Composite Materials and their Properties. Ing. Bohuslav Cabrnoch, Ph.D. VZLÚ, a.s.

Transcription

1 Composite Materials and their Properties Ing. Bohuslav Cabrnoch, Ph.D. VZLÚ, a.s.

2 Composite material Introduction Material made from two or more constituent materials with significantly different physical or chemical properties that, when combined, produce a material with characteristics different from the individual components. Reinforcement Matrix Fibers short, long, continuous Short l/d = (fiber dia. 10 mm l = 0,5 5 mm) Long l/d 500, usually l = mm Load transfer Bind the reinforcement in place Distribute the stresses among the reinforcement Protect the reinforcement against external influence Determine electric and chemical properties Provide interlaminar strength

3 Introduction Fillers Fillers are inert substances added to reduce the resin cost and/or improve its physical properties Hardness, stiffness or impact strength Additives Low shrink Fire resistance Ultraviolet Stabilisers Electrical conductivity

4 Introduction Why composite materials? Specific strength R m /r Specific stiffness E/r Fatigue resistance Corrosion and chemical resistance Complex shapes Costs Electric properties Thermal properties Composites have directional tailoring capabilities to meet the design requirements. The fibre pattern can be laid in a manner that will tailor the structure to efficiently sustain the applied loads.

5 Specific Strength [MPa.cm 3 /g] Specific strength and stiffness 250 Introduction C-IM/E 60% 200 C-HS/E 60% G-S/E 60% G-E/E 60% A-49/E 60% A-149/E 60% C-HM/E 60% C-UHM/E 60% T6 0 Ti6Al4V 2090-T83 (Li) L-ROL T4 Specific Stiffness [GPa.cm 3 /g]

6 Classification of Composites Introduction Composites Fiber Particulate Single-layered Sandwich Multi-layered Laminate Continual Discontinuous Unidirectional Multidirectional Randomly oriented Oriented

7 Reinforcing Fibers Glass (E, S, D) Quartz Basalt Carbon (HS, IM, HM, UHM) Polymeric (aramid, UHMW PE) Boron (B W, B C ) Ceramic (SiC, Al 2 O 3 ) Metallic (Stainless steel, W, Mo) Reinforcing Fibers

8 Reinforcing Fibers Glass Fibers E-glass S-glass D-glass Quartz Most widespread Higher strength and stiffness Manufacturing of radomes Silica glass Manufacturing of radomes

9 Carbon / Graphite Fibers Reinforcing Fibers Carbon fibers poly-acrylo-nitrile (PAN) based fiber consist of 91 to 94% carbon carbonization about C Graphite fibers PAN or pitch based fiber consist over 99% carbon graphitisation at to C

10 Carbon / Graphite Fibers HS (HT, HTA) High Strength Reinforcing Fibers Elongation at fraction about 2,0% Tensile modulus about 240 GPa IM (AM) Intermediate Modulus Low elongation at fraction about 2,0% Tensile modulus about 300 GPa HM High Modulus Elongation at fraction about 1,0% Tensile modulus about 450 GPa UHM (VHM) Ultra High Modulus Pitch-based Low elongation at fraction about 0,4% Tensile modulus up to 935 GPa

11 Reinforcing Fibers Polymeric Fibers Aramid Aromatic polyamide, aramid, APA Kevlar, Twaron Moisture uptake Sensitive to UV UHMW PE Ultra high molecular weight PE Dyneema, Spectra Low density (r = 970 kg/m 3 ) Chemical resistance General properties High toughness (Impactresistant) High wear resistance Difficult machining Low compression strength Bullet proof vests Armouring

12 Reinforcing Fibers Boron Fibers Boron is deposited on tungsten or carbon substrate High fiber diameter about 100 mm Higher strength in compression than in tension Structures loaded by compression

13 Ceramic Fibers General properties Reinforcing Fibers High density kg/m 3 Excellent temperature resistance C Very good chemical resistance Silicon Carbide (SiC) Manufacturing Silicon Carbide is deposited on tungsten or carbon substrate high fiber diameter about 140 mm Metallic, ceramic or carbon matrix Aluminium oxide (Al 2 O 3 ) Fiber dia. about mm Dielectric (Radom)

14 Reinforcing Fibers Comparison of reinforcing fiber properties E glass S glass D glass Quartz HS carbon IM carbon HM carbon UHM carbon Kevlar 49 Kevlar 149 UHMW PE Boron SiC Al 2 O 3 Diameter [mm] Density [g/cm 3 ] Tensile Modulus [GPa] Tensile Strength [GPa] 2,54 2,48 2,16 2,20 1,78 1,8 2,1 2,2 1,44 1,47 0,97 2,59 3,04 3, ,4 4,4 2,5 3,4 4,4 5,6 3,6 3,8 3,6 3,4 2,7 3,6 3,45 1,9 Cost [$/kg]

15 Reinforcement forms Reinforcing Fibers Filament Strand An assembly of simultaneously produced parallel continuous filaments, slightly bonded and without intentional twist Yarn A continuous element, directly usable for textile operation, made with either: A given number of continuous filaments (one or several strands) held together with twist A number of discontinuous filaments, held together with twist Roving A collection of parallel strands (assembled roving) or parallel continuous filaments (direct roving) assembled without intentional twist Mat Randomly oriented chopped strands (Chopped strand mat - CSM) Randomly swirled continuous strands (Continuous filament mat - CFM) Loosely held together with a binder

16 Reinforcing Fibers Reinforcement forms Braids Braid Braided sleeve Unidirectional fabric (UD) A flat structure with a great number of yarns in one direction Minimally 90% of reinforcing fibers in one direction

17 Reinforcing Fibers Reinforcement forms Fabrics Woven fabrics Roving, yarn Different weaves (plain, twill, satin) Spread Tow Fabric (STF) Stitched fabrics, Non-crimp fabric NCF Biaxial (e.g. 0 /90 ; ±45 ) Triaxial (e.g. 0 /±45 ; 90 /±45 ) Quadriaxial (e.g. 0 /90 /±45 ) Hybrid Carbon/Aramid Carbon/Glass Carbon/UHMW PE

18 Reinforcing Fibers Fabric weave styles Plain High crimp Low drapeability Plain weave Twill Average crimp Average drapeability Twill weave 2/2 Satin Low crimp Good drapeability Satin weave

19 Fiber parameters Reinforcing Fibers Cross-section of fiber yarn Tex linear density (weight per unit length, i.e. 1 g/1 km = 1 tex) and fiber density K and fiber diameter carbon fibers Fiber Sizing - K = x 1000 number of filaments in yarn (3K, 6K, 12K, 24K, 48K,...) Surface treatment of fibers for better adhesion to matrix Lower friction, improve fiber handling Protection against abrasion

20 Matrix materials Polymeric (PMC) Thermosets Thermoplastics Metallic (MMC) Al, Ti, Mg, Ni alloys Ceramic (CMC) Carbon Glass Al 2 O 3, Si 3 N 4, SiC Matrices High temperature applications Increasing of toughness and strength of ceramics Carbon-carbon composites (C-C) High temperature applications up to C Biocompatible - surgical implants High temperature applications Pursuit of low cost C-C

21 Polymeric Matrices Thermosets Unsaturated polyesters (UP) Vinyl esters (VE) Epoxy resin (EP) Phenolic resin (PF) Cyano esters (CE) Bismaleimids (BMI) Thermosetting polyimides (PI) Thermoplastics PPS (polyfenylensulfid) PEI (polyetherimide) PEEK (polyetheretherketon) Thermoplastic polyimide (PI) Matrices

22 Matrices Thermosets Thermoplastics Compression strength Excellent Good Toughness Good Excellent Damage tolerance Good Excellent Fatigue resistance Excellent Good FST parameters Good Excellent Dielectric properties Good Excellent Moisture uptake Up to 2% Max. 0,1% Manufacturing process Irreversible Reversible (recycling) Manufacturing premises Clean room Standard Processing temperature [ C] Manufacturing time [min] Storage Freezer / limited Unlimited at RT Joining Bonding, mech. joints Bonding, mech. joints, welding

23 Thermoset Matrices Unsaturated polyesters (UP) Low cost Low viscosity and versatility Lower strength than that epoxies Fair weatherability High curing shrinkage Poor chemical resistance Vinyl ester resins (VE) Matrices Inherent toughness with outstanding heat and chemical resistance Corrosion-resistance Less shrinkage during cure Epoxy resin (EP) Low shrinkage Excellent adhesive properties Good chemical resistance Good mechanical properties including toughness

24 Matrices Thermoset Matrices Phenolic resins(pf) Low cost, Low mechanical strength, Dimensional and thermal stability, Excellent FST properties Cyano esters (CE) Superior dielectric properties Low moisture absorption Superior elevated temperature properties along with excellent properties at cryogenic temperature. Bismaleimidy (BMI) Superior to epoxy in maximum hot-wet use temperature. In comparison to conventional epoxies, bismaleimides have higher temperature resistance. Thermoset polyimides (PI) Excellent strength retention for long term in C Laminates are porous Long post cure is required

25 Matrices Comparison of thermosetting matrices properties UP VE PF EP CE BMI PI Density [g/cm 3 ] 1,1-1,23 1,12-1,13 1,0-1,25 1,1-1,2 1,19-1,28 1,2-1,32 1,43-1,89 Tensile modulus [GPa] 3,1-4,6 3,1-3,3 3,0-4,0 2,6-3,8 3,3-3,7 3,5-5,0 3,1-4,9 Tensile strength [MPa] Elongation [%] 1,0-6,5 3,0-8,0 1,8 1,5-8,0 1,9-2,5 1,5-3,3 1,5-3,0 Tg [ C] Costs [$/kg] 1,1 2,2 2,6 4,4 0,9 1,2 2,

26 Matrices Thermoplastic matrices PPS (Poly-phenylen-sulphide) Low moisture uptake Excellent dimensional stability Good chemical resistance Excellent wear resistance PEI (Poly-ether-imide) Toughness Temperature resistance Good FST properties PEEK (Poly-ether-ether-keton) Excellent temperature resistance up to 315 C High toughness Excellent wear resistance Excellent FST properties Thermoplastic polyimide (PI) High temperature applications

27 Matrices Comparison of thermoplastic matrices properties PPS PEI PEEK PI Density [g/cm 3 ] 1,35 1,27 1,30 1,35 1,48 Tensile modulus [GPa] 3,8 3,3 3,5 3,6-4,1 Tensile strength [MPa] Elongation [%] ,4-6 Tg [ C] Costs [$/kg]

28 GLARE GLARE GLAss-REinforced fibre metal laminate Laminate composed of aluminium and glassfiber prepreg layers. The UD prepreg layers may be aligned in different directions Fokker Stork + Delft University + NLR Major advantages over conventional Al alloys: Better "damage tolerance" behaviour (especially impact and metal fatigue) Better corrosion resistance Better fire resistance Lower specific weight

29 Sandwiches Sandwiches Bending strength and stiffness Structural damping Thermal and acoustic insulation Facing Skins normal forces (tension, compression, bending) Core shear forces between skins Skin Flange Adhesive Core Adhesive Skin Web

30 Sandwiches Sandwich Cores Honeycomb Metallic Non-metallic Structural foam (rigid foam) Metallic Non-metallic Balsa wood Plywood Parabeam Nida-Fusion Cork Bulk materials

31 Sandwiches Honeycomb Metallic Al alloys (3003, 2024, 5052, 5056), (Hexcel, Euro-composites) Stainless steel Titanium Non-metallic Aramid paper (Nomex ), (Hexcel, Eurocomposites, Schütz) Aramid fabric Glass fabric Carbon fabric Polypropylene PP (Nida-Core)

32 Sandwiches Honeycomb Cell shape Cell size Wall thickness Poor forming Difficult machining Terminology Material directions T L = ribbon direction W = expansion direction

33 Sandwiches Honeycomb Cell Configurations Hexagonal - most common and effective Reinforced Hexagonal Rectangular (OX) - formability in single curvature Flex-core formability in compound curvatures Double Flex-core formability in compound curvatures Square

34 Structural foam (Rigid foam) Semi-product Plates / Sheets Foamed in-situ Metallic Sandwiches Al alloys (Alporas manufacturer Gleich) Non-metallic PS PUR (General Plastics, Nida core) PIR = Poly-iso-cyanurate Phenolic PF Epoxide EP PET (Airex, Nida core) PVC (DIAB, Airex) PEI (Airex R.82) PMI = Poly-methakryl-imide (Rohacell ) SAN = Styren-Acrylo-Nitril co-polymer (Corecell )

35 Sandwiches Structural Foams Lower mechanical properties than honeycombs at the same density Closed cells Mechanical properties depend on density Easy machining Thermo formable Lower costs than honeycombs (PS, PVC, PET, PUR, PIR) Thermal insulation Higher damping than honeycombs Lower moisture uptake than honeycombs

36 Sandwiches 3D CORE (Nida-Core) XPS, PET, SAN or PUR structural foam Closed cells A foam core from honeycomb shaped foam elements connected by small joints Intended for infusion technologies Formable at RT Thermo formable for higher curvatures

37 Balsa wood It is cut perpendicular to the grain direction (End-grain balsa) High compression strength Density kg/m 3 Thickness 5 76 mm Sandwiches

38 Sandwiches Parabeam 3D glass reinforcement Woven from E-glass yarn and consists of two deck layers connected by vertical yarns. The z-directional yarns, which are woven through the deck layers. As the fibers are impregnated, the fabric rises to a pre-set height. Thickness 3 22 mm

39 Nida Fusion Sandwiches Fiberglass reinforcements on each side of the foam Closed cell foam core Fiberglass roving stitched through the 3 elements, thus forming Triangulated Truss Network Intended for infusion processes Formable NidaFusion STO NidaFusion STF PUR, PIR or PF rigid foam PE or PP flexible foam

40 Sandwiches Cork Natural material Highly porous Suitable for infusion technologies Easy conformable Thermal insulation Structural damping CoreCork (Amorim) Density kg/m 3 Thickness mm

41 Sandwiches Bulk material Polyester nonwoven containing microspheres Easy conformable Good plywood replacement Thickness 1 10 mm Coremat, Soric, MatLine

42 Sandwiches Comparison of sandwich cores

43 Compression strength [MPa] Sandwiches Comparison of honeycombs and foams compression strength Pěna PMI WF Pěna PVC Pěna PEI Pěna PET 15 Alporas Pěna PUR Voština Al 3003 Voština Al Voština Al 5056 Voština sklo Pěna PS Voština Nomex Balsa Korek Density [kg/m 3 ]

44 Shear strength [MPa] Sandwiches Comparison of honeycombs and foams shear strength 7 Pěna PMI WF Pěna PVC Pěna PEI Pěna PET 6 Alporas Pěna PUR Voština Al 3003 Voština Al Voština Al 5056 Voština Nomex Voština sklo Balsa 4 Pěna PS Korek Density [kg/m 3 ]

45 Structural adhesives Epoxies Acrylics Urethanes Adhesives Hot Curing temperature C One component, Film adhesive Resistance to elevated temperatures and moisture Cold Curing at RT, optionally post-cured Two component pastes Lower mechanical properties Curing at RT Two component pastes High toughness Less sensitive to surface treatment Nasty odours Quick curing at RT Two component pastes Elastic