at room temperature contac

20、t molding 表面模塑2. by the application of heat and/or pressure usingAutoclaves (热压罐) vaccuum bags液压 pressure bagsconventional metal stamping冲压 machinery7.5 Composite processingTwo stages involved:1. Layup 铺叠 or combining of the reinforcement and matrix materials2. Molding模塑 or curing固化 stage Curing The

21、 drying or polymerization of the resinous matrix to form a permanent bond between the fibers and the matrix materialTypes of hybrid composites (continued)3. Interply/intraply层间/层内混杂 The plyies of interply/intraply hybrides stacked in a specific sequence4. Superhybrids超混杂aluminum Resin-matrix-composi

22、te plies and metal-matrix-composite plies stacked in a specific sequencearamid/epoxyTypes of hybrid composites: 4 typesglass1. Interply层间混杂 plies from two or more different unidirectional composites stacked in aspecific sequencegraphite2. Intraply层内混杂 two or more different fibers mixed in the same p

23、lyHybrid composites混杂复合材料 combine two or more different fibers in a common matrix matrix: thermoset or thermoplastic fiber: continuous and chopped greatly expand the range of properties that can be achieved with advanced composites cost less than materials reinforced only with graphite or boronParti

24、culate (Particle) composites颗粒复合材料 * Contain reinforcing particles of one or more materials suspended in a matrix of different material.* A reinforcing particle can be defined as having all its dimensions nearly equal. Metallic or nonmetallic, do not chemically combine with the metallic or nonmetall

25、ic matrix material.* Factors affect the properties of particulate composites The size, shape, and spacing of particles, their volume fraction, and their distribution all contribute to the properties of these materials5Compression molding 模压成型 (matched die molding)A matched mold, open & Sheet molding

26、close during each molding compound SMCcycleTooling cost determining factor, complex equipment, Charge materials坯料 Molding compounds, SMCsBulk moldingor BMCscompound BMC Pressures : 1.72MPa Temperature: 120CSMCs片状模塑料BMCs块状模塑料 Closed molding processes闭式压模成型 Use a mold that consists of two sections tha

27、t open and close during each molding cycle Types1. Compression molding模压成型(matched die molding)2. Injection molding注射模塑 3. Resin transfer molding树脂转移模塑 Spray-up喷射成型 Reduces layup timeFiber chopper Resin lines Spray liquid resin andchopped fibersContinuous simultaneously onto anstrand fibers open mol

28、d To build up successiveSpray gunlaminations Single, open moldOpen mold Spray gun (喷枪)Contact moldingHand layup手工涂敷 The simplest, oldest, most labor-intensive method1. Apply the mold releasing agent 脱模剂 Five steps involved: 2.Apply the thin gel coating 胶 衣 Glass reinforcement Hand 3.Application of t

29、he dry fiber reinforcement Moldand impregnation of 浸润 the fiber withroller resin through the use of hand rolling Layers are built up to the desired thicknessresinprepregs 5pri:pre 预浸料坯 may be used4. Curing at room temperature Contact molding 表面模塑: The form of curing固化 without the application of heat

30、5. Removal of the fully hardened part from the moldOpen-mold processes敞口模塑加工 v Use a single-mold surface to produce laminated FRP structuresv Types Differ mainly in the manner in which the laminations are applied to the mold1. Hand layup手工涂敷 2. Spray-up喷射成型 3. bag molding 袋塑成型 4. Automated tape-layi

31、ng自动叠带成型 v Mold materials: plaster, GFRP, etc.v Applied to low-volume productsTypes of molding processes1. Open-mold processes敞口模塑加工 2. Closed molding processes闭式压模成型 6Compression molding vs injection molding Compression molding compared to injection molding Uses simplified tools Accommodates high f

32、iber volume fractions and long fiber lengths Makes parts with better physical and mechanical propertiesq Longer cycle time (1 to several min. compared to less than 1 min.)Injection molding 注射模塑 Molten thermoplastic (TP) , and thermosetting (TS) matrix materials are formed into a closed mold and held

33、 until the materials solidify1. Filler, reinforcing agents, other additives reduced to powder or granular form arefeed into the injection machine from a hopper2. It takes longer to mold and cure a TS than a TP3. Suitable for high production of TP partsInjection molding 注射模塑 CavityHopperGranulesScrew

34、ramHydraulicHeaterscylinder formold clamp and openingMovable half of moldTypes of injectionmachinesStationary half of mold 1. Plunger活塞 2. Reciprocating screwCompression molding- Applications模压成型 Products with complex three-dimensional shapes Parts制件 with large surface areas Good finish on all surfa

35、ces High production rates are involved with smaller tolerances Compression-molded SMC composites find many uses in the automobile industry High-strength automobile road wheels, SMC 50 polyester compositeCompression molding- Features模压成型 Simplified tools Accommodate high fiber volumefractions & long

36、fiber lengthsfinished parts with better physical & mechanical properties Mass-produce high-strength parts limited in size by the press equipment High production rates involved with smaller tolerances Good finish on all surfaces表面光洁 Compression molding-steps involved模压成型 1. Fiber reinforcement,Sheet

37、moldingpreform positioned in acompound SMCopen mold 2. Resin poured on top3. Mold closed4. Pressure is applied5. Material is heated To cause cross-linkingBulk molding6. Mold openedcompound BMCcharge 坯料 resin + chopped fibers (filler: CaCO3)7FabricszxyResin transfer molding (RTM)树脂转移模塑 1. The dry rei

38、nforcement, cut and shaped, is first placed in a mold cavity2. Mold closed3. The resin is added to wet out the reinforcement and eliminate air trappedin pores or voids in the preform型坯 4. Resin curedResin transfer molding (RTM)树脂转移模塑 PumpDry reinforcementVent and vacuumCatalyzed Resin混好固化剂的树脂 Struct

39、ural reaction injection molding(SRIM)结构反应注射成型 RIM used to encapsulate包裹 an insert or core, when the core is made of fiberglass, the process is called SRIM. SRIM resin is rapidly introduced into themold and reacts quickly to cure fully within a few minutes It requires the wet out of the preform型坯 to

40、occur rapidlyReinforced reaction injection molding(RRIM)增强反应注射成型 v Reinforcement in the form of very short fibers (chopped fibers: 100mm in Length) or particulate are added to the mold, the mold is closed and the resin is injected into it in a processv Reinforcement used with TS resins1. Glass fille

41、r (microspheres微球, hollow & solid)2. Mineral fillers: clay, talc, mica3. Metallic powders4. Fibers: glass, aramid, carbonv Applications: Carbon and glass hybrid composite Glass-reinforced PA radiator tanks for automotive radiators 汽车的散热器 Reaction injection molding (RIM)反应注射成型 1. Two or more TS monom

42、ers are forced into a impingement (mixing) chamber.2. The mixture is injected into a mold cavity and begin to polymerize or cross-link (1min).3. Polyurethane: commonly used resin system, two components: polyol 多醇 & isocyanate 二（多）异 酸酯 Reaction: the use of TS polymers which polymerize (cross- link or

43、 cure)8Wind angle (a) 缠绕角 An angle measured between the axis of the mandrel and the lay of the filaments. the circumference of the mandrel tana =the pitch of the filamentsHoop directionCircumference周向 (环向)sE5kQmfErEns Axial direction轴向a圆周 axispitchfilament单丝 螺距 mandrel芯模 Filament winding单丝缠绕成型 Speci

44、al machines toHelical windingwind the glass reinforcement around a mandrel (芯模) continuous glass strand纤维束 or filament单丝Circumferential windingis passed through a resin bath prior to winding onto a revolving mandrelPolar windingResin transfer molding (RTM) Advantages 树脂转移模塑优点 Allows the precise cont

45、rol of the fiber reinforcement in high concentrations Capable of producing large, integrated sections with complex geometries Both long and short fibers used Low-cost E-glass fibers, mats, woven fabrics A variety of resins usedVariations of RTM Pertain to (有关) the application of a pressure different

46、ial on the resin flow into the mold1. High-speed resin transfer molding (HSRTM)2. Flexible resin transfer molding (FRTM)3. Continuous resin transfer molding (CRTM)4. Vacuum resin transfer molding (VARTM)RTM equipment and productPreform Structures9Pultrusion equipmentsPultrusion shapes and MoldsUsed

47、to produce beams, channels, and pipes Graphite-reinforced, epoxy composite T-beam7.5.4 Pultrusion 拉挤成型 Preform diePullers成型模具牵引器 Fiber creel纤维轴架 Cure dieResin tank固化模具树脂浴 Pull a fiber or a bundle of continuous filaments through a resin system for impregnation As the fiber/resin bundle travels through the curing die, polymerization occurs A composite structure emerges fr